Abstract:
An automatic recirculation airflow damper for use in electronic enclosures utilizing multiple air moving devices to cool electronic components within the enclosure. When an air moving device is removed, the damper automatically closes an orifice associated with the absent air moving device, thus preventing the loss of cooling air from the vacated orifice and the subsequent reduction in cooling capacity. In some embodiments, the damper is attached to the enclosure with hinges. In certain embodiments, the damper is configured with elastomeric material such that the interface between the orifice and the damper offers high impedance to airflow while the damper is in a closed position. The automatic recirculation airflow damper reduces electronic thermal failures and therefore increases the reliability of a system equipped with the device.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to maintaining airflow in order to cool electronic components. Specifically, the invention relates to apparatus and systems to maintain airflow over electronic components when an air moving device is absent. 
   2. Relevant Art 
   The electronics industry is constantly striving for increased performance in electronic products. The increased performance is commonly achieved through higher and higher levels of integration, resulting in the use of components that dissipate more heat per unit volume. As the number of components increases within a given computer, the amount of heat generated by electronic components also increases. The increase in generated heat per unit volume has not been tracked by an equal reduction in power dissipation for the individual components. For example, on densely populated circuit boards, the power dissipation per unit area continues to increase. 
   Many electronic components are designed to work at relatively low temperatures. Typically, heat removal is achieved by blowing cool air over the components with a fan. Some configurations cool by creating high pressure within the enclosure, using a fan to draw cool air into the enclosure, and direct the cool air over heat transfer components as the air seeks a lower pressure exhaust orifice. Other configurations cool by creating low pressure within the enclosure using a fan to exhaust hot air, thereby drawing cool air into an inlet orifice and over heat transfer components on the way to the exhaust orifice. 
   As the number of components per printed circuit assembly has increased, the amount of heat dissipated per component has increased, and the density of printed circuit assemblies in rack mounted equipment has increased, traditional single fan cooling is no longer sufficient to effectively remove heat. Computer manufacturers have subsequently used more powerful fans and blowers and employed multiple air moving devices to create the airflow necessary to remove the heat from the electronics enclosure. 
   Typically, air moving devices have moving parts and tend to have a high duty cycle. Low-cost air moving devices are often used to reduce system cost. As a result, air moving devices often have a lower reliability than other components of a typical computer system. In addition, air moving devices often create acoustic noise, which noise tends to increase over time with wear and cause annoyance to users and maintenance personnel. 
   The aforementioned characteristics often lead to frequent replacement of the air moving devices. Since removal of an air moving device does not directly effect operation of the system, the air moving device is frequently replaced without turning off system power. Even if other air moving devices remain operational during replacement, a gap left by removing the defective air moving device often disturbs air flow and may permit cool air to escape from the enclosure without removing heat generated by the electronic components. If many air moving devices are present, some air moving devices may be removed without immediate replacement. 
   When airflow is inadequate to cool electronic components even for just a few moments, some electronic components may sense a thermal runaway condition and shutdown—resulting in risky and potentially costly system crashes. Other components may be damaged or degraded. Due to the risks associated with inadequate airflow, there is a need to maintain adequate airflow during replacement. Accordingly, there is a need for a mechanisms and systems that maintain proper airflow over heat generating components while an air moving device is absent. 
   BRIEF SUMMARY OF THE INVENTION 
   The present invention has been developed in response to the present state of the art, and in particular, in response to the problems and needs in the art that have not yet been fully solved by currently available electronic cooling systems. Accordingly, the present invention has been developed to provide an apparatus and system for automatically maintaining air flow over electronic components while one or more of a group of air moving devices is absent, thus overcoming many or all of the above-discussed shortcomings in the art. 
   In one aspect of the present invention, a device for automatically obstructing air flow through an orifice associated with an absent air moving device, includes an orifice cover and a cover actuator, the cover actuator configured to move the orifice cover from an open position to a closed position, covering the orifice, in response to removal of an associated air moving device. In certain embodiments, the orifice cover is a plate. In some embodiments, the cover actuator is a spring. In certain embodiments, the cover is attached to an enclosure wall by a hinge. In some embodiments, the cover actuator is a torsion spring. In certain embodiments, an elastomeric material is attached to the damper plate at the point where the cover interfaces with the orifice to further restrict air passage. 
   In another aspect of the present invention, a system for automatically obstructing air flow through an orifice associated with an absent air moving device, that includes an enclosure wherein cooling airflow is provided by multiple air moving devices, an orifice cover associated with each air moving device, and one or more cover actuators that position the orifice cover over the orifice at the time the associated air moving device is removed. The air moving devices are attached to the enclosure such that a mechanical interference is created between the air moving device and the orifice cover, forcing the orifice cover away from the orifice and into a vacant space. When the air moving device is removed the orifice cover automatically covers the orifice and prevents air from escaping through the orifice, thus enabling cooled air to pass over heat transfer components on the way to an exhaust orifice. 
   These and other features and advantages of the present invention will become more fully apparent from the following description and appended claims, or may be learned by the practice of the invention as set forth hereinafter. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In order that the advantages of the invention will be readily understood, a more particular description of the invention briefly described above will be rendered by reference to specific embodiments that are illustrated in the appended drawings. Understanding that these drawings depict only typical embodiments of the invention and are not therefore to be considered to be limiting of its scope, the invention will be described and explained with additional specificity and detail through the use of the accompanying drawings, in which: 
       FIG. 1  is a block diagram illustrating one embodiment of an electronic component cooling system with automatic airflow damper of the present invention, wherein one of the air moving devices has been removed; 
       FIG. 2  is a side view illustration further depicting one embodiment of the electronic component cooling system of  FIG. 1 ; 
       FIG. 3  is a front view illustration depicting one embodiment of an automatic airflow damper of the present invention; 
       FIG. 4  is a side view illustration depicting one embodiment of an actuated automatic airflow damper of the present invention; 
       FIG. 5  is a front view illustration depicting one embodiment of an actuated automatic airflow damper of the present invention; 
       FIG. 6  is a side view illustration depicting one embodiment with a motor of an actuated automatic airflow damper of the present invention; and 
       FIG. 7  is a front view illustration depicting one embodiment with a motor of an actuated automatic airflow damper of the present invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   It will be readily understood that the components of the present invention, as generally described and illustrated in the Figures herein, may be arranged and designed in a wide variety of different configurations. Thus, the following more detailed description of the embodiments of the apparatus, method, and system of the present invention, as represented in  FIGS. 1 through 5 , is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. 
   Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment and the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. 
     FIG. 1  is a block diagram illustrating one embodiment of an electronic component cooling system  100  of the present invention. The depicted embodiment includes cool air  110 , orifices  115 , orifice covers  120 , heat transfer components  130 , air moving devices  140 , cover springs  145 , a printed circuit board  150 , an enclosure  160 , an exhaust orifice  170 , and heated air  180 . The electronic component cooling system  100  automatically adjusts for the absence of an air moving device  140 . 
   In the depicted arrangement, the air-moving devices  140   a  and  140   c  draw the cool air  110  into the enclosure  160 , creating positive pressure. As the pressurized air seeks the lower pressure of the exhaust orifice  170 , cool air  110  is directed across the printed circuit board  150 . The cool air  110  removes heat from the heat transfer components  130 , and then flows through the exhaust orifice  170  as heated air  180 . 
   The orifice covers  120  are sized to cover the orifices  115  where cool air  110  is drawn into the enclosure  160  by the air moving devices  140 . In one embodiment, the orifice covers  120  are attached to the enclosure  160  by hinges (not shown). Cover springs (not shown) beneath orifice covers  120   a  and  120   c  exert torques directed to move orifice covers  120   a  and  120   c  into a closed position against orifices  115   a  and  115   c . The depicted embodiment illustrates a condition wherein the air moving devices  140   a  and  140   c  displace the orifice covers  120   a  and  120   c  into vacant spaces below air moving devices  140   a  and  140   c.    
   In the depicted arrangement, no air moving device is present at orifice  115   b  enabling cover springs  145   b  to position orifice cover  120   b  against orifice  115   b  and stop airflow through orifice  115   b . With inlet orifice  115   b  closed, positive pressure is maintained within the enclosure  160 , forcing air across the printed circuit board  150  and out the exhaust orifice  170 . If airflow was not blocked by the orifice cover  120   b , the cool air  110  would enter the enclosure through orifices  115   a  and  115   c  and directly exit the enclosure through orifice  115   b . This recirculating flow of the cool air  110  would significantly reduce the flow of cool air over the heat transfer components  130 . The recirculating flow of the cool air  110  would also significantly reduce the flow of the heated air  180  out of the exhaust orifice  170 , and thereby severely limit the ability of the cooling system  100  to remove heat from the enclosure  160 . 
     FIG. 2  is a side view illustration further depicting one embodiment of the automatic airflow damper system  100 . The illustration depicts many of the elements shown in  FIG. 1  such as the inlet orifice  115 , an air moving device  140 , an orifice cover  120 , a cover spring  145 , and an enclosure  160 . The depicted air moving device  140  may correspond to the air-moving devices  140   a  and  140   c  shown in  FIG. 1 . 
   The air moving device  140  draws cool air into the enclosure  160  through the inlet orifice  115 . The orifice cover  120  is sized to cover the inlet orifice  115  when in a vertical, closed position, a seal  150  blocking airflow between the enclosure  160  and orifice cover  120 . The cover spring  145  is attached to the enclosure  160  and the orifice cover  120 . The cover spring  145  is configured to exert a torque on the orifice cover  120  directed to rotate the orifice cover  120  about a lower edge  155  to seat against the inlet orifice  115 . The air moving device  140  is attached to the enclosure  160  such that the air moving device  140  interferes with the orifice cover  120  motion toward the inlet orifice  115 , forcing the orifice cover  120  into a vacant space beneath the air moving device  140 . The seal  150  allows the orifice cover  120  to pivot to the vacant space. 
     FIG. 3  is a front view illustrating one embodiment of an automatic airflow damper system  300 . The depicted embodiment includes an air moving device  140 , an orifice cover  120 , cover actuators  145 , and part of an enclosure wall  360 . The air moving device  140  draws cool air into an enclosure through an inlet orifice (not shown) behind the air moving device  140 . The orifice cover  120  is sized to cover the inlet orifice (not shown) behind the air moving device  140  when in a vertical, closed position. 
   The cover actuators  145  are attached to the enclosure wall  360  and the orifice cover  120 . In the depicted embodiment, the cover actuators are torsion springs. In another embodiment, the cover actuators are spring loaded pistons. In yet another embodiment, the cover actuators comprise a motor  605  as shown in  FIGS. 6 and 7 . The depicted cover actuators  145  are configured to exert a torque on the orifice cover  120 , directing rotation of the orifice cover  120  toward the inlet orifice (not shown) behind the air moving device  140 . The air moving device  140  is attached to the enclosure wall  360  such that it creates a mechanical interferes between the orifice cover  120  and the air moving device  140 , forcing the orifice cover  120  into a vacant space beneath the air moving device  140 . 
     FIG. 4  is a side view illustrating one embodiment of an actuated automatic airflow damper system  400 . The depicted embodiment includes an inlet orifice  115  as shown in  FIG. 1 , an orifice cover  120  shown in  FIG. 1 , a cover actuator  145  as illustrated in  FIG. 1 , and an enclosure  160  as shown in  FIG. 1 . An air moving device (not shown) that is normally attached to the enclosure wall adjacent to the inlet orifice  115  is absent. The orifice cover  120  is forced against the inlet orifice  115  by the torque exerted on the orifice cover  120  by the cover actuator  145 . With the orifice cover  120  covering the inlet orifice  115 , positive air pressure within the enclosure  160  cannot escape through the inlet orifice  115 . 
     FIG. 5  is a front view illustrating one embodiment of an actuated automatic airflow damper system  500 . The depicted embodiment includes a orifice cover  120  as illustrated on  FIG. 1 , cover actuators  145  as shown in  FIG. 1 , and a portion of an enclosure wall  360  as shown in  FIG. 3 . An air moving device (not shown) that is normally attached to the enclosure wall adjacent to the inlet orifice  115  is absent. 
   The orifice cover  120  is sized to cover the inlet orifice (not shown) behind the orifice cover  120 . The cover actuators  145  are attached to the enclosure wall  360  and the orifice cover  120 . The orifice cover  120  is forced against the inlet orifice (not shown) behind the damper plate  120  by the torque exerted on the orifice cover  120  by the cover actuators  145 . With the orifice cover  120  covering the inlet orifice (not shown), positive air pressure within the enclosure cannot escape through the inlet orifice  115 . 
   The present invention facilitates cooling of electronic components while an air moving devices is absent. Without the automatic recirculation airflow damper of the current invention, the orifices associated with an absent air moving devices allow cool air to escape without removing heat from the electronic components in an enclosure. This lack of heat removal may cause high dissipation electronic components to overheat, and subsequently fail prematurely. 
   The configuration of the current invention wherein a orifice cover automatically covers the orifice associated with an absent air moving device is effective in maintaining positive or negative air pressure within the enclosure, enabling the cool air to remove heat from electronic components. The current invention promotes cooling of the enclosure during the time when an air moving device is being replaced. It also promotes cooling when an air moving device is removed and not replaced for a period of time, by insuring that the cool air drawn into the enclosure by the remaining air moving devices is directed past the electronic components that need to be cooled. 
   The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes that come within the meaning and range of equivalency of the claims are to be embraced within their scope.