Abstract:
Disclosed is a compact and integrated fan, pump, and heat exchanger system where air-cooling is performed via the fan, liquid cooling is performed via a pump, and the drilled pump diffusers act as a heat exchanger. The pump has drilled diffusers through which liquid passes into the volute, the drilled diffusers are streamlined and thus act as fan stator blades. Hot liquid is centrifuged and carried inside the drilled diffusers while air flows around the outside surfaces of the drilled diffusers. A heat transfer occurs where heat transfers from the hot liquid into the air stream.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The present invention is related to fan and pump devices, and more specifically to liquid cooling systems using axial-flow fans and centrifugal pumps. The present invention is still more specifically directed to method and apparatus for liquid cooling using a compact configuration of axial-flow fan and centrifugal pump devices. 
         [0002]    Classical cooling units utilize three (3) separate components (fan, pump, and heat exchanger) located far apart to continuously perform the desired function of removing heat out of a liquid. For example, automobiles have a cooling system which includes a fan, a pump, and a heat exchanger. Some electronics and avionics cooling systems also include the same three basic components, and some home air conditioning systems also utilize all three components. 
         [0003]    The basic three components perform three basic functions: the fan delivers cold air; the pump delivers hot liquid; and the heat exchanger transfers heat from the liquid to the air. These three individual components are typically located far apart and thus occupy a large overall volume. 
         [0004]    Axial flow fans are fans in which the direction of the flow of the air from inlet to outlet remains unchanged. Guide, or stator, vanes can be provided to smooth the airflow by minimizing or otherwise reducing swirl and thus improve air flow efficiency. 
         [0005]    Centrifugal pumps are pumps that use a rotating impeller to increase the pressure of a fluid. The fluid enters the pump impeller along or near to the rotating axis and is accelerated by the impeller, flowing radially outward into a diffuser or chamber of a volute, from where it exits an outlet, and into a downstream piping system for example. A centrifugal pump typically includes a rotating impeller that increases the velocity of the incoming fluid. A casing, or volute, of the pump then acts to convert this increased velocity into an increase in pressure, resulting in fluid flow. The centrifugal pump typically employs a diffuser to deliver the liquid radially into the volute and then into the outlet. 
       BRIEF SUMMARY OF THE INVENTION 
       [0006]    The present invention provides a liquid cooling system comprising a unique combination of a fan and a unique pump/heat exchange component, thereby avoiding the need for a separate, space-consuming heat exchanger. The result is a compact and lower cost thermal system for liquid cooling. Of course, any fluid (such as air or other gases) other than a liquid can be cooled according to the present invention. 
         [0007]    The inventors have coined the term “fanpump” to describe a class of turbomachines which comprise two-wheels rotating about a common shaft, the first wheel is an axial-flow fan and the second wheel is a centrifugal pump. The present invention integrates three functions, namely, air cooling, liquid cooling, and heat exchange into this single two-wheel turbomachine. The fan delivers air while the pump delivers liquid. The third function is performed at the interface of the pump drilled diffusers since liquid flows inside the drilled diffusers while air flows around the drilled diffusers. Thus, although only two components (fan plus pump) are integrated, the “fanpump” device performs three (3) functions: the fan delivers air for cooling; the pump delivers liquid to be cooled; and at the surface of the drilled diffusers heat is transferred from liquid to air to effect cooling of the liquid. 
         [0008]    The fanpump cooling device, apparatus, or system can be driven by a common drive source, such as a common drive shaft. In the case of a motor-driven device, the drive shaft can be driven by a single motor. Still another alternative is to drive the fan portion of the fanpump device and the pump component with separate, independently controlled drive sources. 
         [0009]    The present invention provides an integrated fan plus a pump and heat exchanger housed in a compact cooling system. Air cooling is provided via an airflow created by the axial-flow fan, liquid cooling is provided via the centrifugal pump, and a heat transfer process is performed at the surface of the drilled pump diffuser elements of the centrifugal pump where heat transfers from the relatively hot liquid to the air stream. The fan and the pump rotate about a common shaft. Cooling devices according to the present invention perform three functions simultaneously: the fan delivers pressurized air flow; the pump delivers pressurized liquid; and heat is exchanged as the hot liquid is diffused inside the drilled pump diffusers while air is flowing about the drilled pump diffusers. 
         [0010]    The present invention eliminates the need for a separate heat exchanger by providing fluid flow within hollow diffuser elements (or channel elements) of the pump. The present invention provides for axial airflow across the diffuser elements. Heat transfer is performed as the hot liquid flows inside the diffuser elements while the colder axial airflow passes across the outside of the diffuser elements. In the present invention, the diffuser elements of the centrifugal pump therefore serve to diffuse the liquid and to provide a heat transfer path for hot liquid flowing inside the diffuser element to the air outside. 
         [0011]    The present invention further provides for the diffuser elements of the centrifugal pump to serve as guard or stator blades to eliminate, minimize, or otherwise reduce swirling activity in the airflow of the axial fan. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]      FIGS. 1A-1C  show three views of an illustrative embodiment of an apparatus for cooling liquids in accordance with the present invention. 
           [0013]      FIG. 2  is a side view of an illustrative embodiment of the apparatus shown in  FIG. 1 . 
           [0014]      FIG. 3A  is a perspective cutaway view of an illustrative embodiment of the apparatus shown in  FIG. 1 . 
           [0015]      FIGS. 3B and 3C  are plan views of the cutaway section illustrated in  FIG. 3A . 
           [0016]      FIG. 4  is a blown up view of an area identified in  FIG. 3B . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0017]      FIGS. 1A-1C  show various exterior views of a cooling apparatus  100  according to an embodiment of the present invention.  FIG. 1A  is a perspective upper view of the cooling apparatus  100 , while  FIG. 1B  is a top view looking down at the apparatus and  FIG. 1C  is a bottom view looking up. The cooling apparatus  100  includes among other elements to be discussed below, a housing  102  that houses an axial fan  104  and a centrifugal pump  106 . The cross-sectional view of  FIG. 3B  more clearly shows the centrifugal pump  106 . Axial fan and mixed-flow fan designs are known. Though embodiments disclosed herein show an axial fan, it is noted that fan  104  can be a mixed-flow fan in an alternate embodiment of the present invention. Likewise, the centrifugal pump and mixed-flow pump designs are known. Thus, although embodiments disclosed herein show a centrifugal pump, it is noted that pump  106  can be a mixed-flow pump. 
         [0018]    Portions of the housing  102  of the cooling apparatus  100  in accordance with the present invention uniquely provide an enclosure (shroud  102   a ) for the axial fan  104  and at the same time provide various components for the centrifugal pump  106 . For example, the housing  102  defines a fan housing for the axial fan  104 . A portion of the housing  102  serves as a fan shroud  102   a  for the fan  104 . The axial fan  104  sits within the space defined by the fan shroud  102   a . The fan  104  comprises fan blades  104   a . The fan blades  104   a  are connected to a fan hub  104   b . The combination of the blades and hub is referred to as the impeller. The axial fan  104  shown in this and following figures is a generic fan design. However, a variety of axial fans and designs are known. Various fan blade (impeller) designs are known. It will be appreciated from the teachings of the present invention, that any suitable axial fan and impeller design can be used. 
         [0019]    In accordance with the present invention, the housing  102  also defines various components comprising the centrifugal pump  106 . For example, a pump shroud  102   d  houses a pump impeller component  106   a  of the centrifugal pump  106 . The view of  FIG. 1C  shows only a small portion of the pump shroud  102   d . A more complete view of the pump shroud  102   d  is given in  FIG. 3B . The pump shroud  102   d  defines a pump inlet  206  ( FIG. 2 ) of centrifugal pump  106  within which is disposed the pump impeller  106   a.    
         [0020]    The housing  102  also defines a diffuser component for the centrifugal pump  106  which is in fluid communication with the pump shroud  102   d . Fluid entering the inlet  206  is forced under the pressure created by operation of the pump impeller  106   a  to flow into the diffuser. Unlike conventional diffuser designs, the housing  102  in accordance with the present invention defines a plurality of diffusers  102   e . The diffusers  102   e  shown in the top view of  FIG. 1B  are partially obscured by the impellers  104   a , but are shown in full view in  FIG. 1C . A feature unique to the present invention is the shape of the diffusers  102   e , they have a blade shape and thus are referred to herein as “diffuser blades” or “diffuser elements.” This aspect of the present invention will be discussed in further detail below. 
         [0021]    The housing  102  also defines the volute of the centrifugal pump  106  that is in fluid communication with the diffuser blades  102   e . In accordance with the present invention, the housing  102  defines a hollow casing  102   b  which serves as the volute. Fluid flowing through the diffuser blades  102   e  will exit the diffuser blades into the chamber of the volute  102   b . The housing  102  also defines a portion  102   c  which provides the pump outlet  208  of the centrifugal pump  106 . 
         [0022]      FIGS. 1A-1C  show a unique combination of the axial fan  104  and the pump  106  integrated into a single compact unit requiring only a single housing  102  and single shaft ( FIG. 3B ) to drive both. Air flows along the axis of rotation via the action of the fan impeller  104   a , and the fluid to be cooled is centrifuged via the action of the pump impeller  106   a.    
         [0023]      FIG. 2  represents a side view of the illustrative cooling apparatus  100  of  FIG. 1  taken from the view line  2 - 2  shown in  FIG. 1A . This figure is used to illustrate the various fluid flows of the apparatus  100 . Operation of the fan  104  will create a pressurized air flow. The incoming air enters through the airflow inlet  202  and is pressurized when the impeller  104  is spinning. This creates an axial flow of air that exits via the airflow outlet  204 . 
         [0024]    In an embodiment of the present invention, the housing  102  comprises two halves which fit together. A seem line  2 - 2  illustrated in  FIG. 2  represents the line of contact between the two halves of the housing  102 . The seem line can be seen in the other figures as well. 
         [0025]      FIG. 3A  shows a perspective cutaway view of the illustrative embodiment of the cooling apparatus shown in  FIG. 1A , taken from the view line  3 - 3 . This figure shows more clearly the integration of the axial fan  104  and centrifugal pump  106  in accordance with the present invention. 
         [0026]    As discussed above, a unique feature of the centrifugal pump  106  in accordance with the present invention is the array of diffuser blades  102   e  which collectively function as a conventional diffuser in a conventional centrifugal pump. Each diffuser blade  102   e  has an opening  304   a  into the volume of space defined by the pump shroud  102   d , where fluid entering inlet  206  is pressurized by pump impeller  106   a . Each diffuser blade  102   e  also has an opening  304   b  into the volute chamber  302 , where fluid flowing through the diffuser blade exits. 
         [0027]    As illustrated in  FIG. 3A , fluid enters the centrifugal pump  106  via the pump inlet  206 . In a specific application of the cooling apparatus  100 , a source of fluid to be cooled is connected to the pump inlet  206 . Though no details are provided in the figure, it is understood that the pump inlet  206  can be provided with a suitable fluid coupling mechanism to connect the apparatus  100  to a fluid source. The fluid can be a gas, but is more commonly a liquid such as water or other liquid coolant. Fluid entering the inlet  206  is pressurized by the spinning action of the pump impeller  106   a , forcing the fluid into the diffuser blades  102   e  through the respective openings  304   a . Fluid continues to flow through the diffuser blades  102   e  where it exits through respective openings  304   b  and into volute chamber  302 . As can be seen in  FIG. 1C , the diffuser blades  102   e  have a curved structure which directs the fluid in toward the outlet  208 . 
         [0028]      FIG. 3B  shows a straight-on view of the cutaway section illustrated in  FIG. 3A . In a particular embodiment of the present invention, the axial fan  104  is driven by a motor provided in the fan hub  104   b .  FIG. 3B  illustrates an example of a brushless DC (direct current) motor  320 . It will be appreciated that any of a number of suitable conventional motor designs can be used, including brushed as well as brushless motors. The brushless motor  320  shown in  FIG. 3B  includes a permanent magnet rotor  312  connected to the hub  104   b , so that rotation of the rotor will cause a corresponding rotation of the hub. The rotor  312  is attached or otherwise connected to a drive shaft component (spindle, axis, etc.)  316  for rotation about an axis of rotation. A stator  314  (more specifically a stator coil or stator winding in the case of brushless motors) is fixedly attached about the drive shaft  316 . Motor drive electronics  318  are provided on printed circuit board mounted near the base of the motor  320 . Suitable connections are made between the motor  320  and the drive electronics  318 , for example in order to provide drive current to the stator windings of stator  314 , and in general to provide communication between the motor and the drive electronics. 
         [0029]    In accordance with the present invention, the centrifugal pump  106  is driven by the same motor  320 . In particular, the impeller  106   a  is mechanically coupled to the drive shaft  316 , permitting the one motor to drive both devices, namely the fan  104  and the pump  106 . The single motor, common drive shaft configuration is advantageous in that it allows for a simple, compact, and low cost unit. 
         [0030]    However, it will be appreciated that alternative drive configurations, nonetheless, can be employed. For example, a common drive can be provided using a common drive shaft where the motor drive is provided at a location separate from the cooling apparatus  100 . It may be desirable to drive the fan  104  with a source separate from the drive source for the pump  106 . For example, it might be desirable to control the airflow velocity of the fan  104  and the fluid flow rate of the pump  106  independently of each other. Still other drive configurations can be employed without departing from the teachings of the present invention. 
         [0031]      FIG. 3B  shows how heat is transferred from hot liquid to the air in accordance with the present invention. The figure shows the path of the airflows created during operation of the fan  104 . Air is pulled into the airflow inlet  202  of shroud  102   a  and is forced through the shroud to create an axial airflow that exits the airflow outlet  204 . Along the way, the airflow passes across the surfaces of the diffuser blades  102   e  which are located in the path of the airflow and downstream of the airflow. When a fluid hotter than the airflow is made to flow through the diffuser blades  102   e , heat from the fluid will conduct across the material of the diffuser blades and into the air of the airflow, thus cooling the fluid. It is noted that the direction of the airflow can be reversed; however, the cooling effect will be reduced. 
         [0032]    The width dimension shown in  FIG. 3C  of the diffuser blades  102   e  can be increased or decreased to provide greater or lesser surface thereby effecting the rate of thermal conduction for any given fanpump design.  FIG. 3C  shows the addition of “winglets” (or fins)  322  that can be formed on the surface(s) of the diffuser blades  102   e . The winglets  322  further increase the surface area of the diffuser blade  102   e  for increased heat exchange capacity. The design and number of winglets  322  may be the same for each diffuser blade  102   e , or can vary from one blade to another. Typically the winglets  322  extend from the surface of the diffuser blade  102   e  by a small distance, e.g., the thickness of a dime, but the specific dimension will depend on a specific application. 
         [0033]    It is understood that larger and/or more numerous winglets  322  will improve heat exchange capacity, but generally at the cost of decreased airflow. Similarly, for the diffuser blades  102   e , namely, larger and/or more diffuser blades  102   e  will improve heat exchange capacity, generally sacrificing airflow efficiency. The specific designs for the diffuser blades  102   e  and the winglets  322 , including numbers of diffuser blades and winglets, will be dictated by the requirements of a specific application. Such design factors are beyond the scope of the present invention, but are nonetheless within the scope of understanding of those of ordinary skill in the art. 
         [0034]    An enlarged view of the area in  FIG. 3B  identified by circle  4  is shown down, upside down, in perspective in  FIG. 4  and illustrates some additional details of the centrifugal pump  106 . As can be seen in  FIG. 4 , the pump impeller  106   a  comprises impeller blades  402  attached to and radially arranged about an impeller ring  402   a . The impeller ring  402   a  slidably fits about a finger  416 . The pump impeller  106   a  spins about the finger  416  within the volume of space  404  defined by the pump shroud  102   d.    
         [0035]    A neck of the shroud  102   d  defines fluid inlet  206  and can be structured or otherwise fitted with a suitable coupling device to allow for cooling apparatus  100  to be connected to the source of fluid to be cooled. Diffuser blades  102   e  can be seen coupled to the pump shroud  102   d.    
         [0036]      FIG. 4  also shows portions of the motor drive components. For example, a portion of the stator  314  of motor  320  can be seen. Similarly, part of the permanent magnet rotor  312  can be seen. The PCB containing the drive circuitry  318  is also visible. As can be seen in the figure (also in  FIGS. 3A and 3B ), bearings  306  provide support for the drive shaft  316  within the housing  102 . 
         [0037]    In the embodiment of the present invention shown in  FIG. 4 , the ring of pump impeller  106   a  is provided with a permanent magnet ring  412 . A corresponding permanent magnet ring  414  is provided about drive shaft  316 . The magnets  412 ,  414  are aligned for mutual attraction between them so that when the drive shaft  316  spins the magnet  414 , the magnet  412  likewise will spin thus driving the pump impeller  106   a . As can be seen in the figure, the finger  416  provides a fluid-tight separation between the pump mechanics of the pump  106  and the fan mechanics of the fan  104 . 
         [0038]    An important aspect of the present invention are the drilled diffuser blades  102   e  which constitute a component of the centrifugal pump  106 . First, as discussed above, they collectively perform the function of a conventional diffuser in a conventional centrifugal pump, namely to deliver the pressurized incoming fluid created by the impeller into to volute. 
         [0039]    A second important aspect of the present invention, as can be seen in the figures, is that the diffuser blades  102   e  are disposed in the path of the airflow of the axial fan  104 . Thus, the flow of fluid resulting from the pressure created by the spinning of the pump impeller  106   a  flows through the diffuser blades  102   e  which are connected to the pump shroud  102   d  and in fluid communication with the volume  404  within the shroud. The fluid consequently also flows in the path of the airflow of the axial fan  104 . The diffuser blades  102   e  thus act as a heat exchangers where heat is transferred from the hot fluid stream inside the diffuser blades to the cooler air stream outside. 
         [0040]    A third important aspect of the present invention is the shape of the diffuser blades  102   e . As can be seen in the figures, the diffuser blades  102   e  have a streamline shape. By placing the diffuser elements of the centrifugal pump  106  squarely within the path of the airflow (airstream), turbulence and swirl effects can arise in the airflow. By shaping the diffuser elements of the centrifugal pump to have an streamlined, aerodynamic shape, the diffuser blades  102   e  can de-swirl the airflow. Because the drilled diffuser blades are streamlined (i.e. outer surface is airfoil shaped) and located downstream of the fan impeller  104   a  they also act like de-swirl vanes (i.e., fan stator blades which remove swirl, created by the fan impeller, from the air stream). 
         [0041]    In a particular embodiment, the diffuser blades  102   e  have an airfoil shape, and more generally have the general shape of a fan blade; hence the inventors have coined the phrase “diffuser blade” as a reminder that the diffuser elements of the present invention have two important functions: first, they are drilled so as to centrifuge (or diffuse) the fluid captured by the pump impeller  106   a ; and second, they are streamlined, i.e., they look like airfoils or fan blades in order to eliminate, minimize, or otherwise reduce air swirl and/or turbulence. The diffuser blades  102   e  therefore serve as conventional “stator blades.” 
         [0042]    It is noted that de-swirling the airflow, though very desirable, is not a critical element of the present invention though it is nonetheless a unique feature of the present invention. Aspects of the present invention include the placement of the diffuser blades  102   e  within the path of the airflow, allowing for the airflow to cool the hotter liquid flowing within the diffuser blades, and allowing for the ability to at least reduce swirl from the airflow. Thus, the diffuser blades  102   e  in accordance with the present invention perform three functions: they diffuse the fluid, they provide heat exchange, and they can de-swirl the airflow. 
         [0043]    Another important aspect of the present invention is the integration of the axial fan  104  and the centrifugal pump  106  into a single unit, where the two rotating wheels (fan impeller  104   a  and pump impeller  106   a ) have a common shaft, motor, and drive housed in a common housing  102 . The inventors have coined the descriptive term “fanpump” to describe such devices. The centrifugal pump design of the present invention allows for the diffuser component of the pump  106  to be placed inline with the airflow of the fan  104  in a compact, space-efficient manner. The design and placement of the volute  102   b  of the pump  106  is equally important in arriving at a compact, space-efficient device. 
         [0044]    As noted above, the housing  102  can be formed of two halves (or more pieces). Each half (piece) can be an injection molded piece. The material can be any suitable type of plastic, or any other material. Preferably, the material that is used has suitable thermal qualities as to promote efficient heat conduction in the diffuser blades  102   e.    
         [0045]    In an embodiment, the diffuser blades  102   e  can be formed of material different from the rest of the housing  102 . Though manufacture of such an embodiment might be more costly due to increased complexity in the manufacture, it may be acceptable if the diffuser blades  102   e  can achieve high thermal efficiency. 
         [0046]    Still other variations are contemplated without departing from the present invention teachings. For example, the axial fan  104  and the centrifugal pump  106  can be driven by separate drive sources. Though this may result in a less compact design and a single drive configuration, a particular application may call for a less compact design; e.g., there may be a benefit to be able to drive the axial fan at speeds, or otherwise be controlled, separately from the pump.