Abstract:
Electronic apparatus is provided including a housing with one or more electronic devices which act as heat sources and a fan provided therein. The fan is arranged to draw air from outside of the housing via one or more inlets such that said air passes over at least one of said electronic devices prior to exiting the housing via one or more outlets. The housing has multiple sides and an inlet is provided on two or more of the sides.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims priority to British Patent Application No. 0516813.3 Filed 17 Aug. 2005.  
       STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT  
       [0002]     Not Applicable  
       THE NAMES OF THE PARTIES TO A JOINT RESEARCH AGREEMENT  
       [0003]     Not Applicable  
       INCORPORATION-BY-REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISC  
       [0004]     Not Applicable  
       REFERENCE TO A MICROFICHE APPENDIX  
       [0005]     Not Applicable  
       BACKGROUND OF THE INVENTION  
     Field of the Invention  
       [0006]     The present invention relates to the cooling of electronic apparatus and more specifically, although not exclusively, to the air cooling of a hard disk drive.  
         [0007]     Hard disk drives (HDDS) are used in a variety of electronic products and are known to create a significant amount of heat during operation. The reliability of a hard disk drive (HDD) is directly related to operating temperature and, in addition, the heat generated by the HDD can adversely affect other surrounding components.  
         [0008]     One commonly accepted solution to this problem is to use a fan to force air over the HDD so as to increase the rate at which heat is dissipated by convection. However, particularly in relation to consumer products, there are a number of other internal components which also need to be cooled. This poses a problem to the product designer, especially since overall dimensions of the product are preferably to be kept to a minimum since there is limited space available to allow optimal cooling configurations.  
         [0009]     While a number of ways of improving cooling efficiency have been explored in relation to personal computers, the use of HDD&#39;s within broadcast data receivers, such as set top boxes, is now becoming more widespread. This is due to the additional functionality offered by Personal Video Recorders (PVR&#39;s) that allow a user to store broadcast data for later viewing.  
         [0010]     Operating life test data has shown that increasing the cooling of the HDD by only a few degrees would prevent a significant number of HDD failures, resulting in cost savings for the manufacturer due to fewer field returns and also avoiding inconvenience for the consumer. Thus, there is a constant need to improve cooling efficiency and reliability.  
         [0011]     Furthermore, it has been found to be a problem that a consumer may inadvertently choose to position a set top box in a location that substantially blocks the inlet or outlet for the cooling airflow. In such a situation an increased strain is placed on the fan, and airflow within the housing will tend to recirculate, causing the temperature of the air within the housing to increase, potentially leading to overheating and failure of one or more electronic components.  
       BRIEF SUMMARY OF THE INVENTION  
       [0012]     The present invention aims to provide an improved electronics cooling arrangement so as to reduce the numbers of product failures.  
         [0013]     According to a first aspect of the present invention there is provided electronic apparatus. The apparatus includes a housing with one or more electronic devices that act as heat sources, and a fan is provided therein. The fan is arranged to draw air from outside of the housing via one or more inlets, such that the air passes over at least one of the electronic devices prior to exiting the housing via one or more outlets. The housing has multiple sides, and an inlet is provided on two or more of the sides.  
         [0014]     Preferably, the inlet extends around a corner of the housing or outer casing so as to allow air to be entrained into the housing from two or more directions. Thus, in one example, a single inlet arrangement extends between at least two sides of the housing. The inlet arrangement is preferably substantially continuous around the corner. In one embodiment, the corner is substantially right-angled such that air can enter the housing from two substantially perpendicular directions. Typically, the inlet includes a number of apertures or slots and the apertures extend around one or more corners of the outer casing.  
         [0015]     The fan can be any powered means via which air is entrained through or into the housing of the apparatus.  
         [0016]     The present invention is particularly advantageous in that it allows airflow from one direction to be substantially cut off without starving the fan, thus, avoiding dependency for air supply in any one face of the product. Particularly in relation to a consumer electronic product, such as a set top box, the life of the fan will not be seriously affected when the product is incorrectly arranged such that airflow from one direction is inadvertently blocked.  
         [0017]     In one embodiment separate inlets are provided on two or more sides of the housing.  
         [0018]     According to one embodiment, the fan is contained within a fan compartment such that the fan draws air into the fan compartment from outside of the housing via the one or more inlets. The air is preferably drawn directly into the fan compartment through the inlet. Typically, the housing includes one or more internal walls defining the fan compartment, the walls isolating the fan from the air within the remainder of the housing. Preferably, the fan compartment has one or more external walls provided by the one or more sides of the housing with the inlets therein. In one embodiment, the fan draws air from all external surfaces of the fan compartment. Typically, the fan compartment is provided within a corner of the housing. The fan axis may be oriented substantially parallel with, perpendicular to, and/or else at an angle to external walls of the compartment.  
         [0019]     The present invention is advantageous in that it provides maximum fan life, and the fan is thus housed in its own incoming air stream that will be at the coolest available air, the external ambient air.  
         [0020]     The housing may be provided with one or more baffles or baffle means for ducting air leaving the fan compartment over the electronic devices, which may include a hard disk drive. The baffles may be arranged to restrict the cross-sectional area of the air flow so as to increase the velocity of the air flow over the HDD. Preferably, the air is directed over one side of the HDD prior to entering one or more other chambers within the housing. The chambers containing further electronic components or devices.  
         [0021]     According to one embodiment, air direction means or a fin is disposed adjacent one or more sides of the HDD and the surface to the fin or air direction means may be profiled to direct airflow onto the one or more surfaces of the hard disk drive. Preferably, the fin or air direction means is generally planar in shape and is provided with a number of oblique formations so as to promote turbulent airflow. The oblique formations may be notches, protruding members or else fingers and these may be punched out of the fin.  
         [0022]     In one particular arrangement, the fin or air direction means is thermally conductive and is attached to one or more sides of the hard disk drive so as to function as a heatsink. Preferably, the fin or air direction means is U-shaped with straight sides arranged to extend either side of the hard disk drive for contact therewith and a further side arranged to be disposed a short distance from the surface of the hard disk drive within the airflow leaving the fan compartment.  
         [0023]     A cowling or partition means may be provided a spaced distance from the side of the hard disk drive such that the fin or air direction means is disposed in the airflow between the cowling or air partition means and the surface of the hard disk drive.  
         [0024]     Thus, according to the present invention, a forced airflow can be funneled into a channel along one side of the hard disk drive and over the fin or air direction means so as to improve cooling by convection. Formations on the fin or air direction means increase the heat transfer through scavenging and trip turbulent flow. The direction of the airflow within the resulting vortices is generally chaotic, causing an increase in the heat energy transferred from the hard disk drive and any associated control electronics.  
         [0025]     Typically, one or more apertures are provided in a baffle, the apertures opening into one or more compartments within the housing, such that air can be bled from the bulk airflow to cool electronic components within the compartments. The baffle is typically located externally to the fan compartment but associated therewith.  
         [0026]     Upon leaving the channel, the air flow may enter into one or more chambers within the housing prior to exiting the housing via one or more outlets provided in the outer casing. The outlets may be provided on two or more sides of the outer casing.  
         [0027]     Preferably, the electronic apparatus is in the form of a set top box or broadcast data receiver (BDR) capable of receiving digital data from a remote broadcaster and decoding the data to provide video, audio and/or auxiliary data. Set top boxes or BDRs are typically used with television systems.  
         [0028]     According to a further aspect of the present invention, there is provided an electronics cooling apparatus for a broadcast data receiver. The apparatus including a fan disposed in fluid communication with a hard disk drive, wherein air driven by the fan is ducted or channeled to one or more surfaces of the hard disk drive. The apparatus includes a fin or air direction means disposed adjacent the hard disk drive such that the airflow induced by the fan passes over the surface of the hard disk drive and the fin or air direction means.  
         [0029]     Typically, the broadcast data receiver is arranged for connection to a television set and takes the form of a PVR.  
         [0030]     Preferably, the fin or air direction means conducts heat away from one or more sides of the HDD in to the included airflow. Typically, the airflow induced by the fan is directed toward substantially one side of the HDD by baffle means extending between the fan and the HDD. However, one or more further sides of the hard disk drive may also be fed by the airflow from the fan. In one particular embodiment, one side of the HDD body has an at least partially exposed aluminum portions, including a motor boss, airflow over which increases the flow of heat from the hard drive.  
         [0031]     According to a further aspect of the present invention there is provided a method of cooling electronics apparatus. The apparatus includes a housing with one or more electronic devices which act as heat sources, and a fan provided therein. The method includes the steps of drawing air from outside of the housing via one or more inlets using a fan such that the air passes over at least one of the electronic devices prior to exiting the housing via one or more outlets, wherein the housing has multiple sides, and an inlet is provided on two or more of the sides to allow air to be drawn into the housing from the two or more sides.  
         [0032]     According to a yet further aspect of the present invention, there is provided a method of cooling electronics apparatus, the apparatus including a fan disposed in fluid communication with a hard disk drive. The method includes the steps of driving air using the fan through a channel or duct to one or more surfaces of the hard disk drive. The apparatus includes a fin or air direction means disposed adjacent the hard disk drive such that the driven airflow included by the fan passes over the surface of the hard disk drive and the fin or air direction means. 
     
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEW OF THE DRAWINGS  
       [0033]     Specific embodiments of the invention are now described with reference to the accompanying drawings.  
         [0034]      FIG. 1  is a cross-sectional view of a cooling arrangement according to the present invention.  
         [0035]      FIG. 2  is a cross-sectional view of an alternative cooling arrangement according to the present invention.  
         [0036]      FIG. 3  is a plan view of a product housing and fan arrangement according to the present invention.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0037]     Referring first to  FIG. 1 , there is shown generally a hard drive enclosure section of an electronic apparatus  10  in the form of a PVR unit. The hard drive enclosure contains HDD  16  disposed between a lid  12  and a base  14 . The HDD can be suspended in the housing via a cradle, can be attached directly to the housing and/or the like.  
         [0038]     An axial fan  18  is arranged upstream of the HDD such that air from the fan is blown over HDD  16 . Fan  18  is contained within an isolated enclosure or compartment  19  and is mounted between lid  12  and base  14  of the housing by way of a mounting plate  20 . Baffle plates  22  and  24  are provided to direct the airflow from the fan towards the underside of HDD  16 . An upper baffle plate  22  is connected between the fan housing  18  and a side of the HDD, while a lower baffle plate  24  is connected between the fan housing and a cowling member  26  such that the baffle plates form a duct such that substantially no air flow is directed over the steel lid of the HDD.  
         [0039]     Baffle plates  22  and  24  are angled to form a nozzle arrangement such that the flow area for the air is reduced towards the HDD. Thus, the velocity of the air flow underneath the HDD is increased, concentrating the airflow over the HDD. Cowling  26  is arranged substantially parallel to the underside of the HDD so as to form a longitudinal channel  28  through which the air from the fan is directed.  
         [0040]     Cowling  26  is supported above the base  14  by a member  34  that serves to dampen or prevent vibration of cowling  26 . In addition member  34  acts as a bulkhead, forming an enclosed chamber between the cowling and the base that can serve as an RF compartment. One or more apertures  36  within the lower baffle plate  24  allow air from the main flow to be bled into the RF compartment at a substantially reduced rate so as to provide a cooling air source for an RF board.  
         [0041]     Fin  30  is arranged longitudinally within channel  28  and, in this embodiment, is substantially parallel to a base of the HDD. Fin  30  acts as a heat sink and is generally U-shaped, with the fin sides extending up the sides of the HDD such that heat is conducted from the sides of the HDD and into the forced air stream. Fin  30  may be made of an aluminum or copper plate that is bolted or otherwise attached to the sides of the HDD to ensure good thermal contact. A material sheet is disposed between the HDD sides and the fin to provide an improved thermal interface.  
         [0042]     The HDD body is typically die-cast aluminum alloy, the conductivity of which is exploited by providing a good thermal path away from the HDD body sides, where there is maximum surface area and minimum thermal path to heat-generating sources, such as the motor and disk/air friction. The upper surface of the HDD body is generally mild steel, that offers poorer thermal conductivity. In addition, the upper surface or lid generally covers an air-filled cavity in which the magnetic disk and heads are housed, making it unsuitable for efficient heat transfer.  
         [0043]     Fin  30  is notched within channel  28  so as to promote the creation of vortices and hence turbulent air flow. By altering the direction of the air flow in this manner, an increased amount of heat can be convected away from the underside of the HDD and improved cooling efficiency is achieved when compared to an undisturbed air flow in which the bulk flow passes down the center of the channel.  
         [0044]     Fingers  32  are punched out of fin  30  in various orientations to direct the flow towards the underbody of HDD  16  and the associated control electronics. Furthermore, the surface area of the heat sink fin is increased for efficient convection.  
         [0045]     In  FIG. 2 , the axial fan has been replaced with a radial fan or blower  40  mounted in fan compartment  19 . Thus, fan  40  draws in air in a different direction to the fan of  FIG. 1 , but the cooling of the HDD is otherwise performed in the same way as the arrangement of  FIG. 1 .  
         [0046]     Using a fin  30  made of a 1 mm thick aluminum plate bolted to the sides of the HDD with a 0.3 mm thermal gap material sheet in combination with the augmented air flow from a 70 mm fan has been found to reduce a typical 10° C. temperature rise during operation to less than 5° C. It is generally found that by increasing the thickness of the fin to a value of 2 mm, or more, further improvements in operation and also the stiffness of the assembly can be achieved.  
         [0047]     Turning now to  FIG. 3 , there is shown a plan view of the cooling arrangement of  FIG. 2  within PVR  10 . The PVR has a front facia  44 , a rear panel  46  and sides  48  and  50 .  
         [0048]     The radial fan  40  draws in air from inlet  42  into the fan compartment  19 . The inlet  42  takes the form of a number of vent holes extending through lid  12  and side  48  such that ambient air can be drawn through at least two external surfaces of PVR  10 . In addition, the base  14  may be provided with inlet vents to the fan chamber  19 . The set top box may be provided with feet (not shown) such that base  14  is raised above a supporting surface so as to allow air to pass into the fan chamber from below the PVR.  
         [0049]     Fan chamber  19  is positioned in the corner of the set top box and forms an enclosure for the fan  40  defined by base  14 , lid  12 , front  44 , and side  48  of the PVR and the internal walls  20  and  52 . By housing the fan in this manner, a constant supply of external ambient air to fan  40  is ensured, and the fan is isolated from recirculating air within the PVR casing.  
         [0050]     The air from fan  40  is then ducted by baffle plates  22  and  24  beneath HDD  16 , as previously described. Upon exiting channel  28 , the exhaust air enters into digital compartment  54  containing a digital board, where a portion of the flow may recirculate so as to cool a power supply unit and other electronic components. In addition, the air bled from the main cooling airflow by way of the apertures  36 , shown in  FIG. 1 , may pass through RF compartment  56 , containing an RF board so as to convect heat from components therein.  
         [0051]     By pressurizing the set top box, the exhaust air from the HDD assembly can be directed wherever required, such as, for example, underneath PCB&#39;s, around heat sink dimples, and out through vent holes in the base.  
         [0052]     Exhaust vents are provided in the side wall  50  as well as in lid  12  and base  14  such that air can exit the set top box in multiple directions. The overall area of exhaust ventilation generally exceeds the area of the inlet so as to reduce back pressure and dust accumulation.  
         [0053]     It will be appreciated by persons skilled in the art that any or any combination of the above-described embodiments can form part of the present invention.