Patent Document

CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based upon and claims the benefit of priority from prior Japanese Patent Application No. 2009-049371, filed Mar. 3, 2009, the entire contents of which are incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an electronic apparatus, and more particularly to a cooling system for the electronic apparatus. 
     2. Description of the Related Art 
     An electronic apparatus such as a television transmitter provided in a base station includes heat generating electronic circuits such as a power amplifier. The electronic circuits may be attached to or removed from a case of the electronic apparatus. When a large amount of heat is generated by driving of the circuits, performance characteristics of the electronic apparatus are decreased. Thus, various cooling mechanisms to cool the electronic circuits maintaining desired performance characteristics have been introduced. 
     For example, Jpn. Pat. Appln. KOKAI Publication No. 2007-243728 discloses a cooling mechanism provided with an exhaust fan to assure cooling reliability. According to the cooling mechanism, the external air is taken in the case of the electronic apparatus, circulated therein, and discharged from the case by the exhaust fan. The electronic circuits are controlled so that the heat generated by the electronic circuits is forced to be expelled from the case. Such forced cooling method is employed to achieve the desired performance characteristics. 
     However, higher-power outputs from recent electronic circuits generate a larger amount of heat to increase an exhaust heat temperature and a temperature of a room, in which the electronic apparatus is placed. Thus, thermal control for the electronic circuits can be difficult without improving air conditioning performance for the room to decrease the temperature of the air taken into the case. 
     In view of power-saving, which is strongly required in these days, it is considered to be important addressing a rise in air conditioning performance. 
     BRIEF SUMMARY OF THE INVENTION 
     According to an embodiment of the present invention, an electronic apparatus comprises: 
     a case configured to house an electronic circuit unit and comprising an air intake, through which external air is taken into the case, and an exhausting opening, from which the air is ejected; 
     an circulator provided in the case and configured to take the external air into the case through the air intake and supply the air to the electronic circuit unit; 
     an evaporation unit provided in the case and configured to cool the air by thermal exchange between the air and a working medium and guide the air to the exhausting opening, the working medium being vaporized as a result of the thermal exchange; and 
     a condenser provided out of the case and configured to liquidize the working medium and supply the working medium to the evaporation unit. 
     According to another embodiment of the present invention, a cooling system for an electronic apparatus comprising an electronic circuit unit, the cooling system comprises: 
     an circulator configured to take external air into a case of the electronic apparatus and supply the air to the electronic circuit unit; 
     an evaporation unit configured to cool the air by thermal exchange between the air and a working medium and guide the air to be ejected from the case of the electronic apparatus, the working medium being vaporized as a result of the thermal exchange; and 
     a condenser provided out of the case and configured to liquidize the working medium and supply the working medium to the evaporation unit. 
     Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
       The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the present invention and, together with the general description given above and the detailed description of the embodiments given below, serve to explain the principles of the present invention. 
         FIG. 1  is a view showing a rear face of an electronic apparatus according to an embodiment of the present invention; 
         FIG. 2  is a view showing a cooling mechanism arrangement for an electronic circuit housed in the electronic apparatus shown in  FIG. 1 ; 
         FIG. 3  is a view showing an arrangement of power amplifiers, exhausting fans, evaporation units, and outdoor units according to the embodiment; 
         FIG. 4  is a view showing a cooling cycle provided by an evaporation unit and an outdoor unit according to the embodiment; 
         FIG. 5  is a view showing a setting of a case of the electronic apparatus, according to an embodiment; and 
         FIG. 6  is a view showing another setting of the case of the electronic apparatus, according to an embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     An embodiment of the present invention will now be described with reference to the accompanying drawings. 
       FIG. 1  shows an electronic apparatus according to an embodiment of the present invention. A case  10  is provided with an air intake  11  which is vertically elongated along a substantially middle portion on a front face of the case  10 , for example. On both sides of a rear face of the case  10 , exhaust openings  12  are also provided, which are vertically elongated. The air intake  11  is located between the exhaust openings  12 . A filter member  13  is provided on the air intake  11  as shown in  FIG. 2 . The air for cooling an exterior is taken into the case  10  through the filter member  13 . 
     Electronic circuits including power amplifiers  14  are stacked in two columns in the case  10 . The air intake  11  is located between the columns. One column of the power amplifiers  14  is communicated with one of the exhaust openings  12  via a duct  15 , which provides an exhaust channel. The other column of the power amplifiers  14  is also communicated with the other of the exhaust openings  12  via another duct  15 , which provides another exhaust channel. 
     It should be noted that another configuration of the air intake  11  and the exhaust openings  12  is possible in the case  10 . 
     In the ducts  15 , exhaust fans  16  are provided in association with the power amplifiers  14 . In one exhaust channel, evaporation units  17  are positioned between an exhaust opening  12  and an exhausting side of an exhaust fan  16 . Also in another channel, evaporation units  17  are positioned between an exhaust opening  12  and an exhausting side of an exhaust fan  16 . The evaporation units  17  in one channel are opposed to the evaporation units  17  in another channel. Each of the evaporation units  17  is individually configured. An internal air is discharged from the ducts  15  through the exhaust fans  16  and blown on the evaporation units  17 . The evaporation units  17  cause thermal exchange between the internal air and a circulating working medium to cool the internal air. The evaporation units  17  guide the internal air to be discharged from the exhaust openings  12 . 
     For example, as shown in  FIG. 3 , outdoor units  18  which include condensing units are connected to the evaporation units  17  via pipelines  19 . The outdoor units  18  are driven by inverter control. According to the inverter control, an effective voltage and a frequency of an alternating-current power output can be arbitrarily controlled. When the inverter control is conducted at a low frequency, power consumption of the outdoor units  18  can be suppressed. Each of the outdoor units  18  includes a compressor  181 , a condenser  182 , and a pressure reducing valve  183 , as shown in  FIG. 4 . The working medium is vaporized in the evaporation unit  17  and supplied to the compressor  181  via the pipeline  19 . The compressor  181  compresses the working medium to raise the pressure, and the condenser  182  liquidizes the working medium. The pressure reducing valve  183  reduces the pressure in the working medium, and then, the working medium is circularly supplied to the evaporation unit  17 . 
     Thus, the evaporation unit  17  causes the thermal exchange between the internal air, which is blown from the exhaust fans  16 , and the working medium, the pressure of which is reduced by the pressure reducing valve  183 , to cool the internal air. The wind power of the exhaust fans  16  ejects the cooled internal air through the evaporation units  17  and the exhaust openings  12 . In the present embodiment, the inverter control is employed in order that cooling the air is driven at a high frequency to assure a high cooling performance and at a low frequency to provide a lower cooling performance. Cooling operation at a low frequency allows the power consumption to be reduced. The cooling operation may be performed at a high frequency as well to provide a higher cooling performance, if necessary. 
     In the above configuration, the case  10  is provided in a room  20  such as a base station. As shown in  FIG. 5 , the front face of the case  10  is opposed to a stationary air conditioner  21 . The power amplifiers  14  are used for a desired operation. The air conditioner  21  ejects air having a temperature (28° C., for example) which is lower than the temperature of the room  20  from an ejection opening  211 . The ejected air is mixed with the air in the room  20 , and the temperature of the room  20  is adjusted. The exhaust fans  16  are driven to take the air conditioned by the air conditioner  21  into the air intake  11  of the case  10 . The air is guided to the power amplifiers  14  and absorbs heat which is generated by driving of the power amplifiers  14 . Thus, the air rises in temperature up to 45° C., for example. Accordingly, the power amplifiers  14  are cooled down. 
     The temperature of the air which has absorbed the heat from the power amplifiers  14  comes to rise up. The air is blown on the evaporation units  17  by the wind power of the exhaust fans  16 . The evaporation units  17  cool the air down (to 33° C., for example) by the thermal exchange with the working medium which is circularly supplied form the outdoor units  18 . The air is ejected from the exhaust openings  12  to the room  20 . 
     A suction opening  212  of the air conditioner  21  sucks the cooled air (33° C., for example) which is expelled from the exhaust openings  12 . The air conditioner  21  further cools the air down toward 28° C. The air is ejected from the ejection opening  211  to the room  20 , to condition the temperature of the room  20 . Thus, when the electronic apparatus is provided with the evaporation units  17  and the outdoor units  18  having a small air conditioning performance, and when the air conditioner  21  is provided with cooling availability which cools the air by 5 degrees, the high-efficiency thermal control is possible and a cooling mechanism which assumes low power can be achieved. The cooling mechanism may be preferable to the electronic apparatus system. The temperature of the air taken in the case  10  is maintained at about 30° C. due to air conditioning by the air conditioner  21 . Therefore, in comparison with the case where the air is not conditioned, the thermal control for the power amplifiers  14  can be performed with the low cooling performance by the evaporation units  17  and the outdoor units  18 . 
     The air taken in the case  10  is warmed up by the power amplifiers  14 , passes through the evaporation units  17  to be subjected to the thermal exchange, and is cooled. The humidity of the air is also reduced and the air is ejected from the exhaust openings  12  to the room  20 . The air conditioner  21  takes in the low humidity air from the room  20  and performs latent heat cooling and sensible heat cooling to condition the air in the room  20 . If the humidity of the air taken in the air conditioner  21  is low, the heat processing is performed under a condition where necessity of the latent heat cooling is decreased and the air conditioner  21  mainly performs sensible heat cooling. Therefore, the cooling performance is improved. Thus, the latent heat cooling need not to be performed and requirement for the cooling performance is relieved. Therefore, the lower cooling performance can sufficiently condition the air in the room  20 . 
     That is, the electronic apparatus is configured as follows. The air intake  11  in the case  10  takes in air from the room  20  that is conditioned by the air conditioner  21  by the exhausting fans  16 . The air absorbs heat generated by driving of the power amplifiers  14 . The air is cooled by the thermal exchange with the working medium of the evaporation units  17 . The cooled air is forced to be ejected from the exhaust openings  12  by the wind force of the exhaust fans  16 . 
     The conditioned air is taken in the air intake  11  and warmed up by the heat emitted from the power amplifiers  14 . The wind power of the exhaust fans  16  guides the air to the evaporation units  17 . The air is cooled by the evaporation units  17  and ejected out of the case  10 . Thus, minimum temperature control for the internal air of the room  20  which is to be taken in the air intake  11  realizes the high-efficient thermal control for the power amplifiers  14  housed in the case  10 . As a result, the air-conditioning performance required to condition the air in the room  20  where the case  10  is set need not be so high. Power-saving in the electronic apparatus system can be improved. 
     For example, in the case of maintaining the electronic apparatus system including repairing the compressor  181  and condenser  182  in any of the outdoor units  18 , a cooling system required to be checked is stopped, while keeping the thermal control for the power amplifiers  14  to be in operation utilizing other cooling systems (or other combinations of the evaporation units  17  and the outdoor units  18 ). Thus, the electronic apparatus system can operate continuously. Therefore, the outdoor units  18 , which require frequent maintenance, can be readily maintained while continuing the operation of the electronic apparatus system. 
     In addition, when the air conditioner  21  breaks down, for example, only the evaporation units  17  and outdoor units  18  may be used to provide a higher cooling performance by the inverter control. Thus, thermal control for the power amplifiers  14  is continuously conducted, and also the electronic apparatus system can operate continuously. 
     According to the embodiment, the evaporation units  17  share the exhausting fans  16  having a long durable period, as a wind power source, which work as the forced cooling means to force heat emission. The exhausting fans  16  compulsory blows wind on the power amplifiers  14  which are continuously driven. Thus, the thermal exchange system is configured. 
     Accordingly, while keeping the case  10  to be in a small size, a durable period of the thermal exchange system utilizing the evaporation units  17  can be prolonged so that the thermal exchange system can be continuously used for substantially the same durable period as the exhausting fans  16 . For example, the exhausting fans  16  are produced, in general, to be operational for a long period which is corresponding to the durable period of the power amplifiers  14 . When the thermal exchange system is established using the evaporation units  17 , which share the exhausting fans  16  that is improved in durability, the thermal exchange system which is durable for a period corresponding to the power amplifiers  14  can be provided readily. 
     In the above embodiment, the exhausting fans  16  of the forced cooling means are provided on the side where the exhausting openings  12  are attached in the case  10 . However, the invention is not so limited. The exhausting fans  16  may be arranged on the side where the air intake  11  is provided, and similar effect to the above embodiment will be achieved. 
     In the above embodiment, the evaporating units  17  are provided in association with the exhausting fans  16 . However, the invention is not so limited. For example, a plurality of evaporating units  17  may be arranged in association with an exhausting fan  16 , and similar effect to the above embodiment will be achieved. 
     In the above embodiment, the evaporating units  17  are housed in the case  10 . However, the invention is not so limited. The evaporation units  17  may be arranged outside of the exhausting openings  12 . 
     In the above embodiment, the air intake  11  in the case  10  is opposed to the ejection opening  211  and the suction opening  212  of the air conditioner  21  which is placed in the room  20 . However, the arrangement is not so limited. For example, as shown in  FIG. 6 , the exhausting openings  12  in the case  10  may be opposed to the ejection opening  211  and the suction opening  212  of the air conditioner  21 . In addition, the air conditioner  21  is not limited to the stationary type. Another configuration of air conditioning devices may be employed to present similar effect. 
     Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.

Technology Category: h