Abstract:
A pump includes: a housing having a heating receiving portion thermally connected to a heat generating element and a pump chamber; a stator; and a rotary member disposed in the pump chamber, and having a stirring portion which stirs a fluid in the pump chamber and a magnet contained within the rotary member.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2004-133537, filed Apr. 28, 2004, the entire contents of which are incorporated herein by reference.  
       BACKGROUND  
       [0002]     1. Field  
         [0003]     The present invention relates to a pump disposed in a liquid-cooling type cooling device which cools, using a liquid refrigerant, a heat generating element such as a central processing unit (CPU), and an electronic apparatus comprising this pump.  
         [0004]     2. Description of the Related Art  
         [0005]     As a pump, a pump described in Jpn. Pat. Appln. KOKAI Publication No. 2003-343492 has been known. This pump has a concave portion in one end face, and comprises a disc-shaped impeller having a plurality of vanes on the other end face. This impeller has a magnetic field generation portion on an inner periphery of the concave portion. The magnetic field generation portion is constituted by fixing an annular member comprising a permanent magnet onto the concave portion of the impeller formed of a resin. As to the magnetic field generation portion, the impeller is formed of a plastic magnet, and a portion corresponding to the magnetic field generation portion is magnetized.  
         [0006]     As another pump, a pump described in Jpn. Pat. Appln. KOKAI Publication No. 11-166500 has been known. It is known that this pump comprises a motor including a stator having a plurality of coils, and a rotor made of a permanent magnet. The stator is molded out of a resin to thereby constitute a molded stator. The rotor is molded out of a resin to thereby constitute a cylindrical molded rotor. The vanes constituting the impeller protrude from an outer periphery of the molded rotor.  
         [0007]     Additionally, in the central processing unit (CPU) for use in an electronic apparatus, a heating amount during operation tends to increase with speeding-up of a process or multi-function. As this thermal countermeasure, in recent years, an electronic apparatus comprising a so-called liquid-cooling type cooling device has been put into practical use. The device cools the CPU by mean of a liquid refrigerant having a specific heat much higher than that of air. In this cooling device, there has been a demand for a pump which has a stable pumping performance and which is capable of cooling the heat generating element satisfactorily for an extend period.  
         [0008]     To obtain a stable performance as the pump, the pump is preferably constituted in such a manner as to rotate a rotary member such as an impeller by the motor having the stator and a rotor magnet constituted of a permanent magnet. However, as described in the Jpn. Pat. Appln. KOKAI Publication No. 2003-343492, in the pump constituted by fixing an annular member (rotor magnet) constituted of the permanent magnet to the concave portion of the impeller formed of a resin, the rotor magnet is exposed to the liquid refrigerant in a pump chamber. Therefore, in the pump constituted in this manner, the rotor magnet is easily corroded by the liquid refrigerant. When the rotor magnet is corroded by the liquid refrigerant, there is a possibility that the performance of the motor drops, the liquid refrigerant is contaminated, and the cooling effect of the refrigerant drops.  
         [0009]     Moreover, in the pump described in the Jpn. Pat. Appln. KOKAI Publication No. 11-166500, the stator is molded out of the resin, the vanes constituting the impeller are protruded on the outer periphery of the cylindrical molded rotor, and it is therefore difficult to miniaturize the pump. Therefore, it is difficult to mount the pump constituted in this manner onto the electronic apparatus constituted by arranging various components in a comparatively dense manner. 
     
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING  
       [0010]     The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the 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 invention.  
         [0011]      FIG. 1  is a perspective view showing a portable computer according to a first embodiment of the present invention;  
         [0012]      FIG. 2  is a perspective view of the portable computer of  FIG. 1  as viewed from the side of a plurality of exhaust ports of the first housing;  
         [0013]      FIG. 3  is a plan view showing a cooling device contained in the first housing;  
         [0014]      FIG. 4  is an exploded perspective view of a pump;  
         [0015]      FIG. 5  is a perspective view of the pump in a state in which a second cover is omitted;  
         [0016]      FIG. 6  is a perspective view showing one example of another rotary member capable of being disposed in the pump;  
         [0017]      FIG. 7  is a sectional view cut along line VII-VII in  FIG. 3 ; and  
         [0018]      FIG. 8  is a sectional view showing the positional relation ships between the pump and a CPU in a portable computer according to a second embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0019]     A first embodiment of the present invention will be described hereinafter with reference to FIGS.  1  to  7 .  FIGS. 1 and 2  show a portable computer  1  which is an electronic apparatus. The portable computer  1  comprises a main unit  2 , and a display unit  3 . The main unit  2  comprises a first housing  10  having a flat box shape. The first housing  10  comprises a bottom wall  11   a , an upper wall  11   b , a front wall  11   c , right and left side walls  11   e ,  11   d , and a rear wall  11   f.    
         [0020]     As shown in  FIG. 1 , the upper wall  11   b  has a palm rest  12  and a keyboard attaching portion  13 . The keyboard attaching portion  13  is disposed behind the palm rest  12 . A keyboard  14  is attached to the keyboard attaching portion  13 . The front wall  11   c , right and left side walls  11   e ,  11   d , and rear wall  11   f  constitute a peripheral wall along a peripheral direction of the first housing  10 .  
         [0021]     As shown in  FIG. 2 , a plurality of exhaust ports  15  are formed in the peripheral wall of the first housing  10 , for example, the rear wall  11   f . These exhaust ports  15  are arranged in a row in a width direction of the first housing  10 .  
         [0022]     As shown in  FIG. 1 , the display unit  3  comprises a second housing  20  having a flat box shape, and a liquid crystal display panel  21  which is a display panel. The liquid crystal display panel  21  is contained in the second housing  20 . The liquid crystal display panel  21  has a screen  21   a  which displays an image. The screen  21   a  of the liquid crystal display panel  21  is exposed to the outside of the second housing  20  through an opening  22  formed in the front surface of the second housing  20 .  
         [0023]     The second housing  20  is supported on a rear end portion of the first housing  10  via a hinge (not shown). Therefore, the display unit  3  is rotatable over a closed position in which the unit is reclined in such a manner as to cover the palm rest  12  and the keyboard  14  from above, and an opened position in which the unit rises in such a manner as to expose the palm rest  12 , keyboard  14 , and screen  21   a.    
         [0024]     As shown in  FIG. 3 , a printed circuit board  30  is contained in the first housing  10 . As shown in  FIG. 7 , the printed circuit board  30  is disposed parallel to the bottom wall  11   a  of the first housing  10 . A CPU  31  which is a heat generating element is mounted on an upper surface of the printed circuit board  30 . The CPU  31  is constituted by a microprocessor which is the nucleus of the portable computer  1 .  
         [0025]     The CPU  31  has a base substrate  32  and an IC chip  33  disposed in a middle portion of the upper substrate of the base substrate  32  and having a flat square shape. The heat output of the IC chip  33  during operation is very large as a result at speeding-up of processing or increasing of functions, and cooling is required in order to maintain stable operation.  
         [0026]     As shown in  FIG. 3 , a liquid-cooling type cooling device  40  which cools the CPU  31  using a liquid refrigerant such as an antifreeze liquid is mounted in this portable computer  1 . The cooling device  40  is contained in the first housing  10 . The cooling device  40  comprises a pump  100  which functions both as a heat receiving portion and a heat exchange unit, a heat radiating portion  50 , a circulation path  60 , an electromotive fan  70  and the like.  
         [0027]     As shown in  FIGS. 4, 5 , and  7 , the pump  100  forcedly circulates the liquid refrigerant in the circulation path  60 , and comprises a pump housing  101  which also functions as the heat receiving portion, a rotary member  102 , a motor  103  having a rotor magnet  103   a  and a stator  103   b , and a control substrate  104 .  
         [0028]     The pump housing  101  comprises a housing main body  110 , a first cover  111 , and a second cover  112 . The housing body  110  has a flat box shape which is one size larger than the CPU  31 , and has a concave portion  113  opened upwards.  
         [0029]     The housing body  110  comprises a main portion  121  having a frame shape, and a heat receiving plate  122  which is a heat receiving portion to close a downward opened opening end of the main portion  121  in a liquid-tight manner. That is, the concave portion  113  is defined by an inner surface of the main portion  121  and an upper surface of the heat receiving plate  122 . The heat receiving plate  122  which also functions as the bottom wall of the concave portion  113  faces the CPU  31 . The lower surface of the heat receiving plate  122  forms a flat heat receiving surface  122   a . The heat receiving plate  122  is preferably formed of a metal material having high thermal conductivity such as copper, aluminum, and aluminum alloy. An O-ring  124  is disposed between the main portion  121  and the heat receiving plate  122 . It is to be noted that The housing body  110  may have an integral structure.  
         [0030]     The first cover  111  formed of a resin closes the opening end of the concave portion  113  in a liquid-tight manner. An O-ring  123  is disposed between The housing body  110  and the first cover  111 . The upper surface of the first cover  111  has a stator containing concave portion  115  which contains the stator  103   b , and a control substrate containing concave portion  116  which contains the control substrate  104 .  
         [0031]     An inner portion of the pump housing  101 , that is, a region surrounded with the concave portion  113  and the first cover  111  is partitioned into a pump chamber  118 , and a reserve tank  119  which accumulates the liquid refrigerant by an annular partition wall  117 . The partition wall  117  is formed integrally with The housing body  110  (main portion  121  in the present embodiment).  
         [0032]     The pump chamber  118  is disposed in the vicinity of one corner portion among four corner portions of the pump housing  101 . That is, the center position of the pump chamber  118  is eccentric with respect to that of the pump housing  101 . The reserve tank  119  is disposed in such a manner as to surround the pump chamber  118  from the remaining three corner portions among four corner portions of the pump housing  101 . A communication port  130  which allows communication between the pump chamber  118  and the reserve tank  119  is formed in the partition wall  117 .  
         [0033]     The housing body  110  (main portion  121  in the present embodiment) is provided with a suction tube  131  and a discharge tube  132 . The suction tube  131  and the discharge tube  132  are arranged horizontally with an interval therebetween. An upstream end of the suction tube  131  protrudes outwards via the side wall (main portion  121  in the present embodiment) of the housing body  110 . A downstream end of the suction tube  131  opens in the reserve tank  119 , and faces the communication port  130  of the partition wall  117 .  
         [0034]     The downstream end of the discharge tube  132  protrudes to the outside via the side wall (main portion  121  in the present embodiment) of The housing body  110 , and is aligned with the upstream end of the suction tube  131 . The upstream end of the discharge tube  132  opens into the pump chamber  118  through the partition wall  117 .  
         [0035]     As best shown in  FIG. 7 , the rotary member  102  has a disc-shaped rotary portion  102   b  and a rotation shaft  102   a  formed integrally with the rotary portion  102   b . The rotary portion  102   b  has a surface (this surface will be hereinafter referred to as the lower surface) facing the heat receiving plate  122 , and a surface (this surface will be hereinafter referred to as the upper surface)  108   b  opposite to the lower surface  108   a . The rotary member  102  is contained in the pump chamber  118  in a posture in which an axis of the rotation shaft  102   a  crosses the heat receiving plate  122 , for example, at right angles. Moreover, as to the rotary member  102 , the rotation shaft  102   a  is rotatably supported by the first cover  111  and the heat receiving plate  122  in a state in which the rotation shaft  102   a  extends over the first cover  111  and the heat receiving plate  122 .  
         [0036]     The motor  103  rotates the rotary member  102 , and has a rotor magnet  103   a  and a stator  103   b . The rotor magnet  103   a  is constituted, for example, of an annular permanent magnet in which a plurality of cathodes and anodes are mutually magnetized. The rotor magnet  103   a  is fixed to the rotary member  102  coaxially with the rotary member  102 , and contained in the pump chamber  118 . At least a region of the rotor magnet  103   a  facing the pump chamber  118  in the outer surface of the magnet is covered with the rotary member  102  in such a manner that the magnet does not contact the liquid refrigerant in the pump chamber  118 . In the present embodiment, the whole region of the outer surface of the rotor magnet  103   a  is covered with the rotary member  102 .  
         [0037]     In detail, the rotor magnet  103   a  is disposed in such a manner as to extend along the peripheral edge of the upper surface  108   b  of the rotary portion  102   b  and to protrude upwards, and is covered with a part of the rotary member  102 . The rotary member  102  is molded/formed, for example, by inserting the rotor magnet  103   a.    
         [0038]     That is, the rotary portion  102   b  has a protruding portion  109  disposed along the peripheral edge of the upper surface  108   b  and protruding in a direction (upward) opposite to a direction (downward) of the heat receiving plate  122 . The rotor magnet  103   a  is disposed in the protruding portion  109 . It is to be noted that in the present embodiment, the rotor magnet  103   a  is formed in such a manner that the length of the magnet in a direction crossing the rotation shaft  102   a  at right angles is less than that in a direction parallel to the rotation shaft  102   a  is shorter and a sectional shape is vertically long rectangular shape (see  FIG. 7 ).  
         [0039]     The rotary member  102  has a stirring portion  107  for stirring the liquid refrigerant in the pump chamber  118  on at least one of the lower surface  108   a  and the upper surface  108   b  of the rotary portion  102   b . When the stirring portion  107  is disposed on the lower surface  108   a  of the rotary member  102 , the liquid refrigerant can be satisfactorily passed in the vicinity of the heat receiving plate  122 . Therefore, when the stirring portion  107  is disposed on the lower surface  108   a  of the rotary member  102 , a cooling effect of the CPU  31  can be enhanced. When the stirring portion  107  is disposed on the upper surface  108   b  of the rotary member  102 , the efficiency of the pump  100  can be raised.  
         [0040]     As the pump  100  disposed in the cooling device  40 , a pump having a high cooling efficiency is preferable. In this case, the stirring portion  107  may be disposed on at least the lower surface of the rotary member  102 . In general, the portable computer  1  has been required to be made this. Therefore, when the pump  100  is mounted on an electronic apparatus as in the portable computer  1 , the pump is preferably as thin as possible. In this case, the stirring portion  107  may be disposed only on the lower surface of the rotary member  102 . Thus, the pump  100  can be made this as compared with a case where the stirring portions  107  are disposed on opposite surfaces (upper and lower surfaces) of the rotary member  102 .  
         [0041]     In the present embodiment, as shown in  FIGS. 4 and 7 , an impeller constituted by disposing the stirring portion  107  having a plurality of vanes  105  on the lower surface of the rotary portion  102   b  is adopted as the rotary member  102 .  
         [0042]     It is to be noted that as the rotary member  102 , a rotary member shown in  FIG. 6 , that is, the rotary member constituted by disposing the stirring portions  107  on the upper and lower surfaces of the rotary portion  102   b  may be adopted. When the stirring portion  107  is disposed on the upper surface  108   b  of the rotary member  102 , the stirring portion  107  is preferably disposed on a tip surface of the protruding portion  109  as shown in  FIG. 6 , and the stirring portion  107  may be disposed in a region other than the tip surface of the protruding portion  109 .  
         [0043]     Moreover, the rotary member  102  is not limited as long as the rotary member is capable of stirring a fluid such as a liquid refrigerant in the pump chamber  118 , and feeding the fluid to the outside of the pump chamber  118  from the inside of the pump chamber  118 . Therefore, the rotary member  102  is not limited to a member (impeller) comprising the stirring portion  107  having the vanes  105 . The rotary member  102  may comprise the stirring portion  107  having, for example, a plurality of concave portions  106  (see  FIG. 6 ). Even when this rotary member  102  is adopted, the fluid in the pump chamber  118  can be stirred, and fed to the outside of the pump chamber  118  from the inside of the pump chamber  118 . The rotary member  102  may comprise the stirring portion  107  having, for example, a spirally formed groove.  
         [0044]     The stator  103   b  constituting the motor  103  is contained in the stator containing concave portion  115  formed in the upper surface of the first cover  111 . Additionally, the stator  103   b  needs to be disposed corresponding to the rotor magnet  103   a  via the first cover  111 . Therefore, the stator containing concave portion  115  is disposed in a position facing the rotor magnet  103   a . The center position of the stator containing concave portion  115  is eccentric with respect to that of the first cover  111 . The control substrate containing concave portion  116  is disposed in a position avoiding the stator containing concave portion  115 .  
         [0045]     The opening of the concave portion  13  is closed by the first cover  111 , and accordingly the stator containing concave portion  115  is formed in such a manner as to enter the rotor magnet  103   a . That is, the stator  103   b  is coaxially disposed inside the rotor magnet  103   a  via the first cover  111 . The stator  103   b  is electrically connected to the control substrate  104 .  
         [0046]     Electric conduction with respect to the stator  103   b  is performed, for example, simultaneously with power supply to the portable computer  1 . By the electric conduction, a rotary magnet field is generated in the peripheral direction of the stator  103   b , and the magnet field is magnetically bonded to the rotor magnet  103   a . As a result, a rotary torque extending along the peripheral direction of the rotary member  102  is generated between the stator  103   b  and the rotor magnet  103   a , and the rotary member  102  rotates.  
         [0047]     The second cover  112  is fixed to the upper surface of the first cover  111 . The stator  103   b  and the control substrate  104  are covered with the second cover  112 . The second cover  112  is a cover for inhibiting leak or evaporation of the liquid refrigerant, and is formed by a metal material such as an aluminum alloy. It is to be noted that the second cover  112  may be omitted.  
         [0048]     The pump  100  constituted in this manner is placed on the printed circuit board  30  in such a manner as to cover the CPU  31  from above. As shown in  FIG. 7 , the pump housing  101  of the pump  100  is fixed to the bottom wall  11   a  of the first housing  10  together with the printed circuit board  30 . The bottom wall  11   a  has boss portions  17  in positions corresponding to four corner portions of the pump housing  101 . The boss portions  17  protrudes upwards from the bottom wall  11   a . The printed circuit board  30  is superimposed upon the tip surfaces of the boss portions  17 . It is to be noted that reference numeral  34  in  FIG. 7  denotes a reinforcing plate which reinforces the printed circuit board  30  from the lower surface.  
         [0049]     The pump  100  is attached to the bottom wall  11   a  of the first housing  10  in such a manner as to cover the CPU  31  from above by the following attaching mechanism. Concave portions  141  are disposed in four corner portions of the pump housing  101 . A bottom wall (corner portions of the heat receiving plate  122 ) which defines the concave portions  141  has through holes  142  through which cylindrical inserts  143  are passed. The inserts  143  have protruding portions  143   a  protruding outwards in a horizontal direction along a peripheral direction on upper ends of the inserts. The inserts  143  have groove portions  143   b  extending along the peripheral direction.  
         [0050]     The pump  100  is pressed onto the CPU  31  as follows by this attaching mechanism. First, the inserts  143  are passed through coil springs  144 . This insert  143  is inserted from the upward opened opening end of the concave portion  141  of the first cover  111 , and the groove portion  143   b  is positioned below the heat receiving surface  122   a  of the pump  100 . A C-ring  145  to prevent dropping is fitted in the groove portion  143   b . Accordingly, the inserts  143  are attached to the pump  100  while the protruding portions  143   a  are urged by the coil springs  144  in a direction detached from the bottom wall defining the concave portions  141 .  
         [0051]     A conductive grease (not shown) is applied to the upper surface of the IC chip  33  or a region of the heat receiving surface  122   a  corresponding to the IC chip  33 , and the heat receiving surface  122   a  of the pump housing  101  is disposed facing the IC chip  33 . Screws  146  passed through the inserts  143  are screwed into the boss portions  17  on the printed circuit board  30 . Accordingly, the inserts  143  are fixed to the boss portions  17 , and the pump  100  is pressed onto the IC chip  33  by elasticity of the coil spring  146 . Accordingly, the IC chip  33  is thermally connected to the heat receiving surface  122   a  of the pump housing  101  via the conductive grease.  
         [0052]     In this portable computer  1 , the pump  100  is fixed onto the printed circuit board  30  in such a manner that a center (center of the heat receiving surface  122   a ) of the pump housing  101  agrees with that of the IC chip  33 . On the other hand, the center (rotation shaft  102   a ) of the rotary member  102  is eccentric from that of the pump housing  101 . Therefore, the center of the IC chip  33  is eccentric from that of the rotary member  102  facing the chip via the pump housing  101 . Consequently, more heat from the IC chip  33  can be absorbed by the liquid refrigerant. That is, to absorb more heat from the IC chip  33  by the liquid refrigerant, the IC chip  33  is preferably disposed facing a position where the liquid refrigerant flows fast via the pump housing  101 . A flow of the liquid refrigerant generated by rotation of the rotor magnet  103   a  becomes fast away from the center of the rotary member  102 . Therefore, by the constitution, more heat from the IC chip  33  can be absorbed by the liquid refrigerant.  
         [0053]     As shown in  FIG. 3 , the heat radiating portion  50  comprises a heat radiating portion main body  51  and a plurality of heat emitting fins  57  thermally connected to the heat radiating portion main body  51 . The heat radiating portion main body  51  comprises a substantially U-shape pipe in which the liquid refrigerant flows. The heat radiating portion main body  51  has a refrigerant inlet  54  and a refrigerant outlet (not shown, disposed inside the drawing surface from the refrigerant inlet in  FIG. 3 ) in such a manner that the refrigerant flows inside. That is, one opening end of the substantially U-shaped pipe constitutes the refrigerant inlet  54 , and the other opening end constitutes the refrigerant outlet. That is, the pipe (heat radiating portion main body  51 ) of the heat radiating portion  50  constitutes a part of the circulation path  60  (the circulation path  60  will be described later in detail).  
         [0054]     The heat radiating portion main body  51  is contained in the first housing  10  in a posture (transversely reclined posture) obtained by rotating the substantially U-shaped pipe by 90° in such a manner that the refrigerant inlet  54  is disposed above and the refrigerant outlet is disposed below. The heat emitting fins  57  are formed, for example, of metal materials superior in thermal conductivity, such as aluminum alloy and copper. The heat emitting fins  57  are formed in square plate shapes. The heat emitting fins  57  are arranged parallel to one another at intervals. The respective heat emitting fins  57  are soldered to the heat radiating portion main body  51 .  
         [0055]     The heat radiating portion  50  is contained in the first housing  10  in a posture in which the heat emitting fins  57  are disposed facing the exhaust ports  15  of the first housing  10 . A pair of brackets  58  are soldered to the heat radiating portion  50 . These brackets  58  are fixed to the boss portions (not shown) protruding from the bottom wall  11   a  of the first housing  10  by screws. Thus, the heat radiating portion  50  is fixed to the bottom wall  11   a  of the first housing  10 .  
         [0056]     The circulation path  60  comprises a first tube  61 , a second tube  62 , and the pipe (heat radiating portion main body  51 ) of the heat radiating portion  50 . That is, the heat radiating portion main body  51  functions as both the heat radiating portion  50  and the circulation path  60 . The first tube  61  connects the discharge tube  132  of the pump  100  to the refrigerant inlet  54  of the heat radiating portion  50 . The second tube  62  connects the suction tube  131  of the pump  100  to the refrigerant outlet of the heat radiating portion  50 . Therefore, the liquid refrigerant is circulated between the pump  100  and the heat radiating portion  50  through the first tube  61  and second tube  62 .  
         [0057]     The electromotive fan  70  feeds cooling air to the heat radiating portion  50 , and is disposed immediately before the heat radiating portion  50 . The electromotive fan  70  comprises a fan casing  71  and a centrifugal impeller  72  contained in the fan casing  71 . The fan casing  71  has a discharge port  71   a  which discharges the cooling air. The discharge port  71   a  is connected to the heat radiating portion  50  via a duct  73 .  
         [0058]     The impeller  72  is rotated/driven by a motor (not shown), for example, when the power supply of the portable computer  1  is turned on, or the temperature of the CPU  31  reaches a predetermined temperature. Accordingly, cooling air is supplied to the heat radiating portion  50  from the discharge port  71   a  of the fan casing  71 .  
         [0059]     Next, an operation of the cooling device  40  will be described.  
         [0060]     During the use of the portable computer  1 , the IC chip  33  of the CPU  31  generates heat. The heat generated by the IC chip  33  is conducted to the pump housing  101  via the heat receiving surface  122   a  of the pump  100 . Since the concave portion  113  (pump chamber  118  and reserve tank  119 ) of the pump housing  101  is filled with the liquid refrigerant, the liquid refrigerant absorbs much heat conducted to the pump housing  101 .  
         [0061]     The electric conduction to the stator  103   b  of the motor  103  is performed, for example, simultaneously with the turning-on of the power supply to the portable computer  1 . Accordingly, a rotation torque is generated between the stator  103   b  and the rotor magnet  103   a , and the rotor magnet  103   a  rotates together with the rotary member  102 . When the rotary member  102  rotates, the liquid refrigerant in the pump chamber  118  is pressurized, discharged from the discharge tube  132 , and guided into the heat radiating portion  50  from the refrigerant inlet  54  via the first tube  61 . The liquid refrigerant heated by heat exchange in the pump housing  101  circulates toward the refrigerant outlet from the refrigerant inlet  54  in the heat radiating portion  50 , and the heat from the IC chip  33  absorbed by the liquid refrigerant is conducted to the heat emitting fins  57  in the process.  
         [0062]     When the impeller  72  of the electromotive fan  70  rotates during the use of the portable computer  1 , the cooling air blows toward the heat radiating portion  50  from the discharge port  71   a  of the fan casing  71 . This cooling air passes among the heat emitting fins  57  disposed adjacent to one another. Accordingly, the heat emitting fins  57  and the heat radiating portion main body  51  are cooled, and much of heat conducted to the heat emitting fins  57  or the heat radiating portion main body  51  rides on the flow of the cooling air, and is discharged to the outside of the first housing  10  from the exhaust ports  15 .  
         [0063]     The liquid refrigerant cooled by the heat radiating portion  50  is guided to the suction tube  131  of the pump housing  101  via the second tube  62 . This liquid refrigerant is returned to the reserve tank  119  from the suction tube  131 . The liquid refrigerant returned to the reserve tank  119  absorbs the heat from the IC chip  33  again while sucked into the pump chamber  118 . When this cycle is repeated, the heat from the IC chip  33  is successively transferred to the heat radiating portion  50 , rides on the flow of the cooling air passing through the heat radiating portion  50 , and is discharged to the outside of the first housing  10 .  
         [0064]     As described above, the pump  100  of the present embodiment comprises the heat receiving plate  122  thermally connected to the heat generating element comprising the CPU  31 , and the pump housing  101  having the pump chamber  118  in which the liquid refrigerant is contained. That is, the pump  100  has a function of the heat receiving portion, and that of the heat exchange unit. Therefore, the pump  100  can be preferably used in the above-described cooling device  40  mounted on the portable computer  1 .  
         [0065]     Moreover, in the pump  100 , at least the region of the rotor magnet  103   a  facing the pump chamber  118  is covered with the rotary member  102 . Concretely, the rotary member  102  formed of a resin is molded and formed by covering the rotor magnet  103   a . Therefore, the rotor magnet  103   a  does not contact the liquid refrigerant in the pump chamber  118 . Therefore, the rotor magnet  103   a  can be inhibited from being corroded by the liquid refrigerant. Consequently, a drop in the performance of the motor  103  caused by corrosion of the rotor magnet  103   a  by the liquid refrigerant, or a drop in the cooling effect by contamination of the liquid refrigerant can be inhibited. Therefore, according to the pump  100 , the heat generating element like the CPU  31  can be satisfactorily cooled for an extended period.  
         [0066]     Additionally, the pump  100  comprises the rotary member  102  having the stirring portion  107  for stirring the liquid refrigerant in the pump chamber  118  on one surface of the lower surface  108   a  and the upper surface  108   b . Therefore, the pump  100  can be formed to be thin as compared with the pump comprising the impeller on whose peripheral surface the vanes are disposed.  
         [0067]     Furthermore, in the pump  100 , the stirring portion  107  for stirring the liquid refrigerant in the pump chamber  118  is disposed only on the lower surface  108   a  of the rotary member  102 . Therefore, the pump  100  can efficiently cool the heat generating element like the CPU  31 , and can be formed to be thinner as compared with a case where the stirring portion  107  is disposed on the lower surface  108   a  and the upper surface  108   b  of the rotary member  102 .  
         [0068]     Moreover, in the pump  100 , the protruding portion  109  is disposed along the peripheral edge of the upper surface  108   b  of the rotary portion  102   b  of the rotary member  102 , and protrudes upwards. Moreover, the rotor magnet  103   a  is disposed in the protruding portion  109 . Therefore, when the stator  103   b  is disposed in the protruding portion  109 , the motor  103  can be easily constituted by the rotor magnet  103   a  and the stator  103   b . Therefore, even when the rotor magnet  103   a  is disposed in the rotary member  102 , the rotary member  102  can be satisfactorily rotated.  
         [0069]     Furthermore, the portable computer  1  of the present embodiment comprises the heat radiating portion  50  which discharges the heat of the CPU  31 ; the pump  100  which feeds the refrigerant to the heat radiating portion  50 ; and the circulation path  60  which circulates the liquid refrigerant between the pump  100  and the heat radiating portion  50  and which transfers the heat from the CPU to the heat radiating portion  50  via the liquid refrigerant. Therefore, the CPU  31  can be satisfactorily cooled by the portable computer  1  of the present embodiment for an extended period.  
         [0070]     A second embodiment of the present invention will be described with reference to  FIG. 8 .  
         [0071]     A pump  100  disposed in a portable computer  1  of the present embodiment is different from the pump  100  of the first embodiment in a sectional shape of a rotor magnet  103   a . That is, in the present embodiment, the rotor magnet  103   a  is formed in such a manner as to have a flat rectangular sectional shape of the magnet, whose length in a direction crossing a rotation shaft  102   a  at right angles is greater than that in a direction parallel to the rotation shaft  102   a . It is to be noted that another constitution is the same as that of the first embodiment including portions (not shown), and therefore denoted with the same reference numerals, and redundant description is omitted.  
         [0072]     In the pump  100  of the present embodiment, the rotor magnet  103   a  is formed in such a manner as to have a flat rectangular sectional shape whose length in a direction crossing the rotation shaft  102   a  at right angles is greater than that in a direction parallel to the rotation shaft  102   a . Thus, a protruding height of a protruding portion  109  of a rotary member  102  can be reduced. Therefore, according to the pump  100  of the present embodiment, a heat generating element like a CPU  31  can be satisfactorily cooled for an extended period in the same manner as in the pump  100  of the first embodiment. Therefore, the pump can be formed to be thin as compared with the pump  100  of the first embodiment.  
         [0073]     Moreover, according to the portable computer  1  of the present embodiment, the heat generating element like the CPU  31  can be satisfactorily cooled for an extended period in the same manner as in the portable computer  1  of the first embodiment, and can be made thin as compared with the portable computer  1  of the first embodiment.  
         [0074]     It is to be noted that in the pumps  100  of the first and second embodiments, the stirring portion  107  is disposed only on the lower surface  108   a  of the rotary member  102 , but the stirring portion  107  may be disposed on at least one of the lower surface  108   a  and the upper surface  108   b  of the rotary member  102 . That is, the stirring portion  107  may be disposed only on the upper surface  108   b  of the rotary member  102 .  
         [0075]     Moreover, the pump of the present invention can be broadly used not only in an electronic apparatus like the portable computer and the cooling device mounted in the apparatus but also in another apparatus. Furthermore, the electronic apparatus of the present invention is not limited to a portable computer, and can be broadly used in a heat generating element and the apparatus comprising the cooling device which cools the heat generating element.