Abstract:
A heat exchanger for exchanging heat with gas made to flow in a flow direction is disclosed. The heat exchanger is provided with: a plurality of plates each having a first side and a second side; a plurality of tubes configured to conduct a thermal medium, the tubes penetrating the plates and being arranged in parallel with each other and on a plurality of planes perpendicular to the flow direction, wherein the tubes on each plane are disposed adjacent to gaps between the tubes on any of adjacent planes so as to form a plurality of serpentine flow lines among the tubes; and a plurality of bridges projecting on the first sides of the plates, the bridges being respectively arranged to be perpendicular to the serpentine flow lines.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is based upon and claims the benefit of priority from the prior Japanese Patent Application Nos. 2006-077169 (filed on Mar. 20, 2006), 2006-012258 (filed on May 15, 2006), and 2006-012259 (filed on May 15, 2006); the entire contents of which are incorporated herein by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a heat exchanger for exchanging heat between gas and a thermal medium. 
         [0004]    2. Description of the Related Art 
         [0005]    Heat exchangers are utilized in various uses. A heat exchanger is provided with a plurality of tubes for conducting a thermal medium and a plurality of fins respectively projecting from the tubes. Any gas subject to heat exchange is pressurized to flow through spaces among the tubes and the fins so as to exchange heat with the thermal medium. For improvement of efficiency of the heat exchange, dimensions of the tubes and the fins are the subject of research. 
       SUMMARY OF THE INVENTION 
       [0006]    An object of the present invention is to provide a heat exchanger which improves efficiency of heat exchange. 
         [0007]    According to a first aspect of the present invention, a heat exchanger for exchanging heat with gas made to flow in a flow direction is provided with: a plurality of plates each having a first side and a second side; a plurality of tubes configured to conduct a thermal medium, the tubes penetrating the plates and being arranged in parallel with each other and on a plurality of planes perpendicular to the flow direction, wherein the tubes on each plane are disposed adjacent to gaps between the tubes on any of adjacent planes so as to form a plurality of serpentine flow lines among the tubes; and a plurality of bridges projecting on the first sides of the plates, the bridges being respectively arranged to be perpendicular to the serpentine flow lines. 
         [0008]    According to a second aspect of the present invention, a heat exchanger for exchanging heat with gas made to flow in a flow direction is provided with: a plurality of plates each having a first side and a second side; a plurality of tubes configured to conduct a thermal medium, the tubes penetrating the plates and being arranged at an even pitch in parallel on a plurality of planes perpendicular to the flow direction, wherein the tubes on each plane are respectively deviated in a lateral direction with respect to the tubes on any of adjacent planes by half of the pitch of the tubes and the half of the pitch is not greater than diameters of the tubes; and a plurality of bridges projecting on the first sides of the plates, the bridges being respectively arranged to be perpendicular to the serpentine flow lines. 
         [0009]    According to a third aspect of the present invention, a heat exchanger for exchanging heat with gas made to flow in a flow direction is provided with: a plurality of plates each having a first side and a second side; a plurality of openings formed on the plates and arranged in a plurality of rows perpendicular to the flow direction, wherein the openings in each row are disposed adjacent to gaps between the openings in any of adjacent rows; a plurality of bridge groups respectively projecting on the first sides of the plates and being disposed at the gaps, each of the bridge groups including a plurality of bridges perpendicular to the flow direction and arranged in a row along the flow direction, a first pair of sub-bridges disposed on an upstream end of the row with respect to the flow direction and slanted from a center to both sides of the first pair toward the flow direction, and a second pair of sub-bridges disposed on a downstream end of the row with respect to the flow direction and slanted from both sides to a center of the second pair toward the flow direction; and a plurality of tubes configured to conduct a thermal medium, the tubes respectively penetrating the openings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  is a schematic cross sectional view of a heat exchanger in accordance with an embodiment of the present invention; 
           [0011]      FIG. 2  is a side view of the heat exchanger; 
           [0012]      FIG. 3  is a sectional view of the heat exchanger taken along a line A-A of  FIG. 1 ; 
           [0013]      FIG. 4  is a perspective view of a plate applied to the heat exchanger; 
           [0014]      FIG. 5  is a plan view of the plate; 
           [0015]      FIG. 6  is a sectional view of the plate taken along a line B-B of  FIG. 5 ; and 
           [0016]      FIG. 7  is a sectional view of the plate taken along a line C-C of  FIG. 5 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0017]    An embodiment of the present invention will be described hereinafter with reference to the appended drawings. 
         [0018]    A heat exchanging unit  17  of the present embodiment is used in a housing such as one shown in  FIG. 1 . The housing is provided with a cylinder  14  and flanges  15 ,  16  fixed at both ends thereof for air-tightening. The exteriors of the flanges  15 ,  16  are further enclosed by walls, which respectively define fluid rooms  23 ,  24 . The heat exchanging unit  17  is provided with a plurality of tubes  18  running along an axis of the cylinder  14 , which liquid-tightly penetrate the flanges  15 ,  16  and have openings at both ends to communicate with the fluid rooms  23 ,  24 . 
         [0019]    The heat exchanging unit  17  is further provided with a plurality of plates  21 , which the tubes  18  penetrate. The plates  21  stand substantially vertical to the axis of the cylinder  14  and are arranged to have even intervals therebetween. 
         [0020]    Referring to  FIG. 2 , the fluid room  23  is liquid-tightly partitioned into two sub-rooms  23   a,    23   b  by a partition  25 . An inlet port  26  is linked with the sub-room  23   a  and an outlet port  27  is linked with the sub-room  23   b,  thereby a thermal medium such as a cooling water is capable of flowing in and out of the fluid room  23 . The thermal medium flowing through the inlet port  26  into the sub-room  23   a  further flows through some of the tubes  18  and then reaches the opposite fluid room  24 . Further, the thermal medium in the fluid room  24  flows through the rest of the tubes  18 , reaches the sub-room  23   b,  and are then exhausted out of the outlet port  27 . 
         [0021]    The cylinder  14  has a partition  28  therein, which runs along the axis, to partition the interior thereof into a gas migration chamber  29  and the rest as shown in  FIG. 3 . The rest of the interior is further partitioned into a gas inflow chamber  32  and a gas outflow chamber  33  by a partition  31  provided at an axial middle of the interior of the cylinder  14  as shown in  FIG. 1 . The cylinder  14  is provided with a gas inflow port  33  and a gas outflow port  35  to respectively communicate with the gas inflow chamber  32  and the gas outflow chamber  33 . 
         [0022]    Gas subject to heat exchange, such as air to be cooled, is made to flow into the gas inflow port  34  by any gas feeding means such as a rotating fan or a pump. The gas flows through the gas inflow port  34  into the gas inflow chamber  32  as indicated by arrows from the top to the right in  FIG. 3 . The gas further flows through the heat exchanging unit  17  as indicated by arrows from the right to the left in  FIG. 3 , and enters the gas migration chamber  29 . The gas migrates in the gas migration chamber  29  from the left to the right of  FIG. 1  and then flows though the heat exchanging unit  17  to the gas outflow chamber  33 . The gas in the gas outflow chamber  33  flows out of the gas outflow port  35 . 
         [0023]    In the course of the aforementioned flow of the gas, the thermal medium exchanges heat with the gas. If cooling water is applied to the thermal medium and air is the gas, the air is cooled by the cooling water as a result of the heat exchange. The cooled air is extracted from the gas outflow port  35 . 
         [0024]    Details of the heat exchanging unit  17  will be described hereinafter with reference to  FIGS. 4-7 . 
         [0025]    The plates  21  are configured to increase contact area with respect to the flowing gas and serve as cooling (or heating) fins. As mentioned above, the gas flowing around the plates  21  is as a whole directed in a direction from one end to another end of each of the plates  21 . The direction is shown as from the right to the left in  FIG. 3  and as from the top to the bottom in  FIG. 5 . Throughout the specification and claims, “a flow direction” with respect to each of the plates  21  is defined as a direction along which the gas is made to flow and correspondent with a direction from one end to another end of each of the plates  21 . 
         [0026]    Each of the plates  21  is provided with a plurality of openings  36  which fixedly support the tubes  18 . The openings  36  are arranged in a plurality of rows which are perpendicular to the flow direction and arranged at even intervals. Positions of the openings  36  in each row are laterally deviated from positions of the openings  36  in the adjacent row by half of a pitch of the openings  36 , thereby the openings  36  in each row are disposed adjacent to gaps between the openings  36  in the adjacent row. The half of the pitch is not greater than the diameter of the openings  36 . 
         [0027]    Collars  37  respectively stand around the openings  36 . The collar  37  serves as a spacer for keeping gaps toward an adjacent plate  21 . The collar  37  further serves to transmit heat between the plate  21  and the tube  18 . 
         [0028]    Respective spaces among the openings  36  are cut or punched out to project from one side of the plate  21  as shown in  FIGS. 4 and 7 . These projections form a group in each space and each projection is formed to be a shape of a bridge having legs at both ends and a flat top spanning the legs as shown in  FIG. 6 . Bridges  39 ,  40 ,  41  at the middle of each group are directed perpendicular to the flow direction and arranged in a row along the flow direction. Upstream of the bridges  39 ,  40 ,  41  with respect to the flow direction, just downstream of one opening  18 , a pair  38  of sub-bridges  38   a,    38   b  is formed. The sub-bridges  38   a,    38   b  are arranged to be symmetrical with respect to the center of the pair and are slanted from the center to both sides of the pair  38  toward the flow direction. Similarly, downstream of the bridges  39 ,  40 ,  41 , just upstream of another opening  18 , a pair  42  of sub-bridges  42   a,    42   b  is formed, however, contrary to the aforementioned sub-bridges  38   a,    38   b,  the sub-bridges  42   a,    42   b  are slanted from both sides to the center of the pair  42  toward the flow direction. 
         [0029]    Arrangement of the tubes  36  respectively inserted in the openings  36  defines a plurality of serpentine flow lines  44  among the tubes  36 , as indicated by serpentine arrows in  FIG. 5 . The bridges  39 ,  40 ,  41  and the sub-bridges  38   a,    38   b,    42   a,    42   b  are arranged along and perpendicular to the serpentine flow lines  44 . Further, the legs of the bridges  39 ,  40 ,  41  and the sub-bridges  38   a,    38   b,    42   a,    42   b  are substantially in parallel with the serpentine flow lines  44 . 
         [0030]    The plate  21  is provided with ribs  43  projecting on the same side as the bridges as shown in  FIG. 7 . The shape of the ribs  43  is not limited to but can be a triangular sectional shape. The ribs  43  run at respective middles of the rows of the openings  18 . 
         [0031]    When assembling the plates  21  and the tubes  18 , one of the plates  21  is handled so that the tubes  18  are inserted to the respective openings  36  thereof. The plates  21  are one by one put under assembly to be combined with the tubes  18 . When one of the plates  21  abuts on another of the plates  21  with interposing the collar  37 , the gap therebetween is regulated by the collar  37  serving as a spacer. After all of the plates  21  and the tubes  18  are assembled, the tubes  18  are broadened so as to fix the tubes  18  with the plates  21 . 
         [0032]    Thereby, the tubes  18  and the plates  21  are combined to form the heat exchanging unit  17 . The assembled heat exchanging unit  17  is combined in the cylinder  14 . 
         [0033]    The heat exchanging unit  17  exchanges heat in accordance with the following manner. 
         [0034]    The gas subject to the heat exchange, such as air to be cooled, is made to flow from the top to the bottom in  FIG. 5 . When the gas goes around any of the tubes  36 , the gas tends to turn aside around an upstream face thereof. Since the sub-bridges  42   a  and  42   b  in the upstream stand there so as to conduct the flow, the flow of the gas is smoothly branched into right and left streams. Then the right stream is conducted by the sub-bridge  38   a  of another group of bridges at the right and the downstream, and the left stream is conducted by the sub-bridge  38   b  of the other group of bridges at the left and downstream. The streams are respectively merged with the other adjacent branched streams. These merged streams are then further branched by the lowermost sub-bridges  42   a  and  42   b  of the current bridge group. Therefore, the streams of the gas are respectively faired along the serpentine flow lines  44 . 
         [0035]    In general, gas flowing among cylindrical bodies such as the tube  18  tends to form stagnation around downstream faces of the cylindrical bodies, however, the faring effect of the bridges prominently reduces the stagnation. Further, since the streams of the gas just downstream of the tube  18  receive force in lateral directions by the ribs  43 , the stagnation is further reduced. Reduction in the stagnation improves efficiency of heat exchange of the heat exchanging unit  17 . 
         [0036]    The streams of the gas further receive force in a direction perpendicular to the plates  21  (perpendicular to a paper face of  FIG. 5 ) from the bridges  38 - 42  and the ribs  43  to three-dimensionally fluctuate. Therefore contact length of the gas with the plates  21  increases and hence efficiency of the heat exchange further increases. 
         [0037]    The ribs  43  may be formed not of continuity as mentioned above but of discontinuity. For example, merely portions just downstream of the tubes  18  may be formed to project but portions just downstream of the bridges  38 - 42  may not be projected. Moreover, the ribs  43  maybe formed in paired parallel rib shapes or half-round sectional shapes, or any other modifications may be applicable. 
         [0038]    Further, the bridges may be formed in other shapes, such as arch shapes. Any bridge between the sub-bridges  38 ,  42  may also be divided in a pair of sub-bridges like as the sub-bridges  38 ,  42 . 
         [0039]    Although the invention has been described above by reference to certain embodiments of the invention, the invention is not limited to the embodiments described above. Modifications and variations of the embodiments described above will occur to those skilled in the art, in light of the above teachings.