Patent Publication Number: US-6662861-B2

Title: Heat exchanger

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is based upon and claims priority from Japanese Patent Application No.  11-354819,  filed Dec. 14, 1999, and is a continuation of PCT/JP008827, filed Dec. 13, 2000. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to a heat exchanger, particularly to a duplex heat exchanger in which a radiator and a condenser for a vehicle are integrated. 
     BACKGROUND OF THE INVENTION 
     According to the invention proposed in Japanese Unexamined Patent Publication 10-231724, for example, the cooling fins of the heat exchanger have a protrusion portion protruded from an end of the tube in the width direction of the tube to the direction perpendicular to the longitudinal direction of the tubes to increase the radiation area, thus improving the radiation ability of the heat exchanger. The width direction of the tube is a direction perpendicular to the longitudinal direction of the tube. 
     As is well known, the louvers on the cooling fin (called a fin hereinafter) are formed in louver board style by cutting and setting up part of the fin, and disturb the airflow around the fin to suppress growth of the temperature boundary layer, thereby improving the heat transfer coefficient between the airflow and the fin. However, since the louvers disturb the airflow, the resistance to the airflow passing through the heat exchanger may be increased. 
     In addition, since the louver is formed by cutting and setting up part of the fin, the thermal conductive area of the fin extending to the end of the protrusion portion is decreased, and thereby a sufficient amount of heat may not be conducted from the tube to the fin, and the improvement in radiation ability appropriate to the increase in radiation area may, accordingly, not be achieved. 
     DISCLOSURE OF THE INVENTION 
     It is therefore an object of the invention to improve the heat exchanging ability of a heat exchanger having fins protruded from an end of the tube in the width direction thereof. 
     In order to achieve the above object, a heat exchanger according to the present invention comprises a plurality of tubes ( 111 ,  121 ) in which fluid flows and which extend to the direction perpendicular to the direction of airflow, and fins ( 112 ,  122 ) which are provided on the outer surface of the tubes ( 111 ,  121 ) to accelerate the heat exchange between air and the fluid, wherein the fins ( 112 ,  122 ) have protrusion portions ( 112   e ,  122   e ) protruded from an end of the tubes ( 111 ,  121 ) in the width direction of the tube to the direction perpendicular to the longitudinal direction of the tubes ( 111 ,  121 ), and uneven portions ( 112   f ,  122   f ) are formed on the protrusion portions ( 112   e ,  122   e ), without cutting part of them, to increase the surface area of the fins ( 112 ,  122 ). 
     In this embodiment, the surface area of the protrusion portions ( 112   e ,  122   e ) may be increased without decreasing the thermal conductive area extending to the end of the protrusion portions ( 112   e ,  122   e ), and thereby a sufficient amount of heat may be conducted from the tubes ( 111 ,  121 ) to the fins ( 112 ,  122 ), especially to the protrusion portions ( 112   e ,  122   e ), and the improvement of radiation ability appropriate to the increase of radiation area may be achieved accordingly 
     In addition, the uneven portions ( 112   f ,  122   f ) do not disturb the airflow as much as the louvers because the uneven portions are not formed by cutting part of the fins in contrast to the louvers, thus decreasing the airflow resistance more than the louver. Although the heat transfer coefficient of the protrusion portions ( 112   e ,  122   e ) may be lower than that in case that the louvers are provided, the surface area of the protrusion portions ( 112   e ,  122   e ) are increased without decreasing the thermal conductive area of the protrusion portions ( 112   e ,  122   e ), and the air volume is increased due to the decrease of airflow resistance, and thereby the radiation ability may be improved, 
     Another embodiment of the present invention comprises a plurality of tubes ( 111 ,  121 ) in which fluid flows and which extend to the direction perpendicular to the direction of airflow, and fins ( 112 ,  122 ) which are provided on the outer surface of the tubes ( 111 ,  121 ) to accelerate the heat exchange between air and the fluid, and on which louvers ( 112   d ,  122   d ) are formed in louver board style by cutting and setting up part of the fins ( 112 ,  122 ), wherein the fins ( 112 ,  122 ) have protrusion portions ( 112   e ,  122   e ) protruded from an end of the tubes ( 111 ,  121 ) in the width direction of the tube to the direction perpendicular to the longitudinal direction of the tubes ( 111 ,  121 ), and the louvers ( 112   d ,  122   d ) formed on the protrusion portions ( 112   e ,  122   e ) are different from the louvers ( 112   d ,  122   d ) formed on the other portions than the protrusion portions ( 112   e ,  122   e ) of the fins ( 112 ,  122 ). 
     In this embodiment, the airflow resistance of the protrusion portions may be decreased, and the improvement in radiation ability appropriate to the increase of radiation area may be achieved accordingly. 
     The heat exchanger of another embodiment of the present invention is a duplex heat exchanger comprising a first heat exchanger ( 110 ) which is a heat exchanger according to the present invention, and a second heat exchanger ( 120 ) which is a heat exchanger according to the present invention arranged in series with the first heat exchanger ( 110 ) in the direction of airflow, wherein the protrusion portions ( 112   e ) of the first heat exchanger ( 110 ) are protruded to the second heat exchanger ( 120 ), and the protrusion portions ( 122   e ) of the second heat exchanger ( 120 ) are protruded to the first heat exchanger ( 110 ). 
    
    
     The present invention will be more fully understood in conjunction with the accompanying drawings and the descriptions of the preferred embodiments of the present invention. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the drawings: 
     FIG. 1 is a perspective view of the duplex heat exchanger of the first embodiment of the present invention viewed from the upstream side of the airflow. 
     FIG. 2 is a perspective view of the duplex heat exchanger of the first embodiment of the present invention viewed from the downstream side of the airflow. 
     FIG. 3 is a perspective view of the fin of the duplex heat exchanger of the first embodiment of the present invention. 
     FIG. 4A is a cross-sectional view of the core part of the duplex heat exchanger of the first embodiment of the present invention. 
     FIG. 4B is a cross-sectional view of the core part along the line A—A shown in FIG.  4 A. 
     FIG. 5 is a perspective view of the core part of the duplex heat exchanger of the first embodiment of the present invention. 
     FIG. 6 is a perspective view of the core part of the duplex heat exchanger of the second embodiment of the present invention. 
     FIG. 7 is a perspective view of the core part of the duplex heat exchanger of the third embodiment of the present invention. 
     FIG. 8 is a perspective view of the core part of the duplex heat exchanger of the fourth embodiment of the present invention. 
     FIG. 9 is a perspective view of the core part of the duplex heat exchanger of the fifth embodiment of the present invention. 
     FIG. 10A is a cross-sectional view of the core part of the duplex heat exchanger of the sixth embodiment of the present invention. 
     FIG. 10B is a cross-sectional view of the core part along the line A—A shown in FIG.  10 A. 
     FIG. 11A is a cross-sectional of the core part of the duplex heat exchanger of a variation of the present invention. 
     FIG. 11B is a cross-sectional view of the fin shown in FIG.  11 A. 
     FIG. 11C is a cross-sectional of the core part of the duplex heat exchanger of another variation of the present invention. 
     FIG. 11D is a cross-sectional view of the fin shown in FIG.  11 C. 
    
    
     PREFERRED EMBODIMENT OF THE PRESENT INVENTION 
     The First Embodiment 
     The first embodiment relates to a duplex heat exchanger, which is a heat exchanger according to the present invention, in which a condenser (radiator, condenser) for a refrigeration cycle system (air conditioner) for a vehicle, and a radiator for cooling the cooling water (cooling liquid) for a water-cooled engine (liquid-cooled internal combustion engine). FIG. 1 is a perspective view of the duplex heat exchanger  100  of the first embodiment viewed from the upstream side of the airflow. FIG. 2 is a perspective view from the water-cooled engine side (downstream side of the airflow). The condenser and the radiator are arranged in series in the direction of airflow so that the condenser is positioned on the upstream side of the radiator. 
     In FIG. 1, reference numeral  110  denotes a condenser (first heat exchanger) for conducting heat-exchange between the refrigerant circulating in the refrigeration cycle system and air to cool the refrigerant. The condenser  110  comprises a plurality of condenser tubes  111  in which the refrigerant (first fluid) flows, condenser fins (first fins)  112  which are provided on the outer surface between each two condenser tubes  111  to accelerate the heat exchange between the refrigerant and the air, header tanks  113  and  114  which are arranged at the both ends in the longitudinal direction of the condenser tubes  111  and are connected to the condenser tubes  111 , etc. 
     The header tank  113  at the right side in the figure supplies and distributes the refrigerant to each condenser tube  111 , and the header tank  114  at the left side in the figure collects the refrigerant after heat exchanging in each condenser tube  111 . 
     The condenser tubes  111  are of a multi-hole structure in which many refrigerant paths  111   a  are formed, and are formed flat in the manner of extrusion work or drawing work, as shown in FIG.  4 A. The condenser fins  112  are integrated with the after-mentioned radiator fins  122 , and the details are discussed later. 
     In FIG. 2, reference numeral  120  denotes a radiator for conducting heat-exchange between the cooling water flowing out from the water-cooled engine and air to cool the cooling water. The radiator  120  comprises a plurality of radiator tubes  121  in which cooling water (second fluid) flows, radiator fins (second fins)  122  which are provided between each two condenser tubes  111  to accelerate the heat exchange between the cooling water and air, header tanks  123  and  124  which are arranged at the both ends in the longitudinal direction of the radiator tubes  121  and are connected to each radiator tube  121 , etc. 
     The reference numeral  130  denotes a side-plate which is arranged at the end of the condenser  110  and the radiator  120  to reinforce both of the condenser  110  and the radiator  120 . The tubes  111  and  121 , the fins  112  and  122 , the header tanks  113 ,  114 ,  123 , and  124 , and the side-plates  130  are integrated by soldering. 
     The fins  112 ,  122  are discussed below. 
     The fins  112 ,  122  are formed in a single piece by a roller forming method as shown in FIG. 3, and are wave form corrugated fins consisting of a plurality of crest portions  112   a ,  122   a , trough portions  112   b ,  122   b , and flat portions  112   c ,  122   c  which connect adjacent crest portions  112   a ,  122   a , and trough portions  112   b ,  122   b.    
     On the flat portions  112   c ,  122   c , the louvers  112   d ,  122   d  are formed in louver board style by cutting and setting up part of the flat portions  112   c ,  122   c  to disturb the airflow passing through the fins  112 ,  122  to prevent growth of a temperature boundary layer. As shown in FIGS. 4A and 4B, connecting portions f are provided at intervals of a plurality of crest portions to connect the fins  112  and  122  so as to keep a distance of more than predetermined length W between the condenser fin  112  and the radiator fin  122 . 
     The predetermined length W is at least more than the thickness of the fin  112  or  122 , and a slit (space) S which is provided by keeping a distance of more than predetermined length w between the condenser fin  112  and the radiator fin  122  functions as a heat transfer suppressing means for suppressing the heat transfer from the radiator  120  side to the condenser  110  side. 
     Furthermore, on the radiator tube  121  side of the condenser fin  112 , a protrusion portion  112   e  is provided which protrudes from an end of the condenser tube  111  in the width direction of the tube to the radiator tube  121 , in the direction perpendicular to the longitudinal direction of the condenser tube  111 . On the condenser tube  111  side of the radiator fin  122 , a protrusion portion  122   e  is provided which protrudes from an end of the radiator tube  121  in the width direction of the tube to the condenser tube  111 , in the direction perpendicular to the longitudinal direction of the radiator tube  121 . 
     In addition, as shown in FIG. 5, on the protrusion portions  112   e ,  122   e , uneven portions  112   f ,  122   f  are formed in wave form in the manner of plastic deformation by a roller forming machine without cutting part of the protrusion portions  112   e ,  122   e  to increase the surface area of the fins  112 ,  122 . The uneven portions  112   f ,  122   f  are also formed so that the ridge direction Dw of the uneven portions  112   f ,  122   f  is substantially parallel with a cutting direction Dr of the louvers  112   d ,  122   d.    
     The ridge direction Dw of the protrusion portions  112   f ,  122   f  is the direction ranging the summits of the crest portions  112   g ,  122   g  (see FIG. 4B) of the wave form uneven portions  112   f ,  122   f , and the cutting direction Dr of the louvers  112   d ,  122   d  is the direction substantially perpendicular to the ridge direction Df ranging the summits of the crest portions  112   a ,  122   a  of the fins  112 ,  122 . 
     Below are described advantages of this embodiment. 
     According to this embodiment, the uneven portions  112   f ,  122   f  are provided on the protrusion portions  112   e ,  122   e  without cutting part of the protrusion portions  112   e ,  122   e , and thereby the surface area of the protrusion portions  112   e ,  122   e  may be increased without decreasing the thermal conductive area of the fins extending to the end of the protrusion portions  112   e ,  122   e.    
     For this reason, a sufficient amount of heat (arrow marks in FIG. 4A) may be conducted from the tubes  111 ,  121  to the fins  112 ,  122  (especially to the protrusion portions  112   e ,  122   e ), and the improvement in radiation ability appropriate to the increase in radiation area may be achieved accordingly. 
     In addition, the uneven portions  112   f ,  122   f  do not disturb the airflow as much as the louver  112   d ,  122   d  because the uneven portion  112   f ,  122   f  are not formed by cutting part of the fins in contrast to the louvers  112   d ,  122   d , thereby decreasing the airflow resistance more than the louvers. 
     Although the heat transfer coefficient of the protrusion portions  112   e ,  122   e  may be lower than that of the other portions (flat portions  112   c ,  122   c ) or the protrusion portion  112   e ,  122   e , on which the louvers  112   d ,  122   d  are provided, the surface area of the protrusion portions  112   e ,  122   e  is increased without decreasing the thermal conductive area of the protrusion portions  112   e ,  122   e , and the air volume is increased due to the decrease of airflow resistance, and thereby the radiation ability may be improved. 
     In addition, since the uneven portions  112   f ,  122   f  are also formed so that the ridge direction Dw of the uneven portions  112   f ,  122   f  is substantially parallel with a cutting direction Dr of the louvers  112   d ,  122   d , the ridge direction Dw and the cutting direction Dr are both substantially perpendicular to the fin material moving direction of the roller forming machine, and thereby the uneven portions  112   f  and  122   f , and the louvers  112   d  and  122   d  may be formed without using a special roller forming machine. For this reason, productivity of the fins  112  and  122  may be improved, and production cost of the fins  112  and  122  (the duplex heat exchanger  100 ) may be reduced accordingly. 
     The Second Embodiment 
     In the first embodiment, the uneven portions  112   f  and  122   f  are formed in a wave form, but in this embodiment, the uneven portions  112   f  and  122   f  are formed with dice-formed unevenness (dimples) as shown in FIG.  6 . 
     The Third Embodiment 
     In the above embodiments, the uneven portions  112   f ,  122   f  are formed on the protrusion portions  112   e ,  122   e  without cutting part of the protrusion portions  112   e ,  122   e . But in this embodiment and after-mentioned embodiments, the uneven portions  112   f ,  122   f  are not provided, but dimensions of lovers (called protrusion portion louvers  112   d ,  122   d  hereinafter) formed on the protrusion portions  112   e ,  122   e  are different from dimensions of louvers (called flat portion louvers  112   d ,  122   d  hereinafter) formed on the other portions than the protrusion portion  112   e ,  122   e.    
     More specifically, the cutting length L of the protrusion portion louvers  112   d ,  122   d  is determined to be decreased with increasing proximity to the protrusion end of the protrusion portions  112   e ,  122   e  as shown in FIG.  7 . 
     Thus, the airflow resistance of the protrusion portion louvers  112   d ,  122   d  may be reduced, and thereby the improvement in radiation ability appropriate to the increase in radiation area may be achieved. 
     Since the temperature difference between the fin and air is generally decreased with increasing proximity to the fin end (the portion farthest from the tube) regardless of the presence or absence of the louver, cooling efficiency of the fin is decreased with increasing proximity to the fin end. Therefore, in this embodiment, the airflow resistance is reduced by decreasing the cutting length L of the protrusion portion louver  112   d ,  122   d  at the end of the protrusion portion  112   e ,  122   e  where the cooling efficiency is very low. 
     The Fourth Embodiment 
     In this embodiment, cutting length L of the protrusion portion louver  112   d ,  122   d  is determined to be increased with increasing proximity to the protrusion end of the protrusion portion  112   e ,  122   e  as shown in FIG.  8 . 
     Thus, the airflow resistance of the protrusion portion louver  112   d ,  122   d  may be reduced, and the radiation ability may be improved accordingly. 
     In addition, the cutting length L at the basal portion side (tube  111 ,  121  side) of the protrusion portions  112   e ,  122   e  having high cooling efficiency is decreased to increase the thermal conductive area, and thereby sufficient amount of heat may be conducted to the basal portion side of the protrusion portions  112   e ,  122   e  having high cooling efficiency. For this reason, the improvement in radiation ability appropriate to the increase in radiation area may be surely achieved. 
     The Fifth Embodiment 
     In this embodiment, as shown in FIG. 9, in the region on the protrusion portion  112   e ,  122   e , corresponding to the main flow path of the air flowing between tubes  111 ,  121 , i.e. the region which is substantially at the center of the protrusion portion  112   e ,  122   e  and is substantially parallel to the airflow, the flat portion  112   h ,  122   h  is provided on which protrusion portion louvers  112   d ,  122   d  are not formed. 
     Thus, the airflow resistance of the region corresponding to the main flow having large flow rate may be reduced, and thereby airflow resistance may be reduced effectively, and the improvement in radiation ability appropriate to the increase in radiation area may be achieved accordingly. 
     As shown in FIG. 9, the flat portions  112   h ,  122   h  are provided so that the cutting length L of the protrusion portion louvers  112   d ,  122   d  is increased with increasing proximity to the protrusion end of the protrusion portions  112   e ,  122   e  as shown in FIG. 9, but the flat portion  112   h ,  122   h  may be provided so that the cutting length L of the protrusion portion louvers  112   d ,  122   d  is decreased with increasing proximity to the protrusion end of the protrusion portions  112   e ,  122   e.    
     The Sixth Embodiment 
     In this embodiment, the cutting angle β of the protrusion portion louvers  112   d ,  122   d  is determined to be decreased with increasing proximity to the protrusion end of the protrusion portions  112   e ,  122   e  as shown in FIG.  10 B. 
     The cutting angle β of the protrusion portion louvers  112   d ,  122   d  is an angle between the protrusion portion louvers  112   d ,  122   d  formed by cutting and setting up part of the flat portions and the flat portions  112   c ,  122   c . β=0 means that a louver is not formed. 
     Thus the airflow resistance of the protrusion portion louvers  112   d ,  122   d  may be reduced, and thereby the improvement in radiation ability appropriate to the increase in radiation area may be achieved. 
     Other Embodiments 
     The heat exchanger of the aforementioned embodiment is a duplex heat exchanger in which a condenser and a radiator are integrated but the present invention may also provide a single heat exchanger such as a condenser or a radiator. 
     For example, FIG.  11 A˜ 11 D show a radiator to which the spirit of the first embodiment of the present invention is implemented. It is apparent from FIG. 11C that protrusion portion  122   e  of the fin  122  may be provided at both side ends of the fin  122 . 
     As described above, the present invention is described based on the particular embodiments, however, it will be understood by those skilled in the art that the embodiments may be subject to numerous adaptations and modifications without departing from the scope and spirit of the invention.