Patent Publication Number: US-7210520-B2

Title: Heat exchanger

Description:
CROSS REFERENCE TO RELATED APPLICATION 
   This application is based upon and claims the benefit of priority of Japanese Patent Application No. 2004-046828 filed on Feb. 23, 2004, the content of which is incorporated herein by reference. 
   FIELD OF THE INVENTION 
   The present invention relates to a heat exchanger, which can effectively be applied to an intercooler for cooling air (intake air) before introduced into an internal combustion engine to support combustion. 
   BACKGROUND OF THE INVENTION 
   A conventional heat exchanger for cooling intake air pressurized by a supercharger before introduced into an internal combustion engine has a core portion having a plurality of tubes and serving as a heat exchanging portion and a header tank communicated with the plurality of tubes in the core portion. 
     FIG. 8  depicts a sectional view of an example of a structure of the above header tank. A core plate  911  to which a tube  922  is blazed and a tank body  912  are joined to each other to form the header tank  910  and a chamber  910   a  therein. Two side walls  912   b  at both sides of the tank body  912  are supported by a support bar  912   a  disposed therebetween and joined thereto such by welding, in a manner of penetrating the chamber  910   a.    
   Recent emission regulation requires to increase boost pressure. If the header tank  910  does not have the support bar  912   a , the boost pressure may deform the tank body  912  to bulge outward, and also deform the core plate  911  to increase a distance between edges  911   b  thereof. This deformation generates a large stress at a connection  911   a  of the core plate  911  and the tube  922  inducing defect such as a fracture at the connection. The support bar  912   a  is for preventing the above defect. 
   However, the above conventional heat exchanger requires to bore the tank body  912  for fixing the support bar  912   a  and to weld the support bar  912   a  to the tank body  912  in a manner of securing the airtightness. The structure of the above heat exchanger makes the manufacture complex and increases manufacturing facilities and the manufacturing processes of the heat exchanger. 
   The inventors of the present invention has focused attention on stress reduction generating at the connection of the core plate and the tube, and discovered a heat exchanger capable of reducing the stress at the connection without the support bar and just by limiting deformation of only the core plate. 
   SUMMARY OF THE INVENTION 
   It is therefore an object of the present invention is to provide a heat exchanger for reducing stress at a connection of a core plate and a tube of the heat exchanger without using a bulging limiter of a tank body of the heat exchanger. 
   To achieve the above object, a heat exchanger according to the present invention comprises a plurality of tubes, header tanks and a support. 
   Fluid flows through the plurality of tubes. 
   The header tanks have a core plate and a tank body, and are disposed at longitudinal end portions of the plurality of tubes in such a manner to be communicated with internal spaces of the plurality of tubes. The core plate has approximately arc-shaped cross-section of which both side fringes are fixed onto the tank body and of which a middle portion fixes thereon the longitudinal end portions of the plurality of tubes and bulges with respect to the both side fringes toward the plurality of tubes. The tank body and the core plate form an internal space of each of the header tanks. 
   The support retains an interval between the both side fringes. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other features and advantages of the present invention will be appreciated, as well as methods of operation and the function of the related parts, from a study of the following detailed description, the appended claims, and the drawings, all of which form a part of this application. In the drawings: 
       FIG. 1  is a front view of an intercooler, or a heat exchanger according to a first embodiment of the present invention; 
       FIG. 2  is a sectional view taken along the line ll—ll in  FIG. 1 ; 
       FIG. 3A  is a schematic developed view of a tank in the first embodiment; 
       FIG. 3B  is a schematic perspective view of the tank in the first embodiment; 
       FIG. 4  is a sectional view of a principal part of an intercooler according to a second embodiment of the present invention; 
       FIG. 5  is a schematic side view of a cylinder in the second embodiment; 
       FIG. 6  is a schematic developed view of a plate in another embodiment; 
       FIG. 7A  is a schematic side view showing a forming process of a cylinder in another embodiment; 
       FIG. 7B  is a schematic side view showing the forming process of the cylinder in the other embodiment; and 
       FIG. 8  is a sectional view of a principal part in a conventional intercooler. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   (First Embodiment) 
   In a first embodiment of the present invention, a heat exchanger according to the present invention is applied to an intercooler  100  shown in  FIGS. 1 and 2 . The intercooler  100  is for cooling intake air pressurized by a supercharger before induced into an internal combustion engine.  FIG. 1  shows therein a part of a core portion  120  of the intercooler  100 , which will be described below. 
   As shown in  FIG. 1 , the intercooler  100  has the core portion  120  and a pair of header tanks  110  located at a left and a right sides of the core portion  120 . The core portion  120  has outer fins  121  and tubes  122  that are laterally disposed between the header tanks  110  and alternately stacked. A pair of side plates  124  is disposed outside of an uppermost and a lowermost outer fins  121  as reinforcements. The above components in the core portion  120  are brazed to each other to be an unit. 
   The header tanks  110  are disposed at both ends of the tubes  122 , which are arranged perpendicular to the header tanks  110 , so as to communicate insides of the header tanks  110  with those of the tubes  122 . Both end portions of each tubes  122  are inserted into and brazed to bores (not shown) formed in core plates  111  of the header tanks  110 . 
   The tube  122  is fabricated in a planular shape by snapping a pair of channel-shape plates into each other so that their openings come closer to each other and brazing them. Inner fins (not shown) are brazed in the tubes  122 , and the outer fins  121  are brazed on outer surfaces of the tubes  122 . The outer fins  121  and the inner fins are made of copper having a required large thermal conductivity, and the tubes  122  and the side plates are made of alloys of copper having a required strength and thermal conductivity. 
   Each of the header tanks  110  is fabricated with the core plate  111  made of 3 mm thick alloys of copper, a tank body  112  and a bottom part (not shown). The core plate  111  and the tank body  112  are brazed or welded onto each other to form an internal space therein. The detailed structure of the header tank  110  will be described below. 
   A right-hand side header tank  110  in  FIG. 1  is for distribution and supply of the intake air to the respective tubes  122  whereas a left-hand side header tank  110  in  FIG. 1  is for collecting the intake air flowing out of the tubes  122 . The right-hand side header tank has an inlet connector  113  in communication with the inside thereof, and the left-hand side header tank has an outlet connector  114  in communication with the inside thereof. The inlet connector  113  is connected to a discharge port of a supercharger (not shown), and the outlet connector  114  is connected to an intake port of an engine (not shown). 
   The cross-sectional area of internal space  110   a  of the header tank  110  gradually decreases in a longitudinal direction thereof as going away from the inlet/outlet connector  113 ,  114 , so as to equalize the airflow in the respective tubes  122 . 
   Stays  130  are fixed on each of the header tanks  110  at the outer side of the intercooler  100 , for fixing the intercooler  100  onto the structural member of a vehicle. 
   The respective components of the core portion  120  are assembled together with the core plate  111  by snapping, by assembly jigs or by fixing, then brazed to be one body with a blazing paste clad on the desirable portion. Then the tank body  112  is welded onto the core plate  111  to be the intercooler  100 . 
   The present invention is characterized in a structure of the header tank  100 . The detailed structure will be described hereinafter with reference to  FIGS. 2 ,  3 A and  3 B.  FIGS. 3A and 3B  depict the forming process of the tank body  112  of the header tank  110 . 
   As shown in  FIG. 2 , the header tank  110  is assembled with the core plate  111  and the tank body  112 , and has the internal space  110   a  therein. The core plate  111  has approximately arc-shaped cross-section, of which a middle portion  111   a  bulges with respect to both side fringes  111   b  (interposing the middle portion  111   a ) toward longitudinal middle portions of the tubes  122 . The tank body  112  has approximately U-shaped cross-section. Both sides of a support  112   a  are fixed onto the fringes  111   b  of the core plate  111 . 
   The tank body  112  including the support  112   a  is formed from a sheet material  200  shown in  FIG. 3A . The sheet material  200  has a body portion  201  for forming the tank body  112  and a pair of support portions  202  interposing the body portion  201  therebetween and for forming the support  112   a . Each of the support portions  202  has a plurality of rectangular notches  203  disposed at a predetermined interval. The portions for forming the support  112   a  interpose the notches  203 . 
   The notches  203  can be formed in punch pressing the sheet material  200  and also be formed by cutting off portions corresponding to the notches  203  from a sheet material punch pressed in an approximately trapezoid shape. The body portion  201  has an approximately trapezoid shape whose width decreased from a right side to a left side thereof in  FIG. 3A , so as to form the header tank  110  having the internal space  110   a  of which a cross-sectional area gradually decreases in the longitudinal direction thereof as going away from the inlet/outlet connector  113 ,  114  as described above. 
   The sheet material  200  shown in  FIG. 3A  is bended to form the approximately U-shaped tank body  112 . Then, a pair of the support  112   a  extending out from the U-shaped body portion  201  are butt-joined to each other by welding, etc.  FIG. 3B  depicts an outline of the tank body  112  and the support  112   a , wherein a thickness and a detailed shape of each component are not shown. 
   The header tank  110  is assembled by fixing the tank body  112  formed with the support  112   a  in a body onto the fringes  111   b  of the core plate  111 . Here, the support  112   a  are connected to the fringes  111   b  of the core plate  111 , so as to retain an interval between a pair of the fringes  111   b.    
   The above configurations and manufacturing method of the heat exchanger  100  serves to reduce the deformation of the core plate  111 , that is, an increase or a decrease of an interval between a pair of the fringes  1   b , even when a large intake air pressure acts on the internal space  110   a  of the header tank  110 . Thus, stress generating at a connection part (the middle portion)  111   a  of the core plate  111  and the tubes  122  is also reduced. 
   The inventors of the present invention have confirmed by an experiment that the intercooler  100  in the first embodiment endures a cyclic intake air pressure fluctuating between 0 kPa and 500 kPa more than 600,000 times, causing no malfunction such as a crack generation at the connection part  111   a  of the core plate  111  and the tubes  122 . 
   The support  112   a  reduces the deformation of the core plate  111 , not by retaining an interval between two side walls at both sides of the tank body  112 , but by retaining the interval between a pair of the fringes  111   b . Thus, it is not necessary to form bores on the side walls of the tank body  112 , to dispose a support bar between the bores and to weld the support bar onto the side walls so as to secure airtightness, as shown in  FIG. 8 . 
   Further, the support  112   a  is formed in a body together with the tank body  112 , and fixed onto the core plate  111  in assembling the header tank  110  by connecting the core plate  111  and the tank body  112 . This configuration reduces manufacturing processes than a conventional method of making the support  112   a  separately and fixing the support  112   a  onto the core plate  111 . 
   Furthermore, the tank body  112  having the support  112   a  in a body can be easily manufactured from the sheet material  200 . 
   (Second Embodiment) 
   A heat exchanger according to a second embodiment differs from that in the first embodiment in having a tank body  112  and a support  112   a  shown in  FIGS. 4 and 5  that are not formed from a sheet material. 
   The tank body  112  and the support  112   a  in the second embodiment is formed in a cylinder  300  of which an outline is shown in  FIG. 5  and made of alloys of copper. The cylinder  300  is formed by hydroforming into a shape having a cross-section shown in  FIG. 4 . The cylinder  300  has a body portion  301  and a support portion  302  integrally as shown in  FIG. 5 . The support portion  302  has a plurality of approximately rectangular openings  303  disposed at a predetermined interval. The openings  303  are formed by cutting respective parts of the support portion  302  by cutting work, laser beam machining, etc. The portions for forming the support  112   a  interpose the openings  303 . 
   The header tank  110  is assembled by fixing the tank body  112  formed with the support  112   a  in a body as described above onto the fringes  111   b  of the core plate  111  as shown in  FIG. 4 . Here, the support  112   a  are connected to the fringes  111   b  of the core plate  111 , so as to retain an interval between a pair of the fringes  111   b.    
   In the second embodiment, the tank body  112  of the header tank  110  is formed in the cylinder  300 , therefore, has an approximately uniform diameter in a longitudinal direction thereof. 
   The above configurations and manufacturing method of the heat exchanger, as in the case of the first embodiment, serves to reduce the deformation of the core plate  111 , that is, an increase or a decrease of an interval between a pair of the fringes  111   b , even when a large intake air pressure acts on the internal space  110   a  of the header tank  110 . Thus, stress generating at a connection part (the middle portion)  111   a  of the core plate  111  and the tubes  122  is also reduced. 
   Further, the support  112   a  is formed in a body together with the tank body  112 , and fixed onto the core plate  111  in assembling the header tank  110  by connecting the core plate  111  and the tank body  112 . This configuration reduces manufacturing processes than a conventional method of making the support  112   a  separately and fixing the support  112   a  onto the core plate  111 . 
   Furthermore, the tank body  112  having the support  112   a  in a body can be easily manufactured from the sheet material  200 . 
   Other Embodiments 
   In the first embodiment, the sheet material  200  has a pair of the support portions  202  in a manner of interposing the body portion  201 . However, the header tank  110  may be formed from a sheet material having a body portion for forming the tank body  112  and a support portion (support portions) for forming the support  112   a  that are arranged in a different manner from that of the sheet material  200 . For example, as shown in  FIG. 6 , the header tank  110  may be formed from a sheet material  200  having one support portion  202  at one side of a body portion  201 . The support portion  202  of the sheet material  200  has a plurality of rectangular openings  203   a  disposed at a predetermined interval. It is not necessary to connect a plurality of support portions  112   a  as in the first embodiment. 
   The second embodiment adopts the cylinder  300  formed by metalforming into a shape having an approximately uniform cross-section in the longitudinal direction thereof and cutting respective parts of the openings  303 . However, the header tank  110  may be formed from a cylinder shaped in a different manner. For example, as shown in  FIG. 7A , the header tank  110  may adopt a cylinder  300  formed by metalforming to have bulging portions  304  at positions where openings are to be provided and cutting the bulging portions  304  to provide the openings  303  as shown in  FIG. 7B . 
   The supports  112   a , which are formed together with the tank body  112  in a body in the above embodiments, may be formed separately from the tank body  112 . 
   The core plate  111 , the tank body  112 , the supports  112   a , the tube  122 , etc., which are made of alloys of copper in the above embodiments, also may be made of other metallic materials such as alloys of aluminum. However, alloys of copper is more suitable for cooling the supercharged air having high temperature and large pressure, than alloys of aluminum whose strength decreases in an environment of high temperature is more than that of alloys of copper. 
   The present invention, which is explained as an intercooler  100  in the above embodiments, may be adopted other kinds of heat exchanger such as an oil cooler. 
   This description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.