Abstract:
A structure for mounting a tube to a header member of heat exchanger is such that the header member has a tube hole and the tube is disposed through the tube hole so that a portion of the tube projects out of and beyond the header member. The portion of the tube which projects outwardly is expanded via the insertion of an expansion wedge to establish a tight contact between the tube and the tube hole.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an expansion wedge for use with a heat exchanger tube which expands the diameter of an opening of a flat tube to be inserted into a tube hole formed in a header member and which brings the opening into close contact with the tube hole, as well as a structure for mounting a tube to a header member of the heat exchanger manufactured through use of the expansion wedge. 
     The present application is based on Japanese Patent Applications No. Hei. 11-44875 and 2000-23925, which are incorporated herein by reference. 
     2. Description of the Related Art 
     According to a known method of manufacturing a heat exchanger, such as a radiator, an opening of a flat tube is expanded while the tube remains inserted into a tube hole formed in a header member, thereby bringing the opening into close contact with the tube hole. Methods described in: for example, Japanese Patent Publication Nos. Sho. 59-180295 and Sho. 60-49861, have already been known as manufacturing methods of this type. 
     FIG. 14 shows a manufacturing method described in Japanese Patent Publication No. Sho. 60-49861. According to this method, a core section  4  is interposed between header members  1  spaced apart from each other by a given distance so as to be mutually oppose. The core section  4  is assembled by alternating arrangement of tubes  2  and corrugated fins  3 . 
     Respective ends of the tubes  2  are inserted into corresponding tube holes  1   a  formed in the header member  1 . Expansion wedges  6  formed on each of jigs  5  disposed on opposite sides of the core section  4  are inserted into openings  2   a  of the tubes  2 , thereby bringing the openings  2   a  into close contact with the tube holes  1   a.    
     Under such a manufacturing method, the openings  2   a  of the tubes  2  are brought into close contact with the tubes holes  1   a , thereby preventing falling of the header members  1  and abating a solder running failure, which would otherwise frequently arise during a brazing process in a subsequent step. 
     Under such a known manufacturing method, a portion of the edge of the opening  2   a  of the tube  2  expanded by the expansion protrusion  6  becomes collapsed, as shown in FIG. 15, thus frequently inducing formation of a collapsed portion  2   b.    
     In the event that the tube  2  becomes partially collapsed, coolant circulating through the tube  2  leaks out from the collapsed portion. For this reason, inspection for collapsed portions requires scrupulous attention and a large number of steps. 
     Considerable research conducted by the present inventor for solving the drawback of the known manufacturing methods shows that, as shown in FIG. 16, a longitudinal side surface  2   c  of the tube  2  becomes inwardly deformed during transportation of the tube  2 , introduction of the tubes  2  into an assembly facility, or assembly of the core section  4  and that, if the expansion protrusion  6  is inserted into the opening  2   a  in this state, the expansion protrusion  6  comes into collision with the longitudinal side surface  2   c, thus inducing formation of the collapsed portion  2   b.    
     It is also found that, even when the longitudinal side surface  2   c  becomes deformed, as shown in FIG. 16, spaces  2   d  remain present in opposite ends of the flat tube  2 . 
     SUMMARY OF THE INVENTION 
     The present invention has been conceived on the basis of the previously-described finding and is aimed at providing an expansion wedge for use with a heat exchanger tube which can readily and thoroughly prevent collapse of an opening of a tube, as well as a structure for mounting a tube to a header member in a heat exchanger manufactured through use of the expansion wedge. 
     Accordingly, the present invention provides an expansion wedge for use with a heat exchanger tube which increases the cross-sectional width of an opening of a flat tube inserted into a tube hole of a header member through use of an expansion section to be inserted into the opening and which brings the opening into close contact with the tube hole, the expansion wedge comprising: an expansion wedge body on which there is formed the expansion section for expanding the distance between longitudinal side surfaces of the tube when being inserted a predetermined depth into the opening of the tube, and guide protuberances which are protrusively formed on the respective longitudinal sides of the expansion section and which are inserted into the spaces provided on the respective sides of the opening of the tube, thereby guiding the expansion section into the opening. 
     Further, the present invention provides a structure for mounting a tube to a header member of a heat exchanger, by means of inserting an opening of a flat tube into a tube hole of a header member, wherein either longitudinal side of the opening of the tube is made so as to have a width greater than that of a center portion, and the opening is brought into press-contact with the tube hole of the header member. 
     In the expansion wedge of the present invention, the guide protuberances formed at the respective longitudinal sides of the expansion section are inserted into the spaces provided on the respective sides of the opening of the tube, thereby guiding the expansion section into the opening. 
     The expansion section is inserted into the opening, thereby increasing the distance between the longitudinal sides of the opening of the tube. As a result, the opening is brought into close contact with the tube hole. 
     In the structure for mounting a tube to a header member, either longitudinal side of the opening of the tube is made so as to have a width greater than that of a center portion, and the respective longitudinal sides of the opening are brought into press-contact with the tube hole of the header member. 
     Features and advantages of the invention will be evident from the following detailed description of the preferred embodiments described in conjunction with the attached drawings. 
     Another aspect of the invention resides in a structure for mounting a flat tube to a header member of a heat exchanger, comprising: a tube hole formed in the header member; and an opening of the flat tube being inserted into the tube hole, the opening of the flat tube having longitudinally opposed end sections and a center section which is located between the end sections, wherein the opening of the flat tube is expanded in such a manner that both longitudinally opposed end sections of the opening of the flat tube have opposed sides which have a width greater than any widths of opposed sides of the center portion of the opening of the flat tube, so that at least the opposed sides of the end sections of the opening of the flat tube are brought into press-contact with the header member around the tube hole. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the accompanying drawings: 
     FIG. 1 is a side view showing an expansion wedge for use with a heat exchanger tube according to a first embodiment of the present invention; 
     FIG. 2 is a front view of the expansion wedge shown in FIG. 1; 
     FIG. 3 is a top view of the expansion wedge shown in FIG. 1; 
     FIG. 4 is a descriptive view showing a tube to be expanded by the expansion wedge shown in FIG. 1; 
     FIG. 5 is a descriptive view showing a method of increasing the cross-sectional width of the tube through use of the expansion wedge shown in FIG. 1; 
     FIGS. 6A-6E show a method of expanding an opening through use of the expansion wedge in a case where a portion of a longitudinal side surface of a tube becomes deformed; 
     FIG. 7 is a side view showing an expansion wedge for use with a heat exchanger tube according to a second embodiment of the present invention; 
     FIG. 8 is a top view of the expansion wedge shown in FIG. 7; 
     FIG. 9 is a front view of the expansion wedge shown in FIG. 7; 
     FIG. 10 is a front view showing a structure for mounting a tube to a header member of a heat exchanger according to one embodiment of the present invention; 
     FIG. 11 is a cross-sectional view for showing details of the expansion wedge shown in FIG. 10; 
     FIG. 12 is a descriptive view showing an angular relationship between the header member and the tube; 
     FIG. 13 is a descriptive view showing a state in which a core section is transported; 
     FIG. 14 is a cross-sectional view showing a known method of expanding a tube; 
     FIG. 15 is a descriptive view showing a tube having a collapsed opening; and 
     FIG. 16 is a descriptive view showing the deformed state of a tube. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention will be described in detail hereinbelow by reference to embodiments shown in the accompanying drawings. 
     FIGS. 1 through 3 show an expansion wedge for use with a heat exchanger tube according to the first embodiment of the present invention. 
     In the present embodiment, an aluminum tube  11  having a flat cross section such as that shown in FIG. 4 is inserted into a tube hole  13   a  of an aluminum header member  13 , as shown in FIG.  5 . In this state, an expansion wedge  15  is inserted into the opening  11   a  of the tube  11 , thereby expanding the cross-sectional width of the opening  11   a  and bringing the opening  11   a  into close contact with the tube hole  13   a.    
     Reference numeral  17  shown in FIGS. 1 through 3 designates a flat expansion wedge body formed from, for example, tool steel. 
     An expansion section  19  is integrally formed with the expansion wedge body  17  so as to locate between an upper two-dot chain line A (viz., a chain line wherein each dash is separated by two dots) and a lower two-dot chain line A′ as shown in FIG.  1 . Further, a guide protuberance  21  is integrally formed on either longitudinal side of the expansion section  19  so as to protrude upwardly from the two-dot chain line A. 
     As shown in FIG. 6C, the expansion section  19  is inserted into the opening  11   a  of the tube  11  to a predetermined depth, thus increasing the distance between longitudinal side surfaces  11   b  of the opening  11   a.    
     Further, as shown in FIG. 6B, the guide protuberances  21  are inserted into the respective sides of the opening  11   a  of the tube  11  and guide the expansion section  19  into the opening  11   a , as shown in FIG.  6 C. 
     Further, as shown in FIGS. 2 and 4, provided that the shorter distance between interior surfaces of the tube  11  is taken as W 2 , the width W A  of a cross section taken along the two-dot chain line A spaced distance L A  from the apex P is set to be identical with W 2 , as shown in FIG.  2 . The guide protuberances  21  are defined between the two-dot chain line A and the apex P. 
     In the present embodiment, a pair of first inclined faces  19   a  are formed between the guide protuberances  21  and meet along the longitudinal center axis (a dot line C in FIG. 3) of the expansion section  19 . 
     As shown in FIG. 2, an angle θ1 between the pair of first inclined faces  19   a  is set to be about 77°. 
     The distance between the apexes P of the pair of guide protuberances  21  is set such that the apexes P correspond to points P 1  provided inside the tube  11  shown in FIG.  4 . 
     In the present embodiment, the tube  11  shown in FIG. 4 is formed from aluminum material having a thickness of 0.25 mm. The longitudinal length L of the opening  11   a  is set to 25.5 mm, and the width W of the opening  11   a  is set to 1.7 mm. 
     As shown in FIG. 3, the expansion edge body  17  has a longitudinal length L 1  of 24 mm and a thickness W 1  of 4.0 mm, and a distance L 2  between the apexes P of the pair of guide protuberances  21  is set to 21.3 mm. 
     A pair of second inclined faces  23  are formed on either side of the expansion section  19  so as to extend from the respective apexes P of the guide protuberances  21  and to be formed integrally with the respective first inclined faces  19   a . In each pair of second inclined faces  23 , the second inclined faces  23  meet along the longitudinal center axis (a dot line C in FIG. 3) of the expansion section  19 . 
     As shown in FIG. 1, an inclined angle θ2 of a ridge line PD hereinafter described is set to about 30°. 
     As shown in FIG. 1, a third inclined face  27  is also formed so as to extend outward from the respective apex P of the guide protuberance  21 . 
     An inclined angle θ3 of the third inclined face  27  is set to about 43°. 
     As shown in FIGS. 1 and 3, a pair of fourth inclined faces  29  are formed on one side of each of the guide protuberances  21  so as to continually extend from the pair of second inclined faces  23  of the guide protuberance  21 . In each pair of the fourth inclined faces  29 , the inclined faces  29  meet along the longitudinal center line (a dot line C in FIG. 3) of the expansion section  19 . 
     In the present embodiment, ridge lines PD are formed so as to extend from each of the apexes P of the guide protuberances  21  toward the longitudinal center of the expansion wedge body  17  as well as to either side of the expansion wedge body  17  in the widthwise direction thereof. 
     The ridge lines PD come into contact with the interior surfaces of the opening  11   a  of the tube  11 , thus expanding the distance between the longitudinal side surfaces  11   b  of the opening  11   a  of the tube  11 . 
     The cross-sectional width of the tube  11  is expanded through use of the previously-described expansion wedge  15  in the following manner. 
     In the present embodiment, the tube  11  such as that shown in FIG. 4 is inserted into the tube hole  13   a  of the header member  13 , as shown in FIG.  5 . In this state, the expansion wedge  15  is inserted into the opening  11   a  of the tube  11 , thus expanding the cross-sectional width of the opening  11   a  and bringing the opening  11   a  into close contact with the tube hole  13   a.    
     In a case where one of the longitudinal side surfaces  11   b  of the opening  11   a  of the tube  11  becomes deformed interiorly, as shown in FIG. 6A, the cross-sectional width of the tube  11  is expanded in the following manner. 
     First, the expansion wedge  15  is moved toward the tube  11 , so that the apex P of the guide protuberance  21  formed on either longitudinal side of the expansion section  19  is inserted into the respective space  11   c  defined in the respective side of the opening  11   a  of the tube  11 . 
     As a result of further insertion of the expansion wedge  15 , the pair of ridge lines PD are brought into contact with the interior surfaces of the longitudinal sides of the opening  11   a  of the tube  11 , and the distance between the longitudinal sides of the opening  11   a  of the tube  11  in respective sides thereof is expanded. As shown in FIG. 6B, the tube  11  eventually becomes deformed, thus ensuring a space  11   d  which permits smooth insertion of the expansion section  19 . 
     Subsequently, as a result of further insertion of the expansion wedge  15 , the expansion section  19  is inserted into the space  11   d . As shown in FIGS. 6C-6D, the distance between the longitudinal side surfaces  11   b  of the tube  11  is expanded by means of the expansion section  19 . 
     FIG. 6D shows a cross-sectional view taken along the line D while the expansion wedge  15  is inserted into the tube  11 , as shown in FIG.  6 C. 
     Further insertion of the expansion wedge  15  into the opening  11   a  results in an increase in the overall distance in the longitudinal direction of the tube  11  between the longitudinal side surfaces  11   b  of the opening  11  of the tube  11 . Accordingly, the opening  11   a  is brought into close contact with the tube hole  13   a.    
     In the present embodiment, FIG. 6B shows a state in which the guide protuberances  21  of the expansion wedge  15  have been inserted into the tube  11  to a depth of 1.5 mm from the respective apexes P. 
     FIG. 6C shows a state in which the guide protuberances  21  have been further inserted into the tube  11  to a depth of 1.5 mm from the state of FIG.  6 B. 
     In the present embodiment, the expansion operation is terminated after the expansion wedge  15  has been inserted 0.5 mm further into the tube  11  from the state of FIG.  6 C. 
     In the expansion wedge  15  for use with a heat exchanger of the present embodiment, the expansion section  19  for expanding the distance between the longitudinal side surfaces  11   b  of the tube  11  when being inserted to a predetermined depth into the opening  11   a  of the tube  11  is formed on the expansion wedge body  17 . Further, the guide protuberances  21  are protrusively formed on the respective longitudinal sides of the expansion section  19 . The guide protuberances  21  are inserted into the spaces  11   c  provided on the respective sides of the opening  11   a  of the tube  11 , thereby guiding the expansion section  19  into the opening  11   a . As a result, the guide protuberances  21  and the expansion section  19  are prevented from colliding with the edge of the tube  11 , thus readily and thoroughly preventing collapse of the opening  11   a  of the tube  11 . 
     FIGS. 7 through 9 show an expansion wedge for use with a heat exchanger according to a second embodiment of the present invention. 
     Reference numeral  17 A provided in these drawings designates a flat expansion wedge body formed from, example, tool steel. 
     An expansion section  19 A is integrally formed with the expansion wedge body  17 A so as to locate between an upper two-dot chain line B and a lower two-dot chain line B′ as shown in FIG.  7 . Further, a guide protuberance  21 A is integrally formed on either longitudinal side of the expansion section  19  so as to protrude upwardly from the two-dot chain line B. 
     In the present embodiment, first inclined faces  33  are formed so as to extend from the respective apexes P of the guide protuberances  21 A and meet at the cross-sectional longitudinal center of the expansion wedge body  17 A. 
     Further, a pair of second inclined faces  35  are formed so as to continually extend from both sides of the first inclined face  33  and meet at the cross-sectional longitudinal center of the expansion wedge body  17 A. 
     As shown in FIG. 7, third inclined faces  37  are formed so as to extend outward and continually from the respective apexes P of the guide protuberances  21 A. 
     More specifically, in the present embodiment, ridge lines PS are formed so as to extend from the respective apexes P of the guide protuberances  31 A toward the longitudinal center of the expansion wedge body  17 A. Further, the ridge lines PS spread to either side in the widthwise direction of the expansion wedge body  17 A. 
     As a result of the ridge lines PS coming into contact with the interior surfaces of the opening  11   a  of the tube  11 , the distance between the longitudinal side surfaces  11   b  of the opening  11   a  of the tube  11  is increased. 
     As shown in FIG. 4, provided that the shorter diameter between the interior surfaces of the tube  11  is taken as W 2 , the width W B  of the cross section taken along line the two-dot chain line B spaced from the apex P by distance L B  is set to be identical with W 2 , and the area defined between the two-chain dot line B and the apex P is taken as the guide protuberance  21 A. 
     In the expansion wedge  17 A for use with a heat exchanger of the present embodiment, the expansion section  19 A for expanding the distance between the longitudinal side surfaces  11   b  of the tube  11  when inserted to a predetermined depth into the opening  11   a  of the tube  11  is formed on the expansion wedge body  17 A. Further, the guide protuberances  21 A are protrusively formed on the respective longitudinal sides of the expansion section  19 A. The guide protuberances  21 A are inserted into the spaces  11   c  provided on the respective sides of the opening  11   a  of the tube  11 , thereby guiding the expansion section  19 A into the opening  11   a . As a result, the guide protuberances  21  and the expansion section  19 A are prevented from colliding with the edge of the tube  11 , thus readily and thoroughly preventing collapse of the opening  11   a  of the tube  11 . 
     FIG. 10 shows one example of a structure for mounting a tube to a header member of a heat exchanger of the present invention. In the present example, either longitudinal side of the opening  11   a  of the tube  11  to be inserted into the tube hole  13   a  of the header member  13  is formed so as to have a width greater than that of a center portion  11   e : specifically, an enlarged section  11   f  is formed in either longitudinal side of the opening  11   a  of the tube  11 . 
     As shown in FIG. 11, the lateral sides of the opening  11   a  of the tube  11  are brought into press contact with the tube hole  13   a  of the header member  13 . 
     The enlarged sections  11   f  are formed in the foregoing manner through use of the expansion wedge of the present invention for use with a heater exchanger tube. 
     The structure for mounting a tube to a header member of a heat exchanger enables fastening of the tube  11  on the header member  13 . As shown in FIG. 12, the tubes  11  can be reliably mounted on the header member  13  at an angle θ of 90°. 
     It has been ascertained that the positional relationship between the header member  13  and the tubes  11  remains sustained even when the heat exchanger has been subjected to cleansing and passed through a drying furnace, a pre-heating furnace, and a baking furnace after assembly of a core section. 
     The mounting structure of the present example enables reliable maintenance of a positional relationship between the header  13  and the tubes  11 . As shown in FIG. 13, when a core section  39  is transported horizontally, the header member  13  can be transported while resting directly on a transport surface  41 . 
     In the existing mounting structure, weak force is applied for retaining the positional relationship between the header member  13  and the tubes  11 . For example, there has been a necessity for taking into consideration protection of the header member  13  from an external force, by placing on the core section  39  a binding and baking jig  43  for binding the core section  39  and by transporting the header member  13  while levitating the same from a transport surface  41 A by means of the binding and baking jig  43 . In contrast, the mounting structure of the present example obviates a necessity for levitating the header member  13 , thus facilitating transportation of the core section  39 . Further, the mounting structure reduces the heat capacity of the binding and baking jig  43 , thus enabling efficient baking. 
     FIG. 13 schematically shows the core section  39 . Reference numeral  45  designates a reinforcement member, and reference numeral  47  designates a corrugated fin. 
     The previous embodiments have described a case where the expansion wedge  15  is moved and inserted into the opening  11   a  of the tube  11  after the tube  11  has been inserted into the header member  13 . However, the present invention is not limited to such embodiments. For instance, after the expansion wedge  15  has been inserted into the tube hole  13   a  of the header member  13  to a predetermined depth, the tube  11  may be moved and the tube hole  13   a  may be expanded simultaneous with insertion of the tube  11  into the tube hole  13   a.    
     Although the previous embodiments have described an example in which the present invention is applied to a radiator, the present invention is not limited to such embodiments. For instance, the present invention can be broadly applied to a heat exchanger, for example, a condenser. 
     The previous embodiments have described a case where a single wedge is formed in the expansion wedge body  17  and a plurality of expansion wedge bodies  17  are incorporated into an assembly machine. However, the present invention is not limited to such embodiments. For example, the expansion wedge body  17  may be formed from long plate material, and wedges may be integrally formed on the plate material at intervals. 
     As has been described above, the expansion wedge for use with a heat exchanger tube comprises an expansion wedge body on which there is formed the expansion section for expanding the distance between longitudinal side surfaces of the tube when being inserted to a predetermined depth into the opening of the tube, and guide protuberances which are protrusively formed on the respective longitudinal sides of the expansion section and which are inserted into the spaces provided on the respective sides of the opening of the tube, thereby guiding the expansion section into the opening. As a result, the guide protuberances and the expansion section are prevented from colliding with the edge of the tube, thereby readily and thoroughly preventing collapse of an opening of a tube. 
     In the structure for mounting a tube to a header member of a heat exchanger, either longitudinal side of the opening of the tube is made so as to have a width greater than that of a center portion, and the opening is brought into press-contact with the tube hole of the header member. Accordingly, the tube can be firmly attached to the header member. 
     Although the invention has been described in its preferred form with a certain degree of particularity, it is understood that the present disclosure of the preferred form can be arrangement of parts without departing from the spirit and the scope of the invention as hereinafter claimed.