Patent Publication Number: US-2022214113-A1

Title: Heat exchanger

Description:
TECHNICAL FIELD 
     The present disclosure relates to the field of heat exchange technology, and in particular, to a heat exchanger. 
     BACKGROUND 
     Heat exchangers are widely used in heat exchange systems such as air conditioning systems. The heat exchanger includes heat exchange tubes and a header. The refrigerant flows into the header, and then flows from the header to the heat exchange tube to exchange heat with external environment. 
     The header assembly includes an end cap. In a heat exchanger using CO 2  as the refrigerant, a high pressure would be generated when the refrigerant flows from the end cap to the header due to a high system pressure. Thus, the header is required to have relatively high pressure resistance performance. 
     SUMMARY 
     The present disclosure provides a heat exchanger, which has good pressure resistance performance. 
     A first aspect of the present disclosure provides a heat exchanger that includes a first header, a second header, heat exchange tubes, and an end cap. Each of the heat exchange tubes has an end connected to the first header and another end connected to the second header. Inner cavities of the heat exchange tubes communicate an inner cavity of the first header with an inner cavity of the second header, and each of the first header and the second header includes two ports disposed in a length direction thereof. 
     The end cap is assembled and fixed to one port of the two ports of the first header or one port of the two ports of the second header. The end cap includes a body and a first opening formed in the body. The body includes a second cavity and a first groove portion. The first groove portion is located between the first opening and the second cavity. 
     The first groove portion includes a first bottom wall close to the first opening. The first bottom wall is provided with a third opening communicating the first opening with the second cavity. The second cavity is in communication with the inner cavity of the first header or the inner cavity of the second header. The first opening is located farther from the inner cavity of the first header or the inner cavity of the second header than the second cavity, and the first opening is configured for inflow or outflow of a refrigerant. 
     A flow area of the first groove portion is greater than a flow area of the third opening, such that an instantaneous pressure of the refrigerant can be reduced after the refrigerant flows from the first opening into a cavity of the first groove portion through the third opening. In this way, impact of the refrigerant flowing into the headers on the headers can be reduced to reduce the pressure resistance requirement of the headers. 
     It should be understood that the above general description and the following detailed description are only exemplary, but are not intended to limit the present disclosure thereto. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a schematic structural view of a heat exchanger according to a first embodiment of the present disclosure; 
         FIG. 2  is an exploded view of the heat exchanger according to the first embodiment of the present disclosure; 
         FIG. 3  is a schematic structural view of a first header according to the first embodiment of the present disclosure; 
         FIG. 4  is a schematic view of a first main plate with a middle rib that is not formed with a hole or opening, according to the first embodiment of the present disclosure; 
         FIG. 5  is a schematic view of a first main plate with a middle rib that is formed with a hole or opening, according to the first embodiment of the present disclosure; 
         FIG. 6  is a schematic structural view of a second main plate according to the first embodiment of the present disclosure; 
         FIG. 7  is a sectional view of a second header according to the first embodiment of the present disclosure; 
         FIG. 8  is an exploded view of a heat exchanger according to a second embodiment of the present disclosure; 
         FIG. 9  is a schematic structural view of a first header according to the second embodiment of the present disclosure; 
         FIG. 10  is an exploded view of a heat exchanger according to a third embodiment of the present disclosure; 
         FIG. 11  is a sectional view of a second header according to the third embodiment of the present disclosure; 
         FIG. 12  is an exploded view of a heat exchanger according to a fourth embodiment of the present disclosure; 
         FIG. 13  is a schematic structural perspective view of a heat exchanger according to a fifth embodiment of the present disclosure; 
         FIG. 14  is an exploded view of the heat exchanger according to the fifth embodiment of the present disclosure; 
         FIG. 15  is an exploded view of a heat exchanger according to a sixth embodiment of the present disclosure; 
         FIG. 16  is a schematic structural perspective view of a heat exchanger according to a seventh embodiment of the present disclosure; 
         FIG. 17  is an exploded view of the heat exchanger according to the seventh embodiment of the present disclosure; 
         FIG. 18  is an exploded view of a heat exchanger according to an eighth embodiment of the present disclosure; 
         FIG. 19  is a schematic structural view of a heat exchanger according to a ninth embodiment of the present disclosure; 
         FIG. 20  is an operation flow chart of the heat exchanger according to the ninth embodiment of the present disclosure; 
         FIG. 21  is a schematic exploded view of the heat exchanger according to the ninth embodiment of the present disclosure; 
         FIG. 22  is a schematic structural view of a first type of header according to the ninth embodiment of the disclosure; 
         FIG. 23  is a schematic structural view of a second type of header according to the ninth embodiment of the disclosure; 
         FIG. 24  is a schematic structural view of a third type of header according to the ninth embodiment of the present disclosure; 
         FIG. 25  is a schematic structural front view of a second main plate of the third type of header according to the ninth embodiment of the present disclosure; 
         FIG. 26  is a schematic structural front view of a first main plate of the third type of header according to the ninth embodiment of the present disclosure; 
         FIG. 27  is a schematic structural view of the second main plate of the third type of header according to the ninth embodiment of the present disclosure; 
         FIG. 28  is a schematic structural view of the first main plate of the third type of header according to the ninth embodiment of the present disclosure; 
         FIG. 29  is a schematic structural view of an end cap of the header according to the ninth embodiment of the present disclosure; 
         FIG. 30  is a schematic front view of the end cover of the header according to the ninth embodiment of the present disclosure; 
         FIG. 31  is a schematic cross-sectional view of the end cap of the header according to the ninth embodiment of the present disclosure; 
         FIG. 32  is a schematic sectional view of the first header fitting with heat exchange tubes after being partially cut off, according to the ninth embodiment of the present disclosure; 
         FIG. 33  is a schematic partial view of  FIG. 32 ; 
         FIG. 34  is a schematic enlarged view of a part A in  FIG. 32 ; 
         FIG. 35  is a schematic sectional view of the first header fitting with the heat exchange tubes according to the ninth embodiment of the present disclosure; 
         FIG. 36  is a schematic partial view of the header according to the ninth embodiment of the present disclosure; 
         FIG. 37  is a schematic structural front view of a fifth type of header according to the ninth embodiment of the present disclosure; 
         FIG. 38  is a schematic structural view of a first main plate of the fifth type of header according to the ninth embodiment of the present disclosure; 
         FIG. 39  is a schematic structural view of a second main plate of the fifth type of header according to the ninth embodiment of the present disclosure; 
         FIG. 40  is a schematic structural view of a first main plate of a sixth type of header according to the ninth embodiment of the present disclosure; 
         FIG. 41  is a schematic structural view of a second main plate of the sixth type of header according to the ninth embodiment of the present disclosure; 
         FIG. 42  is a schematic structural front view of the sixth type of header according to the ninth embodiment of the present disclosure; and 
         FIG. 43  is a schematic structural front view of a seventh type of header according to the ninth embodiment of the present disclosure. 
     
    
    
     The drawings are incorporated into the description herein and constitute a part thereof, showing embodiments of the present disclosure. The drawings are illustrated in conjunction with the description to explain the principle of the present disclosure. 
     DESCRIPTION OF EMBODIMENTS 
     Embodiments of the present disclosure will be described in detail hereinafter with reference to the accompanying drawings in order to make objections, technical solutions and advantages of the present disclosure clearer. It should be understood that the embodiments described below are merely some of, rather than all of the embodiments of the present disclosure. Based on the embodiments of the present disclosure, all other embodiments made by those skilled in the art without any inventive step shall fall within the scope of the present disclosure. 
     First Embodiment 
     The first embodiment of the present disclosure provides a heat exchanger. As shown in  FIGS. 1 and 2 , the heat exchanger includes a first header  1 , a plurality of rows of heat exchange tubes  3 , and a second header  2 , which are arranged sequentially from top to bottom. 
     Referring to  FIG. 3 , the first header  1  includes a first main plate  11  and a second main plate  12  located below the first main plate  11 . The first main plate  11  and the second main plate  12  are assembled to form the first header  1 . It should be understood that the first main plate  11  and the second main plate  12  may be two parts of one component, or may be a single piece formed by assembling two separated components. Alternatively, the second main plate  12  and the first main plate  11  are fixed together by brazing. 
     The first main plate  11  includes at least one middle rib  111  that is supported on the second main plate  12  and is capable of dividing the first main plate  11  into a plurality of through grooves  112 . The through grooves  112  extend in a direction parallel to a longitudinal direction of the first header  1 . A circulation cavity is formed between the second main plate  12  and each of the through grooves  112 , and adjacent circulation cavities are arranged in parallel with each other in a direction perpendicular to an axial direction of the first header  1 . In this embodiment, a cross section of each of the through grooves  112  may be in a semicircular, semi-elliptical, or rectangular shape, etc., and may also be in other shapes capable of forming the through grooves  112 . Moreover, each of the through grooves  112  may be the same or different from each other in volume. 
     At least one of the circulation cavities forms a first flow passage  10 , and at least one of the circulation cavities forms a second flow passage  20 . It should be noted that, in this embodiment, the first flow passage  10  communicates with a first flow port  6 , and the second flow passage  20  communicates with a second flow port  7 . In a case where the heat exchanger is used as a condenser, a high-temperature gaseous heat transfer medium is capable of flowing from the first flow port  6  into the first flow passage  10 , circulating in the heat exchange tubes  3  to exchange heat therein, and then flowing out of the second flow port  7  through the second flow passage  20  (In this case, the heat transfer medium is in a liquid state or a gas-liquid mixed state). In a case where the heat exchanger is an evaporator, the heat transfer medium in the liquid state is capable of flowing from the second flow port  7  into the second flow passage  20 , circulating in the heat exchange tubes  3  to exchange heat therein, and then flowing out of the first flow port  6  through the first flow passage  10  (In this case, the heat transfer medium is in the gaseous state). A total volume of the first flow passages  10 , i.e., a sum of the volumes of all the first flow passages  10 , is greater than that of the second flow passages  20 , i.e., a sum of the volumes of the second flow passages  20 . With this configuration, the heat transfer medium for heat exchange can flow at a relatively high flow rate in the heat exchanger. 
     Alternatively, in this embodiment, the heat exchanger may include at least two first flow passages  10  and at least one second flow passage  20 . Further, all of the at least two first flow passages  10  are located at the same side of the second flow passage  20  to facilitate inflow of the heat transfer medium. 
     Further, the at least two first flow passages  10  may be independent from each other and not in communication with each other, as shown in  FIG. 4 . In this case, the heat transfer medium flowing through the first flow port is divided by the middle rib  111  located between two adjacent first flow passages  10  to respectively flow into the two adjacent first flow passages  10 . 
     A hole or opening  113  (the opening  113  shown in  FIG. 5 ) may be formed at the middle rib  111  located between two adjacent first flow passages  10 , such that the two adjacent first flow passages  10  are in communication with each other. In this case, the heat transfer medium flowing through the first flow port is divided by the middle rib  111  located between the two adjacent first flow passages  10  to respectively flow into the two adjacent first flow passages  10 , and then the heat transfer medium in a respective one of the first flow passages  10  flows into at least one adjacent first flow passage  10  through the hole or opening  113  formed at the middle rib  111 . 
     Referring to  FIG. 6 , the second main plate  12  may be a U-shaped structure, and the first main plate  11  is disposed inside the U-shaped structure of the second main plate  12 , thereby forming a structure in which the second main plate  12  encloses the first main plate  11 . The second main plate  12  and the first main plate  11  are then fixed and connected by brazing. It should be understood that the second main plate  12  may also be a plate-shaped structure. In this case, the first main plate  11  is directly supported on the second main plate  12  and fixed to the second main plate  12  by brazing. 
     As shown in  FIG. 6 , the second main plate  12  is provided with a plurality of rows of first heat exchange tube apertures  121 , through which the heat exchange tubes  3  penetrate. The heat exchange tubes  3  are brazed at the first heat exchange tube apertures  121 , such that the heat exchange tubes  3  are fixed to the second main plate  12  and sealed at joints. In this embodiment, the number of rows of the first heat exchange tube apertures  121  is the same as that of the heat exchange tubes  3 , and each of the heat exchange tubes  3  passes through a respective one of the first heat exchange tube apertures  121 . The first heat exchange tube apertures  121  are configured to allow the heat transfer medium in the heat exchange tubes  3  to flow into the first flow passages  10  or allow the heat transfer medium in the first flow passages  10  to flow into the heat exchange tubes  3 , and to allow the heat transfer medium in the heat exchange tubes  3  to flow into the second flow passage  20  or allow the heat transfer medium in the second flow passage  20  to flow into the heat exchange tubes  3 . In this embodiment, a flange  122  is disposed at a periphery of each of the first heat exchange tube apertures  121  and extends in a direction away from the first main plate  11 . The flange  122  is capable of increasing a contact area with the respective heat exchange tube  3 , such that a relatively large brazing surface is formed between the heat exchange tubes  3  and the second main plate  12  with a stronger brazing strength. In other embodiments, the flange may also extend toward the first main plate  11 . 
     Alternatively, each of the first heat exchange tube apertures  121  may be an elongated, circular, or rectangular aperture, which depends on a shape of the assembled heat exchange tube  3 . In this embodiment, the first heat exchange tube aperture  121  is an elongated aperture, and the heat exchange tube  3  is correspondingly a flat pipe. Further, a height of the flange  122  is associated with a thickness of the heat exchange tube  3  and is 0.7-1.3 times the thickness thereof. 
     In this embodiment, the heat exchanger is provided with the plurality of rows of heat exchange tubes  3 . Further, each of the first flow passages  10  and each of the second flow passages  20  are provided with one row of heat exchange tubes  3 , respectively. The number of rows of heat exchange tubes  3  is same as a total number of the through grooves  112  for forming the first flow passages  10  and the second flow passages  20 . Alternatively, the heat exchanger may be provided with two first flow passages  10  and one second flow passage  20 , and thus three rows of heat exchange tubes  3  are provided. 
     It should be understood that, in this embodiment, each of the first flow passages  10  and each of the second flow passages  20  are provided with one row of heat exchange tubes  3 , respectively. However, one row of heat exchange tubes  3  may be provided for a plurality of first flow passages  10 , or a plurality of rows of heat exchange tubes  3  may be provided for one first flow passage  10 . Alternatively, one row of heat exchange tubes  3  may be provided for a plurality of second flow passages  20 , or a plurality of rows of heat exchange tubes  3  may be provided for one second flow passage  20 . The present disclosure is not limited to the above embodiments as long as the flow of the heat transfer medium is not affected. 
     In this embodiment, a density of the heat transfer medium flowing in the first flow passages  10  is less than that of the heat transfer medium flowing in the second flow passages  20 . As for the same amount of the heat transfer medium, the volume of the heat transfer medium in the first flow passage  10  is greater than that of the heat transfer medium in the second flow passages  20 . Further, a total volume of the first flow passages  10  is greater than that of the second flow passages  20 , and the number of the heat exchange tubes  3  communicating with the first flow passages  10  is greater than that of the heat exchange tubes  3  communicating with the second flow passages  20 . With this configuration, the heat transfer medium for heat exchange can flow at the relatively high flow rate in the heat exchanger. 
     As shown in  FIG. 1 , the heat exchanger further includes an end cap  8 , onto which the first flow port  6  and the second flow port  7  are disposed. 
     It should be understood that the heat exchanger may be provided with one first flow port  6 . In this case, the first flow port  6  communicates with all the first flow passages  10 . Alternatively, the heat exchanger may be provided with a plurality of first flow ports  6 . In this case, each of the first flow ports  6  communicates with a respective one of the first flow passages  10 . 
     In this embodiment, the second header  2  communicates with an end of each of the heat exchange tubes  3  that is not in communication with the first flow passage  10  and the second flow passage  20 . That is, both ends of the heat exchange tube  3  are connected to the first header  1  and the second header  2 , respectively. 
     As shown in  FIGS. 2 and 7 , the second header  2  in this embodiment includes a third main plate  21  and a fourth main plate  22  that are brazed to one piece. The third main plate  21  is located below the fourth main plate  22 . Each of the third main plate  21  and the fourth main plate  22  is a flat plate structure. Referring to  FIG. 7 , the third main plate  21  has a flat top surface, and the fourth main plate  22  has a flat bottom surface. Since each of the third main plate  21  and the fourth main plate  22  has the flat plate structure, the second header  2  in this embodiment has a more compact structure. 
     The third main plate  21  is formed with a recess  211  that is cooperated with the fourth main plate  22  to form a third flow passage  30 . Specifically, the recess  211  is configured to accommodate all the heat exchange tubes  3 . In this embodiment, the recess  211  has a width greater than a maximum distance between two outermost rows of heat exchange tubes  3 , and a depth that is within a range of ⅓ to ½ of a thickness of the third main plate  21 . 
     In this embodiment, the fourth main plate  22  is formed with a plurality of rows of second heat exchange tube apertures  221 , each of which corresponds to one heat exchange tube  3 . Further, one end of each of the plurality of rows of heat exchange tubes  3  passes through the respective second heat exchange tube aperture  221  and is in communication with the third flow passage  30 . Each of the second heat exchange tube apertures  221  has an outer flange that protrudes in a direction away from the third main plate  21 . The outer flange is capable of increasing a contact area of the second heat exchange tube aperture  221  with the heat exchange tube  3 , thereby increasing the connection strength between the second heat exchange tube aperture  221  and the heat exchange tube  3 . In this embodiment, the second heat exchange tube aperture  221  is connected with the heat exchange tube  3  by brazing. In this embodiment, the second heat exchange tube aperture  221  has a length greater than a width of a necking portion of the heat exchange tube  3 , and a width greater than a thickness of the heat exchange tube  3 . The flange of each second heat exchange tube aperture  221  has a height that is 0.7-1.3 times the thickness of the respective heat exchange tube  3 . In other embodiments, the flange of each second heat exchange tube aperture  221  may also extend toward the third main plate  21 . 
     It should be understood that in the second header  2  according to this embodiment, the recess  211  may be directly formed in the fourth main plate  22 , the third main plate  21  may only have a flat plate structure, and the third flow passage  30  is formed between the recess  211  and the third main plate  21 . 
     The following description illustrates an operation principle of the heat exchanger as described in this embodiment, which is used as a condenser. 
     Firstly, a gaseous heat transfer medium enters through the first flow port  6 , and then flows to the first flow passage  10  of the first header  1 , which has a relatively large total volume. At this time, the heat transfer medium flows into the heat exchange tubes  3  communicating with the first flow passage  10  and exchanges heat with other mediums. The heat transfer medium finally flows into the third flow passage  30  of the second header  2  through the heat exchange tubes  3  communicating with the first flow passage  10 , and flows into the heat exchange tubes  3  communicating with the second flow passage  20  through the third flow passage  30 . The heat transfer medium then flows into the second flow passage  20  through the heat exchange tubes  3  communicating with the second flow passage  20 , and further exchanges heat with other mediums such as air during this process. Finally, the heat transfer medium flows out of the second flow port  7  and the heat exchange is completed, and at this moment, the heat transfer medium is in the liquid state or the gas-liquid mixed state. 
     The following description illustrates an operation principle of the heat exchanger as described in this embodiment, which is used as an evaporator. 
     Firstly, a heat transfer medium in a liquid or gas-liquid mixed state flows into the second flow passage  20  of the first header  1 , which has a relatively small total volume, through the second flow port  7 . At this moment, the heat transfer medium flows into the heat exchange tubes  3  communicating with the second flow passage  20  and exchanges heat with other mediums. The heat transfer medium flows into the second header  2  through the heat exchange tubes  3  in communication with the second flow passage  20 , and flows into the heat exchange tubes  3  in communication with the first flow passage  10  through the third flow passage  30 . Thereafter, the heat transfer medium flows into the first flow passages  10  through the heat exchange tubes  3  in communication with the first flow passages  10 , and further exchanges heat with other mediums, such as air. The heat transfer medium finally flows out of the first flow port  6 , and the heat exchange is completed. At this time, the heat transfer medium is in the gaseous state. 
     In the heat exchanger according to this embodiment as described above, the heat transfer medium flows in the gaseous state in the first flow passages  10 , and flows in the liquid or gas-liquid mixed state in the second flow passages  20 . The total volume of the first flow passages  10  is greater than that of the second flow passages  20 , and the total volume of the flow channels of the heat exchange tubes  3  in communication with the first flow passages  10  is greater than that of the flow channels of the heat exchange tubes  3  in communication with the second flow passages  20 . Accordingly, when a predetermined amount of the heat transfer medium flows in the heat exchanger, the gaseous heat transfer medium is capable of flowing in the flow passages with the larger total volume, and when the heat transfer medium in the liquid or gas-liquid mixed state can flow in the flow passages with the smaller total volume. Therefore, the heat transfer medium required for heat exchange is capable of flowing at the relatively high flow rate, thereby improving the heat exchange performance. Moreover, the heat exchanger has higher structural strength and is applicable to high-pressure heat transfer mediums. 
     Second Embodiment 
     The difference between the second embodiment and the first embodiment is the structure of the first header  1 . Specifically, as shown in  FIGS. 8 and 9 , a first header  1  according to the second embodiment includes a first main plate  11 , a second main plate  12  and a first middle plate  13 . The first main plate  11  and the second main plate  12  in this embodiment are the same as those described in the first embodiment in structure. The difference between the second embodiment and the first embodiment is in that in the second embodiment, middle ribs  111  of the first main plate  11  in this embodiment are supported on the first middle plate  13 , the second main plate  12  encloses the first middle plate  13  and the first main plate  11 , and the second main plate  12 , the first middle plate  13  and the first main plate  11  are fixed and connected with each other by brazing to form a first flow passage  10  and a second flow passage  20 . 
     Specifically, the first middle plate  13  in the second embodiment is formed with a plurality of rows of first elongated apertures  131 , and the number of rows of the first elongated apertures  131  is the same as a sum of numbers of the first flow passage  10  and the second flow passage  20 . Further, the first elongated apertures  131  are in a one-to-one correspondence with the first heat exchange tube apertures  121 . That is, each row of first elongated apertures  131  corresponds to one first flow passage  10  or one second flow passage  20 . The first flow passage  10  and the second flow passage  20  are formed among the through grooves  112  of the first main plate  11 , the first elongated apertures  131 , and the second main plate  12 . The first middle plate  13  is disposed between the first main plate  11  and the second main plate  12 , and the first main plate  11 , the first middle plate  13  and the second main plate  12  are fixed and connected with each other by brazing. Thus, the strength of the overall structure of the first header  1  is increased. 
     The first heat exchange tube apertures  121  of the second main plate  12  are in one-to-one correspondence with the first elongated apertures  131 , and one end of the heat exchange tube  3  hermetically passes through the first heat exchange tube aperture  121  and is received in the first elongated aperture  131 . 
     Other structures of the heat exchanger according to the second embodiment are the same as those in the first embodiment, and the operation principle thereof is also the same as that described in the first embodiment, and thus the detailed description thereof will be omitted herein. 
     Third Embodiment 
     The difference between the third embodiment and the first embodiment is the structure of the second header  2 . Specifically, as shown in  FIGS. 10 and 11 , the second header  2  according to the third embodiment includes a third main plate  21 , a fourth main plate  22  and a second middle plate  23 . The third main plate  21  and the fourth main plate  22  are the same as those described in the first embodiment in structure. The difference between the third embodiment and the first embodiment is in that in the third embodiment, the fourth main plate  22 , the second middle plate  23  and the third main plate  21  are fixed and connected with each other by brazing to form a third flow passage  30 . 
     Specifically, the second middle plate  23  according to the third embodiment is formed with a plurality of rows of second elongated apertures  231 , and a number of rows of the second elongated apertures  231  is the same as that of rows of the heat exchange tubes  3 . The second elongated apertures  231  are in one-to-one correspondence with the second heat exchange tube apertures  221 . That is, one of the second elongated apertures  231  corresponds to one of the heat exchange tubes  3 . The third flow passage  30  is formed among the recess  211  of the third main plate  21 , the second elongated apertures  231 , and the fourth main plate  22 . In this embodiment, the second middle plate  23  is disposed between the third main plate  21  and the fourth main plate  22 , and the third main plate  21 , the second middle plate  23  and the fourth main plate  22  are fixed and connected with each other by brazing. Thus, the strength of the overall structure of the second header  2  is increased. 
     The second heat exchange tube apertures  221  of the fourth main plate  22  are in one-to-one correspondence with the second elongated apertures  231 , and one end of the heat exchange tube  3 , which is not in communication with the first header  1 , hermetically passes through the second heat exchange tube aperture  221  and is received in the second elongated aperture  231 . Other structures of the heat exchanger according to the third embodiment are the same as those in the first embodiment, and the operation principle thereof is also the same as that described in the first embodiment, and thus the detailed description thereof will be omitted herein. 
     Fourth Embodiment 
     The difference between the fourth embodiment and the second embodiment is the structure of the second header  2 . Specifically, as shown in  FIG. 12 , the structure of the second header  2  in this embodiment are the same as that described in the third embodiment. That is, the second header  2  in this embodiment includes a second middle plate  23 . In addition, other structures of the heat exchanger according to the fourth embodiment are the same as those in the second embodiment, and the operation principle thereof is also the same as that described in the second embodiment, and thus the detailed description thereof will be omitted herein. 
     Fifth Embodiment 
     In the fifth embodiment, the first header  1  of the first embodiment is additionally provided with a first partition plate  4  to realize a four-flow-path heat exchange. Specifically, as shown in  FIGS. 13 and 14 , in this embodiment, each of the first flow passage  10  and the second flow passage  20  of the first header  1  includes a first end and a second end. The first end of the first flow passage  10  and the first end of the second flow passage  20  are located at the same side (the left side in  FIG. 13 ), and the second end of the first flow passage  10  and the second end of the second flow passage  20  are located at the same side (the right side in  FIG. 13 ). Furthermore, the first end of the first flow passage  10  communicates with the first end of the second flow passage  20 . For example, this communication may be achieved by a hole or opening formed in the middle rib  111  between the first flow passage  10  and the second flow passage  20 . In addition, the first flow port  6  communicates with the second end of the first flow passage  10 , and the second flow port  7  communicates with the second end of the second flow passage  20 . 
     The first partition plate  4  is disposed between the first end and the second end of the first flow passage  10 , and between the first end and the second end of the second flow passage  20 . The first partition plate  4  between the first end and the second end of the first flow passage  10  is configured to partition the first flow passage  10 , and the first partition plate  4  between the first end and the second end of the second flow passage  20  is configured to partition the second flow passage  20 . The first main plate  11  is formed with a set of partition plate apertures (not shown in the figures) in a width direction thereof, and each of the first partition plates  4  is inserted into a respective one of the partition plate apertures. The first partition plate  4  is provided such that each of the first flow passage  10  and the second flow passage  20  is partitioned into a first section and a second section, which can realize a multi-flow-path flow of the heat transfer medium. It should be noted that the first sections close to the first flow port  6  and the second flow port  7  are not in communication with each other, and the second sections away from the first flow port  6  and the second flow port  7  are in communication with each other, thereby achieving the four-flow-path heat exchange. 
     The third flow passage  30  includes two flow channels independent from each other. One of the flow channels communicates with the heat exchange tubes  3  in communication with all the first flow passages  10 , and the other of the flow channels communicates with the heat exchange tubes  3  in communication with the second flow passage  20 . That is, in this embodiment, referring to  FIG. 14 , the third main plate  21  of the second header  2  is formed with two recesses  211 , and each of the two flow channels is formed between the second main plate  12  and a respective one of the recesses  211 . In this embodiment, each of the two flow channels has a first end and a second end. Further, the first ends of the two flow channels are located at the same side, and the second ends of the two flow channels are located at the other side. Furthermore, the first ends of the flow channels, the first ends of the first flow passages  10  and the first end of the second flow passage  20  are all located at the same side of the heat exchanger, and the second ends of the flow channels, the second ends of the first flow passages  10  and the second end of the second flow passage  20  are all located at the other side of the heat exchanger. 
     The following description illustrates an operation principle of the heat exchanger as described in this embodiment, which is used as a condenser. 
     Firstly, a heat transfer medium flows into the second sections of the first flow passages  10 , which are located between the first partition plates  4  and the first flow port  6 , through the first flow port  6 . At this time, the heat transfer medium is flowing in a first flow path. Then, the heat transfer medium flows into the heat exchange tubes  3  in communication with the second sections of the first flow passages  10  and flows along the heat exchange tubes  3 , and exchanges heat with other medium such as air. Thereafter, the heat transfer medium flows into the second section of the flow channel of the flow passage  30  along the heat exchange tubes  3 , in which this second section corresponds to the heat exchange tubes  3 , and then the heat transfer medium flows into the first section of this flow channel. Then, the heat transfer medium flows into the heat exchange tubes  3  in communication with this first section. At this time, the heat transfer medium is flowing in a second flow path, in which the heat transfer medium further exchanges heat with other mediums, and finally flows into the first sections of the first flow passages  10 . 
     Thereafter, the heat transfer medium flows into the first section of the second flow passage  20  through the first sections of the first flow passages  10 , and flows into the heat exchange tubes  3  in communication with the first section of the second flow passage  20 . The heat transfer medium further exchanges heat with other mediums during the flowing. At this time, the heat transfer medium is flowing in a third flow path. Then, the heat transfer medium flows into the first section of the other flow channel corresponding to the second flow passage  20  and flows into the second section of the other flow channel, and then flows into the heat exchange tubes  3  in communication with the second section of the second flow passage  20  through the second section of the other flow channel. At this time, the heat transfer medium is flowing in a fourth flow path, in which the heat transfer medium exchanges heat with other medium, and finally flows into the second section of the second flow passage  20 . Thereafter, the heat transfer medium flows out of the second flow port  7  in communication with the second section of the second flow passage  20 , and the heat exchange process is completed. 
     The heat exchanger according to this embodiment is provided with the first partition plates  4 , achieving the four-flow-path heat exchange, which further improves the heat exchange effect. 
     Sixth Embodiment 
     The difference between the sixth embodiment and the fifth embodiment is in that the first header  1  in the sixth embodiment includes a first middle plate  13 , as shown in  FIG. 15 . In this case, the first middle plate  13  is formed with first elongated apertures  131  at a side of each of the first partition plates  4  and third elongated apertures  132  at the other side of each of the first partition plates  4 . The first elongated apertures  131  are located at the side of the first partition plate  4  close to the first flow port  6 . The third elongated apertures  132  are disposed away from the first flow port  6 . The third elongated apertures  132  are configured to communicate the first flow passages  10  and the second flow passage  20  to allow the heat transfer medium to flow from the first flow passages  10  into the second flow passage  20 . 
     However, it should be understood that the second header  2  in this embodiment may further include a second middle plate  23 , the structure and mounting position of the second middle plate  23  are the same as those of the second middle plate  23  described in the third embodiment, and the detailed description thereof will be omitted herein. 
     Other structures of the heat exchanger according to the sixth embodiment are the same as those in the fifth embodiment, and the operation principle of the heat exchanger in this embodiment is also the same as that described in the fifth embodiment, and thus the detailed description thereof will be omitted herein. 
     Seventh Embodiment 
     In the seventh embodiment, the two flow channels of the second header  2  in the fifth embodiment are additionally provided with a second partition plate  5 , and the structure of the recess  211  is modified, to realize a six-flow-path heat exchange. Specifically, the third flow passage  30  of the second header  2  in this embodiment includes a first flow channel, a second flow channel, and a third flow channel, as shown in  FIGS. 16 and 17 . The first flow channel and the second flow channel are partitioned by the second partition plate  5 , and the first flow channel and the third flow channel are also partitioned by the second partition plate  5 , so that the three flow channels are independent from each other. 
     In this embodiment, as shown in  FIG. 17 , the recess  211  may include a first recess  212 , a second recess  213  and a third recess  214 . The second partition plate  5  is disposed between the first recess  212  and the second recess  213 , and between the first recess  212  and the third recess  214 . The first flow channel, the second flow channel and the third flow channel are formed by the second partition plate  5 , the fourth main plate  22 , and the three recesses. 
     In this embodiment, the first flow channel communicates with the heat exchange tubes  3  between the first ends of the first flow passages  10  and the second partition plate  5 , and communicates with the heat exchange tubes  3  between the first end of the second flow passage  20  and the second partition plate  5 , respectively. 
     The second flow channel communicates with the heat exchange tubes  3  between the second ends of the first flow passages  10  and the second partition plate  5 , and the third flow channel communicates with the heat exchange tubes  3  between the second end of the second flow passage  20  and the second partition plate  5 . 
     In this embodiment, the third main plate  21  may be formed with a partition plate aperture (not shown in the figures), into which the second partition  5  is inserted to form the three flow channels. 
     In this embodiment, the second partition  5  is horizontally disposed at a side of the first partition plates  4  away from the first flow port  6 , such that a length of a flow passage of the first header  1  at a first side (the right side in  FIG. 16 ) of the first partition plate  4  is greater than that of the first flow channel, wherein this flow passage of the first header  1  includes the first end of the first flow passages  10  and the first end of the second flow passage  20 . With this structure, the six-flow-path heat exchange structure of the heat exchanger can be achieved. 
     Other structures of the heat exchanger according to the seventh embodiment are the same as those in the fifth embodiment, and thus the detailed description thereof will be omitted herein. 
     The following description illustrates an operation principle of the heat exchanger as described in this embodiment, which is used as a condenser. 
     Firstly, a heat transfer medium flows into channels between the second end of the first flow passage  10  (the right side in  FIG. 17 ) and the first partition plates  4  through the first flow port  6 , and then flows into the heat exchange tubes  3  in communication with channels between the second end of the first flow passage  10  and the first partition plates  4 , and flows along these heat exchange tubes  3 . At this time, the heat transfer medium exchanges heat with other mediums such as air. This is the first flow path. 
     The heat transfer medium flows into the second flow channel, and due to the action of the second partition plate  5 , the heat transfer medium will flow into the heat exchange tubes  3  located between the first partition plates  4  and the second partition plate  5  and communicating with the first flow passages  10 . The heat transfer medium further exchange heat with other mediums. This is the second flow path. 
     Thereafter, the heat transfer medium then flows into channels between the first ends of the first flow passages  10  (the left side in  FIG. 17 ) and the first partition plate  4 , then flows into the heat exchange tubes  3  communicating with channels between the first ends of the first flow passages  10  and the second partition plate  5 , and further exchanges heat with other mediums again. This is the third flow path. 
     After flowing into the first flow channel, the heat transfer medium flows along the heat exchange tubes  3  communicating with a channel between the first end of the second flow passage  20  and the second partition plate  5 , and exchanges heat with other mediums. In this case. This is the fourth flow path. 
     The heat transfer medium flows into a channel between the first end of the second flow passage  20  (the left side in  FIG. 17 ) and the first partition plates  4 , and then flows into the heat exchange tubes  3  that are located between the first partition plates  4  and the second partition plate  5  and communicate with the second flow passage  20 . In this case, the heat transfer medium exchanges heat with other mediums. This is the fifth flow path. 
     After flowing into the third flow channel, the heat transfer medium flows into the heat exchange tubes  3  communicating with a channel between the second end of the second flow passage  20  (the right side in  FIG. 17 ) and the first partition plate  4 , and further exchanges heat with other mediums. The heat transfer medium finally flows into the channel between the second end of the second flow passage  20  (the right side in  FIG. 17 ) and the first partition plate  4 , and flows out of the second flow port  7 . The heat exchange process is completed. This is the sixth flow path. 
     In a case where the heat exchanger in this embodiment is used as an evaporator, the heat transfer medium flows from the second flow port  7  and out of the first flow port  6 . A flow direction of the heat transfer medium is opposite to that of the heat transfer medium in the case where the heat exchanger is used as the condenser, and thus the detailed description thereof will be omitted herein. 
     The heat exchanger according to this embodiment is capable of realizing the six-flow-path heat exchange, which further improves the heat exchange performance. 
     Eighth Embodiment 
     The difference between the eighth embodiment and the seventh embodiment is in that the first header  1  in this embodiment includes a first middle plate  13 . As shown in  FIG. 18 , the structure of the first middle plate  13  in this embodiment is the same as that of the first middle plate  13  described in the second embodiment. Other structures of the heat exchanger according to the eighth embodiment are the same as those in the seventh embodiment, and the operation principle of the heat exchanger in this embodiment is also the same as that described in the fifth embodiment, and thus the detailed description thereof will be omitted herein. 
     However, it should be understood that the second header  2  in this embodiment may further include a second middle plate  23 , and the structure and mounting position of this second middle plate  23  are the same as those of the second middle plate  23  described in the third embodiment. Accordingly, the detailed description thereof will be omitted herein. 
     Ninth Embodiment 
       FIG. 19  is a schematic structural view of a heat exchanger according to a ninth embodiment of the present disclosure,  FIG. 20  is an operation flow chart of the heat exchanger according to the ninth embodiment of the present disclosure, and  FIG. 21  is a schematic exploded view of the heat exchanger according to the ninth embodiment of the present disclosure. As shown in  FIGS. 19 to 21 , the heat exchanger according to the ninth embodiment of the present disclosure includes heat exchange tubes  3 , a first header  1 , and a second header  2 . Alternatively, the heat exchange tubes  3  may be arranged in two rows including a front row and a rear row. Each of the heat exchange tubes  3  is connected to the first header  1  at one end thereof, and is connected to the second header  2  at the other end thereof. Each of the heat exchange tubes  3  has an inner cavity in communication with an inner cavity of the first header  1  and an inner cavity of the second header  2 . 
     Alternatively, the heat exchanger further includes fins  9  and a cover plate  14 . The fins  9  are at least partially attached to the heat exchange tubes  3 . The cover plate  14  is disposed outside the outermost fin  9 . The attachment between the fins  9  and the heat exchange tubes  3  is capable of improving the heat exchange efficiency of the heat exchanger. The cover plate  14  is capable of protecting the fins  9  and the heat exchange tubes  3 . 
     It should be understood that the cover plate  14  may be an aluminum plate or the heat exchange tube  3 . In a case where the cover plate  14  is the heat exchange tube, this heat exchange tube, however, does not perform the heat exchange and only functions to protect the fins  9  and the heat exchange tubes  3 . 
       FIG. 22  is a schematic structural view of a first type of header according to the ninth embodiment of the present disclosure. As shown in  FIG. 22 , a header  100  is also provided in this embodiment. The header  100  described in this embodiment may be used as at least one of the first header  1  or the second header  2  as described above. 
     The header  100  includes a first main plate  11  and a second main plate  12  that are hermetically connected with each other. 
     In this embodiment, the first main plate  11  and the second main plate  12  may be fixed and connected by brazing to form the header  100  of substantially “8” shape. However, the first main plate  11  and the second main plate  12  may also be connected by riveting, adhesive or other processes. 
     The first main plate  11  includes a first rib  103  and at least two first curved sections  104 . The first rib  103  is connected to two adjacent first curved sections  104  at one end thereof, and is attached and connected to the second main plate  12  at the other end thereof. The second main plate  12  includes at least one second curved section  105  that is disposed to correspond to the at least one first curved section  104 . 
     In the header as described above, the first rib  103  is provided to increase the strength of the header. Further, the first rib  103  is attached to the second main plate  12  so as to increase a welding area between the first main plate  11  and the second main plate  12 . The first curved sections  104  and the second curved section  105  are provided to increase the strengths of the first main plate  11  and the second main plate  12 . Therefore, the header  100  has a strong ability to withstand pressure. 
       FIG. 23  is a schematic structural view of a second type of header according to the ninth embodiment of the present disclosure. As shown in  FIG. 23 , in this embodiment, the second main plate  12  includes a first straight section  107  connected to the second curved section  105 , and the second curved section  105  corresponds to the first curved section  104 . The first straight section  107  is at least partially attached to the first rib  103 . The first straight section  107  is at least partially attached to the first rib  103  so that the welding area between the first main plate  11  and the second main plate  12  is further increased, thereby improving the strength of the header  100 . 
       FIG. 24  is a schematic structural view of a third type of header according to the ninth embodiment of the present disclosure,  FIG. 25  is a schematic front structural view of a second plate in the third type of header according to the ninth embodiment of the present disclosure, and  FIG. 26  is a schematic front structural view of a first plate in the third type of header according to the ninth embodiment of the present disclosure. As shown in  FIGS. 24 to 26 , in this embodiment, the first main plate  11  includes a first rib  103  and two or more first curved sections  104 . The second main plate  12  includes a first straight section  107  and two or more second curved sections  105 . The first straight section  107  is connected with two adjacent second curved sections  105 . The second curved sections  105  are disposed in a one-to-one correspondence with the first curved sections  104 . The first straight section  107  is attached to the first rib  103 . In this embodiment, the second curved sections  105  are disposed in a one-to-one correspondence with the first curved sections  104 , so that the strength of the header  100  is further improved. 
     In this embodiment, referring to  FIG. 25 , the first straight section  107  may include a first fitting surface  107   a , to which an end surface of the first rib  103  is attached. Referring to  FIG. 24 , a first cavity  130  is formed between the first main plate  11  and the second main plate  12 . The first cavity  130  includes at least two chambers  130   a , and the first rib  103  is located between two adjacent chambers  130   a.    
     In this embodiment, the first rib  103  may be a strip-shaped rib with a flat end surface. The first fitting surface  107   a  is a flat surface. The flat surface of the first rib  103  is attached to the flat surface of the first fitting surface  107   a , thereby increasing the welding area. 
     In an alternative embodiment, the second main plate  12  further includes second straight sections  108 , each of which is connected to the second curved section  105  or the first straight section  107 . Each of the second straight sections  108  includes a second fitting surface  108   a . The first main plate  11  further includes second ribs  109 . Alternatively, each of the second ribs  109  may be a strip-shaped rib with a flat end surface. Each of the second ribs  109  is connected to two adjacent first curved sections  104  at one end thereof, and is attached to the second fitting surface  108   a  with an end surface of the other end thereof. 
     Each of the chambers  130   a  includes two or more sub-chambers, and each of the second ribs  109  are located between two adjacent sub-chambers. 
     It should be understood that the second ribs  109  are located in the chambers  130   a . Alternatively, each of the second ribs  109  may be formed with a communication groove or a communication aperture to communicate two adjacent sub-chambers. Each second rib  109  may be partially formed with the communication groove or the communication aperture to cooperate with the partition structure, such that partial regions of the two adjacent sub-chambers communicate with each other and another partial regions of the two adjacent sub-chambers are independent from each other to form different flow paths. 
     The second ribs  109  are configured to further increase the strength of the header  100  so as to withstand a pressure of a refrigerant. Alternatively, the second ribs  109  may be arranged symmetrically with respect to the first rib  103  as a center axis. Each of the second ribs  109  is configured to divide the chambers  130   a  into two sub-chambers. However, the second ribs  109  may also be arranged asymmetrically with respect to the first rib  103 , which can also further increase the strength of the header  100 . The following description will take a four-flow-path and a three-flow-path as examples. 
     In an alternative embodiment, at least one of the first rib  103  or the second ribs  109  are provided with a third rib  110 , as shown in  FIG. 26 . It should be understood that the third rib  110  is formed by extending at least one of the first rib  103  or the second ribs  109  in a direction away therefrom. For example, the first rib  103  is disposed on the first main plate  11 , and the third rib  110  is formed by extending the first rib  103  toward the second main plate  12  in a direction away from an end of the first main plate  11 . 
     Alternatively, the third rib  110  may be a strip-shaped rib, a triangular rib or other ribs. The third rib  110  may be disposed at any position of an end of the first rib  103 , and/or may be disposed at any position of an end of the second rib  109 . At least one of the first straight section  107  or the second straight section  108  is provided with a fitting aperture  108   b  (refer to  FIG. 27 ), and the third rib  110  is fixed in the fitting aperture  108   b . The third rib  110  is configured to further improve the strength of the header  100 . Alternatively, after the third rib  110  is fitted into the fitting aperture  108   b , a portion of the third rib  110  penetrating through the fitting aperture  108   b  can be further twisted and fixed, which improves the connection strength between the first main plate  11  and the second main plate  12 . 
     In this embodiment, for example, the third rib  110  is provided at the second rib  109 . As shown in  FIGS. 23 to 27 , each of the second ribs  109  is provided with a third rib  110  with a predetermined thickness and height. The thickness of the third rib  110  W1 may be ¼-½ of a thickness W2 of the second rib  109 . In this way, after the third rib  110  is fitted with the fitting aperture  108   b , the width of the second rib  109  is large enough to limit the position of the third rib  110 , to ensure that the third rib  110  is reliably connected with the fitting aperture  108   b . The height H of the third rib  110  may be within a range of 2 mm-9 mm. In this way, when the third rib  110  penetrates through the fitting aperture  108   b , an exposed portion of the third rib  110  can be more convenient to be clamped by a tool for twisting. The twisted third rib  110  further increases the connection strength between the first main plate  11  and the second main plate  12 . 
     The third rib  110  is tightly connected with the fitting aperture  108   b  of the second main plate  12  to fix, position and connect the first main plate  11  and the second main plate  12 , which improves the reliability of the connection between the first main plate  11  and the second main plate  12 . 
     It should be understood that the third rib  110  may be disposed only at the first rib  103 . In this case, the first straight section  107  is correspondingly provided with the fitting aperture  108   a . Alternatively, the third rib  110  may be disposed only at the second rib  109 . In this case, the second straight section  108  is correspondingly provided with the fitting aperture  108   b . Alternatively, the third rib  110  may also be disposed both at the first rib  103  and the second rib  109 . In this case, each of the first straight section  107  and the second straight section  108  is formed with a respective fitting aperture. It should be noted that the present disclosure is not limited to the above embodiments as long as the reliability of the connection between the first main plate  11  and the second main plate  12  can be improved. 
     It should be understood that referring to  FIG. 33 , in a length direction of the first rib  103  or the second rib  109 , the third ribs  110  may be continuously distributed on at least one of the first rib  103  or the second ribs  109 , or distributed on at least one of the first rib  103  or the second ribs  109  at a predetermined interval. The third ribs  110  may be evenly or unevenly distributed, or the third ribs  110  may be densely or sparsely distributed. The third ribs  110  may be distributed on the first rib  103  and the second ribs  109  in the same manner or different manners. It should be noted that the present disclosure is not limited to the above embodiments as long as the reliability of the connection between the first main plate  11  and the second main plate  12  can be improved. 
       FIG. 27  is a schematic structural view of a second main plate of a third type of header according to an embodiment of the present disclosure, and  FIG. 28  is schematic structural view of a first main plate of the third type of header according to the embodiment of the present disclosure. As shown in  FIGS. 27 and 28 , in an alternative implementation, the second main plate  12  is provided with partition plate grooves  124 , and the header  100  further includes the first partition plates  4  (see  FIGS. 21 and 33 ). One of the partition plates  4  is fixed into one of the partition plate grooves  124 . Referring to  FIG. 28 , the first rib  103  of the first main plate  11  is formed with communication grooves  103   a  located at a side of each of the first partition plates  4 . The adjacent chambers  130   a  are in communication with each other through the communication groove  103   a . The chambers  130   a  are isolated from each other at the other side of the first partition plate  4 . It should be appreciated for those skilled in the art that the chambers  130   a  may also be in communication with each other by providing communication apertures, and the present disclosure is not limited to the above communication grooves  103   a.    
     The header  100  may be provided with a plurality of groups of first partition plates  4 . The plurality of groups of first partition plates  4  corporate with the partition plate grooves  124  to divide each of the chambers  130   a  into a plurality of sub-chambers in a length direction of the header  100 . With these sub-chambers, the refrigerant is capable of flowing in a plurality of flow paths. Each of the first partition plates  4  may also be an integrated structure and corporate with the partition plate groove  124  as a whole. The first partition plate  4  with the integrated structure may also divide the cavity  130   a  into the plurality of sub-chambers in the length direction of the header  100 , so that the refrigerant can flow in the plurality of flow paths through the plurality of sub-chambers. A flow process of the multi-flow-path will be described in detail below. 
     As shown in  FIG. 27 , the first main plate  11  or the second main plate  12  may also be provided with receiving grooves  126 . Alternatively, the receiving grooves  126  may be obtained by punching press of a puncher, or may be integrally formed by casting or the like. Each of the receiving grooves  126  matches a necking portion  43  of the respective heat exchange tube  3  in shape and size. Specifically, the receiving grooves  126  may be, for example, an opening in a rectangular shape or a waist shape. The heat exchange tube  3  is usually a flat tube. Referring to  FIGS. 31 and 32 , the heat exchange tube  3  of the flat tube shape has the necking portion  43  that is inserted into a respective one of the receiving grooves  126 . 
     As shown in  FIG. 27 , in this embodiment, the receiving grooves  126  are formed at the second main plate  12 . Correspondingly, each of the second ribs  109  on the first main plate  11  may be provided with a notch to avoid an end of each of the heat exchange tubes  3 . The notch has a width matching a thickness of the necking portion  43  of the heat exchange tube  3  such that at least part of the necking portion  43  is received in the notch. When the at least part of the necking portion  43  of the heat exchange tube  3  is inserted into the notch, an insertion depth of the necking portion  43  is configured in a manner that an end of the necking portion  43  cannot contact an inner wall of the notch and the flow of the refrigerant cannot be interfered. It should be understood that the first main plate  11  may also be formed with the receiving grooves, and the second main plate  12  may be provided with the second ribs  109  and the notches. The present disclosure is not limited thereto. 
     In this embodiment, an end of each of the heat exchange tubes  3  is received in one of the notches. However, the ends of two or more heat exchange tubes  3  may be received in the one of the notches. In this case, the width of the notch is greater than or equal to a sum of a distance between two or more heat exchange tubes  3  and a thickness of all the heat exchange tubes  3 , as long as the ends of the necking portions  43  of all the heat exchange tubes  3  cannot contact with the inner wall of the notch and the flow of the refrigerant cannot be interfered. 
     In this embodiment, the heat exchange tubes  3  may be fixed to the second main plate  12  by brazing after being inserted into the receiving grooves  126 . 
       FIG. 29  is a schematic structural view of an end cap of the header according to the embodiment of the present disclosure,  FIG. 30  is a schematic front view of the end cover of the header according to the embodiment of the present disclosure, and  FIG. 31  is a schematic transverse sectional view of the end cover of the header according to the embodiment of the present disclosure. 
     Referring to  FIGS. 21, 29 to 31 , a header  100  according to an embodiment of the present disclosure further includes a blocking cap  16  and an end cap  8 . The blocking cap  16  is configured to at least block an end of the first cavity  130 , and the end cap  8  is disposed at the other end of the first cavity  130  without the blocking cap  16 . The end cap  8  has an inlet and/or an outlet that communicate with the first cavity  130 , respectively. The inlet is configured for an inflow of the refrigerant, and the outlet is configured for an outflow of the refrigerant. The end cap  8  is assembled with the first header  1  or the second header  2  to form a header assembly. 
     It should be understood that the inlet and the outlet may be disposed on the same end cap, or may be disposed on two end covers, respectively. The present disclosure is not limited to the above embodiments as long as the inflow and outflow of the refrigerant will not be interfered. 
     Referring to  FIG. 27 , a blocking cap groove  125  may be provided at the second main plate  12 . The blocking cap  16  is fitted with the blocking cap groove  125  to seal the end at a side of the header  100 . In this embodiment, the first header  1  of the heat exchanger is provided with the blocking cap  16  at one end thereof and the end cap  8  at the other end thereof. The second header  2  of the heat exchanger may be provided with the blocking caps  16  at both ends. However, the blocking cap  16  and the end cap  8  may also be arranged based on an actual flow path design, which is not further limited herein. 
       FIG. 32  is a schematic sectional view of the first header fitting with the heat exchange tubes after being partially cut off, according to the embodiment of the present disclosure.  FIG. 33  is a schematic partial view of the first header shown in  FIG. 32 .  FIG. 34  is a schematic enlarged view of a part A shown in  FIG. 32 .  FIG. 17  is a schematic sectional view of the first header fitting with the heat exchange tubes according to an embodiment of the present disclosure. 
     Taking a four-flow-path as an example and referring to  FIGS. 19, 20, 27, 28, and 35 , the first header  1  of the heat exchanger according to the embodiment of the present disclosure includes a first end A 1  and a second end A 2 . The second header  2  includes a third end A 3  and a fourth end A 4 . The first end A 1  and the third end A 3  are located at the same side, and the second end A 2  and the fourth end A 4  are located at the same side. In this embodiment, the inlet and the outlet are both located at the first end A 1 , and the second end A 2 , the third end A 3 , and the fourth end A 4  are all provided with the blocking caps. The first header  1  is provided with the first partition plates  4 . A part of the first rib  103  of the first header  1  located between the first partition plates  4  and the second end A 2  are formed with communication grooves  103   a , and a part of the first rib  103  of the first header  1  located between the first partition plates  4  and the second end A 2  are not formed with a communication groove. In addition, the first rib of the second header  2  is not formed with a communication groove. An operation principle of the four-flow-path of the heat exchanger according to the embodiment of the present disclosure as an evaporator will be described below. 
     Firstly, a refrigerant flows into a sub-chamber  131   c  and a sub-chamber  131   d  (as shown in  FIG. 24 ) of the first header  1  between the first partition plates  4  and the first end A 1  through the inlet. At this time, as shown in  FIGS. 20 and 21 , the refrigerant flows in a first flow path. In this first flow path, the refrigerant flows downwardly to a sub-chamber  131   c  and a sub-chamber  131   d  of the second header  2  located between the first partition plates  4  and the third end A 3  along rear tubes  42  communicating with the sub-chamber  131   c  and the sub-chamber  131   d  located between the first partition plates  4  and the first end A 1 , and the refrigerant exchanges heat with the air to evaporate and absorb heat. It should be noted that the second header  2  is not provided with the first partition plate  4 , and the phrase “between the first partition plates  4  and the third end A 3 ” refers to between the third end A 3  and a projection of the first partition plates  4  on the third header  3 . 
     Thereafter, the refrigerant flows into a sub-chamber  131   c  and a sub-chamber  131   d  of the second header  2  between the first partition plates  4  and the fourth end A 4 , and flows in a second flow path. It should be noted that the second header  2  is not provided with the first partition plate  4 , and the phrase “between the first partition plates  4  and the third end A 3 ” refers to between the third end A 3  and the projection of the first partition plates  4  on the third header  3 . The refrigerant flows upwardly along the rear tubes  42  communicating with the sub-chamber  131   c  and the sub-chamber  131   d  between the first partition plates  4  and the fourth end A 4 , and continues to evaporate and absorb the heat. 
     Next, the refrigerant flows to a sub-chamber  131   c  and a sub-chamber  131   d  of the first header  1  between the second end A 2  and the first partition plates  4 . With the communication grooves  103   a , the refrigerant flows from a sub-chamber  131   c  and a sub-chamber  131   d  of the first header  1  between the second end A 2  and the first partition plates  4  into a sub-chamber  131   a  and the sub-chamber  131   b  of the first header  1  between the second end A 2  and the first partition plates  4 , and then flows in a third flow path. The refrigerant flows downwardly to a sub-chamber  131   a  and a sub-chamber  131   b  of the second header  2  between the fourth end A 4  and the first partition plates  4  along front tubes  41  communicating with a sub-chamber  131   a  and a sub-chamber  131   b  between the second end A 2  and the first partition plates  4 . 
     Subsequently, the refrigerant flows into a sub-chamber  131   a  and a sub-chamber  131   b  of the second header  2  between the third end A 3  and the first partition plates  4 , and flows in a fourth flow path. The refrigerant flows upwardly along the front tubes  41  communicating with a sub-chamber  131   a  and a sub-chamber  131   b  of the second header  2  between the third end A 3  and the first partition plates  4 , and flows out of the outlet communicating with a sub-chamber  131   a  and a sub-chamber  131   b  of the first header  1  between the first end A 1  and the first partition plates  4 . 
     An operation principle of the four-flow-path of the heat exchanger according to the embodiment of the present disclosure as a condenser will be described below. 
     Firstly, the refrigerant flows into the sub-chamber  131   a  and the sub-chamber  131   b  of the first header  1  between the first end A 1  and the first partition plates  4  through the inlet. At this time, the refrigerant flows in a first flow path. The refrigerant flows downwardly to the sub-chamber  131   a  and the sub-chamber  131   b  of the second header  2  between the first partition plates  4  and the third end A 3  along the front tubes  41  communicating with the sub-chamber  131   a  and the sub-chamber  131   b  between the first partition plates  4  and the first end A 1 , and the refrigerant is cooled and liquefied. It should be noted that the second header  2  is not provided with the first partition plate  4 , and the phrase “between the first partition plates  4  and the third end A 3 ” refers to between a projection of the first partition plates  4  on the third header  3  and the third end A 3 . 
     Thereafter, the refrigerant flows into the sub-chamber  131   a  and the sub-chamber  131   b  of the second header  2  between the first partition plates  4  and the fourth end A 4 , and flows in a second flow path. It should be noted that the second header  2  is not provided with the first partition plate  4 , and the phrase “between the first partition plates  4  and the fourth end A 4 ” refers to between a projection of the first partition plates  4  on the third header  3  and the fourth end A 4 . The refrigerant flows upwardly to the sub-chamber  131   a  and the sub-chamber  131   b  of the first header  1  between the first partition plates  4  and the second end A 2  along the front tubes  41  communicating with the sub-chamber  131   a  and the sub-chamber  131   b  between the first partition plates  4  and the fourth end A 4 . With the communication grooves  103   a , the refrigerant flows from the sub-chamber  131   a  and the sub-chamber  131   b  of the first header  1  between the first partition plates  4  and the second end A 2  to the sub-chamber  131   c  and the sub-chamber  131   d  of the first header  1  between the first partition plates  4  and the second end A 2 . 
     Next, the refrigerant flows in a third flow path. The refrigerant flows downwardly along the rear tubes  42  communicating with the sub-chamber  131   c  and the sub-chamber  131   d  of the first header  1  between the first partitions  4  and the second end A 2 , and is cooled and liquefied. 
     Finally, the refrigerant flows to the sub-chamber  131   c  and the sub-chamber  131   d  of the second header  2  between the fourth end A 4  and the first partition plates  4 , and flows in a fourth flow path. Then, the refrigerant flows upwardly along the rear tubes  42  communicating with the sub-chamber  131   c  and the sub-chamber  131   d  between the fourth end A 4  and the first partition plates  4 , and flows out of the outlet communicating with the sub-chamber  131   c  and the sub-chamber  131   d  of the first header between the first end A 1  and the first partition plates  4 . 
     In this embodiment, as shown in  FIGS. 29 to 31 , the end cap  8  includes a body  141  and a first opening  142  formed at the body  141 . 
     The first opening  142  may be a circular opening or other openings, and may be directly formed at the body  141  or connected to a pipe body on the body  141 . A channel of the pipe body may be formed as the first opening  142 . 
     The body  141  further includes a second cavity  143  and a first groove portion  144 . The first groove portion  144  is located between the first opening  142  and the second cavity  143 . The first groove portion  144  includes a first bottom wall  145  close to the first opening  142 . The first bottom wall  145  includes a third opening  145   a  to communicate the first opening  142  with the second cavity  143 . The second cavity  143  is in communication with the inner cavity of the first header  1  or the inner cavity of the second header  2 . The first opening  142  is farther from the inner cavity of the first header  1  or the inner cavity of the second header  2  than the second cavity  143 . A flow area of the first groove portion  144  is greater than that of the third opening  145   a . The flow area herein refers to a volume of the fluid flowing through a flow cross-section per unit time. For example, in this embodiment, the flow area of the first groove portion  144  refers to a volume of the fluid flowing through a flow cross-section of the first groove portion  144  per unit time. 
     The first opening  142  of the end cap  8  may be used as a refrigerant inlet or a refrigerant outlet, which is not limited thereto. In a case where the first opening  142  is used as the inlet, when the refrigerant flows from the first opening  142  into the first groove portion  144  through the third opening  145   a , since the flow area of the first groove portion  144  is greater than that of the third opening  145   a , an impact of the refrigerant flowing into the first cavity  130  of the header  100  on the header  100  is reduced during the inflow of the refrigerant and thus the pressure-resistant requirement of the header  100  is reduced. 
     When the first opening  142  is used as the outlet, the refrigerant can flow from the first groove portion  144  into the fourth opening  145   a  at a more uniform flow rate. 
     In an alternative implementation, a width of the first groove portion  144  in a transverse extension direction of the first bottom wall  145  is greater than a width of the third opening  145   a  in the transverse extension direction of the first bottom wall  145 . In this embodiment, the first groove portion  144  may be a waist-shaped groove, and the third opening  145   a  may be a circular aperture. A dimension of a major axis of the waist-shaped groove is greater than a diameter of the circular aperture. Alternatively, a dimension of a minor axis of the waist-shaped groove may be equal to the diameter of the circular aperture. However, the dimension of the minor axis of the waist-shaped groove may be greater or less than the diameter of the circular aperture, as long as the third opening  145   a  can communicate the first opening  142  with the second cavity  143 . Alternatively, a center of the third opening  145   a  is coincident with that of the first groove portion  144 , such that the refrigerant is capable of being evenly diverted toward both sides when flowing out of the third opening  145   a , thereby achieving uniform diverted flows. However, the first groove portion  144  may have other shapes, such as a rectangular shape and a circular shape, and the third opening  145   a  may be an aperture of other shapes, such as a profiled aperture or an elliptical aperture. 
     In an alternative implementation, the body  141  further includes a first channel  145   b  that is formed by extending the third opening  145   a  in a direction from the second cavity  143  toward the first opening  142 . The first channel  145   b  is located between the first opening  142  and the first groove portion  144 , and is in communication with the first opening  142  and the first groove portion  144 , respectively. A width of the first channel  145   b  in the transverse extension direction of the first bottom wall  145  is smaller than that of the first groove portion  144  in the transverse extension direction of the first bottom wall  145 . 
     For example, the first opening is a circular opening, the first channel  145   b  is a circular channel and an external pipeline is a circular pipe. An inner diameter of the first channel  145   b  may be the same as an opening diameter of the third opening  145   a . The external pipeline for the inflow of the refrigerant is inserted into the first opening  142 , and an inner diameter of the external pipeline is equal to an inner diameter of the first channel  145   b . After flowing into the heat exchanger, the refrigerant passes through the first channel  145   b  at a smaller flow rate, and then flows into the first groove portion  144  through the third opening  145   a  to be diverted, thereby further reducing the impact of the refrigerant on the header  100 . 
     In the embodiment as described above, the body  141  is formed with a second opening  146 . The second opening  146  may be a circular opening or have other shapes. The second opening  146  may be directly formed at the body  141  or connected to the pipe body on the body  141 , and the channel of the pipe body may be formed as the second opening  146 . 
     The body  141  further includes a second groove portion  147 . The second groove portion  147  includes a second bottom wall  148  close to the second opening  146 . The second bottom wall  148  includes a fourth opening  148   a  that is configured to communicate the second opening  146  with the second cavity  143 . A flow area of the second groove portion  147  is greater than that of the fourth opening  148   a . The flow area herein refers to a volume of the fluid flowing through a flow cross-section per unit time. For example, in this embodiment, the flow area of the second groove portion  147  refers to a volume of the fluid flowing through a flow cross-section of the second groove portion  147  per unit time. 
     The second opening  146  of the end cap  8  may be used as a refrigerant inlet or a refrigerant outlet, which is not limited thereto. In a case where the second opening  146  is used as the refrigerant inlet, when the refrigerant flows from the second opening  146  into the second groove portion  147  through the fourth opening  148   a , since the flow area of the second groove portion  147  is greater than that of the fourth opening  148   a , an instantaneous pressure of the refrigerant is capable of being reduced during the inflow of the refrigerant. In this way, the impact of the refrigerant on the header  100  can be reduced when the refrigerant flows into the first cavity  30  of the header  100 . 
     When the second opening  146  is used as the refrigerant outlet, the refrigerant flows from the second groove portion  147  into the fourth opening  148   a  at a more uniform flow rate. 
     In an alternative implementation, a width of the second groove portion  147  in a transverse extension direction of the second bottom wall  148  is greater than a width of the fourth opening  148   a  in the transverse extension direction of the second bottom wall  148 . In this embodiment, the second groove portion  147  may be a waist-shaped groove, and the fourth opening  148   a  may be a circular aperture. A dimension of a major axis of the waist-shaped groove is greater than a diameter of the circular aperture. Alternatively, a dimension of a minor axis of the waist-shaped groove may be equal to the diameter of the circular aperture. However, the dimension of the minor axis of the waist-shaped groove may also be greater or smaller than the diameter of the circular aperture, as long as the third opening can communicate the first opening with the second cavity. Alternatively, a center of the third opening is coincident with that of the first groove portion, such that the refrigerant is capable of being evenly diverted toward both sides when flowing out of the fourth opening  148   a  to the second groove portion  147 , thereby achieving uniform diverted flows. However, the second groove portion  147  may also have other shapes, such as a rectangular shape and a circular shape, and the fourth opening  148   a  may be an aperture of other shapes, such as a profiled aperture or an elliptical aperture. 
     In an alternative implementation, the body  141  further includes a second channel  148   b  that is formed by extending the fourth opening  148   a  in a direction from the second cavity  143  toward the second opening  146 . The second channel  148   b  is located between the second opening  146  and the second groove portion  147 , and is configured to be in communication with the second opening  146  and the second groove portion  147 , respectively. A width of the second channel  148   b  in the transverse extension direction of the second bottom wall  148  is smaller than that of the second groove portion  147  in the transverse extension direction of the second bottom wall  148 . 
     For example, the second channel is a circular channel and an external pipeline is a circular pipe. An inner diameter of the second channel  148   b  may be the same as an opening diameter of the fourth opening  148   a . When the second channel  148   b  is used as an input channel, the external pipeline for the inflow of the refrigerant is inserted into the second opening  146 , and an inner diameter of the external pipeline is equal to an inner diameter of the second channel  148   b . After flowing into the heat exchanger, the refrigerant passes through the second channel  148   b  at a smaller flow rate, and then flows into the second groove portion  147  through the fourth opening  148   a  to be diverted, thereby further reducing the impact of the refrigerant on the header  100 . 
     In a case where the second channel  148   b  is used as an output channel, the refrigerant flows into the second channel  148   b  from the second groove portion  147 , which achieves more uniform flow of the refrigerant. 
     In an alternative implementation, the first groove portion  144  and the second groove portion  147  may be symmetrically arranged about a center line of the end cap  8 , which can result in more uniform distribution of the refrigerant. Similarly, the first channel  145   b  and the second channel  148   b  are symmetrically arranged about the center line of the end cap  8 , and the third opening  145   a  and the fourth opening  148   a  are symmetrically arranged about the center line of the end cap  8 , so as to achieve more uniform distribution of the refrigerant. 
     In this embodiment, the header  100  includes the first main plate  11  and the second main plate  12  connected with each other. The first cavity  130  is formed between the first main plate  11  and the second main plate  12 . At least one of the first main plate  11  or the second main plate  12  is provided with a first rib  103 . The first cavity  130  includes at least two chambers  130   a , and the first rib  103  is disposed between adjacent chambers  130   a.    
     The header  100  further includes the end cap  8  according to any one of the embodiments of the present disclosure. The end cap  8  is configured to block the first cavity  130  at one end of the first cavity, and the first opening  142  communicates with one of the chambers  130   a  through the first groove portion  144 . 
     It should be understood that the header  100  may include an end cap  8  that only has the first opening  142 , or may include an end cap that has both the first opening  142  and the second opening  146 . When the end cap has both the first opening  142  and the second opening  146 , the first ribs  103  abut against the body  141 , and the first ribs  103  are located between the first opening  142  and the second opening  146  as well as between the first groove portion  144  and the second groove portion  147 , to prevent the first opening  142  and the second opening  146  from being communicated with each other at the end cap. In the end cap  8 , the flow area of the first groove portion  144  is greater than that of the third opening  145   a . Therefore, the impact of the refrigerant on the header  100  will be further reduced when the refrigerant flows into the chambers  130   a  of the header  100 . 
     As shown in  FIGS. 28 and 33 , in this embodiment, a distance from each of the first partition plates  4  to the end cap  8  is smaller than a length of a portion of the first rib  103  without the communication groove  103   a . In this way, sealing performance at the first partition plates  4  is improved. However, the distance from each of the first partition plates  4  to the end cap  8  may be equal to the length of the portion of the first rib  103  without the communication groove  103   a , and the present disclosure is not limited thereto. In this embodiment, the length of the portion of the first rib  103  without the communication groove  103   a  may be greater than that of a portion of the first rib  103  formed with the communication groove  103   a . However, the length of the portion of the first rib  103  without the communication groove  103   a  may be smaller than or equal to that of the portion of the first rib  103  formed with the communication groove  103   a , and the present disclosure is not limited thereto.  FIG. 36  is a schematic partial view of a header according to an embodiment of the present disclosure. Referring to  FIGS. 34 and 36 , in an alternative implementation, at least one of the first main plate  11  or the second main plate  12  includes second ribs  109 , and each of the chambers  130   a  includes two or more sub-chambers, and the second ribs  109  are located between two adjacent sub-chambers. 
     A width of the first groove portion  144  is greater than that of the second rib  109  facing the first groove portion  144 . After the refrigerant flows out of the first groove portion  144 , most of the refrigerant flows into the chambers  130   a  from both sides of the second rib  109 , rather than vertically impacting the second ribs  109 , thereby reducing the impact on the second ribs  109 . 
     In an alternative implementation, an end of the second rib  109  facing toward the end cap  8  is formed with a third groove  109   b . The third groove  109   b  functions to further prevent the refrigerant from directly impacting the second rib  109  after flowing out of the first groove portion  144 . 
     Similarly, the third groove  109   b  is disposed such that when flowing out of the chamber  130   a , the refrigerant will not be applied by excessive resistance, and thus can smoothly flow into the second cavity  143  and then flow out of the outlet. 
     It should be understood that the third groove  109   b  may be a square groove as shown in  FIG. 36 . However, the third groove  109   b  may also be a U-shaped or V-shaped groove, or other profiled grooves. The present disclose is not limited to the above embodiments as long as the third groove can prevent the refrigerant from directly impacting the second rib  109 . 
     In an alternative implementation, as shown in  FIGS. 24 to 26 and 29 to 31 , the first main plate  11  includes two or more first curved sections  104 , and the second main plate  12  includes a first straight section  107  and two or more second curved sections  105 . The first straight section  107  is configured to connect two adjacent second curved sections  105 , and each of the second curved sections  105  corresponds to one of the first curved sections  104 . That is, the second curved section  105  and the first curved section  104  cooperate with each other, and are assembled with the first rib  103  or the second ribs  109  to form the sub-chambers as described above. 
     The body  141  includes an upper body  141   d  and a lower body  141   e . The upper body  141   d  includes third curved sections  141   a  corresponding to the first curved sections  104 . The lower body  141   e  includes third straight sections  141   b  corresponding the first straight section  107  and the second straight sections  108 , and fourth curved sections  141   c  corresponding to the second curved sections  105 . The third straight sections  141   b  are configured to connect two adjacent fourth curved sections  141   c . One of the fourth curved sections  141   c  corresponds to a respective one of the third curved sections  141   a.    
     In this embodiment, when the end cap  8  fits with the first main plate  11  and the second main plate  12 , the third straight sections  141   b  of the end cap  8  is capable of being attached to the first straight section  107  and the second straight sections  108 , the third curved sections  141   a  is capable of being attached to the first curved sections  104 , and the fourth curved sections  141   c  is capable of being attached to the second curved sections  105 . 
     The header  100  and the heat exchanger according to the embodiments of the present disclosure is capable of improving the overall strength of the header  100  and reducing the impact of the refrigerant on the header  100 . 
       FIG. 37  is a schematic structural front view of a fifth type of header according to an embodiment of the present disclosure,  FIG. 38  is a schematic structural view of a first main plate of the fifth type of header according to an embodiment of the present disclosure, and  FIG. 39  is schematic structural view of a second main plate of the fifth type of header according to an embodiment of the present disclosure. 
     Referring to  FIGS. 37 to 39 , the header according to this embodiment is different from the headers as described in the above embodiments in that the first main plate  11  and the second main plate  12  are connected by a first fixing member  17 . 
     Alternatively, the first rib  103  is provided with a first through hole  103   b , and the first straight section  107  is provided with a second through hole  107   b . The header includes the first fixing member  17  that is fixed to and penetrates through the first through hole  103   b  and the second through hole  107   b . Alternatively, the first fixing member  17  may be a rivet or other fasteners. 
     In this embodiment, other structures of the first main plate  11  and the second main plate  12  are the same as those described in the above embodiments, and the detailed description thereof will be omitted herein. 
     In the header and heat exchanger according to the embodiment of the present disclosure, the first main plate  11  and the second main plate  12  are connected by the first fixing member, thereby improving the strength of the header. 
       FIG. 40  is a schematic structural view of a first plate of a sixth type of header according to an embodiment of the present disclosure,  FIG. 41  is a schematic structural view of a second plate of the sixth type of header according to the embodiment of the present disclosure, and  FIG. 42  is a schematic front structural view of the sixth type of header according to the embodiment of the present disclosure. 
     Referring to  FIGS. 40 to 42 , the header according to this embodiment is different from the headers as described in the above embodiments in that the first main plate  11  and the second main plate  12  are connected by first fixing members  17  in this embodiment. Specifically, each of the second ribs  109  is provided with a first through hole  103   b , and each of the second straight sections  108  is provided with a second through hole  107   b.    
     The header  100  includes the first fixing members  17 , and each of the first fixing members  17  may be a rivet or other fasteners. The first fixing member  17  is fixed to and penetrates through a respective one of the first through holes  103   b  and a respective one of the second through holes  107   b.    
     In this embodiment, other structures of the first main plate  11  and the second main plate  12  are the same as those described in the above embodiments, and the detailed description thereof will be omitted herein. 
     In the header according to the embodiment of the present disclosure, the first main plate  11  and the second main plate  12  are connected by the first fixing members  17 , thereby improving the strength of the header. 
     It should be understood that, in other embodiments, the first rib  103  and the second rib  109  may be provided with the first through hole  103   b , and the first straight section  107  and the second straight section  108  may be provided with the second through hole  107   b . The first fixing member  17  is fixed to and penetrates through the first through hole  103   b  and the second through hole  107   b . In the header according to this embodiment, a plurality of first fixing members  17  are provided to connect the first main plate  11  and the second main plate  12 , which can further improve the strength of the header. 
     Referring to  FIG. 33 , the first through holes  103   b  may be continuously arranged on the second rib  109  as shown in  FIG. 14 , or may be arranged on the first ribs  103  at a predetermined interval, which is not further limited herein. 
       FIG. 43  is a schematic structural front view of a seventh type of header according to an embodiment of the present disclosure. With the structure as described above, the first rib  111  may be provided with the first through hole  103   b , and the second rib  109  may be provided with the third rib  110 , so that the strength of the header is improved. However, the first rib  111  may be provided with the third rib  110 , and the second rib  109  may be provided with the first through hole  103   b.    
     It is noted that the above descriptions are only the preferred embodiments of the present disclosure and the technical principles thereof. It should be understood by those skilled in the art that the present disclosure is not limited to these specific embodiments described herein, and various changes, modifications and substitutions can be made by those skilled in the art without departing from the scope of the present disclosure. Therefore, although the present disclosure has been described in more detail by the above embodiments, the present disclosure is not limited to the above embodiments, and may also include more other equivalent embodiments without departing from the concept of the present disclosure. The scope of the present disclosure is defined by the appended claims.