Patent Publication Number: US-2021180883-A1

Title: Heat exchanger with one-piece through fittings

Description:
TECHNICAL FIELD 
     The present disclosure relates to heat exchanger construction, and particularly to a heat exchanger having through-holes to permit passage of heat transfer fluid through the heat exchanger, and to thermal management systems incorporating such heat exchangers. 
     BACKGROUND 
     Thermal management systems for vehicles may include two or more heat exchangers connected in parallel to common inlet and outlet manifolds. In some configurations, the individual heat exchangers of the system may include a pair of through-holes which function as inlet and outlet ports, and as parts of the inlet and outlet manifolds to distribute the heat transfer fluid to other heat exchangers in the system. An example of such a heat exchanger structure is illustrated in FIG. 1 of commonly assigned U.S. Pat. No. 10,006,722, which is incorporated herein by reference in its entirety. 
     The heat exchangers shown in FIG. 1 of U.S. Pat. No. 10,006,722 are provided with face seals surrounding the through openings on both sides of the heat exchanger, to enable the formation of sealed fluid connections with inlet and outlet manifolds provided in a frame structure. Some configurations use tubular fittings instead of face seals to form the fluid connections. These fittings may project at right angles from both sides of the heat exchanger, and are sealingly secured to the external surfaces of the heat exchanger. Where both the inlet and outlet ports of the heat exchanger comprise through-holes, a total of four fittings are required, two at the inlet port and two at the outlet port. 
     In addition, it may be difficult to achieve sufficient concentricity between two fittings provided on opposite sides of a through-hole, given that the alignment of the fittings is subject to positional tolerances. Also, in some heat exchanger constructions, the area of the fluid flow passage in the vicinity of each through-hole lacks internal support, and additional support elements may be required inside the fluid flow passage to prevent deformation of the plates in the vicinity of the through-hole. Such support elements are also disclosed in above-mentioned U.S. Pat. No. 10,006,722. In addition, where the fittings are brazed to the outer, unclad, surfaces of plates comprising the heat exchanger, rings of brazing filler metal may be required between the sealing surfaces of the fitting and the heat exchanger plate, thereby increasing the number of components required for assembly. 
     There is a need for an improved fitting construction of heat exchangers which include through-holes. 
     SUMMARY 
     In accordance with an aspect of the present disclosure, there is provided a heat exchanger comprising a first plate having an inner surface, an outer surface and at least one first hole; and a second plate having an inner surface, an outer surface and at least one second hole. Each of the at least one first holes is in opposed, spaced relation to one of the at least one second holes. A fluid flow passage is defined between the inner surfaces of the first and second plates. The heat exchanger further comprises at least one through fitting, each of the through fittings having a one-piece structure and comprising a first portion, a second portion, and a third portion between the first and second portions. 
     According to an aspect, the first portion of each of the at least one through fittings extends through one of the at least one first holes of the first plate and has a first end opening. 
     According to an aspect, the second portion of each of the at least one through fitting extends through one of the at least one second holes of the second plate and has a second end opening, each of the at least one through fitting having a hollow interior extending from the first end opening to the second end opening. 
     According to an aspect, the third portion of each of the at least one through fitting is located between the first and second plates and has an outer periphery located radially outwardly of an outer surface of the first portion and an outer surface of the second portion. 
     According to an aspect, the third portion of each of the at least one through fitting has a first radially-extending surface in contact with the inner surface of the first plate and a second radially-extending surface in contact with the inner surface of the second plate. 
     According to an aspect, at least one communication passage is provided through the third portion of each of the at least one through fitting between the fluid flow passage and the hollow interior of the through fitting. 
     According to an aspect, the fluid flow passage extends between an inlet port and an outlet port. 
     According to an aspect, each of the inlet port and the outlet port is in the form of a through-opening comprising an opposed pair of the at least one first and second openings. 
     According to an aspect, the first, second and third portions of each through fitting are in concentric arrangement with one another along an axis of the through fitting, and are formed from a single cylindrical tube. 
     According to an aspect, each through fitting has a first end with a first end opening provided in the first portion, an opposite second end with a second end opening provided in the second portion, and a hollow interior extending between the first and second end openings. 
     According to an aspect, for each through fitting and each through opening, a first fluid-tight seal is provided between the outer surface of the first portion and the inner periphery of one of the first holes, and a second fluid-tight seal is between the outer surface of the second portion and the inner periphery of one of the second holes. 
     According to an aspect, for each through fitting, an outer periphery of the third portion is located radially outwardly of the outer surfaces of the first and second portions. 
     According to an aspect, the third portion of each through fitting has a first radially-extending surface and an opposite second radially-extending surface, wherein the first and second radially-extending surfaces are annular and flat. 
     According to an aspect, the first radially-extending surface of each through fitting is in contact with the inner surface of the first plate and the opposite second radially-extending surface is in contact with the inner surface of the second plate. 
     According to an aspect, the first and second plates are comprised of an aluminum alloy, and the inner surfaces of the plates are provided with a clad layer of a brazing alloy. In this case, the first and second radially-extending surfaces are sealingly joined to the inner surfaces of the first and second plates, with the clad layer forming a braze joint between the first and second radially-extending surfaces of the third portion and the inner surfaces of the first and second plates. 
     According to an aspect, a thickness of the third portion is slightly less than or substantially the same as a height of the fluid flow passage in an area surrounding each of the first and second openings. 
     According to an aspect, the third portion of each through fitting comprises a plurality of the communication passages. 
     According to an aspect, each of the communication passages extends radially through the third portion, and the communication passages are spaced apart along a circumference of the third portion. 
     According to an aspect, the third portion of each through fitting has a first radially-extending surface and an opposite second radially-extending surface, and wherein each of the communication passages comprises a notch formed in the third portion of the through fitting, such that the first and second radially-extending surfaces are interrupted by the communication passages. 
     In accordance with another aspect of the present disclosure, there is provided a thermal management system comprising a plurality of heat exchangers as described herein, wherein the heat exchangers are fluidly connected in parallel flow arrangement, and wherein the heat exchangers are spaced apart from one another to receive a component to be cooled and/or heated between outer surfaces of adjacent pairs of the heat exchangers. 
     In accordance with yet another aspect of the present disclosure, there is provided a method for manufacturing a through fitting for a heat exchanger as described herein. The method comprises: (a) providing a cylindrical tube having a sidewall and defining a tube axis; (b) forming a plurality of openings in the sidewall, the openings being aligned along the tube axis and spaced apart along a circumference of the sidewall; (c) applying an axial force along the tube axis to deform the tube and form a radially outwardly extending corrugation, wherein the corrugation includes the plurality of openings; and (d) flattening the corrugation. The corrugation, after it is flattened, comprises the third portion of the through fitting. 
     According to an aspect of the method described herein, the plurality of openings included in the flattened corrugation comprises the at least one communication passage of the through fitting. 
     According to an aspect of the method described herein, an initial height of the openings in the sidewall of the cylindrical tube, as measured along the tube axis, is about twice a radial width of the third portion of the through fitting, as measured perpendicular to the tube axis. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Exemplary embodiments of the present disclosure will now be described, by way of example, with reference to the accompanying drawings, in which: 
         FIG. 1  is a perspective view of a plurality of heat exchangers in parallel flow arrangement; 
         FIG. 2  is a cross section along line  2 - 2 ′ of  FIG. 1 ; 
         FIG. 3  is an enlarged close-up of a portion of  FIG. 1 ; 
         FIG. 4  is a perspective view of a one-piece through fitting; 
         FIG. 5  is a vertical cross-section through the one-piece through fitting of  FIG. 4 ; 
         FIG. 6  is a top plan view of the one-piece through fitting of  FIG. 4 ; 
         FIG. 7  is an explanatory plan view of a known fitting arrangement; 
         FIG. 8  is an explanatory view of a through fitting according to a second embodiment; and 
         FIGS. 9A, 9B and 9C  illustrate steps in a method for manufacturing a through fitting. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  illustrates a plurality of heat exchangers  10  which are arranged for parallel flow arrangement, and  FIGS. 2 and 3  show close-up views of a portion of one of the heat exchangers  10 . As used herein, the term “parallel flow arrangement” means that the heat exchangers  10  are joined or adapted to be joined to common inlet and outlet manifolds which distribute the heat transfer fluid to the plurality of heat exchangers  10 . 
     Each heat exchanger  10  comprises a first plate  12  having inner and outer surfaces  14 ,  16 , and a second plate  18  having inner and outer surfaces  20 ,  22 . 
     The first and second plates  12 ,  18  may include peripheral flanges  24 ,  26  along which the first and second plates  12 ,  18  are sealingly joined together, for example by brazing. The first and second plates  12 ,  18  may be comprised of an aluminum alloy, and the inner surfaces  14 ,  20  of the plates  12 ,  18  may be provided with a clad layer of a brazing alloy (not shown) which, when heated to a sufficiently high temperature, melts to form a braze filler metal which forms a braze joint between the peripheral flanges  24 ,  26 . 
     Portions of the first and second plates  12 ,  18  located inwardly of the peripheral flanges  24 ,  26  are spaced apart from one another, with a fluid flow passage  28  being defined between the inner surfaces  14 ,  20  of the first and second plates  12 ,  18 . 
     The fluid flow passage  28  extends between an inlet port  30  and an outlet port  32 . In the present embodiment, the inlet and outlet ports  30 ,  32  are located along the same end of the heat exchanger  10 , and the fluid flow passage  28  is schematically shown as being U-shaped. It will be appreciated, however, that the relative locations of the inlet and outlet ports  30 ,  32  and the configuration of the fluid flow passage  28  are exemplary only, and are not material to the present disclosure. In heat exchangers according to alternate embodiments, the inlet and outlet ports  30 ,  32  may be located at opposite ends of the heat exchanger, or one or both ports  30 ,  32  may be located between the ends of the heat exchanger. The fluid flow passage  28  may include one or more elements to guide the flow of heat transfer fluid between the inlet and outlet ports  30 ,  32 , such as embossments in the first and/or second plates  12 ,  18 , a separate embossed middle plate between the first and second plates  12 ,  18 , and/or corrugated fins or turbulizers between the first and second plates  12 ,  18 . 
     Each of the inlet port  30  and the outlet port  32  are in the form of through-openings, that is, the inlet and outlet ports  30 ,  32  both extend through the heat exchanger  10  and are in fluid communication with the fluid flow passage  28 . Each of these through-openings  30  or  32  comprises a first hole  34  formed in the first plate  12  and a second hole  36  formed in the second plate  18 , the first hole  34  and the second hole  36  being in opposed, spaced relation to each other. In the present embodiment, the first and second holes  34 ,  36  are circular holes of substantially the same diameter and are substantially concentric, within applicable tolerances. 
     Providing inlet and outlet ports  30 ,  32  in the form of through-openings facilitates the connection of a plurality of heat exchangers  10  in parallel flow arrangement, as shown in  FIG. 1 , with the inlet ports  30  of adjacent heat exchangers  10  being in alignment with one another and the outlet ports  32  of adjacent heat exchangers  10  being in alignment with one another. For example, as shown in  FIG. 1 , the direction of fluid flow through the aligned inlet and outlet ports  30 ,  32  is parallel to the y-axis, while the plates  12 ,  18  and the fluid flow passage may be aligned along the x-axis, the x and y axes being at right angles to each other. The heat exchangers  10  of  FIG. 1  are parallel to each other (along x-axis) and are spaced apart from one another to permit a component to be cooled and/or heated to be inserted between the outer surfaces of adjacent heat exchangers  10 , and in thermal contact therewith. For example, the component to be cooled and/or heated may comprise a battery cell of a rechargeable vehicle battery (not shown). A battery thermal management system for cooling and optionally heating rechargeable vehicle batteries may include a large number of such heat exchangers  10  fluidly connected in parallel flow arrangement, with at least one battery cell being received between adjacent heat exchangers  10 , and with the flat side of at least one battery cell being in thermal contact with each outer surface of each heat exchanger  10 , for example as described in commonly assigned U.S. patent application Ser. No. 16/688,390 filed on Nov. 19, 2019 and in above-mentioned U.S. Pat. No. 10,006,722. Rigid or flexible tubular fluid connections (not shown) may be formed between the inlet ports  30  of adjacent heat exchangers  10  and between the outlet ports  32  of adjacent heat exchangers  10 . The thermal management system may include separate inlet and outlet manifolds (not shown) to which the through fittings are connected by the fluid connections. Alternatively, the fluid connections may directly connect the fittings of adjacent heat exchangers together, in which case the inlet and outlet manifolds may be comprised entirely of the through fittings and the tubular fluid connections which connect them together. 
     Each of the inlet ports  30  and outlet ports  32  of heat exchangers  10  is provided with a one-piece through fitting  38  having a first portion  40 , a second portion  42  and a third portion  44  located between the first and second portions  40 ,  42 . In the present embodiment, the first, second and third portions  40 ,  42 ,  44  of the one-piece through fitting  38  are in precise concentric arrangement with one another along the y-axis, and may be formed from a single cylindrical tube. 
     The through fitting  38  has a first end with a first end opening  46  provided in the first portion  40 , and an opposite second end with a second end opening  48  provided in the second portion  42 . A hollow interior  50  of the through fitting  38  extends between the first and second end openings  46 ,  48 . 
     The first portion  40  of each through fitting  38  extends through one of the first holes  34  of the first plate  12 , and is closely received therein. Similarly, the second portion  42  of each through fitting  38  extends through one of the second holes  36  of the second plate  18 , and is closely received therein. Fluid-tight seals are formed between the outer surface of the first portion  40  and the inner periphery of the first hole  34 , and between the outer surface of the second portion  42  and the inner periphery of the second hole  36 . In the present embodiment, the holes  34 ,  36  are circular and the first and second portions  40 ,  42  of through fitting are cylindrical tubular elements having a circular cross-section, although other shapes may be used so long as a fluid-tight seal is provided between the through fitting  38  and the holes  34 ,  35  of plates  12 ,  18 . Although not essential, the first and second holes  34 ,  36  in the present embodiment are of the same diameter, and the first and second portions  40 ,  42  of through fitting have the same diameter. 
     The third portion  44  of through-fitting  38  extends radially outwardly (along x-axis) beyond the outer surfaces of the first and second portions  40 ,  42 , with an outer periphery  52  located radially outwardly of the outer surfaces of the first and second portions  40 ,  42 . In the present embodiment the third portion  44  has an annular shape with the outer periphery  52  being circular, and concentric with the first and second portions  40 ,  42  of through fitting  38 . 
     The third portion  44  of the through fitting  38  has a first radially-extending surface  54  (top surface in  FIGS. 2 and 3 ), and an opposite second radially-extending surface  56  (bottom surface in  FIGS. 2 and 3 ), the surfaces  54  and  56  being annular and flat. The first radially-extending surface  54  is in contact with the inner surface  14  of first plate  12  and the second radially-extending surface  56  is in contact with the inner surface  20  of the second plate  18 . The first and second radially-extending surfaces  54  may be sealingly joined to the inner surfaces  14 ,  20  of the first and second plates  12 ,  18 , with the clad layer on the inner surfaces  14 ,  20  forming a braze joint between the surfaces  54 ,  56  of third portion  44  and the respective inner surfaces  14 ,  20  of plates  12 ,  18 . 
     Therefore, the thickness of the third portion  44 , as measured along the y-axis between the first and second radially-extending surfaces  54 ,  56  is slightly less than or substantially the same as the height of the fluid flow passage  28  in the area surrounding each of the inlet and outlet ports  30 ,  32 . The third portion  44  therefore provides structural support for the heat exchanger  10  in the area of the inlet and outlet ports, which is subject to deformation due to the relative thinness and flatness of the sheet metal material comprising the first and second plates  12 ,  18 . The presence of the third portion  44  of through fitting  38  therefore avoids the need to provide support structures between the plates  12 ,  18  in the vicinity of inlet and outlet ports  30 ,  32 . Such alternate support structures may take the form of separate components which are inserted between the plates  12 ,  18  during assembly, or embossments in the plates. The present embodiment avoids the need for such alternate support structures, thereby reducing the number of components and/or simplifying the structure of the plates  12 ,  18 . 
     Fluid communication between the hollow interior  50  of through fitting  38  and the fluid flow passage  28  is provided through the third portion  44  of through fitting  38 . In this regard, at least one communication passage  58  is provided between the outer periphery  52  of third portion  44  and the hollow interior  50  of the through fitting  38 . As shown in the present embodiment, the through fitting  38  comprises a plurality of communication passages  58 . The communication passages  58  may extend radially through the third portion  44 , and may be provided in spaced relation throughout the entire circumference of the third portion  38 . However, in other embodiments, the communication passages  58  may be only located along a portion of the circumference of third portion  58  so as to guide the fluid flow in a specific direction. 
     The communication passages  58  may be enclosed between the first and second radially-extending surfaces  54 ,  56  of the third portion  44 . However, in the present embodiment, the communication passages  58  comprise notches formed in the third portion  44  of through fitting  38 , such that the first and second radially-extending surfaces  54 ,  56  are interrupted by the communication passages  58 . 
     The through-fitting may be manufactured by various methods.  FIGS. 2-6  show that the third portion  44  comprises two layers, and is in the form of a flattened corrugation or flange. Such a corrugation may conveniently formed by deforming an unsupported portion of a cylindrical tube by applying a force along the axis of the tube, to form a corrugation which is flattened and simultaneously reduced in thickness, if required, to form the third portion  44 . The communication passages  58  may be formed, for example by machining, after formation of the flattened corrugation. Alternatively, as further described below, the communication passages  58  may be formed by providing rectangular openings in the wall of the cylindrical tube, before deformation. The height of the rectangular openings in the cylindrical tube will be approximately twice the width of the third portion (i.e. radial distance between the outer periphery  52  and the outer surfaces of first and second portions  40 ,  42 . 
       FIG. 7  shows a known through fitting arrangement for an inlet or outlet port  102  of a heat exchanger  100  comprising first and second plates  104 ,  106  provided with holes  108 ,  110 . Each hole  108 ,  110  is provided with a fitting  112  having a hollow interior, and provided with a radial flange  116  which forms a sealed connection to the outer surface of the first or second plate  104 ,  106 . The fittings  112  may also include end portions  118  which are received inside holes  108 ,  110  to locate the fittings  112  inside the holes  108 ,  110 . As will be appreciated, positional tolerances may cause the fittings  112  of holes  108 ,  110  to be slightly out of concentric alignment with each other. 
     Furthermore, the outer surfaces of plates  104 ,  106  of heat exchanger  100  are not typically provided with a clad layer of brazing alloy. Therefore, annular shims (not shown) comprising brazing alloy may be required between flanges  116  and the outer surfaces of plates  104 ,  106 . As a result, the through fitting arrangement of  FIG. 7  requires two separate fittings  112  and may additionally require two annular brazing shims. 
     Also, because the fittings  112  are secured to the outer surfaces of plates  104 ,  106 , they do not provide internal support for the relatively thin plates  104 ,  106  of heat exchanger  100  in the vicinity of holes  108 ,  110 . Without the provision of additional support elements between the plates  104 ,  106 , the plates  104 ,  106  may be deformed, for example during assembly of a thermal management system comprising a plurality of heat exchangers  100  in parallel flow arrangement. Thus, the heat exchanger  100  of  FIG. 7  is susceptible to undesirable deformation, and/or may require additional support elements to prevent deformation. 
       FIG. 8  illustrates a portion of a heat exchanger  120  according to a second embodiment. Heat exchanger  120  shares a number of like elements with heat exchanger  10  described above, and these like elements are identified with like reference numerals. 
     Heat exchanger  120  is identical to heat exchanger  10  except for the structure of through fitting  38 , in which the third portion  44  is in the form of a single-layer radially projecting flange, which may be formed by molding and/or machining. Also, the communication passages  58  are enclosed between the first and second radially-extending surfaces  54 ,  56 , and may be in the form of radially-extending cylindrical bores extending from the outer periphery  52  to the hollow interior  50 . 
       FIGS. 9A, 9B and 9C  schematically show the steps in a method for manufacturing a through fitting  38  as described herein.  FIG. 9A  shows a cylindrical tube  60  having a plurality of rectangular openings  62  formed in its sidewall, the openings  62  being aligned along the tube axis and being spaced apart along the circumference of the tube wall. Axial forces are applied to the tube  60  as indicated by arrows in  FIGS. 9A and 9B , and these axial forces cause the tube  60  to be deformed to form a radially outwardly extending corrugation  64 . Continued deformation of the tube  60  as shown in  FIG. 9B  will flatten the corrugation  64  and, as shown in  FIG. 9C , the corrugation  64  may be further flattened so as to form the third portion  44  of the through fitting  38 , to flatten the first and second radially-extending surfaces  54 ,  56  and to optionally reduce the thickness of the corrugation  64 , as indicated by the arrows in  FIG. 9C , so that it will fit between the first and second plates  12 ,  18  of a heat exchanger  10 . As can be seen from  FIGS. 9A to 9C , the initial height of the rectangular openings  62  along the tube axis, as shown in  FIG. 9A , is approximately twice the width of the third portion  44 , as measured perpendicular to the tube axis from the outer periphery  52  to the outer surfaces of first and second portions  40 ,  42 . 
     While various embodiments have been described in connection with the present disclosure, it will be understood that certain adaptations and modifications of the described exemplary embodiments can be made as construed within the scope of the present disclosure. Therefore, the above discussed embodiments are considered to be illustrative and not restrictive.