Abstract:
A heat exchanger comprises a casing defining a chamber for liquid, an internal spacer inside the chamber and means for detecting the presence of the spacer. The detecting means may comprise an aperture in the casing to receive a projection on the spacer so that the projection can be seen.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit and priority of United Kingdom Patent Application No. 0807437.9, filed Apr. 23, 2008. The entire disclosure of the above application is incorporated herein by reference. 
       FIELD 
       [0002]    The invention relates to a heat exchanger, a method of making a heat exchanger and a kit. 
       BACKGROUND 
       [0003]    This section provides background information related to the present disclosure which is not necessarily prior art. 
         [0004]    An example of a known heat exchanger is an oil cooler. A known prior oil cooler is described in EP-A-1593923. The oil cooler of EP-A-1593923 comprises a plurality of casings of elongate substantially flattened shape arranged in a stack. Each of the casings is formed from two half shells connected together along a peripheral strip thereof. The half shells are made of aluminum sheet. Aligned holes in the casings allow fluid communication between the casings. A corrugated plate or turbulator is arranged inside each casing and turbulators are also arranged between adjacent casings to increase the efficiency of heat exchange. Oil flows through the casings and air circulates between the casings to cool the oil. Two spacers are provided between adjacent casings, one spacer at each end of the casings. The spacer surrounds the hole through which adjacent casings communicate with each other and includes radial ribs. 
         [0005]    The inventors have found when making a heat exchanger of large size, the weight of the stack of casings, together with the clamping pressure applied during brazing of the stack can lead to deformation of the oil chamber. 
       SUMMARY 
       [0006]    This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features. 
         [0007]    According to one aspect of the invention there is provided a heat exchanger comprising a casing defining a chamber for liquid, a spacer inside the chamber and means to enable detection of the presence of the spacer. 
         [0008]    By placing a spacer inside the chamber, the spacer will resist collapse of the chamber or deformation of the chamber enabling a heat exchanger to be made which comprises a tall or heavy stack or which can resist clamping pressure without deformation. By providing means to enable detection of the presence of the spacer, it can be ensured that a spacer is always present and hence failure in manufacture is avoided and premature failure in use of the heat exchanger due to the absence of the spacer is also avoided. 
         [0009]    The detection means may take any suitable form and may comprise means to enable visual detection of the spacer. In a preferred embodiment the wall of the liquid chamber defines at least one aperture enabling at least part of the spacer to be seen. This not only enables a visual check of whether a spacer is present, it also provides a leak path from the casing so that the heat exchanger will not pass a leak test in which the casing is pressurized. The liquid chamber may be elongate and the or at least one aperture may be in the end wall. 
         [0010]    The casing defining the liquid chamber may be made of two parts which are attached together with the spacer between them. The or at least one aperture may be provided at the join between the two parts. The two parts may be brazed together. Preferably the or at least one aperture is defined by a rebate in each of the two parts. In this way, as well as acting as a visual indication of the presence of the spacer, the projection on the spacer also acts to locate the two parts with respect to one another. 
         [0011]    The detection means in a preferred embodiment includes at least one projection on the spacer which protrudes into the or at least one aperture in the wall of the chamber so that it is visible. The outer end of the or each projection may lie flush with the outer surface of the wall of the liquid chamber, but preferably projects from the outer surface of the wall of the liquid chamber. 
         [0012]    The detection means may include means to inhibit movement of the spacer and may include means to inhibit movement of the spacer away from the or at least one aperture. Preferably, the or at least one projection is shaped so that it cannot be withdrawn through the aperture. In this way, the spacer is held in place. The or at least one projection and the aperture in which the projection is received are preferably in complementary shapes. The or at least one projection may have a tapered shape. The or at least one projection may have a head connected to the main body of the spacer through a reduced width neck. 
         [0013]    The or each projection is preferably at least 3 to 6 mm wide, most preferably at least 5 mm wide. 
         [0014]    The heat exchanger may comprise a stack of casings with the liquid chambers arranged to communicate with one another. External spacers may be provided between adjacent casings in the stack. 
         [0015]    In an alternative embodiment, the detection means comprises a leak orifice in the casing defining the chamber, the leak orifice being covered by the spacer. Thus, if the spacer is not present, the leak orifice is uncovered and there is a leak path from the chamber to outside. The heat exchanger can then be subject to a pressure test, and the leak resulting from the uncovered orifice will be detected thereby detecting the absence of the spacer. The liquid chamber may be elongate and the spacer may be arranged at one end. 
         [0016]    In this embodiment, the heat exchanger preferably includes an external spacer to space two casings apart, the external spacer overlapping incompletely the position of the spacer inside the casing so as not to cover the orifice. 
         [0017]    According to another aspect of the invention there is provided a heat exchanger comprising a casing defining a chamber for liquid, a spacer inside the chamber and at least one projection on the spacer received in a hole in the wall of the chamber to locate the spacer. 
         [0018]    The hole may or may not be a through hole. The or each projection serves to locate the spacer. 
         [0019]    The hole may be an existing hole with another function, such as the opening for communication with an adjacent casing, or may be a dedicated hole for the projection. 
         [0020]    Preferably, the or at least one projection is shaped so that it cannot be withdrawn from the hole. In this way, the spacer is held in place. The or at least one projection and the hole in which the projection is received are preferably in complementary shapes. The or at least one projection may have a tapered shape. The or at least one projection may have a head connected to the main body of the spacer through a reduced width neck. 
         [0021]    The or each projection is preferably at least 3 to 6 mm wide, most preferably at least 5 mm wide. 
         [0022]    According to another aspect of the invention there is provided a kit of parts for brazing together to make a heat exchanger, the kit comprising two parts to be connected together to form a fluid chamber, a spacer to be placed between the two parts to be brazed to both of the parts, each of the parts including a flat peripheral surface to be brazed to a flat peripheral surface on the other part, one or both of the flat peripheral surfaces being interrupted by a rebate, the rebate or rebates forming an aperture when the flat peripheral surfaces of the parts are in contact, the spacer including a projection to sit in the aperture and be brazed to the surfaces defining the aperture. 
         [0023]    Preferably, both of the flat peripheral surfaces are interrupted by a rebate. In this way, the projection on the spacer acts to locate the two parts with respect to one another. 
         [0024]    The spacer may include a plurality of projections to be received in a plurality of rebates in the parts. 
         [0025]    The or at least one projection and the aperture in which the projection is received are preferably in complementary shapes. The or at least one projection may have a tapered shape. The or at least one projection may have a head connected to the main body of the spacer through a reduced width neck. 
         [0026]    The or each projection is preferably at least 3 to 6 mm wide, most preferably at least 5 mm wide. 
         [0027]    The heat exchanger may be any suitable type of heat exchanger but in a preferred embodiment is an oil cooler. 
         [0028]    The oil cooler may be for use in any suitable technical context, but is preferably for use in a vehicle, preferably an automotive vehicle, for cooling engine oil, or may be for use in a generator. 
         [0029]    According to a further aspect of the invention there is provided a method of making a heat exchanger, the method comprising the steps of:
       placing a first part so that a hollow defined in the part faces upwards surrounded by a flat peripheral surface; placing a spacer in the hollow in the part, stacking a second part on the first part so that a flat peripheral surface of the second part is in contact with the flat peripheral surface of the first part and such that a fluid chamber is defined between them; the spacer including a projection which is received in a rebate in one or both of the flat peripheral surfaces, the rebate or rebates forming an aperture when the flat peripheral surfaces of the parts are in contact; brazing the parts and the spacer together.       
 
         [0031]    Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
     
    
     
       DRAWINGS 
         [0032]    The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure. 
           [0033]      FIG. 1  is an exploded perspective view of one end of the heat exchanger in the first embodiment; 
           [0034]      FIGS. 2   a  and  2   b  are a plan view and perspective view of the internal spacer of the heat exchanger of the first embodiment; 
           [0035]      FIGS. 3   a  and  3   b  are a plan view and respective view respectively of the external spacer of the heat exchanger of the first embodiment; 
           [0036]      FIGS. 4   a  to  c  are a side elevation, plan view and perspective view of a gallery plate of the heat exchanger of  FIG. 1  and  FIG. 4   d  is a fragmentary detail perspective view of one end of the gallery plate; 
           [0037]      FIG. 5  is an end view of the heat exchanger in the first embodiment; 
           [0038]      FIGS. 6A and 6B  are a plan view and perspective view respectively of an internal spacer in a second embodiment of the invention; 
           [0039]      FIGS. 7A and 7B  are a plan view and perspective view respectively of an internal spacer in another embodiment of the invention; 
           [0040]      FIGS. 8A and 8B  are a plan view and perspective view respectively of an internal spacer in a further embodiment of the invention; 
           [0041]      FIG. 9  is a fragmentary detail perspective view from one end of a heat exchanger including the internal spacer of  FIGS. 8A and 8B ; 
           [0042]      FIG. 10  is a fragmentary detail perspective view of a gallery plate in another embodiment; 
           [0043]      FIG. 11  is a plan view of an internal spacer in the embodiment of  FIG. 10 ; and, 
           [0044]      FIG. 12  is a plan view of a heat exchanger in the embodiment of  FIG. 10 . 
       
    
    
       [0045]    Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings. 
       DETAILED DESCRIPTION 
       [0046]    Example embodiments will now be described more fully with reference to the accompanying drawings. 
         [0047]    The heat exchanger  10  of the first embodiment of the invention comprises a plurality of casings  12  each made of two parts constituted by gallery plates  14 . The heat exchanger  10  also includes internal spacers  16  and external spacers  18 . 
         [0048]    As shown in  FIGS. 4A to 4D , each gallery plate  14  is in the form of a shallow tray with a floor  20 , side wall  22  and around the top of the side wall  22  an outwardly extending flange  24  presenting an upwardly facing, flat, horizontal surface  26  around the periphery of the tray. At each end, the gallery plate  14  includes an opening  28  centrally in the floor  20  for connection to another casing  12 . Each gallery plate  14  is made of sheet aluminum which is cut and then drawn into shape. Each opening  28  defines a downwardly extending rim  30  which is interrupted by two tabs  32 . The tabs  32  are arranged in laterally opposed positions and are a little longer than the rim  30 . At each end of the gallery plate  14 , the peripheral surface  26  is interrupted by a square notch or rebate  34 . The rebate  34  is thus defined by a portion  36  of the top of the side wall  22  and two parallel, straight, opposed edges  38  of the flange  24 . 
         [0049]    Each internal spacer  16  is flat and has a main body  40  which is generally C shaped in plan being dimensioned and shaped to fit in the hollow presented at the end of the tray shaped gallery plate  14  and partially surround the opening  28  in the gallery plate  14  without overlapping the opening  28 . The internal spacer  16  includes a projection or tab  42  to fit into the rebate  34 . The projection  42  extends substantially from the midpoint of the curve of outer edge  44  of the C shaped main body  40 . The projection  42  is substantially T shaped and comprises a straight, parallel sided neck part  46  leading to a wider head part  48 . The neck  46  is 5 mm wide. 
         [0050]    Each external spacer  18  is generally of semicircular shape in plan and has a central bore  50  which is generally round in shape with opposed rectangular cut outs  52 . 
         [0051]    The gallery plates  14 , internal spacers  16  and external spacers  18  are made of aluminum alloy, such as 3000 series alloy, clad with aluminum brazing alloy, such as 4000 series alloy. 
         [0052]    To construct the heat exchanger  10  of the first embodiment, a gallery plate  14  is placed with the peripheral surface  26  facing upwards. 
         [0053]    An internal spacer  16  is then placed on the floor  20  of the gallery plate  14  at each end in the hollow presented by the tray shaped gallery plate  14 . The outer edge  44  of the main body  40  of the internal spacer  16  is complementary with and is located by the side wall  22  of the gallery plate  14  while the projection  42  is received in the rebate  34 . The neck  46  of the projection  42  lies in the rebate  34  and the head  48  lies beyond the rebate  34  and is wider than the rebate  34 . The lower surface  54  of the neck  46  contacts the portion  36  of the top of the side wall  22  of the gallery plate  14  and the side surfaces  56  of the neck  46  contact the opposed edges  38 . The flat internal spacer  16  has greater depth than the depth of the hollow of the gallery plate  14  so that it stands proud of the gallery plate  14 . 
         [0054]    A second gallery plate  14 ′ is then arranged in an inverted position and placed on top of the first gallery plate  14 . The floor  20  of the second gallery plate  14 ′ will contact the upper surface  58  of the internal spacer  16  and the peripheral surface  26 ′ of the second gallery plate  14 ′ will contact the peripheral surface  26  of the first gallery plate  14 . At the rebate  34 , the portion  36  of the top of the side wall  22  of the second gallery plate  14 ′ contacts the upper surface  60  of the neck  46 , and the side surfaces  56  of the neck  46  contact the opposed edges  38 ′ of the flange  24 ′ of the second gallery plate  14 ′. The two gallery plates  14 ,  14 ′ thus form a casing  12  from which the head  48  of each internal spacer  16  protrudes. The casing  12  defines a chamber  8  between the gallery plates  14 ,  14 ′ for fluid. 
         [0055]    An external spacer  18  is then placed on top of the second gallery plate  14 ′ at each end, the bore  50  in each external spacer  18  receiving the rim  30 ′ of the second gallery plate  14 ′ and the cut outs  52  receiving the tabs  32 ′ to locate the external spacer  18  on the casing  12  formed by the two gallery plates  14 ,  14 ′. 
         [0056]    This sequence of placement of parts is then repeated to form a stack to the height required. 
         [0057]    Turbulators (not shown) may be provided in the casings  12  and/or between the casings  12 . 
         [0058]    The assembled heat exchanger  10  can then be inspected. 
         [0059]    Visual inspection of the ends of the casings  12  will enable the absence of any internal spacers  16  to be detected by the absence of the protruding head  48  of an internal spacer  16  leaving an aperture in the casing  12 .  FIG. 5  shows a casing  12  including an internal spacer  16 . 
         [0060]    The assembly is then clamped vertically and brazed. 
         [0061]    The peripheral surfaces  26 ,  26 ′ of the gallery plates  14 ,  14 ′ will braze together and it is seen that the gallery plates  14 ,  14 ′ will form a brazed seal around the neck  46  of the projection  42  of the internal spacer  16 . 
         [0062]    The completed heat exchanger  10  can then be pressure tested. 
         [0063]    A pressure test will also reveal a missing internal spacer  16 , because the missing spacer  16  will result in an aperture at the two rebates  34  and hence leakage. 
         [0064]    The internal spacer  16  also serves to locate the gallery plates  14 ,  14 ′ one on the other. The internal spacer  16  locates the gallery plates  14 ,  14 ′ with respect to lateral movement. The internal spacer  16  also locates the gallery plates  14 ,  14 ′ with respect to axial movement due to the head  48 . 
         [0065]    The projection  42  also ensures that the internal spacer  16  is located correctly with respect to the gallery plates  14 ,  14 ′. The heat exchanger  10  may be assembled by hand, and an internal spacer  16  may be accidentally positioned too far back from the end of the gallery plate  14 , or may be twisted, rather than placed symmetrically in the gallery plate  14 . As the gallery plates  14 ,  14 ′ are drawn, they have a curved junction  62  between the floor  20  and the side wall  22 . The internal spacer  16  can thus ride up the junction  62  and be incorrectly positioned laterally and/or axially. The requirement for the projection  42  to be received in the rebate  34  ensures that it is positioned correctly. In particular, the neck  46  of the projection  42  locates the internal spacer  16  laterally and the head  48  of the projection  42  together with the edge  44  of the spacer main body  40  locates the internal spacer  16  axially with respect to the gallery plate  14 . 
         [0066]    The heat exchanger  10  of the first embodiment may be used as an oil cooler in a large internal combustion engined vehicle. The construction is particularly suitable for large oil coolers and/or where there is high internal pressure. 
         [0067]      FIGS. 6A and 6B  show an internal spacer  16  in a second embodiment. The same reference numerals will be used for equivalent features. Only the differences from the first embodiment will be described. 
         [0068]    The internal spacer  16  of the second embodiment has two projections  42 . It is thus more effective in locating itself and the gallery plates  14 ,  14 ′ and provides two indications, namely the two heads  48 , of the presence of the spacer  16 . 
         [0069]      FIGS. 7A and 7B  show an internal spacer  16  in another embodiment. The same reference numerals will be used for equivalent features. Only the differences from the first embodiment will be described. 
         [0070]    The internal spacer  16  in this embodiment lacks the head  48  on the projection  42 . The end  64  of the spacer  16  lies flush with the external surfaces of the flanges  24 ,  24 ′ of the gallery plates  14 ,  14 ′. The projection  42  thus provides a visual indication of the presence of the spacer  16  and serves to locate the spacer  16  and gallery plates  14 ,  14 ′ laterally. 
         [0071]      FIGS. 8A and 8B  show an internal spacer  16  in a further embodiment. The same reference numerals will be used for equivalent features. Only the differences from the first embodiment will be described. The projection  42  in this embodiment is wedge shaped with the wider end  66  away from the main body  40  of the internal spacer  16 . The rebate  34  is of a complementary wedge shape, so that the projection  42  of the internal spacer  16  is received as a good fit in dovetail fashion in the rebate  34 .  FIG. 9  shows the assembly. The projection  42  thus provides a visual indication of the presence of the spacer  16  and serves to locate the spacer  16  and gallery plates  14 ,  14 ′ both laterally and axially with respect to the gallery plates  14 ,  14 ′. 
         [0072]      FIGS. 10 ,  11  and  12  show a heat exchanger in another embodiment. The same reference numerals will be used for equivalent features. Only the differences from the first embodiment will be described. 
         [0073]    In this embodiment, there is an orifice  70  through the floor  20  of each gallery plate  14 , the orifice being further from the end of the gallery plate  14  than the opening  28  and offset to one side, as shown in  FIG. 10 . The internal spacer  16  is of the same general shape as in the first embodiment, but the C shaped main body  40  has longer arms  72 , as shown in  FIG. 11 . 
         [0074]    When the parts of the heat exchanger are assembled as shown in  FIG. 12 , the extended arms  72  of the internal spacer  16  overlap and cover the orifice  70  to block the orifice  70 . The orifice  70  is so far back that it is not covered by the external spacer  18 . 
         [0075]    Thus, when the heat exchanger has been brazed, the pressure test will reveal if any internal spacers  16  have been omitted because the orifice  70  will form a leak path which will be detected. 
         [0076]    The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the invention, and all such modifications are intended to be included within the scope of the invention.