Patent Publication Number: US-9903661-B2

Title: Heat exchanger plate with bypass zone

Description:
RELATED APPLICATIONS 
     This application is the National Stage of International Patent Application No. PCT/EP2012/062585, filed on Jun. 28, 2012, which claims priority to and all the advantages of French Patent Application No. FR 11/02061, filed on Jun. 30, 2011, the content of which is incorporated herein by reference. 
     The invention relates to a plate for a heat exchanger of a motor vehicle, a core of plates of such an exchanger and a heat exchanger equipped with such a core. It relates in particular to the field of charge air coolers. 
     An engine for a motor vehicle comprising a turbocharger and referred to as a turbocharged engine is already familiar. In order to function, such a turbocharged engine may be supplied by a system for the admission of air or by a system for the admission of a mixture of air and exhaust gases collected at the exhaust from the engine, referred to as recirculated exhaust gases. The expression charge air for the engine is used below to denote both the air coming from a system for the admission of air and the mixture coming from a system for the admission of a mixture of air and recirculated exhaust gases. 
     With the aim of increasing the density of the charge air for the engine, it is familiar from the prior art to cool the said charge air by means of a heat exchanger, also referred to as a charge air cooler (RAS). 
     First of all, use has been made primarily of charge air coolers of the tubes and inserts type permitting an exchange of heat between the charge air circulating inside the tubes and a flow of air coming from the exterior of the vehicle and circulating between the tubes. 
     Heat exchangers comprising a core formed from a stack of superposed plates, allowing an exchange of heat between the charge air and a coolant fluid, in general a liquid, have also been proposed. A plate is in the form of a rectangular elongated panel comprising two transcurrent ports. The stacked plates alternatively form circulation channels for the charge air to be cooled and circulation channels for the coolant fluid. 
     The charge air to be cooled enters into the heat exchanger via one of its lateral faces, referred to as the upstream face, in such a way as to circulate in the circulation channels for the charge air to be cooled, in order to be cooled by contact with the plates situated above and below inside which the coolant fluid circulates. The cooled charge air then exits from the exchanger via the opposite lateral face, referred to as the downstream face. The expressions “upstream” and “downstream” are also used in the rest of the description to designate, respectively, the inlet and the outlet for the flow of charge air in the core of the heat exchanger. 
     In order to cause the coolant fluid to circulate inside the exchanger, inlet channels and collection channels for the coolant fluid are provided in a part of the core. The plates thus comprise raised edges, around each of their two ports, extending perpendicularly to the plane of the plate in such a way as to form these inlet channels and collection channels for the coolant fluid when the plates are stacked. 
     The part of the core of the exchanger corresponding to the inlet channels and collection channels for the coolant fluid does not, however, participate in the exchange of heat. An exchange zone intended to encourage the exchange of heat with the fluid and a zone permitting the fluid to bypass the said exchange zone, referred to as the bypass zone, corresponding to the zone in which the inlet channels and collection channels for the coolant fluid are formed, can thus be observed. More specifically, the spaces situated around the ports permit the circulation of charge air uncooled, or insufficiently cooled, from the upstream towards the downstream of the core, which presents major inconveniences in terms of the thermal performance. 
     A device  10 , illustrated in  FIG. 1 , comprising a wall  12  attached to the lateral upstream face  14  of the exchanger and allowing a part of the flow of charge air to be prevented from entering into the core of the exchanger at the level of the bypass zone, is already familiar. Such a device is not satisfactory, however, in particular for reasons of assembly. 
     In order to improve the situation, the invention relates to a plate for a heat exchanger, the said plate being intended to be stacked with another plate of a heat exchanger in order to form a pair of plates arranged in order to permit, between the said plates, the circulation of a fluid to be cooled, the plate exhibiting a zone, referred to as the exchange zone, intended to encourage the exchange of heat with the fluid, and a zone, referred to as the bypass zone, capable of permitting the fluid to bypass the said exchange zone, the plate being characterized in that it comprises in addition means originating from the plate configured in such a way as to force a circulation of the fluid in the exchange zone. 
     The bypass zone is thus created by means originating from the plate. These means are accordingly created at the time of the manufacture of the plate and are no longer required to be attached to the core, as was the case in previous solutions. 
     Preferably, the means originating from the plate extend perpendicularly to the plane of the plate. Such a configuration facilitates the circulation of the fluid towards the exchange zone. 
     Advantageously, the plate is in the form of a panel comprising two upstream and downstream edges and comprising, in the bypass zone, an inlet port for a coolant fluid and a collection port for the said coolant fluid, the means originating from the plate comprising an upstream partition extending from the upstream edge of the plate and configured in such a way as to block the circulation of the fluid at the level of the inlet port and/or a downstream partition extending from the downstream edge of the plate and configured in such a way as to block the circulation of the fluid at the level of the collection port. 
     According to one aspect of the invention, the lengths of the upstream partition and/or of the downstream partition are identical or greater than the largest dimension of the ports in the direction of the upstream and/or downstream edges. The fluid to be cooled is thus directed in its entirety towards the exchange zone, which makes the heat exchanger even more efficient. 
     According to a further aspect of the invention, the plate is rectangular and exhibits two long edges and two short edges, the said long edges defining the said upstream and downstream edges, the inlet port and the collection port being pierced in a zone close to one of the short edges. 
     According to one aspect of the invention, the upstream and downstream partitions are parallel. 
     According to one aspect of the invention, the upstream and downstream partitions exhibit an oblique distal edge. 
     According to a further aspect of the invention, the means originating from the plate comprise a central partition extending between the inlet port and the collection port. 
     The invention also relates to a core comprising a plurality of plates as defined above stacked one on top of the other in such a way that two adjacent plates, forming a pair, define a circulation channel for the fluid to be cooled, and two plates of two different and adjacent pairs form a circulation channel for the coolant fluid. 
     According to one aspect of the invention, the partitions of two plates of one and the same pair of plates overlap. 
     Advantageously, a turbulator is arranged between two plates of one and the same pair of plates in such a manner as to encourage the exchange of heat between the fluid to be cooled and the coolant fluid, the said turbulator having a height substantially identical to that of the partitions. 
     The invention also relates to a heat exchanger comprising a core as defined above. 
    
    
     
       Other characteristics and advantages of the invention will be appreciated from the following description made with respect to the accompanying figures that are provided by way of non-limiting examples. Identical reference designations are given to similar objects. 
         FIG. 1 , which has already been commented upon, is a top view of a familiar plate of a core of a heat exchanger. 
         FIG. 2  is a perspective view, partially exploded, of a familiar heat exchanger. 
         FIG. 3  is a perspective view of a plate according to the invention. 
         FIG. 4  is a perspective view of a pair of plates according to the invention, between which a turbulator is inserted. 
         FIG. 5  is a partial view in cross section of a pair of plates according to the invention illustrating the superposition of a partition of one of the plates with a partition of the other plate. 
         FIG. 6  is a perspective view of a heat exchanger comprising a plurality of pairs of plates according to the invention. 
         FIG. 7  is a partial view in perspective of a pair of plates according to the invention comprising a partition between the inlet ports and the collection ports for the coolant liquid. 
     
    
    
       FIG. 2  depicts a familiar heat exchanger  20  with a familiar core  21  of plates. It should be noted that the plates according to the invention may be utilized in an exchanger of this type in place of the familiar plates. 
     Such a heat exchanger  20  permits the exchange of heat between a fluid to be cooled and a coolant fluid. In the rest of the description, the fluid to be cooled is air. This does not have any restrictive effect on the scope of the present invention, for which, in another type of heat exchanger, the fluid to be cooled could be another gas. 
     The heat exchanger  20 , illustrated in  FIG. 2 , comprises:
         an upper wall  22  comprising an inlet pipe  23   a  for a coolant fluid and a collection pipe  23   b  for the said cooling liquid,   two lateral walls  24   a  and  24   b,      one open lateral upstream face (not visible) and one open lateral downstream face  26 ,   a lower wall, and   a core  21  comprising a plurality of pairs of plates  25  stacked one on top of the other between the lower wall and the upper wall  22 .       

     Such a core  21  permits an exchange of heat between the charge air and the coolant fluid, in general a liquid. For this purpose, the stacked plates  25  alternately form circulation channels for the charge air to be cooled and circulation channels for the coolant fluid. More specifically, two plates  25  of one and the same pair form a circulation channel for the charge air to be cooled, and two plates  25  of two different and adjacent pairs form a circulation channel for the coolant fluid. 
     In order to cause the coolant fluid to circulate between the plates  25  of the core  21  of the exchanger  20 , inlet channels and collection channels for the coolant fluid are provided in a part of the core  21 . 
     The inlet pipe  23   a  and the collection pipe  23   b  of the exchanger  20  respectively permit the inlet and the collection of the coolant fluid in the circulation channels for the coolant fluid. 
     In order to admit the air to be cooled, an inlet box  28  for air to be cooled may be installed on the open lateral upstream face of the heat exchanger  20 . Similarly, in order to collect the air, after having been cooled by its passage between the plates of the heat exchanger  20 , a collecting box  29  for the cooled air may be installed on the open lateral downstream face  26  of the heat exchanger  20 . 
     The coolant fluid thus enters the heat exchanger via the inlet pipe, circulates inside the inlet channel, circulates between the pairs of plates stacked in the circulation channels for the fluid, and then exits from the exchanger via the collection channel and then the collection pipe. 
     In order to eliminate some of the previously mentioned drawbacks of the prior art, the invention relates to a plate  30  of a core for a heat exchanger, as illustrated in  FIG. 3 . Such a plate  30  is present here in the form of a rectangular, elongated panel extending in a plane P along a longitudinal axis X and comprising an upper face ( 31   a ), a lower face (not visible), two extremities  31   b  and  31   c , an inlet port  32  for the coolant fluid and a collection port  34  for the coolant fluid, provided in a zone close to one  31   b  of the extremities of the plate  30 . The plate exhibits the form of bowl (inverted in  FIG. 3 ), the inlet port  32  and the collection port  34  communicating with the bottom of the bowl in order to define one or a plurality of circulation channels for coolant fluid. 
     The plate  30  comprises, around the inlet port  32  for the coolant fluid, an edge  33  extending perpendicularly to the plane P of the plate  30 . Similarly, the plate  30  comprises, around the collection port  34  for the coolant fluid, an edge  35  extending perpendicularly to the plane P of the plate  30 . The edges  33  and  35  permit the inlet channel and the collection channel respectively for the coolant fluid to be formed perpendicularly to the plane P of the plate, for the height of the core formed by the stack of plates  30 . 
     The plate  30  exhibits a zone, referred to as the exchange zone, ZE, intended to encourage the exchange of heat between the air and the coolant fluid and a zone, referred to as the bypass zone, ZBP, capable of permitting the air to bypass the said exchange zone ZE. 
     In the plate  30  according to the invention illustrated in  FIG. 3 , means originating from the plate are configured in such a way as to force a circulation of the fluid inside the exchange zone ZE. They are present here in the form of:
         an upstream partition  36  having a length L extending from the edge of the plate  30 , substantially perpendicularly to the plane P of the plate  30 , at the level of the port  32 , along an axis perpendicular to the longitudinal axis of the plate  30 , and   a downstream partition  37  having a length L extending from the edge of the plate  30 , substantially perpendicularly to the plane P of the plate  30 , at the level of the port  34 , along an axis perpendicular to the longitudinal axis of the plate  30 .       

     The bypass zone ZBP thus extends between the upstream partition  36  and the downstream partition  37 . The exchange zone extends over the rest of the plate  30 . And the passage of the air at the level of the said bypass zone ZBP is blocked. 
     Two plates  30  according to the invention may be assembled one on top of the other, as illustrated in  FIG. 4 , as a pair of plates  30 , in such a way as to form a circulation channel for the flow of air F to be cooled. More specifically, a plate  30  as illustrated in  FIG. 3  may be inverted and arranged on another, non-inverted plate  30 , as illustrated in  FIG. 3 , in such a way as to form the said pair. It should be noted that the size of the edges  33  and  35  extending from the contour of the ports perpendicularly to the plane P of the plate  30  may be different between the two plates of one and the same pair of plates, in such a way that they are complementary and fit together in order to form the inlet and collection channels when the two plates are assembled as a single pair. 
     As illustrated in  FIG. 4 , an internal insert or turbulator  40  may be inserted, for example before assembly, between two plates  30  of a pair of plates  30 . Such a turbulator  40  permits the exchange of heat to be improved. 
     The bypass zone ZBP is defined substantially by the space created between the upstream partition  36 , the downstream partition  37  and the two plates  30  assembled as a pair of plates  30 . The exchange zone ZE is defined substantially, between the two plates  30  assembled as a pair of plates  30 , by the space for the circulation of the air, into which the turbulator  40  is inserted. 
     As illustrated in  FIG. 5 , which is a view in cross section perpendicular to the longitudinal axis X of the plate  30  of an assembled pair of plates  30 , the distal extremities  36 ′ and  37 ′, respectively of the partitions  36  and  37 , may be configured in such a way that the partitions  36  and  37  are superposed, overlap or fit together easily. 
     For this purpose, the partitions  36  and  37  may, for example, exhibit oblique distal edges. In  FIG. 5 , the distal extremity  36 ′ is curved towards the interior of the space defined by the assembly of two plates  30 , and the distal extremity  37 ′ is curved towards the exterior of the space defined by the assembly of two plates  30 . Thus, when the two plates are superposed in order to be assembled as a pair of plates  30 , the opposing curves of the distal extremities  36 ′ and  37 ′ make the assembly of the two plates  30  easier. 
     For the same purpose, the partitions  36  and  37  of one and the same plate  30  are not symmetrical in relation to the longitudinal axis X of the said plate  30 . Thus, when two same plates  30  of one and the same pair of plates are opposite one another, with one of the plates being rotated through 180° about the longitudinal axis X in relation to the other, the partition  36  of one of the plates is offset in the direction of the small sides of the plates  30 , in relation to the partition  37  of the other plate, which facilitates their overlapping. 
     As illustrated in  FIG. 6 , when the pair of plates  30  is installed in a heat exchanger  50 , the flow of air F passes through the core  52 , between each pair of plates  30 , defining a circulation channel for air to be cooled, from the upstream towards the downstream, in such a way as to be cooled by the circulating coolant fluid, inside each channel for circulation of the coolant fluid, between the plates  30  of two different pairs. 
     The partitions  36  and  37  made from the material of the plate  30  form an upstream wall (not visible), by stacking the plates  30 , allowing the flow of air F to be blocked at the level of the lateral upstream face of the heat exchanger  50 , and a downstream wall  54  allowing the flow of air F to be blocked at the level of the lateral downstream face of the heat exchanger  50 . The upstream and downstream walls  54  thus prevent the circulation of air at the level of the bypass zone of the core. The exchange zone ZE is defined between the upstream and downstream portions of the core, which are open for the circulation of the air to be cooled. 
     It should be noted that, in  FIG. 6 , the inlet pipe  23   a  and the collection pipe  23   b  are depicted only partially, for reasons of clarity, and that the lower wall  51  of the heat exchanger  50  is visible. 
     In the described embodiment, the means originating from the plate configured in such a way as to force a circulation of the fluid in the exchange zone ZE are arranged both on the upstream face and on the downstream face  26  of the heat exchanger  50 . In a further embodiment of the invention, the means originating from the plate could only be arranged, for example, on the upstream face of the heat exchanger  50 . 
     In an embodiment illustrated in  FIG. 7 , the plate  70  comprises a central partition extending between the inlet port  74  and the collection port  76  forming the circulation channels for the coolant fluid. This central partition in this case is made from the material of the two plates  70   a  and  70   b  and comprises two raised edges  71   a  and  71   b  extending substantially perpendicularly to the plates  70   a  and  70   b  in such a way as to block the flow of air between the exchange zone ZE and the bypass zone ZBP. The central partition furthermore comprises raised edges  72   a  and  72   b  in order to increase the blocking of the flow between the exchange zone ZE and the bypass zone ZBP between the inlet port  74  and the collection port  76 . 
     The bowl-shaped form  73  of the plate  70   b , arranged to guide the coolant fluid between the inlet port  74  and the collection port  76 , can also be appreciated from this figure. 
     The plates  30 , as well as the rest of the core, are advantageously made of metal, for example aluminium and/or aluminium alloys.