Patent Publication Number: US-2018038661-A1

Title: Heat Exchanger for a Cooling System, Cooling System, and Assembly

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of PCT International Application No. PCT/EP2016/061234, filed May 19, 2016, which claims priority under 35 U.S.C. § 119 from German Patent Application No. 10 2015 210 231.9, filed Jun. 3, 2015, the entire disclosures of which are herein expressly incorporated by reference. 
    
    
     BACKGROUND AND SUMMARY OF THE INVENTION 
     The invention relates to a heat exchanger for a cooling system of a motor vehicle, a cooling system for a motor vehicle as well as an assembly comprising an engine and a cooling system. 
     Heat exchangers are used in cooling systems in order to transfer heat energy of a fluid to a different medium which flows around the heat exchanger. For example, the medium can be air and the fluid can be water so that the heat exchanger is a water cooler through which air flows. Such heat exchangers are normally used in the field of motor vehicle engine technology since current engines have to be water-cooled as a result of their high specific output in order to be able to adequately discharge the generated heat. This means that the heat of the engine is transferred to the water and discharged from the engine via the heated water. The water flows from the engine into the heat exchanger, wherein the water heated by the engine heat interacts with the air which flows around the heat exchanger and is thus cooled. Such cooling is generally referred to as indirect cooling since the engine does not discharge the excess heat directly to the ambient air, rather initially to the fluid. 
     The cooling systems in which the heat exchangers are used are normally formed as closed overpressure systems. This means that a pressure valve is provided in the cooling circuit which generates an overpressure between 1.2 and 1.5 bar so that the boiling point of the fluid is above 120° C. 
     The heat exchangers known from the prior art can be divided into two groups which are referred to as heat exchangers with I-throughflow and heat exchangers with U-throughflow. 
     The heat exchangers with I-throughflow are characterized in that the heat exchanger has a supply connection on a first side and a return connection on a second side opposite the first side. The fluid supplied to the heat exchanger flows through the heat exchanger in a heat exchanger region therefore only in one direction, wherein the cooling of the fluid is performed via cooling ribs around which air flows. 
     The heat exchangers with I-throughflow have the disadvantage that the connections are provided on opposite sides, as a result of which installation and assembly are made correspondingly more difficult since tubes must be connected from both sides. In order to avoid this problem, it is known from the prior art that a complex tube guide is guided from the return connection to the fluid pump. However, this results in higher materials costs and higher weight since an additional hose or an additional tube must be provided. The assembly outlay and the assembly costs are furthermore increased. 
     In contrast, the heat exchangers with U-throughflow have the supply connection and the return connection on the same side of the heat exchanger. Within the heat exchanger, the two connections open in each case into several tubes which form a transition in turn into a collecting and distributor portion or proceed therefrom, as a result of which the deflection of the fluid in the heat exchanger is possible. The number of tubes from the supply connection to the collecting and distributor portion is identical to the number of tubes of the collecting and distributor portion up to the return connection since the counter-pressure is kept as low as possible as a result of this. The fluid thus flows via the supply connection through a first tube into the collecting and distributor portion and from the collecting and distributor portion via a second tube to the return connection. This results in a doubling of the flow distance in the heat exchanger region which results in an increase in the counter-pressure with the same flow quantity if the number of tubes is reduced. A counter-pressure which is higher by a factor of 6 is produced, for example, in the case of halving the tubes. This requires a pump with a correspondingly higher drive output in order to be able to counteract the counter-pressure. Such a pump also increases, however, the power loss, as a result of which the efficiency of the cooling system is correspondingly reduced. 
     It is therefore known from the prior art to operate the heat exchangers with U-throughflow with a low throughflow quantity in order to counteract the enormous rise in the counter-pressure. As a result of this, however, the temperature difference between the supply connection and the return connection becomes higher, i.e. in the case of the same admissible maximum temperature, the average coolant temperature becomes lower. The average driving input temperature difference in the heat exchanger accordingly becomes lower, which results in a correspondingly inferior cooling performance of the heat exchanger. 
     In order to again counteract this inferior cooling performance, it is known from the prior art to form the heat exchangers with U-throughflow to be larger than the heat exchangers with I-throughflow so that the same cooling performance can be provided. As a result of this, however, further disadvantages arise since the heat exchanger has larger dimensions, as a result of which, among other things, the air resistance increases, which is disadvantageous in particular when using the heat exchanger in a motorcycle. 
     An object of the invention is to provide a heat exchanger as well as a cooling system which has a simple and compact structure as well as high cooling performance. 
     This and other objects are achieved in accordance with embodiments of the invention. According to a preferred embodiment, a heat exchanger for a cooling system of a motor vehicle, in particular of a motorcycle, includes a housing, a supply connection via which a fluid can be supplied to the heat exchanger, and a return connection via which the cooled fluid can be discharged from the heat exchanger. The heat exchanger includes a heat exchange region in which the fluid interacts with a medium in order to be cooled where it discharges heat energy to the medium. The supply connection and the return connection are arranged on a common connection side of the housing. The heat exchanger region includes a plurality of heat exchanger tubes through which the fluid flows from the connection side to a side opposite the connection side. A singular discharge tube leads from the opposite side to the return connection. 
     The basic concept of the invention is to provide a heat exchanger which externally corresponds to a heat exchanger with U-throughflow since the supply connection and the return connection are formed on the same connection side, as a result of which the heat exchanger can be expediently installed or mounted. Moreover, the heat exchanger internally resembles a heat exchanger with I-throughflow since the fluid flows via a plurality of heat exchanger tubes from the supply connection in a direction through the heat exchange region. The singular tube which forms the return flow of the fluid to the return connection represents a return, formed in the heat exchanger, of the fluid which flows through the heat exchanger which corresponds in terms of the heat exchange region to a heat exchanger with I-throughflow. Return to the return connection is thus carried out via a single discharge tube. 
     One aspect provides that the heat exchanger tubes open in each case into a collecting portion which is fluidly connected to the return connection. The fluid which flows through the respective heat exchanger tubes is collected in the collecting portion of the heat exchanger. The collecting portion differs from a collecting and distributor portion known from the prior art in that no distribution to individual tubes is carried out since the fluid collected in the collecting portion is guided jointly via the singular discharge tube to the return connection. 
     According to a further aspect, the hydraulic diameter of the discharge tube is approximately equal to or greater than that of all heat exchanger tubes. As a result of the larger throughflow cross-section, it is possible that the fluid flowing through the individual heat exchanger tubes can be discharged via the singular discharge tube to the return connection and then out of the heat exchanger. The larger throughflow cross-section ensures that the counter-pressure only rises to a small degree. A more powerful pump is accordingly not required. The heat exchanger can furthermore be operated with the normal throughflow quantities, as a result of which there is no deterioration in cooling performance. The heat exchanger correspondingly also does not require a larger space in order to provide comparable cooling performance as is required in the prior art. 
     Moreover, the discharge tube can be arranged in a lower region of the heat exchanger in the installation position of the heat exchanger. As a result of this, advantages are achieved in terms of pressure distribution in the singular discharge tube and the individual heat exchanger tubes. This in turn improves the cooling performance of the heat exchanger. 
     A further aspect provides that the heat exchanger tubes are arranged in an upper region of the heat exchanger in the installation position of the heat exchanger. The upper region is particularly well suited to the heat exchanger tubes since more air flows around this region of the heat exchanger in the installation position. Correspondingly, higher cooling performance of the heat exchanger is produced as a result of this. 
     In particular, the fluid is water and/or the medium is air, for example. The heat exchanger can accordingly be a water cooler around which air flows. 
     According to a further aspect, the supply connection opens into a fluid distributor portion running along the connection side, from which the heat exchanger tubes connected in parallel proceed. The fluid supplied via the supply connection to the heat exchanger is distributed in the fluid distributor portion to the individual heat exchanger tubes so that fluid flows uniformly through the heat exchanger tubes, as a result of which a correspondingly high cooling performance of the heat exchanger is produced. 
     The supply connection and the return connection can lie next to each other and preferably at a lower end portion of the connection side in the installation position. As a result of this, mounting of the heat exchanger and connecting the heat exchanger in the cooling system are made easier since the connections are easily accessed. A higher degree of freedom in terms of the configuration of the design of the cooling system and/or the engine is achieved since the two connections are arranged in a small region so that only this small region has to be accessible from outside. 
     The invention furthermore relates to a cooling system for a motor vehicle, in particular for a motorcycle, with a fluid pump and a heat exchanger of the above-mentioned type. The above-mentioned advantages in terms of the heat exchanger can be transferred in an analogous manner to the cooling system. The fluid pump can be formed in particular as a water pump. 
     The invention further relates to an assembly comprising an engine as well as a cooling system of the above-mentioned type or a heat exchanger of the above-mentioned type. The engine is fluidly connected to the heat exchanger and is cooled by the fluid. The engine has a fluid inlet and a fluid outlet which are fluidly connected to the return connection or the supply connection, in particular wherein the fluid inlet and the fluid outlet are formed on a common side of the engine. As a result of this, a very compact design of the assembly is produced since the respective flow connections between the engine and the heat exchanger can be easily formed. A higher degree of freedom of configuration is furthermore achieved since only small regions in which the connections are formed have to be accessible from the outside. 
     Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a plan view of a heat exchanger according to the invention; 
         FIG. 2  is a schematic sectional view of the heat exchanger according to the invention; and 
         FIG. 3  is a schematic representation of an assembly according to the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
     A heat exchanger  10  for a cooling system of a motor vehicle is shown in  FIG. 1 . The heat exchanger  10  has a housing  12 . 
     The heat exchanger  10  includes a supply connection  14  as well as a return connection  16  which are both arranged on a connection side  18  of the housing  12 . The supply connection  14  and the return connection  16  are arranged in a lower end portion  19  of the connection side  18  in the installation position. 
     The supply connection  14  is fluidly connected to the return connection  16 . The flow connection is formed via several heat exchanger tubes  20  as well as a singular discharge tube  22 . The heat exchanger tubes  20  are provided in the embodiment shown. 
     The heat exchanger  10  furthermore has a fluid distributor portion  24  and a collecting portion  26  which are shown in particular in  FIG. 2 . The collecting portion  26  runs substantially parallel to the fluid distributor portion  24  which runs along the connection side  18 . The heat exchanger tubes  20  connected in parallel as well as the singular discharge tube  22  run parallel to one another and in each case perpendicular to the fluid distributor portion  24  and proceed from the fluid distributor portion  24  and open next to one another into the collecting portion  26 . 
       FIGS. 1 and 2  show the heat exchanger  10  in its installation position so that the upper region in the figures corresponds to the upper region in the installation position. It is apparent from this that the heat exchanger tubes  20  are arranged in an upper region  27  of heat exchanger  10 , whereas the discharge tube  22  is arranged in a lower region  28  of heat exchanger  10  in the installation position. 
     The mode of operation of the heat exchanger  10  is explained below. 
     A fluid, which can, for example, be water, is supplied to the heat exchanger  10  via the supply connection  14 . The fluid can flow from an engine (not shown) to the heat exchanger  10  so that the fluid is heated as a result of the heat discharged in the engine. 
     The fluid supplied via the supply connection  14  then flows into the fluid distributor portion  24  in which the fluid is distributed to the individual heat exchanger tubes  20  in a homogeneous manner. Individual heat exchanger tubes  20  jointly form a heat exchange region  29  around which a medium flows, for example, air. The heated fluid discharges its heat energy to the medium. As a result of the large number of the heat exchanger tubes  20  and their small diameter, a large interaction surface is created for the medium via which a correspondingly high cooling performance can be provided. 
     The heat exchanger tubes  20  interact with the fluid distributor portion  24  in such a manner that the fluid flows in a uniform manner through the heat exchanger tubes  20 , as a result of which greater cooling performance and improved efficiency of the heat exchanger  10  are ensured. 
     The fluid flowing through the heat exchanger tubes  20  reaches, at the end of the heat exchanger tubes  20 , the collecting portion  26  in which the fluid is collected, which fluid flows through individual heat exchanger tubes  20 . The collecting portion  26  is fluidly connected to the singular discharge tube  22  which is in turn coupled to the return connection  16 . All the fluid collected in the collecting portion  26  is accordingly guided via the singular discharge tube  22  to the return connection  16 . The fluid can subsequently be discharged via the return connection  16  out of the heat exchanger  10  and supplied to the engine (not shown). All the fluid supplied to the heat exchanger  10  is thus returned via the single discharge tube  22  once the fluid has flowed through the heat exchange region  29 . 
     The fluid thus flows through individual heat exchanger tubes  20  only in one direction, namely from the connection side  18  to a side  30  opposite the connection side  18  on which the collecting portion  26  is formed. The collecting portion  26  thus extends along the opposite side  30 . 
     The singular discharge tube  22  forms the return for the fluid which flows through the heat exchange region  29  since it returns the fluid from the opposite side  30  to the connection side  18 . The discharge tube  22  is integrated in the heat exchanger  10  so that no additional assembly of hoses or other return components is required. 
     The heat exchange region  29  is primarily formed by the plurality of heat exchanger tubes  20 . The singular discharge tube  22  can likewise interact with the medium. 
     So that the throughflow quantity flowing through the heat exchanger  10  is high, the discharge tube  22  has a larger throughflow cross-section than one of many heat exchanger tubes  20 . In particular, the hydraulic diameter of the discharge tube  22  is approximately equal to or greater than that of the sum of all heat exchanger tubes  20 . As a result, it is ensured that no high counter-pressure is generated which would result in a small throughflow quantity. It is therefore not necessary to use a correspondingly more powerful fluid pump or a heat exchanger with a large surface area. The heat exchange region  29  corresponds substantially in terms of size to that of a heat exchanger  10  with I-throughflow, wherein cooling performance thereof is also comparable. 
     As a result of the larger diameter of the discharge tube  22 , it is ensured that the counter-pressure does not rise to such an extent that a higher power of a water pump (not shown) is required. As a result of the only small rise in the counter-pressure, an approximately identical throughflow quantity can act on the heat exchanger  10 . 
     The heat exchanger  10  is correspondingly created which externally has the form of a heat exchanger with U-throughflow since the supply connection  14  and the return connection  16  are formed on a common connection side  18  of the housing  12 . However, flow only takes place through the heat exchange region  29  in one direction, which is why the heat exchanger  10  corresponds in terms of the design principle of the heat exchange region  29  to that of a heat exchanger with I-throughflow. The heat exchanger  10  furthermore has the efficiency and cooling performance of a heat exchanger with I-throughflow. 
     An assembly  32  which has an engine  34  and a cooling system  36  is shown schematically in  FIG. 3 . 
     The cooling system  36  includes a heat exchanger  10  of the above-mentioned type as well as a fluid pump  38  which is arranged in a flow connection  40  which connects the return connection  16  of the heat exchanger  10  to a fluid inlet  42  of the engine  34 . A flow connection  44  is furthermore shown which is formed between a fluid outlet  46  of the engine  34  and the supply connection  14  of the heat exchanger  10 . The cooling circuit formed in this manner ensures adequate cooling of the engine  34 . 
     The fluid inlet  42  and the fluid outlet  46  can be arranged on a common side  48  of the engine  34 , in particular in a small region  50  of the common side  48  so that the fluid inlet  42  and the fluid outlet  46  are directly adjacent. As a result of this, a compact design of the entire assembly  32  is achieved since the connections  14 ,  16  on the heat exchanger  10  are also formed in a lower end portion  19  of the common connection side  18 . 
     There are thus created in general a heat exchanger  10 , a cooling system  36  as well as an assembly  32  which have a simple, compact structure and nevertheless high cooling performance. 
     The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof.