Abstract:
A plate heat exchanger for cooling a first fluid by a second fluid, including a plurality of stacked heat exchanger plates forming separate flow channels therebetween with a cover plate on one side and a base plate on the other side of the stacked plates. The plates have a plurality of aligned openings defining inlet and outlet channels each communicating with selected ones of connected flow channels. In one form, the cover plate includes a conveying channel guiding one of the fluids to a desired position along the length of the heat exchanger, and the base plate includes a conveying channel guiding the other of the fluids to a desired position along the length of the heat exchanger. In another form, the conveying channels for both of the fluids are in the same one of the cover or base plate.

Description:
CROSS REFERENCE TO RELATED APPLICATION(S) 
   Not applicable. 
   STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
   Not applicable. 
   REFERENCE TO A MICROFICHE APPENDIX 
   Not applicable. 
   TECHNICAL FIELD 
   The present invention is directed toward heat exchangers, and particularly toward relatively long plate heat exchangers. 
   BACKGROUND OF THE INVENTION AND TECHNICAL PROBLEMS POSED BY THE PRIOR ART 
   Plate heat exchangers have been used, for example, with motor vehicles in order to control the temperature of the gear oil using the coolant of the vehicle engine. Such plate heat exchangers have included stacked heat exchanger plates, each of which have openings which form channels in the stack of heat exchanger plates and which serve to introduce and lead away the fluids from flow channels between the plates. 
   Such heat exchangers have been used in a wide variety of different environments in which the connections for the fluids may vary, as may the restricted space available for the heat exchanger. It is know to provide transfer channels with an upper plate and a lower plate in order to guide a fluid to a desired position of the inlet or outlet. Plate heat exchangers generally of this type are variously shown, for example, in DE 41 25 079 A1, WO 94/29659 and EP 614 061 A1. However, such designs have limited ability to economically adapt to the great variety of environments in which such heat exchangers might be used. 
   The present invention is directed toward overcoming one or more of the problems set forth above. 
   SUMMARY OF THE INVENTION 
   In one aspect of the present invention, a plate heat exchanger for cooling a first fluid by a second fluid is provided, including a plurality of stacked heat exchanger plates forming separate flow channels therebetween with a cover plate on one side and a base plate on the other side of the stacked plates. The plates have a plurality of aligned openings defining inlet and outlet channels each communicating with selected ones of connected flow channels. The cover plate includes a conveying channel guiding one of the fluids to a desired position along the length of the heat exchanger, and the base plate includes a conveying channel guiding the other of the fluids to a desired position along the length of the heat exchanger. 
   In one form of this aspect of the invention, one of the fluids is oil. 
   In another form of this aspect of the invention, a thermostat-control valve in a housing is provided on one of the base and cover plates, with the valve including a thermostat-control in the housing and the housing being in communication with flow of one of the fluids. In a further form, the valve housing includes a first connection to a first source of the one fluid and a second connection to a second source of the one fluid, and the fluid from the first source is a different temperature than the fluid from the second source and the valve adjusts communication with the first and second sources depending on the temperature of the other fluid. In another further form, the housing includes a chamber in which the thermostat-control is in contact with the other fluid and a compartment for the one fluid hydraulically connected to an inlet channel of the plate heat exchanger, where the compartment includes a first connector for connecting to a first source of the one fluid and a second connector for connecting to a second source of the one fluid, the first and second sources having fluid having different temperatures. In a still further form, the plate having the conveying channel carrying the other fluid includes a cut-out with a flow-deflection element for guiding the other fluid into the chamber. 
   In still another form of this aspect of the present invention, the conveying channel in one of the cover and base plate transfers one of the fluids from a heat exchange outlet to a desired position along the one plate. 
   In yet another form of this aspect of the present invention, the flow channels for one of the fluids extend between an inlet for the one fluid and an outlet for the one fluid, the one fluid inlet and the one fluid outlet being substantially at opposite longitudinal ends of the heat exchanger, and the inlet channel for the other of the fluids divides the other fluid into first and second partial streams. The first partial stream enters the flow channels for the other of the fluids at one end of the heat exchanger. The second partial stream flows from the one end of the heat exchanger through one of the conveying channels to the opposite end of the heat exchanger and enters the flow channels for the other of the fluids at the opposite end of the heat exchanger. In one direction of flow of the other fluid, the first and second partial streams have converging flow in the flow channels and, in an opposite direction of flow, have diverging flow in the flow channels. 
   In a further form, a middle channel for the flow channels of the other fluid is provided, where the middle channel is an outlet of converging flow when the other fluid flows in the one direction, and is inlet for diverging flow when the other fluid flows in the opposite direction. In a still further form, the middle channel communicates with one of the conveying channels, with the one conveying channel communicating with a connector located at a distance from the middle channel along the longitudinal direction of the heat exchanger. In a still further form, the connector is an outlet connector. 
   In another aspect of the present invention, a plate heat exchanger for cooling a first fluid by a second fluid is provided, including a plurality of stacked heat exchanger plates forming separate flow channels therebetween. The plates have a plurality of aligned openings defining inlet and outlet channels each communicating with selected ones of connected flow channels. At least one upper plate and at least one lower plate are provided on opposite sides of the stacked plates, with a first conveying channel in one of the upper and lower plates guiding one of the fluids to a desired position along the length of the heat exchanger and a second conveying channel in the same plate, the second conveying channel being a transfer channel for guiding the other of the fluids to a desired position along the length of the heat exchanger. 
   In one form of this aspect of the present invention, a second transfer channel for the other of the fluid is arranged on one of the upper and lower plates. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a top view of one embodiment of a plate heat exchanger according to the present invention; 
       FIG. 2  is a bottom view of the  FIG. 1  heat exchanger; 
       FIG. 3  is a side cross-sectional view of the  FIG. 1  heat exchanger; 
       FIG. 4  is a perspective section view similar to  FIG. 3 ; 
       FIG. 5  is a top view an alternate embodiment plate heat exchanger according to the present invention; 
       FIG. 6  is a bottom view of yet another alternative embodiment of the present invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   The plate heat exchanger  10  according to the present invention and illustrated in the Figures is a gear oil cooler, which may be used, for example, in a motor vehicle in order to control the temperature of the gear oil using the coolant of the vehicle engine. 
   As also disclosed in our U.S. patent application entitled “Thermostat-Control Valve for Heat Exchanger” (filed on the same day as the present application), the disclosure of which is hereby incorporated by reference, a thermostat-control valve  14  is provided for controlling the temperature of the coolant based on the oil temperature to provide a desired advantageous temperature of the oil as cooled by the heat exchanger  10 . The valve  14  may be suitably mounted in a housing  16  which is secured on one of the heat exchanger plates (e.g., the cover plate  20 ), as by suitable fasteners  22 . 
   As best illustrated in  FIGS. 3 and 4 , the housing  16  has a chamber  28  hydraulically separated from a compartment  30 . A thermostat  32  protrudes into the chamber  28 , and suitable elements of the control valve  14  (e.g., valve rod, valve plate, etc.) extend into compartment  30 , with hydraulic separation achieved with seals on the thermostat  32 . On the housing  16  which forms the compartment  30 , there is a connection  36  for cooled coolant fluid CC and another connection  38  for preheated coolant HC. Depending on the actual temperature of the oil to be cooled (as measured in chamber  28 ), the thermostat  32  will suitably adjust (e.g., by moving the valve rod with the valve plate) in such a way that either only cooled coolant CC, only heated coolant HC or a mixture of CC and HC will flow from the compartment  30  into the inlet channel  40  for the coolant of the plate heat exchanger  10 . It should be appreciated, however, that the illustrated thermostat-control valve  14  and related structure is merely one example of a type of control which may be advantageously used with the present invention in order to keep or bring the gear oil as close as possible to the optimum desired temperature. It should be appreciated that still other coolant control structures could be used. It should still further be appreciated that, depending upon the environment, heat exchangers employing other aspects of the present invention could be advantageously used without such a coolant control system as well. 
   Oil flow through the heat exchanger (indicated by dashed arrows, whereas coolant flow is indicated by solid arrows) is as follows. Oil enters the heat exchanger  10  through the oil inlet connector  44 , from which it is suitably distributed through alternate flow channels  46  between the heat exchanger plates  48 , such as is known to those skilled in the art. Oil exits the flow channels  46  into the outlet channel  50  and passes through the outlet channel  50  to a conveying channel  52  formed in the cover plate  20 . The oil flows through the outlet channel  52  to the outlet connector  54  of the heat exchanger  10 . Thus, it can be seen that the oil inlet and outlet connectors of the heat exchanger  10  may be advantageously provided at many different positions, depending upon the requirements of the system with which it is used, by the simple expedient of forming different conveying channels in the cover plate  20 . 
   In the conveying channel  52  for the oil, there is a cut-out  56  with a flow-deflecting element  58  which guides the cooled oil into the chamber  28  and to the thermostat  32  (such flow being indicated by the dashed arrow in  FIG. 3 ), whereby the thermostat  32  may advantageously detect the temperature of the oil after cooling in the heat exchanger  10  to determine whether more or less cooling is desirable, and adjust the mix of cool and preheated coolant CC and HC accordingly. 
   Flow of the coolant will now be described. As previously indicated, coolant flow is indicated in the figures by solid arrows. 
   The desired mixture of coolant flows from the compartment  30  to the coolant inlet channel  60 , from which it is divided into two partial streams: partial stream C 1  which enters there into coolant flow channels  62  between the heat exchanger plates  48 , and partial stream C 2  which flows through a transfer channel  70  formed in the bottom or base plate  72 . 
   Though only a single arrow C 1  is shown in  FIG. 3 , it should be understood that there advantageously are multiple coolant flow channels  62  through which partial stream C 1  is split. The coolant flow channels  62  typically alternate with the oil flow channels  46 , with suitable openings and closures provided around the coolant inlet channel  60  to connect the coolant inlet channel  60  with the coolant flow channels  62  (and separate the coolant inlet channel  60  from the oil flow channels  46 ). 
   Partial stream C 2  flows through the transfer channel  70  to the diametrically opposed end of the plate heat exchanger  10 , where it enters a second coolant inlet channel  76  and, from that channel  76 , passes through the coolant flow channels  62  in a direction which is substantially concurrent with the oil flow in the oil flow channels  46  (i.e., from left to right in  FIGS. 1-4 ), and substantially counter to the flow direction of partial stream C 1  in the coolant flow channels  62  (from right to left in  FIGS. 1-4 ) (i.e., the two partial flows converge). 
   A coolant outlet channel  80  is arranged approximately in the middle of the plate heat exchanger  10 , whereby the coolant of both partial streams C 1 , C 2  exits the coolant flow channels  62  and, from there, flows into a second transfer channel  82 , arranged on the cover plate  20 , leading to outlet connection  86  for the coolant. The outlet connection  86  and the outlet channel  80  are at a distance from one another. Thus, it can be seen that the coolant inlet and outlet connectors of the heat exchanger  10  may be advantageously provided at many different positions, depending upon the requirements of the system with which it is used, by the simple expedient of forming different transfer channels in the cover and/or base plate  20 ,  72 . Moreover, it should be appreciated that the coolant flow could readily be reversed if desired, with the partial streams of coolant in that case having a divergent flow direction in the flow channels  62 . 
   Thus, with the present invention, it has become possible to guide the inlets and outlets for both media to freely-selectable positions in the regions of the base plate  72  and cover plate  20 . This is done by appropriate design of the conveying and transfer channels  50   70 ,  82 , each of which can have any arbitrary form. It can be seen from this that, as a result of the invention, the connection possibilities of the heat exchanger can be improved significantly in very tight housings. 
   It should also be appreciated that the division of the coolant streams into partial streams C 1   m  C 2  can be influenced in the desired direction by, for example, dimensioning of flow channels  62  and transfer channels  70 ,  82  appropriately, and/or by corresponding choice of channel lengths in the desired direction. Moreover, it should be appreciated that the present invention may be particularly advantageous with plate heat exchangers which have a relatively small number of relatively long flow channels  46 ,  62 , in order to reduce pressure loss. 
   As illustrated particularly in  FIG. 4 , the cover plate  20  of the plate heat exchanger  10  may advantageously include a projection  90  which protrudes above the stack formed from heat exchanger plates  48 , which projection  90  may be advantageously used to make a suitable vibration-damping fastening  92 ,  94  of the plate heat exchanger  10  to the system with which it is used. 
   An alternate structure embodying the present invention is shown in  FIG. 5  which is substantially similar to the embodiment shown in  FIGS. 1-4 . Accordingly, the same reference numbers are used for the same parts, wherein a prime (“′”) has been added to similar but slightly modified parts. 
   With this alternate embodiment, the positions of the oil inlet connector  44  and oil outlet connector  54  are unchanged. The transfer channels  70 ′,  82 ′ and the conveying channel  52 ′ are straight and located in one of the plates (cover plate  20 ′ in this example), although it should be appreciated that any arbitrary shape could have been used, including a curved shape. A thermostat-control valve  14  is also included on the cover plate  20 ′ with this embodiment (though it could be arranged in other locations) and it should be appreciated that this valve  14  may be the same as described with the first described embodiment (though turned ninety degrees and located centrally relative to the cover plate  20 ′). 
   As should be appreciated by the solid arrows in  FIG. 5 , the coolant stream in this embodiment enters the heat exchanger at about its center and then is split into the two partial streams C 1 ′, C 2 ′ to flow in opposite directions through the transfer channel  70 ′ to the two diametrically opposed ends of the plate heat exchanger to the inlet channels  60 ′,  76 ′. 
     FIG. 6  illustrates yet another embodiment of the present invention, in which the transfer channel  70 ′ has bends  98  (the same reference numbers are used for the same parts with this embodiment, wherein a double prime (“″”) has been added to similar but slightly modified parts. Such a configuration could be advantageously used, for example, in a heat exchanger which is to be used in an environment in which the coolant outlet is desired to be in the middle of the bottom plate  72 ″. From these examples, it should thus be appreciated that the conveying and transfer channels may be easily manufactured in a wide variety of configurations, as may be desired to accommodate the position of various components, such as inlet and outlet connectors, based on system design requirements. Such simplicity of manufacture may readily use common core components, such as the plates  48 , with essentially one the bottom and/or top plates requiring modification for different environment requirements. 
   Accordingly, it should be appreciated that heat exchangers according to the present invention may be advantageously used to inexpensively provide for advantageous use in many different applications (e.g., with motor engines in a wide variety of vehicles) in which a wide variety of configurations for connecting the heat exchanger to the supply of both fluids may be required. Further, it should be appreciated that the present invention may also be used to provide cooling in an environment in which the heat exchangers is relatively long, and to provide such operation with minimized pressure loss despite such configuration. 
   Still other aspects, objects, and advantages of the present invention can be obtained from a study of the specification, the drawings, and the appended claims. It should be understood, however, that the present invention could be used in alternate forms where less than all of the objects and advantages of the present invention and preferred embodiment as described above would be obtained.