Patent Publication Number: US-6039112-A

Title: Plate-type heat exchanger and method of making same

Description:
BACKGROUND AND SUMMARY OF THE INVENTION 
     This application claims the priority of prior application 197 09 601.8 filed in Germany on Mar. 8, 1997, the disclosure of which is expressly incorporated by reference herein. 
     The invention relates to a plate-type heat exchanger, particularly an oil/coolant cooler, which comprises several plates which are arranged in parallel to one another and which form respective hollow chambers between one another which are provided with corrugated metal turbulence sheets for increasing the heat transfer and through which one of the respective media which participate in the heat transfer flows in an alternating manner. 
     A plate-type heat exchanger of this type is known from European Patent Document EP 06 23 798 A2, where trough-shaped heat exchanger plates were provided whose surrounding edges are placed against one another when the heat exchanger plates are stacked upon one another and which can then be tightly soldered to one another to form hollow chambers. In this case, each of the turbulence inserts inserted between the heat exchanger plates consists in a conventional manner of a thin metal sheet, preferably an aluminum sheet, which, in a rolling and cutting operation, was provided with a plurality of corrugations which are situated side-by-side and behind one another and which, viewed in the rolling direction, are arranged in different rows or are offset with respect to one another. These inserts are used for increasing the heat transfer capacity. However, when they are inserted between the inflow and outflow opening in their rolling direction or transversely to the rolling direction, they impair the pressure drop and the distribution of the media. 
     It is an object of the invention to construct a plate-type heat exchanger of the initially mentioned type such that a more uniform flow of the heat transfer media through the hollow chambers is achieved even when the metal turbulence sheets used for increasing the heat transfer are inserted. 
     For achieving this object, it is provided in the case of a plate-type heat exchanger of the initially mentioned type to divide the metal turbulence sheets into sections in which a different alignment exists of the course of the corrugations. 
     As a result of this measure, the flow can encounter different flow resistances in sections and it becomes possible in this manner to achieve an also largely uniform distribution of the heat transfer media in the individual hollow chambers despite the arrangement of the metal turbulence sheets. Deflection installations in the chambers through which the flow is forced may be eliminated. This also eliminates the expenditures for arranging such deflection walls inside the hollow chambers. 
     As a further development of the invention, in the case of turbulence metal sheets which were produced by rolling in the initially described manner, the desired alignment with respect to the rolling direction can simply be selected differently, and it was found to be particularly simple for the rolling direction in the sections to be in each case rotated by 90° with respect to that of the adjacent sections. Viewed from the inflow and outflow openings of the hollow chambers, this will result in sections with higher flow resistances and those with lower flow resistances, and the sections can be placed and designed such that the flowing medium is forced by the flow resistances to flow through the whole space of the hollow chamber in a flow which is as uniform as possible. 
     As a further development of the invention, the sections can be set off with respect to one another by separating cuts which may, for example, have defined contours or may be straight separating cuts. In a particularly simple manner, three sections can be formed by two diagonal cuts which are arranged mirror-symmetrically with respect to a transverse center plane which is symmetrically situated between the assigned inflow and outflow openings of the hollow chamber such that two outer sections, which have one inflow or outflow opening respectively, and an approximately trapezoidal center section are created. 
     As a further development of the invention, the diagonal sections can be arranged to be sloped at an angle of 30° with respect to the transverse center plane. In this case, the respective inflow or outflow opening is placed in the narrower area of the assigned outer section. In this embodiment, three different parts of the metal turbulence sheets respectively can then be placed in the hollow chambers. 
    
    
     Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a top view of a plate-type heat exchanger constructed according to a preferred embodiment of the present invention; 
     FIG. 2 is a lateral view of the plate-type heat exchanger of FIG. 1; 
     FIG. 3 is an enlarged schematic view depicting a turbulence insert arranged in the plate-type heat exchanger according to FIGS. 1 and 2 in one of the hollow chambers; 
     FIG. 4 is a lateral view of the turbulence insert of FIG. 3; 
     FIG. 5 is an enlarged view of a partial section of one of the sections of the turbulence insert of FIG. 3, taken along Line V--V of FIG. 3; and 
     FIG. 6 is a view of another section of the turbulence insert of FIG. 3 taken in the direction of the arrow VI. 
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
     FIGS. 1 and 2 show an oil/coolant cooler for a motor vehicle engine in the case of which it is important to house a heat transfer capacity which is as large as possible in a space which is as small as possible. In this case, the oil cooler according to FIGS. 1 and 2 consists of several trough-shaped disks 1 and 2 which are stacked above one another and which form respective chambers between one another in a known manner through which the oil or the coolant to be cooled flows in a respective alternating manner, which coolant is taken, for example, from the coolant of the motor vehicle engine which is not shown. 
     In the case of the embodiment shown, the oil enters into a common connection piece 3 and leaves the cooler through the connection piece 4. Coolant enters through the connection piece 5 and leaves the cooler through the connection piece 6. In this case, the inflow and outflow connection pieces for the oil and the coolant may be arranged on the same side of the cooler body or on opposite sides. This does not change the flow through the individual hollow chambers which is important in the present case. The inflow and outflow openings for one medium are sealed off in the hollow chamber through which the other heat transfer medium flows by means of one inserted spacer disk respectively. In a modified embodiment, the spacer elements are a component of the disks 1 and/or 2 which are provided, for example, with set-off passages. The joint inflow connections 3 therefore supply several hollow chambers with oil in which the oil flows to the outflow connection 4. In the same manner, the inflow connection 5 in each case supplies the hollow chambers with coolant which adjoin the hollow chambers through which the oil flows, which coolant then flows out through the outflow connection piece 6. 
     FIGS. 3 and 4 show a turbulence insert 7 which is arranged in one of the hollow chambers through which the oil flows. However, similar turbulence inserts are also provided in the chambers through which the coolant flows. 
     FIG. 3 therefore shows by means of broken lines that the inflow and outflow openings 5 and 6 for the coolant are sealed off by spacer disks 8 for the illustrated hollow chamber through which the oil flows. The oil therefore enters into the illustrated hollow chamber through the opening 3, flows through the turbulence insert in the hollow chamber and leaves the hollow chamber through the outflow connection 4. 
     FIG. 3 shows that the turbulence insert 7 is divided into three sections 7a, 7b, and 7c which are each separated from one another by a respective diagonal cut 9 arranged sloped at an angle α of approximately 30° with respect to a transverse center plane 10 and symmetrically thereto. In section 7a, whose narrower side faces the inflow opening 3, a turbulence insert 11 is situated which corresponds to the shape of section 7a--only a rectangular shape portion is shown--whose rolling direction, like that of section 7c, is in parallel to a longitudinal center plane 13 and thus perpendicular to the transverse center plane 10. For a better understanding, the rolling directions are schematically indicated by respective dash-dotted line arrows 14. Transversely to the rolling direction, gate-type openings 15 (FIG. 6) are therefore created which, however, in adjacent rows, have different widths so that in a known manner respective slot-type openings 16 are created between adjacent gates, which slot-type openings 16 permit a flow not only transversely through the gates 15 but also in a direction perpendicularly thereto. However, it is clearly indicated that a flow in the direction of the gates, that is, a flow starting from the inflow opening 3 in the direction of the arrow 17 encounters little resistance to the flow, while a flow in the direction of the arrow 18 must overcome a much greater resistance because such a flow would have to take place exclusively through the slots 16. It therefore becomes clear that, in section 7a, because of the lower resistance, the flow from the inflow opening 3 can take place much more easily in the direction of the arrow 17 than in the direction of the arrow 18. The flow away from the opening 3 will therefore essentially also propagate in the direction of the arrow 17 while only a relatively small fraction of the flow will take place in the direction of the separating cut 9 (arrow 18). 
     Section 7b has a metal turbulence sheet arrangement which is rotated by 90° with respect to that of section 7a. In this case, the rolling direction 14 extends in parallel to the transverse center plane 10 which means that in this section 7b, the flow in the direction of the two arrows 17 must overcome relatively little resistance. However, since the center section 7b has a trapezoidal construction and has the largest width in its lower area, thus, in the area where the inflow and the outflow respectively is arranged in the adjacent sections 7a and 7c, the overall resistance of the flow in this section 7a will also be larger in the lower area than in the areas situated above. This has the result that the flow is distributed largely uniformly on section 7b since also the inflow from section 7a takes place largely uniformly by way of the separating cut 9. 
     In section 7c, the metal turbulence sheet 11 is in turn arranged analogously to that in section 7a. The flow in the direction of the arrow 18 is therefore also subject to a greater resistance than in the direction of arrow 17. The overall arrangement of the three sections 7a, 7b and 7c with the different alignment of the rolling direction 14 of the metal turbulence sheets in each case assigned to the sections therefore causes a uniform distribution of the flow in the hollow chamber without the requirement of separate separating walls or the like. 
     FIG. 5 shows that the gates 15 are rotated with their axes by 90° with respect to those of the gates of the metal turbulence sheets 11. 
     In the embodiment shown, three metal turbulence sheets in the shape of the sections 7a, 7b and 7c are separately placed into the assigned hollow chamber. These sections may also be connected with one another according to certain contemplated embodiments. 
     Depending on the method in which the flow is to be influenced, it is also contemplated to provide, instead of the straight separating cuts 9, also separating cuts in a curved shape by means of which an influencing of the flow can also be achieved according to the correspondingly constructed sections. Finally, it is also contemplated in certain embodiments to offset the rolling direction 14 in adjacent sections not by 90° but by other angles with respect to one another so that also in this manner, according to the desired flow pattern, a special influencing of the flow can be achieved. 
     FIGS. 3 and 4 show a chamber through which oil flows. The chamber through which the coolant flows is also equipped with metal turbulence sheets according to sections 7a, 7b and 7c. The flow of the coolant in the then formed sections from the inflow connection piece 5 to the outflow connection piece 6 is also influenced in the basically endeavored manner. However, since the coolant is much less viscous, slightly different aspects must be considered here during the distribution of the flow. However, it was found that the identical design of the metal turbulence sheets which was selected for the two hollow chambers (oil and coolant) causes the desired uniformity of the flow in all hollow chambers at low expenditures. Although a separate construction of the turbulence inserts or of the turbulence sections for the chambers through which the oil and the coolant flow would be possible according to contemplated embodiments, such arrangements would require much higher expenditures than the preferred embodiments with similar turbulence inserts. 
     Although the invention has been described and illustrated in detail, it is to be clearly understood that the same is by way of illustration and example, and is not to be taken by way of limitation. The spirit and scope of the present invention are to be limited only by the terms of the appended claims.