Plate Heat Exchanger

Abstract

A plate heat exchanger has openings in the plates defining supply and return ducts extending through a plate stack. The supply and return ducts are hydraulically connected to flow ducts located between the plates and to a tube arranged coaxially in each of the supply and return duct. The tubes have holes in the tube wall in order to provide the hydraulic connection to the flow ducts. A simple and cost-effective plate heat exchanger which can withstand high pressures is achieved by the tubes extending through the entire stack to form a tie rod between a top side and an underside of the plate stack. The tube has a diameter corresponding to the diameter of the openings in the plates such that the tube wall is firmly metallurgically connected to at least some edges of the openings.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to German Patent Application No. 10 2015 010 289.3 filed Aug. 20, 2015, the entire contents of which are hereby incorporated by reference herein.

FIELD OF THE INVENTION

The invention relates to a plate heat exchanger having openings in the plates, which are formed by supply or return ducts extending through a plate stack, said supply or return ducts being hydraulically connected to flow ducts located between the plates. and to a tube arranged coaxially in the supply or return duct, having holes in the tube wall of said tube for providing the hydraulic connection to the flow ducts.

BACKGROUND

U.S. Pat. No. 3,976,128A discloses an evaporator which is constructed as a plate and fin heat exchanger. In order to improve the performance thereof, the tube was arranged in the supply duct coaxially with the holes in the tube wall of said tube. The performance improvement is achieved by specific positioning, proposed therein, of the holes at the circumference of the tube wall. The strength of the known heat exchanger cannot be improved to the extent that would be desired and also necessary at particularly high internal pressures.

In the case of a known plate heat exchanger used as an oil cooler (shown as the prior art heat exchanger of FIG. 12) solid annular discs R are arranged between the plates in the region of the opening edges in order to control the high internal pressure

SUMMARY

One problem addressed by the invention is to simplify the production of the plate heat exchanger, without neglecting the strength thereof.

According to one aspect of the invention, the tube extends through the entire stack in order to form a tie rod between a top side and an underside of the plate stack. The tube has a diameter corresponding to the diameter of the openings in the plates such that the tube wall is firmly connected metallurgically to at least some edges of the openings. In order to reinforce the abovementioned metallic connection, at least some of the opening edges are provided with a flange bearing against the tube wall.

The abovementioned terms “top side” and “underside” are primarily independent of their spatial arrangement, i.e. should be understood as two opposite sides of the plate stack.

As a consequence of the implementation of the invention, the previously provided solid annular discs can be dispensed with. On account of the coaxial tube being configured as a tie rod, the plate heat exchanger according to the invention has sufficient strength with respect to very high internal pressures. It is lighter than the previous heat exchangers and it has also become producible with lower costs on account of the numerous annular discs being dispensed with.

The provision of flanges or collars at the opening edges simultaneously also serves for the firm metallic connection between adjacent opening edges of adjacent plates, with the result that the hydraulic separation between the flow ducts is achieved.

The proposed solution can be applied in plate heat exchangers which are arranged in a housing and also in what are known as “housingless” plate heat exchangers, as is otherwise also apparent from the following description of exemplary embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a perspective view of a plate heat exchanger according to an embodiment of the invention, which is to be arranged in a housing (not shown).

FIG. 2 shows a longitudinal section through this plate heat exchanger.

FIG. 3 is an enlarged illustration of a tube which is located coaxially in the supply duct and in the return duct of the plate heat exchanger.

FIGS. 4A-4C contain several illustrations of differently designed tubes.

FIG. 5 is similar to FIG. 1, but omits key features from FIG. 1 and instead shows details which are not visible in FIG. 1.

FIG. 6 is an enlarged detail view of the area indicated as IV in FIG. 3.

FIGS. 7-10 show enlarged details of different opening edges which are metallurgically connected to the coaxial tube, to be more precise with the tube wall thereof.

FIG. 11 shows a plan view of a “housingless” plate heat exchanger as an outline with in each case one coaxial tube in the supply and return ducts thereof.

FIG. 12 shows a longitudinal section of a plate heat exchanger from the prior art, which has solid rings R introduced between the plates around the hole edges.

DETAILED DESCRIPTION

Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the accompanying drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or limited otherwise, the terms “mounted,” “connected,” “supported,” and “coupled” and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings. Further, “connected” and “coupled” are not restricted to physical or mechanical connections or couplings.

The exemplary embodiments described in the following text make it possible to dispense with the abovementioned rings R, but to retain high internal-pressure resistance of the plate heat exchanger.

The plate heat exchanger in the exemplary embodiments shown is an oil cooler for cooling oil, for example transmission oil, by means of a coolant, without being limited thereto.

The plate heat exchanger according to FIGS. 1-3 and 5-10 has two openings 1 in all of the plates 2. The plates 2 have been stacked to form a plate stack 3 such that, by means of the openings 1, supply ducts and a return ducts extending through the plate stack 3 are formed, which both have the reference sign 10. The two ducts 10 are hydraulically connected to flow ducts 11 located between the plates 2. As FIG. 2 shows, oil flows into the supply ducts 10 (on the right), flows through the flow ducts 11 and, after corresponding cooling, passes into the return duct 10 (on the left). A further flow duct 11.1 is in each case located between the flow ducts 11. The flow ducts 11.1 are flowed through by the coolant. The coolant is symbolized by block arrows arranged on the left and right (FIG. 2). The housing (not shown) has corresponding openings (not shown) for the entry and exit of the liquid coolant.

Fins (not illustrated) or the like are optionally provided in the flow ducts 11. Studs 13 that butt against one another or similar plate formations are provided in the flow ducts 11.1 of the exemplary embodiment. The studs 11 can be replaced, for example also by other fins.

A coaxially arranged tube 4 is located in both the supply duct and the return duct 10. The tube 4 has holes 40 arranged in the tube wall 41 thereof. The holes 40 allow the mentioned hydraulic connection to the flow ducts 11 and have therefore been arranged exactly at the heights of the flow ducts 11. The shape of the holes 40 can vary. FIG. 2 shows round holes 40. FIGS. 3 and 4 show elongate holes 40. Further shapes and also different cross-sectional sizes are conceivable and have also been contemplated for other embodiments of the invention that are not shown.

With regard to the through-flow of the flow ducts 11, the arrangement, discernible in FIG. 5, of the holes 40 has proved advantageous. It can be seen therein that the tube wall 41 is formed in a circumferential portion 44, directed in the longitudinal direction of the plate heat exchanger, without holes 40. As a result, all regions of the flow ducts 11 are flowed through better, that is to say are involved better in heat exchange, this being advantageous with regard to efficiency. A considerable quantity of oil is initially forced to flow around the supply duct 10 before it flows in the longitudinal direction, or in the direction of the return duct 10. The return duct 10 is also initially flowed around before the oil passes into same.

The tube 4 has a tie-rod function. Therefore, it extends through the entire stack 3 and is firmly metallurgically bonded to a top side and an underside of the plate stack 3. In the embodiment of FIGS. 1-3, thick-walled flanges 9 are provided on the top side, which rest on a more stable plate 8. The stack 3 also has a stable lower plate 7 on the underside. As is best discernible from FIGS. 3 and 6, a brazing gap 43 has been provided to enhance the tie-rod functionality, said brazing gap 43 contributing considerably to the strength of the brazed connection because it will receive a larger quantity of braze material. A ring 45 of braze alloy may be necessary if the provided amount of braze is insufficient. Furthermore, a collar 80 on the upper plate 8 can contribute to increasing the strength. The collar 80 can project into the gap 43. A similar collar can be located at a corresponding hole in the lower plate 7.

A further contribution with regard to the strength is achieved in that the tube 4 has a diameter corresponding to the diameter of the openings 1 in the plates 2. In this way, the tube wall 41 is firmly connected metallurgically, preferably brazed, to all of the edges 6 of the openings 1 in the exemplary embodiment. At least some opening edges 6 should have the connection.

FIGS. 7-10 show partial cross-sectional views of various possible alternative design details for select embodiments of the invention. Certain less relevant details of the plate heat exchanger have been removed or simplified in order to best illustrate the details of interest. Each of FIGS. 7-10 show only half an opening edge, or half a tube 4, this being made clear by the indicated axis A. In addition, the number of flow ducts illustrated has been reduced to a single open flow duct arranged between two closed flow ducts. While most embodiments of the invention will include more of each kind of flow duct, such additional flow ducts can be provided by repeating instances of the depicted geometry, and thus do not need to be shown in order to adequately describe the invention. Additionally, those portions of the heat exchanger along the longitudinal direction between the end of the thick-walled flange and the far ends of the plates have been removed for the figures, but are as shown in FIG. 2.

It is highly advantageous for the edges 6 to be provided with a flange or collar 60 bearing against the tube wall 41 (FIG. 7), in order to further strengthen the metallic connection. As shown in FIGS. 7-10, such a flange 60 is provided on alternating ones of the plates 2. The adjacent and interleaved ones of the plates 2 are provided with an opening 1 that is larger in diameter than the opening 1 provided in those plates having a flange 60. In this manner, the flanges 60 can be metallurgically joined to the tube 4 to provide structural strength along the stack height, while other metallurgical joints between the adjacent plates are provided immediately adjacent to and radially outward of the supply and return ducts 40 in order to hydraulically separate the closed flow ducts for the oil from the open flow ducts for the liquid coolant.

The interleaved plates 2 that are not directly bonded to the tube 4 can still be provided with a flange along the opening edge, as shown in the alternative of FIGS. 9 and 10. Adjacent plates 2 can be joine to one another at the flanges as shown, so that the aforementioned flange 60 is arranged between the tube wall 4 and the flange of the adjacent plate and is bonded to both, thereby further increasing the strength of the tie-rod. In order to increase the rigidity of the edges 6, it is also possible to additionally form a circumferential protuberance 14, as shown in FIG. 10.

At an end located opposite an inlet 30 or an outlet 50, the coaxial tube 4 has a closure cap 42 or the like firmly connected metallurgically to the tube 4. The closure cap 42 can be a differently formed individual part (FIGS. 4A and 4B). It can also be formed in one piece with the tube 4, however, as is shown in the design according to FIG. 4C.

The outline according to FIG. 11 is intended merely to show that the proposed subject matter can also be implemented in what is known as a “housingless” plate heat exchanger of known construction.

As is known, this differs from the above in that the plate stack 3 has second flow ducts 12 (not shown, merely indicated by means of an arrow) located between the plates 2, said second flow ducts 12 being hydraulically connected to second supply or return ducts 20 formed from second plate openings 5, wherein the tube 4 is also or only located in one of the second supply or return ducts 20, wherein the holes 40 in the tube wall 41 of said tube provide the hydraulic connection to the second flow ducts 12. Dashed circles are intended to indicate inserted tubes 4 in all supply and return ducts 10, 20.

Various alternatives to the certain features and elements of the present invention are described with reference to specific embodiments of the present invention. With the exception of features, elements, and manners of operation that are mutually exclusive of or are inconsistent with each embodiment described above, it should be noted that the alternative features, elements, and manners of operation described with reference to one particular embodiment are applicable to the other embodiments. The embodiments described above and illustrated in the drawings are presented by way of example only and are not intended as a limitation upon the concepts and principles of the present invention. As such, it will be appreciated by one having ordinary skill in the art that various changes in the elements and their configuration and arrangement are possible without departing from the spirit and scope of the present invention.

Claims

1. A plate heat exchanger comprising:

a plurality of plates arranged to form a plate stack, first openings of the plates aligned to form a supply duct extending through the plate stack and second openings of the plates aligned to form a return duct extending through the plate stack, flow ducts being located between the plates to hydraulically connect the supply and return ducts;

a first tube arranged within the supply duct and extending through the entire plate stack, a first end of the first tube being metallurgically joined to a top side of the plate stack and a second end of the first tube being metallurgically joined to a bottom side of the plate stack in order to function as a first tie-rod connection through the plate stack; and

a second tube arranged within the return duct and extending through the entire plate stack, a first end of the second tube being metallurgically joined to a top side of the plate stack and a second end of the second tube being metallurgically joined to a bottom side of the plate stack in order to function as a second tie-rod connection through the plate stack.

2. The plate heat exchanger of claim 1, further comprising:

a first thick-walled flange arranged at the top side of the plate stack and joined to an uppermost plate of the plate stack, the inlet duct extending through the first thick-walled flange, wherein the metallurgical joint at the first end of the first tube is located within the first thick-walled flange; and

a second thick-walled flange arranged at the top side of the plate stack and joined to the uppermost plate of the plate stack, the return duct extending through the second thick-walled flange, wherein the metallurgical joint at the first end of the second tube is located within the second thick-walled flange.

3. The plate heat exchanger of claim 2, wherein the metallurgical joints a the first end of the first and second tubes comprise braze material arranged in one or more gaps between the first end of the first and second tubes and the first and second thick-walled flanges, respectively.

4. The plate heat exchanger of claim 1, wherein the first and second tubes each comprise a closure cap metallurgically connected to the second end of said tube.

5. The plate heat exchanger of claim 1, wherein:

at least some of the first openings are provided with first flanges defining a diameter of said first openings that corresponds with a diameter of the first tube, the first tube being metallurgically joined to the first flanges; and

at least some of the second openings are provided with second flanges defining a diameter of said second openings that corresponds with a diameter of the second tube, the second tube being metallurgically joined to the second flanges.

6. The plate heat exchanger of claim 5, wherein:

the first tube includes a plurality of first holes arranged in a wall of the first tube, the plurality of first holes being arranged between those locations where the first tube is metallurgically joined to the first flanges in order to provide a hydraulic connection between the supply duct and the flow ducts; and

the second tube includes a plurality of second holes arranged in a wall of the second tube, the plurality of second holes being arranged between those locations where the second tube is metallurgically joined to the second flanges in order to provide a hydraulic connection between the return duct and the flow ducts.

7. The plate heat exchanger of claim 6, wherein the first and second tubes each include a circumferential wall portion, directed in a longitudinal direction of the plate heat exchanger, that is without any of the first and second holes.

8. The plate heat exchanger of claim 6, wherein the pluralities of first and second holes are arranged so that a considerable quantity of fluid received into the supply duct is initially forced to flow around the supply duct before flowing in a longitudinal direction of the plate heat exchanger and a considerable quantity of fluid received from the flow ducts is initially forced to flow around the return duct before being received into the return duct.

9. The plate heat exchanger of claim 5, wherein at least some of the first openings are of a diameter that is larger than the diameter of the first tube and wherein at least some of the second openings are of a diameter that is larger than the diameter of the second tube.

10. The plate heat exchanger of claim 9, wherein the flow ducts are hydraulically isolated from cooling fluid flow ducts arranged between the flow ducts by metallurgical joints between plates having a first flange and plates having a first opening of a diameter that is larger than the diameter of the first tube, and by metallurgical joints between plates having a second flange and plates having a second opening of a diameter that is larger than the diameter of the second tube.

11. The plate heat exchanger of claim 10, wherein those first openings having a diameter that is larger than the diameter of the first tube are provided with third flanges, at least some of those third flanges being metallurgically bonded to the first flanges.

12. The plate heat exchanger of claim 10, wherein those second openings having a diameter that is larger than the diameter of the second tube are provided with third flanges, at least some of those third flanges being metallurgically bonded to the second flanges.

13. A plate heat exchanger comprising:

a plurality of plates arranged to form a plate stack, adjacent plates in the plate stack being spaced apart to provide a first plurality of closed flow ducts for a flow of oil through the plate heat exchanger and a second plurality of open flow ducts for a flow of liquid coolant through the plate heat exchanger, the first and second pluralities of flow ducts being arranged in alternating sequence;

a first tube extending through the entire plate stack to provide a supply duct for the flow of oil, the first tube having a plurality of holes to hydraulically connect the first plurality of flow ducts to the supply duct; and

a second tube extending through the entire plate stack to provide a return duct for the flow of oil, the second tube having a plurality of holes to hydraulically connect the first plurality of flow ducts to the return duct, wherein at least some of the plurality of plates are metallurgically joined to the first tube and the second tube.

14. The plate heat exchanger of claim 13, wherein the pluralities of holes in the first and second tubes are arranged in intervals along a stacking direction of the plate stack, the metallurgical joints between said at least some of the plurality of plates and the first and second tubes being located between the intervals.

15. The plate heat exchanger of claim 14, wherein the first and second tubes each include a circumferential wall portion, directed in a longitudinal direction of the plate heat exchanger, that is without any of the holes.

16. The plate heat exchanger of claim 14, wherein the pluralities of holes are arranged so that a considerable quantity of oil received into the supply duct is initially forced to flow around the supply duct before flowing in a longitudinal direction of the plate heat exchanger and a considerable quantity of oil received from the closed flow ducts is initially forced to flow around the return duct before being received into the return duct.

17. The plate heat exchanger of claim 13, wherein each of the plates includes a first opening coaxially aligned with the first tube and a second opening coaxially aligned with the second tube, at least some of the plurality of plates being provided with a flange along a continuous edge of the first opening, at least some of the plurality of plates being provided with a flange along a continuous edge of the second opening, the metallurgical joints between the plates and the first and second tubes being provided at the flanges.

18. The plate heat exchanger of claim 17, wherein the plurality of plates comprises:

a plurality of first plates, each of which is provided with a flange along a continuous edge of at least one of the first and second opening, said flange being metallurgically joined to the corresponding one of the first and second tubes; and

a plurality of second plates interleaved with the first plates, each of the second plates being metallurgically joined to an adjacent one of the plurality of first plates at a first location adjacent to and radially outward of the first tube and at a second location adjacent to and radially outward of the second tube in order to hydraulically separate the first plurality of closed flow ducts from the second plurality of open flow ducts.

19. The plate heat exchanger of claim 18, wherein at least some of said metallurgical joints between the first plates and the second plates are located at said flanges.

20. The plate heat exchanger of claim 13, further comprising:

a first thick-walled flange arranged at a top side of the plate stack and joined to an uppermost plate of the plate stack, the inlet duct extending through the first thick-walled flange, an end of the first tube being metallurgically joined to the first thick-walled flange; and

a second thick-walled flange arranged at the top side of the plate stack and joined to the uppermost plate of the plate stack, the return duct extending through the second thick-walled flange, an end of the second tube being metallurgically joined to the second thick-walled flange.