U.S. patent application number 14/681283 was filed with the patent office on 2015-10-08 for brazed heat exchanger.
The applicant listed for this patent is Modine Manufacturing Company. Invention is credited to Roman Fleitling, Klaus Mohrlok.
Application Number | 20150285572 14/681283 |
Document ID | / |
Family ID | 54146149 |
Filed Date | 2015-10-08 |
United States Patent
Application |
20150285572 |
Kind Code |
A1 |
Fleitling; Roman ; et
al. |
October 8, 2015 |
BRAZED HEAT EXCHANGER
Abstract
A brazed heat exchanger having a stack of heat exchanger plates,
each with an inflow hole and an outflow hole, that are arranged
such that closed and open flow ducts for different media alternate
in a stack direction. In the open flow ducts are two endpieces with
a hole whose edge extends around the inflow hole or around the
outflow hole respectively. The endpieces are deformed metal sheets
with corrugations that form ducts, The metal sheets include flow
openings for the medium flowing through the open flow ducts. The
hole edges are deformed and have a height approximately
corresponding to a height of the open flow duct, and are arranged
close to a rim hole of the inflow hole or of the outflow hole.
Inventors: |
Fleitling; Roman;
(Reutlingen, DE) ; Mohrlok; Klaus; (Schlaitdorf,
DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Modine Manufacturing Company |
Racine |
WI |
US |
|
|
Family ID: |
54146149 |
Appl. No.: |
14/681283 |
Filed: |
April 8, 2015 |
Current U.S.
Class: |
165/167 |
Current CPC
Class: |
F28D 2021/0049 20130101;
F28F 3/025 20130101; F28F 3/042 20130101; F28F 2275/04 20130101;
F28D 9/0043 20130101; F28F 9/268 20130101; F28D 9/0006 20130101;
F28F 3/027 20130101; F28F 21/089 20130101 |
International
Class: |
F28F 9/26 20060101
F28F009/26; F28F 3/02 20060101 F28F003/02 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 8, 2014 |
DE |
10 2014 005149 |
Claims
1. A brazed heat exchanger configured to be received in a housing
and configured to transfer heat between a first medium and a second
medium, the brazed heat exchanger comprising: a plurality of heat
exchanger plates arranged to form a stack, each of the plurality of
heat exchanger plates having a thickness and including an inflow
hole and an outflow hole, the plurality of heat exchanger plates
arranged in the stack to define a plurality of closed flow ducts
between adjacent heat exchanger plates for the first medium and a
plurality of open flow ducts between adjacent heat exchanger plates
for the second medium, the closed and open flow ducts alternating
in a stack direction of the plurality of heat exchanger plates; and
first and second endpieces in each of the plurality of open flow
ducts, wherein the first and second endpieces each include a metal
sheet with corrugations that form ducts, each having a flow opening
for the second medium flowing through the open flow ducts, the
first and second endpieces each further include a hole having an
edge that is deformed such that the edge has a height approximately
corresponding to a height of the open flow ducts, wherein the edge
of each of the first endpieces extends around the inflow hole and
the edge of each of the first endpieces is close to a rim hole of
the inflow hole, wherein the edge of each of the second endpieces
extends around the outflow hole and the edge of each of the second
endpieces is close to a rim hole of the outflow hole.
2. The brazed heat exchanger of claim 1, wherein the edge of each
of the first endpieces is formed with a braze gap around the inflow
hole, and wherein the edge of each of the second endpieces is
formed with a braze gap around the outflow hole.
3. The brazed heat exchanger of claim 1, wherein the rim holes of
the inflow hole and of the outflow hole of two of the plurality of
heat exchanger plates forming one of the plurality of closed flow
ducts engage into one another and bear against one another in
opposite directions.
4. The brazed heat exchanger of claim 2, wherein the edge of each
of the first and second endpieces is approximately vertically
standing, wherein the braze gaps of the first and second endpieces
are arranged between the approximately vertically standing edge and
the rim hole.
5. The brazed heat exchanger of claim 1, wherein the ducts of the
first and second endpieces have at least two different duct
lengths.
6. The brazed heat exchanger of claim 1, wherein at least one of
the ducts of the first and second endpieces has a curvature.
7. The brazed heat exchanger of claim 6, wherein the curvature
corresponds approximately to a curvature of the edge and runs
approximately concentric thereto.
8. The brazed heat exchanger of claim 6, wherein at least one of
the ducts of the first and second endpieces are of arcuate form so
as to extend around a center, with a flow opening at the start of
the duct and a flow opening at the end of the duct.
9. The brazed heat exchanger of claim 1, wherein a longest of the
ducts of the first and the second endpieces extends close to the
edge and around a major part of a circumference thereof.
10. The brazed heat exchanger of claim 1, wherein the open and the
closed flow ducts are formed from pairs of the heat exchanger
plates, wherein the closed flow ducts are arranged within the plate
pairs and the open flow ducts are arranged between the plate
pairs.
11. The brazed heat exchanger of claim 1, wherein the closed flow
ducts include lamella.
12. The brazed heat exchanger of claim 1, wherein the open flow
ducts are formed outside regions occupied by the metal sheets with
studs formed into the heat exchanger plates.
13. The brazed heat exchanger of claim 12, wherein the studs are
formed with a height approximately half that of the open flow duct,
with opposite studs being supported and connected by brazing.
14. The brazed heat exchanger of claim 1, wherein between one side
of one of the first endpieces and one heat exchanger plate, there
is situated a braze foil or paste which approximately corresponds
to a circumference of said first endpiece.
15. The brazed heat exchanger of claim 14, wherein between the
other side of said one of the first endpieces and an other heat
exchanger plate, there is arranged another braze foil or paste
which extends approximately over the entire other heat exchanger
plate, including one of the second endpieces.
16. The brazed heat exchanger of claim 15, wherein the other braze
foil or paste is situated at least at locations at which brazing is
performed, wherein said braze foil or paste has voids at other
locations where no brazing is performed.
17. The brazed heat exchanger of claim 1, wherein the metal sheets
are configured so as to be able to admit flow from opposite
directions.
18. A brazed heat exchanger configured to be received in a housing
and configured to transfer heat between a first medium and a second
medium, the brazed heat exchanger comprising: a plurality of heat
exchanger plate pairs arranged into a stack, open flow ducts
arranged between adjacent ones of the heat exchanger plate pairs; a
vertical inflow duct extending through the stack at a first end of
the stack and a vertical outflow duct extending through the stack
at a second end of the stack, the vertical inflow and outflow ducts
being fluidly connected by a closed flow duct within each of the
heat exchanger plate pairs to allow for the first medium to flow
between the vertical inflow and outflow ducts; and a plurality of
metal sheets provided within the open flow ducts at both the first
end and the second end of the stack, each of the metal sheets being
joined to adjacent ones of the heat exchanger plate pairs to
provide structural support thereto, wherein each of the plurality
of metal sheets is provided with ducts to allow for flow of the
second medium around the vertical inflow and outflow ducts.
19. The heat exchanger of claim 18, wherein the metal sheets are
deformed to have corrugations corresponding in height to the open
flow ducts arranged between adjacent ones of the heat exchanger
plate pairs, the ducts provided within the metal sheets being
defined by said corrugations.
20. The heat exchanger of claim 18, wherein each of the ducts
provided within the metal sheets includes a flow opening at the
start of the duct and a flow opening at the end of the duct,
wherein at least some of said flow openings are in fluid
communication with the open flow ducts arranged between adjacent
ones of the heat exchanger plate pairs.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to German Patent
Application No. 10 2014 005149, filed Apr. 8, 2014, the entire
contents of which are hereby incorporated by reference herein.
BACKGROUND
[0002] The present invention relates to a brazed heat exchanger
which is arranged in a housing and which has a stack of heat
exchanger plates.
[0003] Alternating closed and open flow ducts, and the arrangement
of the stack in a housing, signify a specific generic type of heat
exchangers, which differ from known heat exchangers without a
housing and with exclusively closed flow ducts inter alia in that
the heat exchangers discussed here have only two openings in the
heat exchanger plates, whereas the other heat exchangers have at
least four openings. Said openings in the plates of both generic
types of heat exchangers provide inlet and outlet ducts extending
vertically through the stack.
[0004] Endpieces are metal parts which are inserted into the flow
ducts and which occupy only a small part of the flow ducts. The
endpieces occupy only two opposite ends of the flow ducts. In the
case of approximately rectangular heat exchanger plates, these are
generally the relatively short sides of the plates or of the flow
ducts formed by means of the plates.
[0005] A heat exchanger of the specific generic type is known from
EP 470 200 B1. Said heat exchanger is situated in a housing (not
shown in said document) with at least one inflow opening and one
outflow opening for the medium flowing through the open flow ducts
of the heat exchanger. In the known heat exchanger, the endpieces
are solid metal plates, the thickness of which corresponds to the
height of the flow ducts. The endpieces have been arranged in the
open and in the closed flow ducts. The endpieces firstly
considerably increase the weight of the heat exchanger, but
secondly lead to an extremely stable heat exchanger which can be
fastened in the housing in an advantageous manner using the solid
endpieces. However, owing to the endpieces, the size of the
heat-exchanging surface area is reduced.
[0006] Another heat exchanger of said generic type is known for
example from EP 1 083 398 A1. Said heat exchanger has lamellae
which are arranged both in the open flow ducts and in the closed
flow ducts and which increase the efficiency of the heat exchange.
In the case of said heat exchanger, a corrugated sheet-metal strip
of circular form has been placed into the closed flow ducts so as
to encircle said openings. Semicircular solid endpieces that have
hitherto been provided are thus replaced. A more lightweight heat
exchanger, which exhibits higher performance, is likewise
realized.
[0007] The heat exchangers are brazed in a brazing furnace and
subsequently inserted into the housing, in which they can perform
their function per se.
SUMMARY
[0008] One object of the invention consists in providing an
advantageous alternative which likewise realizes a relatively
lightweight brazed heat exchanger in a housing, with high heat
exchange performance, without the stability of the heat exchanger
being significantly reduced, wherein the quality of the brazed
connections should be ensured.
[0009] In one embodiment, the endpieces are deformed metal sheets
with corrugations which form ducts, which metal sheets are provided
with flow openings for the medium flowing through the open flow
ducts. The sheet-metal thickness of the deformed metal sheets
approximately corresponds to the sheet-metal thickness of the heat
exchanger plates. In one exemplary embodiment, said thickness is
approximately 0.2-0.5 mm. A deformed hole edge of the hole of the
deformed metal sheet has a height approximately corresponding to a
height of the open flow duct.
[0010] A braze gap of a size of approximately 0.2 mm is situated
between the approximately vertically standing hall edge and the
edge of the inflow hole or of the outflow hole respectively. Such
braze gaps impart a capillary action on the molten braze. The edge
of the inflow hole and of the outflow hole respectively has been
deformed. Said edge has rim holes. The rim holes each point into
the open flow ducts, in which the deformed metal sheets are
situated. The rim hole of one plate of one plate pair is connected
to a rim hole of the next plate of the next plate pair. The rim
holes have been plugged one inside the other.
[0011] It has been identified that such a design not only achieves
the desired performance improvements and weight reduction but can
also provide advantages in terms of manufacturing in the case of
brazed heat exchangers.
[0012] The brazing process is performed in a brazing furnace,
wherein a weight or a force acts on the heat exchanger during the
brazing process. For this purpose, the heat exchanger must firstly
be preassembled and prepared for the brazing process. It has been
found that, in particular, the special hole edge design of the
deformed metal sheet and the arrangement thereof close to the
inflow hole or to the outflow hole respectively generates stability
comparable to that obtained with solid endpieces. Furthermore, it
is possible to produce sealed and durable brazed connections even
though the surfaces to be brazed are considerably smaller than in
the prior art.
[0013] A housing, in one embodiment, is a structure which at least
substantially encompasses the brazed heat exchanger and which has
at least one inlet for the medium flowing through the open flow
ducts and with an outlet through which the medium passes after
flowing through the open flow ducts. A housing of said type may
accordingly likewise be regarded as a flow duct into which the
stack of heat exchanger plates, with endpieces in the open flow
ducts and with lamellae in the closed flow ducts, is inserted after
the brazing process.
[0014] Closed flow ducts, in one embodiment, are flow ducts which
are characterized by a sealed, closed connection extending in
encircling fashion around the edges of in each case two heat
exchanger plates and which have two holes in the heat exchanger
plates, wherein one hole constitutes an inflow hole, and the other
hole constitutes an outflow hole. The closed flow duct is situated
in each case between the two plates that can be regarded as the
above-mentioned plate pair.
[0015] Since the heat exchanger plates form a stack, inflow holes
which are in alignment in the stack give rise to a vertical inflow
duct extending through the stack, and the outflow holes in a
streamlined configuration give rise to a vertical outflow duct
extending through the stack.
[0016] To form the inflow duct, the inflow hole of one plate is
connected in each case to the inflow hole of an adjacent plate of
the next plate pair by virtue of an open flow duct arranged in each
case in between being bridged, so as to ensure the separation
between the media. The same applies with regard to the outflow
holes or with regard to the formation of the outflow ducts.
[0017] Since the corrugations provide a brazed connection to the in
each case two plates that delimit an open flow duct, the desired
stability is also attained, in particular around said inflow and
outflow ducts.
[0018] Other aspects of the invention will become apparent by
consideration of the detailed description and accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] FIG. 1 shows a cross section through an inlet or outlet duct
of a heat exchanger according to an embodiment of the invention,
without showing the housing;
[0020] FIG. 2 shows a detail of an endpiece from FIG. 1;
[0021] FIG. 3 shows an endpiece, two of which are arranged in each
open flow duct of the heat exchanger of FIG. 1;
[0022] FIG. 4 shows a perspective view of the heat exchanger of
FIG. 1 situated in a housing;
[0023] FIG. 5 shows the heat exchanger from FIG. 4, in which the
upper plates are shown in an exploded illustration;
[0024] FIG. 6 shows a longitudinal section through the heat
exchanger situated in the housing of FIG. 4;
[0025] FIG. 7 shows a detail of a lamella situated in the closed
flow ducts of a heat exchanger according to some embodiments;
[0026] FIG. 8 shows details of relevance with regard to the brazing
of the heat exchanger of FIG. 1;
[0027] FIG. 9 shows a further one of several possible alternative
designs of a hole edge of the endpiece, similarly to FIG. 2.
[0028] 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.
DETAILED DESCRIPTION
[0029] The brazed heat exchanger of the embodiment shown, which is
situated in a housing 40, is an oil cooler by means of which an
oil, such as transmission oil, engine oil or the like, is cooled or
adjusted to the appropriate temperature by means of cooling liquid.
The oil flows through the closed flow ducts 2, and the cooling
liquid flows through the housing 40 and the open flow ducts 3 of
the oil cooler.
[0030] Other embodiments (not shown) may be provided which relate
to charge-air cooling, exhaust-gas cooling or else to refrigerant
cooling or refrigerant condensation or refrigerant evaporation, to
name but a few further advantageous applications.
[0031] The brazed heat exchanger arranged in the housing 40 has a
stack of heat exchanger plates 1a, 1b which are equipped with in
each case one inflow hole 10 and one outflow hole 11. The housing
40 (FIGS. 4-6) can be closed by means of a cover (not shown) or the
like. The housing 40 may however also be a so-called cavity of an
engine or transmission housing, wherein the upper, open side points
into the interior thereof. The plates 1a, 1b are arranged such that
closed and open flow ducts 2, 3 for oil and for cooling liquid
alternate in a stack direction. In the open flow ducts 3 only,
there are arranged two endpieces 20 which each have a hole 21. The
edge 22 of the hole 21 of one endpiece 20 extends around the inflow
hole 10, and the edge of the hole 21 of the second endpiece 20
extends correspondingly around the outflow hole 11. This can be
seen most clearly from FIGS. 1 and 3 in conjunction with FIG. 4 or
5.
[0032] The endpieces 20 are deformed metal sheets with corrugations
24 that form ducts 23. The thickness of the metal sheets 20
corresponds approximately to the thickness of the heat exchanger
plates 1a, 1b. Here, "corresponds" is to be understood to mean that
the heat exchanger plates 1a, 1b may have for example a metal sheet
thickness in the range from 0.2-0.5 mm. The thickness of the
endpieces 20 could then for example even be 0.15 mm or 0.5-0.7 mm
in order to still lie in the range intended to be covered by
"corresponds". In this connection, it is also pointed out that the
duct height of the open flow ducts 2 may, in a practical exemplary
embodiment, be approximately 1.5-3 mm. The closed flow ducts 3 are
approximately 2-4 mm high (FIG. 1).
[0033] The ducts 23 of the endpieces 20 are provided with flow
openings 25 for the cooling liquid flowing through the open flow
ducts 3. The hole edge 22 is deformed and has a height h which
approximately corresponds to a height of the open flow duct 3.
Large tolerances should not be permitted with regard to said height
h. The hole edge 22 is arranged sealingly, in encircling fashion,
against a rim hole 12 of the inflow hole 10 or of the outflow hole
11 respectively. This is shown in FIGS. 2 and 3.
[0034] As is also shown in said figures, a braze gap 26 is situated
between the approximately vertically standing hole edge 22 and the
rim hole 12. The braze gap 26 may for example be 0.1-0.3 mm in
size. During the brazing process, the braze gap 26 will, owing to
its capillary action, fill with braze material and thus ensure
sealed and durable connections.
[0035] By contrast to FIG. 2, FIG. 9 shows that the deformed hole
edge 22 may also have an inwardly pointing bent flange 22a for
further reinforcement. Reference signs not shown in FIG. 9 may be
gathered from FIG. 2. In FIGS. 2 and 9, the hole edge 22 extends
upward from the heat exchanger plate lb, which is at the bottom in
the image, to the upper plate la. In further embodiments that are
not shown, the hole edge 22 extends from top to bottom.
[0036] With regard to the said rim holes 12 at the inflow hole 10
and at the outflow hole 11, it can be seen from FIGS. 1 and 2 that
said rim holes engage into one another and bear against one another
in opposite directions. As can be seen, the rim holes 12 connect
the closed flow ducts 2 to one another and, at the same time, each
bridge the open flow ducts 3 arranged in between.
[0037] Furthermore, it can be seen from FIG. 3 that the ducts 23 of
the endpieces 20 have different duct lengths. Some of the ducts 23
are provided with a curvature. In the exemplary embodiment shown,
the curvature corresponds approximately to a curvature of the hole
edge 22. Other, in particular shorter ducts 23 do not have a
curvature. The direction and form of the ducts 23 may be adapted on
a case-by-case basis.
[0038] Some of the ducts 23 are of arcuate form. They extend around
a center situated approximately in the middle of the hole 21. The
ducts 23 have a flow opening 25 at the start of the ducts 23 and
another flow opening 25 at the end of the ducts. In embodiments
that are not shown, the ducts 23 have been provided with more than
two flow openings 25, for example in the flanks of the undulations
24.
[0039] It is of note that the longest of the ducts 23 is situated
close to the hole edge 22 and extends around the major part of the
circumference thereof. In this way, in the edge region of the
holes--together with the deformed hole edge 22 described
above--adequate stability is provided, which is expedient in
particular during the course of the brazing process in order to
prevent the so-called collapse of the plates 1a, 1b under the
action of the brazing temperature.
[0040] The open and closed flow ducts 2, 3 are formed from pairs of
heat exchanger plates 1a, 1b. The closed flow ducts 2 are situated
within the plate pairs. The open flow ducts 3 are arranged between
the plate pairs.
[0041] The closed flow ducts 2 are completely filled with a lamella
27 (FIGS. 5-7). The corrugated lamellae 27 have offset incisions in
the corrugation flanks and have two openings which correspond to
the inflow hole 10 and to the outflow hole 11 respectively.
[0042] The open flow ducts 3 are provided, at least outside the
regions occupied by the endpieces 20, with studs 32 formed into the
heat exchanger plates 1a, 1b, or with similar turbulence
elements.
[0043] The studs 32 are formed with a height approximately half
that of the open flow duct 3, with opposite studs 32 being
supported and connected by brazing. In embodiments that are not
shown, the studs 32 have a height corresponding to the duct height,
such that said studs can be supported on the opposite planar plate
1a or 1b.
[0044] The solid heat exchanger of the exemplary embodiment is
composed of a suitable high-grade steel. In embodiments that are
not shown, an aluminium alloy or some other steel is used as
material. For the brazing of high-grade steel, use is often made of
braze foils or braze pastes, because the coating of high-grade
steel sheets with braze containing Cu or Ni is at present
associated with high costs.
[0045] It can be seen from FIG. 8 that, between one side of the
endpieces or of the deformed metal sheet 20 and one heat exchanger
plate 1a, there is situated a braze foil 33 which approximately
corresponds to the circumference of the metal sheet 20. It can also
be seen that, between the other side of the deformed metal sheet 20
and the other heat exchanger plate lb of the next pair, there is
arranged another braze foil 34 which extend approximately over the
entire heat exchanger plate 1b, including the second deformed metal
sheet 20. In embodiments that are not shown, the said braze paste
is used instead of the braze foil 33.
[0046] To save on expensive braze material, the inventors have
formed voids in the other braze foil 34 at the locations at which
no brazed connection is provided. The corresponding voids are
denoted by the reference sign 35.
[0047] The formation of the stack is facilitated by the hole 21 in
the endpieces and by the rim holes 12 that correspond therewith.
The fact that the form of the lamellae 27--with their two
openings--is adapted to the form of the closed flow ducts 2 (FIG.
5) is also conducive to easier stacking On the stack there are
often also situated connection flanges 14 which form an elongation
of the inlet and the outlet duct 10, 11. On the other end of said
ducts 10, 11 there are arranged closure disks 13. The stack of heat
exchanger plates 1a, 1b, endpieces 20, lamellae 27, connection
flanges 14 and closure pieces 13 is brazed in a brazing furnace.
After the stack is brazed, it is inserted into the housing 40.
[0048] As can be seen from the said FIG. 3, the deformed metal
sheets 20 have been configured such that they can admit flow from
opposite directions. In this case, the performance-increasing
advantages are at least approximately maintained. This can also be
explained on the basis of FIG. 4 or FIG. 5. The housing 40 has
multiple inlets and outlets 41-46. In a practical exemplary
embodiment, these will generally not be provided. In general--but
not always--there will be only a single inlet, for example 41, 42
or 43, and a single outlet 44, 45 or 46. It can be seen from FIG. 4
that the endpieces 20 can admit flow or discharge flow in opposite
directions indicated by means of the arrows, without their
advantageous effect being impaired. Inlets and outlets on the
housing 40 may also be arranged on the top and/or on the bottom,
that is to say not in the plate plane as shown in FIGS. 4 and 5,
but perpendicular thereto.
[0049] In each case two deformed metal sheets 20 arranged in an
open flow duct 3 are of identical form. In the exemplary
embodiment, their shape can be regarded as being approximately
D-shaped. Circular metal sheets 20 are likewise possible. In
general, the shape of said metal sheets is adapted to the plate
geometry. The deformed metal sheets 20 have a region in which flow
is admitted and a region in which flow is discharged. The metal
sheets 20 are arranged such that, in each open flow duct 3, in the
case of the metal sheet 20 arranged at the inlet side, the arcuate
region of the D shape of said metal sheet 20 can be regarded as the
region in which flow is admitted, and the approximately straight,
terminating region can be regarded as the region in which flow is
discharged. In the case of the metal sheet 20 arranged at the
outlet side, the conditions are the opposite, because in the case
of said metal sheet 20, the straight, terminating region
constitutes the region in which flow is admitted, and the arcuate
region constitutes, in this case, the region in which flow is
discharged. The ducts 23, with flow openings 25, formed in the
metal sheet 20 are now arranged such that approximately identical
conditions with regard to pressure losses prevail at both metal
sheets 20, even though these admit flow from opposite
directions.
[0050] Various features and advantages of the invention are set
forth in the following claims.
* * * * *