U.S. patent application number 11/993608 was filed with the patent office on 2010-05-13 for heating apparatus comprising a thermoelectric device.
This patent application is currently assigned to WEBASTO AG. Invention is credited to Jens Baade, Jorn Budde, Michael Stelter.
Application Number | 20100115968 11/993608 |
Document ID | / |
Family ID | 37068562 |
Filed Date | 2010-05-13 |
United States Patent
Application |
20100115968 |
Kind Code |
A1 |
Budde; Jorn ; et
al. |
May 13, 2010 |
HEATING APPARATUS COMPRISING A THERMOELECTRIC DEVICE
Abstract
The invention relates to a heating apparatus (10) comprising a
thermoelectric device with several thermoelement legs (20). A wall
(12) and a heat exchanger (26) which are in contact with the
thermoelement legs are configured in an electrically insulating
manner while the thermal contact is established via electrically
conductive layers (22) that interconnect the end zones of the
thermoelement legs (20) as desired.
Inventors: |
Budde; Jorn; (Potsdam,
DE) ; Baade; Jens; (Neubrandenburg, DE) ;
Stelter; Michael; (Chemnitz, DE) |
Correspondence
Address: |
FITCH EVEN TABIN & FLANNERY
120 SOUTH LASALLE STREET, SUITE 1600
CHICAGO
IL
60603-3406
US
|
Assignee: |
WEBASTO AG
Stockdorf
DE
|
Family ID: |
37068562 |
Appl. No.: |
11/993608 |
Filed: |
June 23, 2006 |
PCT Filed: |
June 23, 2006 |
PCT NO: |
PCT/DE2006/001079 |
371 Date: |
January 13, 2010 |
Current U.S.
Class: |
62/3.3 ;
62/3.7 |
Current CPC
Class: |
H01L 35/30 20130101;
H01L 35/00 20130101; B60H 1/2203 20130101; B60H 2001/2275
20130101 |
Class at
Publication: |
62/3.3 ;
62/3.7 |
International
Class: |
F25B 21/02 20060101
F25B021/02 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 23, 2005 |
DE |
10 2005 029 184.8 |
Aug 4, 2005 |
DE |
10 2005 036 768.2 |
Claims
1. A heating apparatus, comprising: a wall, the inside of which has
adjoining it a region for the routing of hot exhaust gases, a
housing which at least partially surrounds the wall, a medium to be
heated flowing through an interspace between the wall and the
housing, and a thermoelectric device which is arranged in the
interspace and has a plurality of thermoelement legs and which is
suitable for generating an electrical voltage on account of a
temperature difference between the exhaust gases and the medium to
be heated, wherein the wall is designed to be at least partially
electrically insulating, in that the thermoelement legs are
fastened with a first end region, by means of electrically
conductive layers), to a heat contact portion of the wall, in that
an at least partially electrically insulating heat exchanger is
provided, which is arranged opposite the heat contact portion of
the wall, in that the thermoelement legs are fastened with a second
end region, by means of electrically conductive layers, to the
electrically insulating heat exchanger, and in that the
electrically conductive layers connect the respective end regions
of the thermoelement legs at least partially to one another.
2. The heating apparatus of claim 1, wherein the wall is comprised
of an electrically insulating ceramic having high thermal
conductivity.
3. The heating apparatus of claim 1, wherein the electrically
insulating heat exchanger consists at least partially of a ceramic
having high thermal conductivity.
4. The heating apparatus of claim 2, wherein the ceramic for the
wall and/or for the electrically insulating heat exchanger has
aluminum nitride.
5. The heating apparatus of claim 1, wherein the electrically
conductive layers connect the thermoelement legs in series with one
another.
6. The heating apparatus claims 1, wherein the electrically
conductive layers connect the thermoelement legs in parallel with
one another.
7. The heating apparatus of claim 1, wherein the electrically
conductive layers connect groups of thermoelement legs in parallel
with one another and connect these groups in series with one
another.
8. The heating apparatus of claim 1, wherein the medium to be
heated is liquid, in particular water, and in that the heat contact
portion lies opposite a flame tube end.
9. The heating apparatus of claim 8, further comprising an
interspace, receiving the thermoelement legs between the wall and
the electrically insulating heat exchanger is sealed off by means
of a sealing device against the ingress of the liquid medium to be
heated, and in that the sealing device is suitable for compensating
thermally induced expansions.
10. The heating apparatus of claims 1, wherein the medium to be
heated is gaseous, in particular air, and in that the heat contact
portion lies in the region of an inlet for the gaseous medium to be
heated.
11. The heating apparatus of claim 10, further comprising an
interspace, receiving the thermoelement legs, between the wall and
the electrically insulating heat exchanger is protected by means of
a windbreak against the ingress of the gaseous medium to be
heated.
12. The heating apparatus of claim 1, wherein the thermoelectric
device is supported on the housing via an elastic connection.
13. The heating apparatus of claim 1, wherein the thermoelectric
device is supported on the housing via a heat exchanger and elastic
means.
14. The heating apparatus of claim 1, wherein the thermoelectric
device is supported on the housing via a heat exchanger and a plate
supporting the heat exchanger and equipped with elastic means.
15. The heating apparatus of claim 14, wherein the heat exchanger
and the plate equipped with elastic means are produced in one
piece.
16. The heating apparatus of claim 1, wherein the elastic
connection comprises cup springs.
17. The heating apparatus of claim 1, wherein a mechanical
connection between the wall and the heat exchanger has a
heat-insulating material.
18. The heating apparatus of claim 17, wherein the heat-insulating
material contains aluminum oxide and/or mullite.
19. The heating apparatus of claim 17, wherein the connection
between the first housing and the heat exchanger has a sealing
device which is suitable for sealing off the thermoelectric device
against the medium to be heated and for compensating thermally
induced expansions.
20. The heating apparatus of claim 19, wherein the wall and the
heat-insulating material and/or the sealing device are produced in
one piece.
21. The heating apparatus of claim 19, wherein the heat exchanger
and the heat-insulating material and/or the sealing device are
produced in one piece.
22. The heating apparatus claim 1, wherein a heat conduction means
is provided between the thermoelectric device and the wall and/or
between the thermoelectric device and the heat exchanger.
23. The heating apparatus of claim 22, wherein the heat conduction
means has a heat conduction paste.
24. The heating apparatus of claim 22, wherein the heat conduction
means has a heat conduction foil.
Description
[0001] The invention relates to a heating apparatus, with a wall,
the inside of which has adjoining it a region for the routing of
hot exhaust gases, a housing which at least partially surrounds the
wall, a medium to be heated flowing through an interspace between
the wall and the housing, and a thermoelectric device which is
arranged in the interspace and has a plurality of thermoelement
legs and which is suitable for generating an electrical voltage on
account of a temperature difference between the exhaust gases and
the medium to be heated.
[0002] A device of this type is known from DE 102 35 601 A1. The
ability to convert heat energy into electrical energy by means of a
device of this type makes it possible to generate the electrical
energy required for operating the heating apparatus, for example
for feeding a blower and a control, in the heating apparatus
itself. The electrical energy thus generated may likewise be made
available to other consumers in the motor vehicle, for example by
feeding into the vehicle electrical power supply. The arrangement
shown in DE 102 35 601 A1 has a thermoelectric device in the form
of a thermoelectric module which is arranged between a first wall
portion forming the "hot side" and a heat exchanger forming the
"cold side". When the heating apparatus is in operation, therefore,
a voltage can be picked up on the thermoelectric module, although
problems with regard to maintaining as high temperature differences
as possible, to thermal expansions and to a deficient thermal
conductivity between the thermoelectric module and the wall portion
or the heat exchanger may arise.
[0003] The object on which the invention is based is to overcome at
least partially these problems of the prior art and in this case,
in particular, to improve the thermal and mechanical conditions of
the arrangement and the configuration possibilities in the
set-up.
[0004] This object is achieved by means of the features of the
independent claim.
[0005] Advantageous embodiments of the invention are specified in
the dependent claims.
[0006] The invention builds on the generic heating apparatus in
that the wall is designed to be at least partially electrically
insulating, in that the thermoelement legs are supported with a
first end region, via electrically conductive layers, on a heat
contact portion of the wall, in that an at least partially
electrically insulating heat exchanger is provided, which is
arranged opposite the heat contact portion of the wall, in that the
thermoelement legs are supported with a second end region, via
electrically conductive layers, on the electrically insulating heat
exchanger, and in that the electrically conductive layers connect
the respective end regions of the thermoelement legs at least
partially to one another. In contrast to the prior art, an
arrangement is selected consisting of individual thermoelement legs
which are supported directly on the heat source or the heat sink
via layers, in particular printed metallic conductor tracks. In
order to make this possible, both the wall or at least that region
of the wall on which the thermoelement legs are arranged and the
heat exchanger are manufactured from electrically insulating, but
nevertheless thermally conductive materials. The electrical
conditions are determined by the arrangement of the electrically
conductive layers which selectively connect the end region of the
thermoelement legs to one another. This arrangement also affords a
suitable starting point, as described in more detail below, for
avoiding thermal shunts between the heat sink and heat source and
for providing a sufficient mechanical compensation capacity with
regard to thermal expansions.
[0007] It is preferable that the wall consists at least partially
of an electrically insulating ceramic having high thermal
conductivity.
[0008] It is likewise advantageous that the electrically insulating
heat exchanger consists at least partially of a ceramic having high
thermal conductivity.
[0009] For example, there may be provision for the ceramic for the
wall and/or for the electrically insulating heat exchanger to have
aluminum nitride. Ceramics of this type can fulfill the
requirements of high thermal conductivity, at the same time with
electrical insulation. Moreover, the printed conductor tracks can,
for example, be manufactured from aluminum, with the result that,
because of the high affinity between aluminum and aluminum nitride,
the connection between the thermoelement legs and the fastening
points is stabilized.
[0010] With regard to the electrical design of the arrangement,
there may be provision for the electrically conductive layers to
connect the thermoelement legs in series with one another.
[0011] It is likewise possible for the electrically conductive
layers to connect the thermoelement legs in parallel with one
another.
[0012] In a development of the embodiments mentioned, there may
likewise be provision for the electrically conductive layers to
connect groups of thermoelement legs in parallel with one another
and to connect these groups in series with one another. Depending
on the electrical requirements, the voltages desired for given
temperature conditions can thus be generated by means of the series
connection of the thermoelement legs, while sufficiently high
currents are made available by virtue of the parallel connection of
individual thermoelement legs or of the thermoelement legs combined
into groups.
[0013] According to a preferred embodiment, there is provision for
the medium to be heated to be liquid, in particular water, and for
the heat contact portion to lie opposite a flame tube end.
[0014] The invention can therefore be employed within the framework
of what is known as a water heating apparatus. In this case, it is
useful to provide the heat contact portion opposite to a flame tube
end, that is to say in the region of the burner bottom. The highest
temperatures occur at this point, so that the thermoelectric device
can operate with high efficiency.
[0015] Expediently, there is provision for an interspace, receiving
the thermoelement legs, between the wall and the electrically
insulating heat exchanger to be sealed off by means of a sealing
device against the ingress of the liquid medium to be heated, and
for the sealing device to be suitable for compensating thermally
induced expansions. The seal thus at the same time ensures that no
water comes into contact with the thermoelement legs and that
sufficient mechanical flexibility is made available for the
compensation of thermal expansions. The seal may have, in
particular, two components. One component is optimized in terms of
heat insulation, and the other component serves for providing the
useful elasticity which compensates thermal expansions. With a
suitable choice of material, these two components may be
implemented in the form of one unitary component, that is to say in
the form of a highly heat-insulating elastic seal. A compound seal
of this type may be designed, for example, as a
silicone/Al.sub.2O.sub.3 seal.
[0016] According to a further preferred embodiment, there is
provision for the medium to be heated to be gaseous, in particular
air, and for the heat contact portion to lie in the region of an
inlet for the gaseous medium to be heated. The invention can
therefore also be implemented within the framework of what are
known as air heating apparatuses. Since the air has the lowest
temperature in the region of the air inlet, but heats up rapidly
when it passes through the heating apparatus, it is expedient, in
order to achieve as high a thermoelectric efficiency as possible,
to arrange the thermoelectric device in the region of the air
inlet.
[0017] With regard to this arrangement of the thermoelectric device
in the air heating apparatus, there is expediently provision for an
interspace, receiving the thermoelement legs, between the wall and
the electrically insulating heat exchanger to be protected by means
of a windbreak against the ingress of the gaseous medium to be
heated. Since the functioning capacity of the device would be
adversely influenced by the contact of the thermoelement legs with
cold air, the simple measure of a windbreak constitutes a useful
development of the invention.
[0018] According to a further embodiment of the invention, there
must be provision for the thermoelectric device to be supported on
the housing via an elastic connection. This mounting of the
thermoelectric device makes available an improvement in the
compensation of thermally induced expansions. The thermoelectric
device is thus held in a stable way, but the elastic mounting makes
sufficient flexibility available.
[0019] For example, this may be implemented such that the
thermoelectric device is supported on the housing via a heat
exchanger and elastic means. The heat exchanger, around which the
liquid or gaseous heat transfer medium flows, can thus assume the
task of providing an elastic connection.
[0020] In a development of this idea, there may be provision for
the thermoelectric device to be supported on the housing via a heat
exchanger and a plate supporting the heat exchanger and equipped
with elastic means.
[0021] In this regard, it is possible for the heat exchanger and
the plate equipped with elastic means to be produced in one
piece.
[0022] In a simple and effective implementation of these
arrangements compensating thermal expansions, the elastic
connection comprises cup springs.
[0023] Furthermore, the invention is developed particularly
advantageously in that a mechanical connection between the wall and
the heat exchanger has a heat-insulating material. Undesirable
thermal compensation between the wall and the heat exchanger is
thereby avoided, so that the thermoelectric device can operate with
high efficiency.
[0024] For example, there may be provision for the heat-insulating
material to contain aluminum oxide and/or mullite.
[0025] Furthermore, it is expedient that the connection between the
first housing and the heat exchanger has a sealing device which is
suitable for sealing off the thermoelectric device against the
medium to be heated and for compensating thermally induced
expansions.
[0026] It is likewise possible for the wall and the heat-insulating
material and/or the sealing device to be produced in one piece.
[0027] In a comparable way, there may be provision for the heat
exchanger and the heat-insulating material and/or the sealing
device to be produced in one piece. The possibility of implementing
these one-piece versions depends, in turn, on the suitable choice
of material for the structural parts used.
[0028] For further improvement in the thermoelectric properties,
there is provision for a heat conduction means to be provided
between the thermoelectric device and the wall and/or between the
thermoelectric device and the heat exchanger. By virtue of such a
heat conduction means, the thermoelement legs are tied thermally to
the heat source and the heat sink in an improved way.
[0029] This may be implemented, for example, in that the heat
conduction means has a heat conduction paste.
[0030] Another possibility is for the heat conduction means to have
a heat conduction foil.
[0031] The invention, then, is explained by way of example by means
of a preferred embodiment, with reference to the accompanying
drawings in which:
[0032] FIG. 1 shows a partial sectional view of a heating apparatus
according to the invention;
[0033] FIG. 2 shows a detail of a heating apparatus according to
the invention;
[0034] FIG. 3 shows a partial sectional view of a further
embodiment of a heating apparatus according to the invention;
[0035] FIG. 4 shows a partial sectional view of a further
embodiment of a heating apparatus according to the invention.
[0036] In the following description of the drawings, the same
reference symbols designate identical or comparable components.
[0037] FIG. 1 shows a partial sectional view of a heating apparatus
according to the invention; FIG. 2 shows a detail of a heating
apparatus according to the invention. The heating apparatus 10,
that is to say, in particular, the heat exchanger arrangement
illustrated in FIG. 1, is of essentially axially symmetrical
construction, an inner wall 12 and an outer housing 16 being
provided. A flame tube 28 is arranged within the wall 12, exhaust
gases which emerge from the flame tube 28 heating the inside of the
wall 12. Between the wall 12 and the housing 16, an interspace 18
is provided, through which a heat transfer medium, for example
water, flows, so that the wall 12 functions as a heat exchanger for
the transmission of combustion heat to the heat transfer medium. A
plurality of thermoelement legs 20 are arranged on a bottom of the
wall 12, said bottom being provided as a heat contact portion 24.
The thermoelement legs 20 are connected to the heat contact portion
24 of the wall 12, in each case with an end region, via
electrically conductive layers 22. The thermoelement legs 20 are
connected via their other end regions to a heat exchanger 26 which
is arranged in the interspace 18 between the wall 12 and the
housing 16. The interspace 32 between the heat contact portion 24
and the heat exchanger 26 is surrounded by a seal 34, so that the
heat transfer medium cannot penetrate into the interspace 32. The
basic tie-up of the thermoelement legs 20 via the electrically
conductive layers is illustrated in the detail A in FIG. 2. The
electrically conductive layers 22 serve for electrically connecting
the thermoelement legs 20 selectively to one another. This is
possible, since both the wall 12 or at least the heat contact
portion 24 and, at least partially, the heat exchanger 26 are
manufactured from electrically insulating material which, however,
easily has sufficient thermal conductivity for operating the
thermoelectric device. Then, for example, two adjacent
thermoelement legs 20 are connected to one another, on their side
facing the wall 12, via the electrically conductive layers 22,
while the next thermoelement leg is tied up electrically on the
side facing the heat exchanger 26. The next thermoelement leg 20,
in turn, is tied up electrically on the side facing the wall 12,
and so on and so forth. If this electrical tie-up is selected, a
series connection of the thermoelement legs 20 is obtained.
Consequently, a thermoelectric voltage, which represents the sum of
thermoelectric voltages of the individual thermoelement legs 20,
can be picked up from the arrangement, using the electrical
connection 44. It is likewise possible to connect the thermoelement
legs electrically in parallel in groups and then to connect these
groups in series. Thus, with a low voltage, an increased current
output is possible. The electrically insulating heat exchanger 26
is connected to the housing 16 in the region of the electrical
connection 44. The connection is made via a seal 46.
[0038] FIG. 3 shows a partial sectional view of a further
embodiment of a heating apparatus according to the invention. The
embodiment of the heating apparatus 10 according to the invention,
as shown in FIG. 3, differs from the embodiment described with
regard to FIG. 1 in that the heat exchanger 26 is supported on the
housing 16 via a plate 40 equipped with cup springs 42. A stable
arrangement is thereby available, reliable thermal contact between
the themoelement legs and the wall 12 and also the heat exchanger
26 being available due to the suitable rating of the spring forces.
In terms of heat contact, there may also advantageously be
provision for a heat conduction means, for example a heat
conduction paste or a heat conduction foil, to be provided between
the thermoelement legs 20 and the wall 12 or the heat exchanger
26.
[0039] In the embodiments according to FIG. 1 and FIG. 3, the
thermoelectric device is arranged in the region in which the
highest exhaust gas temperatures are available. In the embodiment
according to FIG. 4, which relates to an air heating apparatus,
this is different, as is described with reference to the following
drawing.
[0040] FIG. 4 shows a partial sectional view of a further
embodiment of a heating apparatus according to the invention. In
addition to the components already described with regard to FIGS. 1
to 3, a fuel supply 46, combustion air ports 48, 50, an exhaust gas
outlet 52 and a hot air outlet 54 can be seen. In contrast to the
embodiments which were described with regard to FIGS. 1 to 3 and
which relate to a water heating apparatus, FIG. 4 illustrates an
air heating apparatus, the heat contact portion 24 of the wall 12
being arranged here in the region of the air inlet 36. Thus, the
heat exchanger 26 comes into contact with the cold air flowing in,
so that the various sides of the thermoelement legs 20 have as high
a temperature difference as possible. In the embodiment
illustrated, the thermoelements 20 are connected in series via the
electrically conductive layers 22. As regards the other connection
variants, reference is made to the statements relating to FIGS. 1
to 3. The connection variants should preferably be selected such
that the voltages occurring in the case of customary temperature
differences are such that, without additional direct voltage
conversion, the voltage emitted by the thermoelement leg can be
utilized either for components of the air heating apparatus or
other vehicle components, for example by feeding into the vehicle
power supply.
[0041] The features of the invention which are disclosed in the
above description, in the drawings and in the claims may be
essential both individually and in any desired combination for the
implementation of the invention.
LIST OF REFERENCE SYMBOLS
[0042] 10 Heating apparatus
[0043] 12 Wall
[0044] 14 Region
[0045] 16 Housing
[0046] 18 Interspace
[0047] 20 Thermoelement leg
[0048] 22 Electrically conductive layers
[0049] 24 Heat contact portion
[0050] 26 Heat exchanger
[0051] 28 Flame tube
[0052] 30 Flame tube end
[0053] 32 Interspace
[0054] 34 Sealing device
[0055] 36 Air inlet
[0056] 38 Windbreak
[0057] 40 Plate
[0058] 42 Cup spring
[0059] 44 Electrical connection
[0060] 46 Seal
[0061] 48 Combustion air port
[0062] 50 Combustion air port
[0063] 52 Exhaust gas outlet
[0064] 54 Hot air outlet
* * * * *