U.S. patent application number 13/458486 was filed with the patent office on 2012-11-29 for exhaust system with heat accumulator.
This patent application is currently assigned to Benteler Automobiltechnik GmbH. Invention is credited to Thorsten Andres, Tobias Dupmeier, Benjamin Reul.
Application Number | 20120297753 13/458486 |
Document ID | / |
Family ID | 47140410 |
Filed Date | 2012-11-29 |
United States Patent
Application |
20120297753 |
Kind Code |
A1 |
Andres; Thorsten ; et
al. |
November 29, 2012 |
EXHAUST SYSTEM WITH HEAT ACCUMULATOR
Abstract
An exhaust system for a combustion engine includes an exhaust
pipe, and a heat accumulator housing in surrounding relationship to
the exhaust pipe. Arranged in the heat accumulator housing are heat
pipes to provide a heat transport of heat energy contained in
exhaust gas. Heat energy thus withdrawn from the exhaust gas can be
carried off via the heat pipes in the heat accumulator housing.
Inventors: |
Andres; Thorsten;
(Paderborn, DE) ; Dupmeier; Tobias; (Paderborn,
DE) ; Reul; Benjamin; (Paderborn, DE) |
Assignee: |
Benteler Automobiltechnik
GmbH
Paderborn
DE
|
Family ID: |
47140410 |
Appl. No.: |
13/458486 |
Filed: |
April 27, 2012 |
Current U.S.
Class: |
60/320 |
Current CPC
Class: |
Y02E 60/14 20130101;
F28D 2020/0013 20130101; F01N 2470/24 20130101; Y02T 10/16
20130101; F28D 20/003 20130101; Y02T 10/12 20130101; F01N 5/02
20130101; F28D 7/106 20130101; F28D 15/02 20130101; Y02E 60/142
20130101 |
Class at
Publication: |
60/320 |
International
Class: |
F01N 5/02 20060101
F01N005/02; F01N 13/08 20100101 F01N013/08 |
Foreign Application Data
Date |
Code |
Application Number |
May 25, 2011 |
DE |
10 2011 103 109.3 |
Claims
1. An exhaust system for a combustion engine, said exhaust system
comprising: an exhaust pipe; a heat accumulator housing in
surrounding relationship to the exhaust pipe; and heat pipes
arranged in the heat accumulator housing to provide a heat
transport of heat energy contained in exhaust gas.
2. The exhaust system of claim 1, wherein the exhaust pipe is
completely encircled by the heat accumulator housing.
3. The exhaust system of claim 1, wherein the heat accumulator
housing is made of a zeolite.
4. The exhaust system of claim 1, wherein the heat accumulator
housing contains a heat storage medium.
5. The exhaust system of claim 1, wherein the heat storage medium
is made of a material that includes zeolite.
6. The exhaust system of claim 3, wherein the heat pipes are
arranged in the zeolite.
7. The exhaust system of claim 3, wherein the heat pipes are
completely enclosed by the zeolite.
8. The exhaust system of claim 1, wherein the heat pipes are
arranged in parallel relationship to an exhaust-gas flow
direction.
9. The exhaust system of claim 1, wherein several of the heat pipes
extend in parallel relationship within the heat accumulator housing
and are united in an end zone of the heat accumulator housing.
10. The exhaust system of claim 1, wherein the heat pipes have an
I-shaped configuration.
11. The exhaust system of claim 1, wherein the heat pipes are
configured to form a closed circuit for circulation of a
medium.
12. The exhaust system of claim 1, wherein the heat pipes are
integrated in a open-loop control or closed-loop control.
13. The exhaust system of claim 1, further comprising a thermal
insulation formed on an outer surface area of the heat accumulator
housing.
14. The exhaust system of claim 12, wherein the thermal insulation
is a metal coating.
15. The exhaust system of claim 1, further comprising a valve
arranged on the heat accumulator housing for controlling a
thermodynamic state in the heat accumulator housing.
16. The exhaust system of claim 15, wherein the valve is configured
as a pressure relief valve.
17. The exhaust system of claim 15, wherein the valve is integrated
in an open-loop control or closed-loop control.
Description
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] This application claims the priority of German Patent
Application, Serial No. 10 2011 103 109.3, filed May 25, 2011,
pursuant to 35 U.S.C. 119(a)-(d), the content of which is
incorporated herein by reference in its entirety as if fully set
forth herein.
BACKGROUND OF THE INVENTION
[0002] The present invention relates to an exhaust system for a
combustion engine.
[0003] The following discussion of related art is provided to
assist the reader in understanding the advantages of the invention,
and is not to be construed as an admission that this related art is
prior art to this invention.
[0004] Combustion engines, e.g. Otto engines or Diesel engines,
consume fuels for operation. As oil reserves are limited, it is
desired to maximize performance of a combustion engine and thus
exploitation of energy contained in the fuel. Due to the Carnot
process, the efficiency of a combustion engine for converting
energy contained in the fuel into mechanical energy is however
limited to 40%. In other words, 2/3 of chemical energy bound in
fuel is not available for the actual purpose of the combustion
engine, i.e. conversion of chemical energy into mechanical energy,
but is lost as loss energy. In order to be able to still exploit
this energy, especially in the automobile industry, there are many
approaches to, for example, recover heat energy or energy bound in
the exhaust and to supply it for an appropriate purpose. For
example, the heat energy can be used for heating the passenger
compartment. Other approaches involve the use of thermoelectric
generators to convert heat energy, contained in the exhaust, into
electric energy which, in turn, can be utilized for operation of a
motor vehicle.
[0005] In order to operate a combustion engine in an optimum
efficiency range, optimal operating conditions have to be
established. The combustion engine which predominantly is made from
metallic material is designed in a way as to run efficiently enough
at operating temperature. In other words, the different thermal
expansions of engine block, pistons, piston rings, cylinder head,
valves and further components are suited to one another in such a
way as to realize optimal efficiency at an average operating
temperature of the core components at about 90.degree. to
100.degree. C., and at this operating temperature the engine
performance is minimized and the charge cycle is optimized. Also
automotive fluids of a combustion engine, e.g. engine oil, or in
downline transmissions, the mechanical components as well as
transmission oils are optimized for use at the respective operating
temperature.
[0006] In particular when cold-start phases are involved which take
place even at a starting temperature of 20.degree. C., but also at
starting temperatures of 0.degree. C. or minus degrees, it is
therefore necessary to quickly heat the individual components to
operating temperature. Various approaches have been proposed
heretofore to recover heat energy of the exhaust gas by withdrawing
heat contained in the exhaust and feeding it to the desired site.
This requires, however, the use of heat exchangers in the region of
the exhaust tract, causing a rise in the exhaust-gas back pressure
so that the overall efficiency of the combustion engine is
adversely affected.
[0007] The tendency to increasingly minimize exhaust emission and
thus accompanying exhaust after-treatment components, e.g. particle
filter or catalytic converter, runs counter however to the removal
of heat from the exhaust gas during the cold-start phase because
the exhaust after-treatment systems require also heat energy to
ensure their full effect. Moreover, oftentimes a heat transfer
medium, especially water, is used that in turn limits however
efficiency and thus results in an inadequate solution.
[0008] It would be desirable and advantageous to provide an
improved exhaust system to obviate prior art shortcomings and to
allow a targeted heat transport without removing from the exhaust
gas excessive amount of heat energy in certain operating
situations.
SUMMARY OF THE INVENTION
[0009] According to one aspect of the present invention, an exhaust
system for a combustion engine includes an exhaust pipe, a heat
accumulator housing in surrounding relationship to the exhaust
pipe, and heat pipes arranged in the heat accumulator housing to
provide a heat transport of heat energy contained in exhaust
gas.
[0010] The present invention resolves prior art problems by
arranging a heat accumulator about part of the exhaust system, e.g.
about at least a region of an exhaust-carrying pipe of the exhaust
tract. The heat accumulator can be designed in the form of a heat
accumulator housing to completely surround or envelope the exhaust
pipe at least in a region thereof in flow direction of the exhaust
gas. Heat pipes can be integrated in the heat accumulator to
establish a connection to a heat sink, advantageously to a
component to which heat is intended to be supplied.
[0011] In particular during cold-start performance, heat from the
heat accumulator is used to heat connected components. In other
words, no energy is removed from the exhaust gas during the
cold-start phase so that the exhaust system according to the
present invention can be arranged upstream of an exhaust gas
after-treatment unit as well as downstream of an exhaust gas
after-treatment unit. The performance of the exhaust gas
after-treatment unit is not, or only insignificantly, impacted by
an exhaust system according to the present invention.
[0012] By arranging the heat accumulator about the exhaust pipe in
accordance with the present invention, there is no need to
integrate any elements in the exhaust gas tract, i.e. inside the
exhaust pipe. Thus, there is no increase in the exhaust-gas back
pressure. When the overall system of the combustion engine has
reached its optimum operating temperature, heat energy contained in
the exhaust gas can be used to charge the heat accumulator in the
absence of any adverse effect on the exhaust gas after-treatment
unit or other elements disposed in the exhaust tract.
[0013] According to another advantageous feature of the present
invention, the exhaust pipe may be completely surrounded by the
heat accumulator housing. The heat accumulator housing may be
configured in the form of a cladding tube, sized to completely
envelope the exhaust pipe at least in a region thereof.
[0014] According to another advantageous feature of the present
invention, the heat accumulator housing, in particular the heat
accumulator located therein, may be made from a zeolite. Dry
zeolite removes water vapor from ambient air as a result of its
hygroscopic character. The attachment of water molecules to the
surface of the zeolite causes the molecule to transform to an
energetically lower state. Water vapor thus gives off energy in the
form of heat to the zeolite, causing the zeolite in turn to
intensely heat up. This heat is then carried away by heat pipes
arranged in the heat accumulator housing. The supply of heat energy
from the exhaust onto the zeolite, in turn, desorbs water molecules
above a certain temperature and the zeolite is returned to its dry
initial state.
[0015] According to another advantageous feature of the present
invention, a heat storage medium can be provided in the heat
accumulator housing, with the heat storage medium being made of a
material that includes zeolite.
[0016] Through selection of a zeolite material and dimensioning of
the heat accumulator housing, the exhaust system according to the
present invention can be best suited to the cold-start performance
of the combustion engine for which the exhaust system is intended
for use. In addition, active or passive open-loop and closed-loop
control of the exhaust system is conceivable by which the exhaust
system can be further modified to the respective operating state to
be adjusted.
[0017] According to another advantageous feature of the present
invention, the heat pipes can be arranged in the zeolite.
Advantageously, the heat pipes can be completely surrounded by the
zeolite. In other words, the heat pipes are fully enclosed in the
heat accumulator housing. The heat pipes emerge from the heat
accumulator housing only in the connection zone, advantageously an
end region of the heat pipes, in order to be able to carry heat out
of the heat accumulator housing.
[0018] According to another advantageous feature of the present
invention, the heat pipes can be arranged in parallel relationship
to an exhaust-gas flow direction. It thus becomes possible to use
especially short distances to conduct heat energy removed from the
exhaust into the heat pipes and from there to carry it off via
fluid located in the heat pipes. Thus, heat energy can be removed
from the exhaust over a length of 50, 100 or also 200 mm and
transferred by heat conduction through the heat accumulator housing
into the heat pipe and carried off from there.
[0019] According to another advantageous feature of the present
invention, several of the heat pipes can be arranged within the
heat accumulator housing. For example, at least five, or more than
seven or even more than ten heat pipes can be arranged in the cross
section of the exhaust pipe radially circumferentially.
[0020] According to another advantageous feature of the present
invention, several of the heat pipes can extend in parallel
relationship within the heat accumulator housing and can be united
in an end zone of the heat accumulator housing. As a result,
several heat pipes which are small in diameter can be used to
prevent the heat accumulator housing from being overdimensioned.
The use of several small heat pipes in cross section enables enough
heat quantity to be carried off from the heat accumulator and
supplied to a respective heat sink in the region of the outlet of
the heat accumulator housing via at least a central heat conduction
in the form of a heat pipe. Overall, this leads to a particularly
compact concept of the exhaust system according to the present
invention.
[0021] According to another advantageous feature of the present
invention, the heat pipes can have an I-shaped configuration.
Advantageously, the heat pipes are configured to form a closed
circuit for circulation of a medium. The schematic cross sectional
representation then forms a circulation circuit. Respective
selection of the respective application is then implemented by
considering the field of use to be expected and the heat quantity
to be transferred.
[0022] According to another advantageous feature of the present
invention, the heat pipes can be integrated in a closed-loop
control or open-loop control. The heat transport can hereby be
controlled and/or regulated by the heat pipe itself. For example,
valves may be arranged in the heat pipes to regulate and/or control
the heat transport within the heat pipe. In this way, the
respective heat transport can be manipulated actively or through
intervention of passively actuated valves. In case of cold-start
performance for example, the heat pipes cause a high heat
dissipation, whereas heat dissipation is minimized via the heat
pipes, when the operating temperature has been reached so that the
heat accumulator can be charged in an optimum manner.
[0023] According to another advantageous feature of the present
invention, a thermal insulation can be formed on an outer surface
area of the heat accumulator housing. Advantageously, the thermal
insulation is a metal coating. As a result of thermal insulation on
the outer side of the heat accumulator housing, heat dissipation to
the ambient air is minimized. This ensures that the heat
accumulator is able to optimally charge in the operating behavior
and the stored heat quantity can be maintained over a longest
possible time period without being wasted through dissipation to
the ambient air. The thermal insulation may also be implemented in
the form of a thermal insulating material, air gap insulation
and/or in the form of a metallic film coating. In particular, it is
possible to provide a reflection of heat energy in the heat
accumulator by the surface of the metallic coating back into the
heat accumulator. This, too, minimizes dissipation of the heat
quantity to the ambient air.
[0024] According to another advantageous feature of the present
invention, a valve can be arranged on the heat accumulator housing
for controlling a thermodynamic state in the heat accumulator
housing. Advantageously, the thermodynamic state of a zeolite can
be regulated and/or controlled via a controllable and regulatable
valve.
[0025] To enrich a zeolite with water molecules, the valve may, for
example, be actively opened. The valve or an additional valve may
be configured as a pressure relief valve for drying the
zeolite.
BRIEF DESCRIPTION OF THE DRAWING
[0026] Other features and advantages of the present invention will
be more readily apparent upon reading the following description of
currently preferred exemplified embodiments of the invention with
reference to the accompanying drawing, in which:
[0027] FIG. 1 is a cross sectional representation of an exhaust
system according to the present invention; and
[0028] FIG. 2 is a side view of an exhaust system according to the
present invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0029] Throughout all the figures, same or corresponding elements
may generally be indicated by same reference numerals. These
depicted embodiments are to be understood as illustrative of the
invention and not as limiting in any way. It should also be
understood that the figures are not necessarily to scale and that
the embodiments are sometimes illustrated by graphic symbols,
phantom lines, diagrammatic representations and fragmentary views.
In certain instances, details which are not necessary for an
understanding of the present invention or which render other
details difficult to perceive may have been omitted.
[0030] Turning now to the drawing, and in particular to FIG. 1,
there is shown an exhaust system according to the present
invention, generally designated by reference numeral 1. The exhaust
system 1 includes an internal exhaust pipe 2 and a heat accumulator
housing 3 in surrounding relationship to the exhaust pipe 2.
Exhaust gas A flows in the exhaust pipe 2 and carries off heat
energy contained in the exhaust pipe 2 by way of heat transfer W
into the heat storage medium 4 of the heat accumulator housing 3.
Currently preferred is the use of zeolite as heat storage medium.
Heat pipes 5 are arranged in the heat accumulator housing 3 to
absorb heat stored in the heat storage medium 4 and to transport it
away. Advantageously, the heat accumulator housing 3 is provided
with an insulating layer 6 upon an outer surface area 6.
[0031] FIG. 2 shows a greatly simplified side view of the exhaust
system 1. The heat accumulator housing 3 has integrated therein
three heat pipes 5 of I-shaped configuration. The heat pipes 5 are
arranged in parallel relation to the exhaust-gas flow direction S
in the heat accumulator housing 3. The heat pipes 5 are united at
an end zone 8 of the heat accumulator housing 3 to form a central
heat pipe 9 by which heat energy carried away by the heat pipes 5
from the not shown heat accumulator to an unillustrated heat
consumer. The heat accumulator housing 3 is further provided with a
valve 10 for regulating and controlling the thermodynamic state of
the heat storage medium 4. In this way, heat quantity to be carried
off via the heat pipes can be regulated and controlled.
[0032] While the invention has been illustrated and described in
connection with currently preferred embodiments shown and described
in detail, it is not intended to be limited to the details shown
since various modifications and structural changes may be made
without departing in any way from the spirit and scope of the
present invention. The embodiments were chosen and described in
order to explain the principles of the invention and practical
application to thereby enable a person skilled in the art to best
utilize the invention and various embodiments with various
modifications as are suited to the particular use contemplated.
[0033] What is claimed as new and desired to be protected by
Letters Patent is set forth in the appended claims and includes
equivalents of the elements recited therein:
* * * * *