U.S. patent application number 10/589333 was filed with the patent office on 2007-12-06 for brayton cycle device and exhaust heat energy recovery device for internal combustion engine.
Invention is credited to Shinichi Mitani, Masahiro Ogawa, Aiko Sugiura.
Application Number | 20070277522 10/589333 |
Document ID | / |
Family ID | 34879366 |
Filed Date | 2007-12-06 |
United States Patent
Application |
20070277522 |
Kind Code |
A1 |
Ogawa; Masahiro ; et
al. |
December 6, 2007 |
Brayton Cycle Device And Exhaust Heat Energy Recovery Device For
Internal Combustion Engine
Abstract
An exhaust heat energy recovery apparatus for an internal
combustion engine that efficiently recovers exhaust heat energy
without increasing engine exhaust back pressure, and a Brayton
cycle apparatus applicable to the exhaust heat energy recovery
apparatus. A Brayton cycle apparatus 1 using a scroll compressor 4
and a scroll expander 6 has a simplified and downsized structure. A
working fluid is compressed inside a scroll compressor 4 and
expanded inside a scroll expander 6 in spaces partitioned and
sealed by combinations of fixed scrolls and orbital scrolls. The
conversion efficiency from heat energy to kinetic energy is high.
Heat is transferred from the exhaust to the working fluid through a
pipe wall of a flow passage 30a and an expander case 12 of the
scroll expander 6. This further downsizes the Brayton cycle
apparatus 1. The back pressure of the energy source including the
exhaust is unaffected.
Inventors: |
Ogawa; Masahiro;
(Toyoake-shi, JP) ; Mitani; Shinichi; (Susono-shi,
JP) ; Sugiura; Aiko; (Toyota-shi, JP) |
Correspondence
Address: |
KENYON & KENYON LLP
1500 K STREET N.W.
SUITE 700
WASHINGTON
DC
20005
US
|
Family ID: |
34879366 |
Appl. No.: |
10/589333 |
Filed: |
January 25, 2005 |
PCT Filed: |
January 25, 2005 |
PCT NO: |
PCT/JP05/01299 |
371 Date: |
July 25, 2007 |
Current U.S.
Class: |
60/597 ;
418/55.1 |
Current CPC
Class: |
F01C 1/0223 20130101;
F01C 11/008 20130101; F04C 18/0207 20130101; F01C 11/004
20130101 |
Class at
Publication: |
060/597 ;
418/055.1 |
International
Class: |
F01C 13/04 20060101
F01C013/04; F01C 1/02 20060101 F01C001/02 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 20, 2004 |
JP |
2004-044967 |
Claims
1. A Brayton cycle apparatus, comprising: a scroll compressor for
compressing a working fluid; a scroll expander for operating in
cooperation with an orbiting action of the scroll compressor,
wherein the working fluid compressed by the scroll compressor is
fed to the scroll expander; and a heating device for heating the
compressed working fluid fed from the scroll compressor to the
scroll expander; wherein the scroll compressor includes a
compressor case, a fixed compression scroll formed in the
compressor case, and an orbital compression scroll combined with
the fixed compression scroll to come in contact with the compressor
case in a slidable manner or to face the compressor case with a
narrow gap therebetween; and the scroll expander includes an
expander case, a fixed expansion scroll formed in the expander
case, and an orbital expansion scroll combined with the fixed
expansion scroll to come in contact with the expander case in a
slidable manner or to face the expander case with a narrow gap
therebetween, the Brayton cycle apparatus further being
characterized by: an orbital partitioning wall for generating an
orbiting action, wherein the orbital compression scroll and the
orbital expansion scroll are arranged on the orbital partitioning
wall in a manner that the orbital compression scroll and the
orbital expansion scroll are located at opposite sides of the
orbital partition; wherein the scroll compressor releases heat
transferred from the scroll expander to the orbital partitioning
wall in the atmosphere through the compressor case.
2. (canceled)
3. (canceled)
4. The Brayton cycle apparatus according to claim 1, wherein the
expander case includes a heat absorption chamber into which the
working liquid introduced into the scroll expander prior to
expansion is introduced, the heat absorption chamber being
partitioned by a wall for heating the working liquid when the
working liquid is expanding.
5. The Brayton cycle apparatus according to claim 1, wherein the
scroll compressor uses atmospheric gas as the working fluid,
compresses the atmospheric gas, and releases the expanded working
fluid into the atmosphere.
6. The Brayton cycle apparatus according to claim 1, wherein the
heating device is a heat exchanger for transferring external heat
to the working fluid through heat exchange.
7. The Brayton cycle apparatus according to claim 1, wherein a wall
surface of the expander is kept warm.
8. A Brayton cycle apparatus comprising: a positive-displacement
compressor for compressing a working fluid; a scroll expander for
generating an orbiting action in cooperation with a compression
action of the positive-displacement compressor, wherein the working
fluid compressed by the positive-displacement compressor is fed to
the scroll expander; and a heating device for heating the
compressed working fluid fed from the positive-displacement
compressor to the scroll expander; wherein a wall surface of the
expander is kept warm.
9. (canceled)
10. An exhaust heat energy recovery apparatus for an internal
combustion engine for recovering exhaust heat energy of the
internal combustion engine as kinetic energy, wherein the exhaust
heat energy recovery apparatus incorporates comprises a Brayton
cycle apparatus including: a compressor for compressing a working
fluid; and an expander to which the working fluid compressed by the
compressor is fed, wherein the compressed working fluid fed from
the compressor to the expander is heated by heat transferred from a
flow passage wall of an exhaust flow passage of the internal
combustion engine; wherein the compressor is a scroll compressor
including a compressor case, a fixed compression scroll formed in
the compressor case, and an orbital compression scroll combined
with the fixed compression scroll to come in contact with the
compressor case in a slidable manner or to face the compressor case
with a narrow gap therebetween; the expander is a scroll expander
including an expander case, a fixed expansion scroll formed in the
expander case, and an orbital expansion scroll combined with the
fixed expansion scroll to come in contact with the expander case in
a slidable manner or to face the expander case with a narrow space
therebetween, the Brayton cycle apparatus further being
characterized by: a heating device, for heating the compressed
working fluid fed from the scroll compressor to the scroll expander
with heat from the flow passage wall, and an orbital partitioning
wall for generating an orbiting action, wherein the orbital
compression scroll and the orbital expansion scroll are arranged on
the orbital partitioning wall in a manner that the orbital
compression scroll and the orbital expansion scroll are located at
opposite sides of the orbital partition; and wherein the orbital
partitioning wall and the compressor case are made of a high
heat-conductive material, and the expander case is made of a
heat-resistant material.
11. (canceled)
12. (canceled)
13. (canceled)
14. The exhaust heat energy recovery apparatus according to claim
10, wherein an aluminum alloy is used as the high heat-conductive
material, and an iron alloy is used as the heat-resistant
material.
15. The exhaust heat energy recovery apparatus according to claim
10, wherein a wall surface of the expander is kept warm.
16. (canceled)
17. (canceled)
18. (canceled)
19. A Brayton cycle apparatus being characterized by comprising: an
orbital partitioning wall having a first surface on which an
orbital compression scroll is formed and a second surface on which
an orbital expansion scroll is formed; a scroll compressor
including the orbital compression scroll and a fixed compression
scroll combined with the orbital compression scroll; a scroll
expander including the orbital expansion scroll and a fixed
expansion scroll combined with the orbital expansion scroll; a
compressed working fluid passage for supplying a compressed working
fluid from the scroll compressor to the scroll expander; and a heat
source for heating the working fluid in the scroll expander through
heat transfer; wherein the scroll compressor has a compressor case
arranged on the first surface, the scroll expander has an expander
case arranged on the second surface, the compressed working fluid
passage has a through-hole formed in the orbital partition, and the
through-hole communicates the interior of the compressor case with
the interior of the expander case.
20. (canceled)
21. The Brayton cycle apparatus according to claim 19, wherein: the
scroll expander has a case fixed to the fixed expansion scroll; and
the heat source comes in contact with the case thereby heating the
working fluid in the scroll expander through the case or the fixed
expansion scroll.
22. (canceled)
23. (canceled)
24. The Brayton cycle apparatus according to claim 2, wherein the
scroll compressor uses atmospheric gas as the working fluid,
compresses the atmospheric gas, and releases the expanded working
fluid into the atmosphere.
25. The Brayton cycle apparatus according to claim 3, wherein the
scroll compressor uses atmospheric gas as the working fluid,
compresses the atmospheric gas, and releases the expanded working
fluid into the atmosphere.
26. The Brayton cycle apparatus according to claim 4, wherein the
scroll compressor uses atmospheric gas as the working fluid,
compresses the atmospheric gas, and releases the expanded working
fluid into the atmosphere.
27. The Brayton cycle apparatus according to claim 5, wherein the
scroll compressor uses atmospheric gas as the working fluid,
compresses the atmospheric gas, and releases the expanded working
fluid into the atmosphere.
28. The Brayton cycle apparatus according to claim 2, wherein the
heating device is a heat exchanger for transferring external heat
to the working fluid through heat exchange.
29. The Brayton cycle apparatus according to claim 3, wherein the
heating device is a heat exchanger for transferring external heat
to the working fluid through heat exchange.
30. The Brayton cycle apparatus according to claim 4, wherein the
heating device is a heat exchanger for transferring external heat
to the working fluid through heat exchange.
31. The Brayton cycle apparatus according to claim 5, wherein the
heating device is a heat exchanger for transferring external heat
to the working fluid through heat exchange.
32. The Brayton cycle apparatus according to claim 24, wherein the
heating device is a heat exchanger for transferring external heat
to the working fluid through heat exchange.
Description
INCORPORATION BY REFERENCE
[0001] This is a 371 national phase application of
PCT/JP2005/001299 filed 25 Jan. 2005, claiming priority to Japanese
Patent Application No. 2004-044967 filed 20 Feb. 2004, the contents
of which are incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The present invention relates to an apparatus realizing a
Brayton cycle and an apparatus for recovering exhaust heat energy
of an internal combustion engine using a Brayton cycle.
BACKGROUND OF THE INVENTION
[0003] To improve the fuel efficiency of an internal combustion
engine, an apparatus for recovering exhaust energy that is
discharged from the engine after fuel is burned has been used. For
example, a Rankine cycle apparatus is mounted on a vehicle together
with an internal combustion engine. A vaporizer arranged in the
Rankine cycle apparatus generates high-temperature high-pressure
vapor by heating water, which is contained in the apparatus, using
exhaust heat energy. An expander generates power using the vapor
(refer for example to Japanese Laid-Open Patent Publication No.
2003-120281).
[0004] As other techniques for recovering exhaust energy, combining
an engine that uses heat, such as a Stirling engine, with an
internal combustion engine (refer for example to Japanese Laid-Open
Patent Publication No. 2001-99003) or directly drawing exhaust into
a scroll expander (refer for example to Japanese Laid-Open Patent
Publication No. 2003-138933) have been proposed.
[0005] However, the apparatus described in Japanese Laid-Open
Patent Publication No. 2003-120281 needs a vaporizer, an expander,
a condenser, and a pump, which functions with a working fluid. This
inevitably increases the volume and the weight of the apparatus.
Thus, even if the apparatus efficiently recovers the exhaust heat
energy, the drive energy of the apparatus or the weight of the
vehicle may become excessive. In this case, the improvement in
engine fuel efficiency would become subtle. The same problem occurs
to the technique using a heat engine, such as a Stirling engine,
which is described in Japanese Laid-Open Patent Publication No.
2001-99003.
[0006] Further, Japanese Laid-Open Patent Publication No.
2003-138933 describes a technique for drawing exhaust into a scroll
expander. This inevitably increases the exhaust back pressure of
the internal combustion engine and lowers the engine output. In
this case, there may be no improvement in the engine fuel
efficiency as a whole.
SUMMARY OF THE INVENTION
[0007] It is an object of the present invention to provide an
exhaust heat energy recovery apparatus for an internal combustion
engine for recovering the exhaust heat energy efficiently without
increasing the exhaust back pressure of the internal combustion
engine. It is another object to provide a Brayton cycle apparatus
applicable to such an exhaust heat energy recovery apparatus.
[0008] The means for achieving the above objects and its advantages
will now be described.
[0009] The present invention provides a Brayton cycle apparatus.
The Brayton cycle apparatus includes a scroll compressor, a scroll
expander that operates in cooperation with an orbiting action of
the scroll compressor, and a heating device for heating a
compressed working fluid that is fed from the scroll compressor to
the scroll expander.
[0010] Unlike a gas turbine Brayton cycle apparatus of the prior
art, this Brayton cycle apparatus uses the scroll compressor and
the scroll expander and simplifies its structure. The simplified
structure downsizes the apparatus. In the Brayton cycle apparatus,
the working fluid is moved, compressed, and expanded inside the
compressor and the expander in partitioned and sealed spaces. Thus,
the efficiency of conversion from heat energy to kinetic energy is
high.
[0011] Further, the heating device heats the working fluid by heat
transfer to drive the Brayton cycle apparatus of the present
invention. Thus, the pressure of the energy source itself causes no
problem, and the back pressure of the energy source including the
exhaust is unaffected.
[0012] In this manner, the Brayton cycle apparatus of the present
invention efficiently converts heat energy to kinetic energy
without increasing the back pressure of the energy source. Thus,
even when the Brayton cycle apparatus of the present invention is
applied to, for example, an internal combustion engine, the
apparatus recovers the exhaust heat energy efficiently without
increasing the exhaust back pressure.
[0013] Preferably, an orbital compression scroll of the scroll
compressor and an orbital expansion scroll of the scroll expander
are arranged at opposite sides of an orbital partitioning wall. The
orbital compression scroll of the orbital partitioning wall comes
in contact with a compressor case in which a fixed compression
scroll is formed in a slidable manner or faces the compressor case
with a narrow space between them. As a result, the orbital
compression scroll is combined with the fixed compression scroll to
form the scroll compressor. The orbital expansion scroll on the
orbital partitioning wall comes in contact with an expander case in
which a fixed expansion scroll is formed in a slidable manner or
faces the expander case with a narrow space between them. As a
result, the orbital expansion scroll is combined with the fixed
expansion scroll to form the scroll expander.
[0014] The scroll compressor and the scroll expander are formed in
this manner so that the Brayton cycle apparatus is further
simplified and downsized.
[0015] Preferably, the scroll compressor releases heat transferred
from the scroll expander to the orbital partitioning wall into the
atmosphere via the compressor case.
[0016] The scroll compressor comes in contact with the scroll
expander through the orbital partitioning wall. Thus, the
compressor case at a low-temperature side receives heat of the
orbital partitioning wall transferred from the scroll expander at a
high-temperature side and releases the heat into the atmosphere.
The heat releasing effect of the compressor case prevents the
orbital partitioning wall from being heated to a high temperature.
As a result, the orbital partitioning wall is prevented from being
deformed by heat, and the dimensional accuracy of the orbital
partitioning wall is maintained. This prevents the working fluid
from leaking, and prevents the friction coefficient during orbiting
of the orbital partitioning wall from becoming large. This
maintains high energy conversion efficiency.
[0017] As a result, the orbital partitioning wall or the compressor
case in particular may be made of a lightweight material with a low
heat resistance. This contributes to further decreasing the weight
of the apparatus.
[0018] Preferably, the scroll expander guides the working fluid
introduced into a heat absorption chamber defined in the expander
case before the introduced working fluid expands so that the
working fluid that is being expanded is heated by a wall of the
heat absorption chamber.
[0019] The scroll expander with this structure enables the working
fluid that is being expanded in the scroll expander to be heated by
the heat of the working fluid prior to compression. This enables
the Brayton cycle apparatus to convert heat energy to kinetic
energy more efficiently without complicating the structure of the
apparatus.
[0020] Preferably, the scroll compressor uses atmospheric gas as
the working fluid and compresses the atmospheric gas, and the
scroll expander releases the expanded working fluid into the
atmosphere.
[0021] The atmospheric gas is used as the working fluid in this
manner and eliminates the need for an apparatus for releasing heat
of the working fluid. This further simplifies and downsizes the
structure of the apparatus.
[0022] Preferably, the heating device is formed as a heat exchanger
for transferring external heat to the working fluid by heat
exchange.
[0023] In this manner, the heating device is formed as a heat
exchanger so that the apparatus is further simplified and
downsized. Further, even when the Brayton cycle apparatus is used
to collect exhaust heat energy of, for example, an internal
combustion engine, the apparatus does not increase the exhaust back
pressure.
[0024] The present invention further provides a Brayton cycle
apparatus including a positive-displacement compressor, a scroll
expander for performing orbiting action in cooperation with the
compression action of the positive-displacement compressor, and a
heating device for heating the compressed working fluid that is fed
from the positive-displacement compressor to the scroll
expander.
[0025] Unlike a conventional gas turbine Brayton cycle apparatus,
the Brayton cycle apparatus uses the positive-displacement
compressor and the scroll expander. Thus, this Brayton cycle
apparatus has a simple structure. The simple structure downsizes
the apparatus. Further, in the Brayton cycle apparatus, the working
fluid is moved, compressed, and expanded inside the compressor and
the expander in partitioned and sealed spaces. Thus, the efficiency
of conversion from heat energy to kinetic energy of the Brayton
cycle apparatus is high.
[0026] Further, the heating device heats the working fluid by heat
transfer to drive the Brayton cycle apparatus of the present
invention. Thus, the pressure of the energy source itself causes no
problem, and the back pressure of the energy source including the
exhaust is unaffected.
[0027] In this manner, the Brayton cycle apparatus of the present
invention converts heat energy to kinetic energy without increasing
the back pressure of the energy source. Thus, when the Brayton
cycle apparatus of the present invention is applied to, for
example, an internal combustion engine, the apparatus recovers the
exhaust heat energy efficiently without increasing the exhaust back
pressure.
[0028] Preferably, a wall surface of the expander in the Brayton
cycle apparatus is kept warm.
[0029] The wall surface of the expander is kept warm in this manner
so that heat energy is prevented from leaking from the expander. As
a result, the expander converts heat energy to kinetic energy
further efficiently.
[0030] The present invention further provides an exhaust heat
energy recovery apparatus for an internal combustion engine. The
energy recovery apparatus uses a Brayton cycle apparatus for
heating a compressed working fluid that is fed from a compressor to
an expander by heat transferred from a flow passage wall of an
exhaust passage of the internal combustion engine. As a result, the
heat energy recovery apparatus recovers the exhaust heat energy as
kinetic energy.
[0031] In this manner, the exhaust heat energy recovery apparatus
of the present invention uses the Brayton cycle apparatus to heat
the working fluid by heat transfer to collect exhaust heat energy
of the internal combustion engine. Thus, the exhaust heat energy
recovery apparatus of the present invention recovers the exhaust
heat energy efficiently without increasing the exhaust back
pressure of the internal combustion engine.
[0032] Preferably, a heating device included in the Brayton cycle
apparatus of the heat energy recovery apparatus is formed as a heat
exchanger for transferring external heat to the working fluid by
heat exchange. This heat exchanger is arranged to come in contact
with the exhaust of the internal combustion engine.
[0033] This structure simplifies and downsizes the exhaust heat
energy recovery apparatus and enables the exhaust heat energy
recovery apparatus to be easily mounted on a vehicle etc. This
exhaust heat energy recovery apparatus recovers the exhaust heat
energy efficiently without increasing the exhaust back pressure of
the internal combustion engine.
[0034] Preferably, the exhaust flow passage is formed as a double
pipe having an inner passage and an outer passage. Heat exchange is
performed between the exhaust flowing through one of the inner
passage and the outer passage of the double pipe and the working
fluid flowing through the other one of the passages.
[0035] In this manner, the exhaust flow passage is formed as a
double pipe to enable such heat exchange so that the compressed
working fluid is easily heated using the exhaust heat energy.
[0036] Thus, the simple and compact structure enables the exhaust
heat energy to be recovered efficiently without increasing the
exhaust back pressure of the internal combustion engine.
[0037] Preferably, the Brayton cycle apparatus includes a scroll
compressor and a scroll expander that are arranged at opposite
sides of an orbital partitioning wall. The orbital partitioning
wall and the compressor case are made of a high heat-conductive
material, and the expander case is made of a heat-resistant
material.
[0038] The compressor case made of a high heat-conductive material
is at a low temperature side in the Brayton cycle apparatus. The
orbital partitioning wall is also made of a high heat-conductive
material. Thus, the compressor case of the Brayton cycle apparatus
is cooled first. This eliminates the need for using a
heat-resistant material for the orbital partitioning wall and the
compressor case. The expander case that directly comes in contact
with the high-temperature working fluid is made of a heat-resistant
material so that the exhaust heat energy recovery apparatus of the
internal combustion engine is formed.
[0039] Preferably, an aluminum alloy is used as the high
heat-conductive material, and an iron alloy is used as the
heat-resistant material.
[0040] In this manner, the use of an aluminum alloy as the high
heat-conductive material contributes to further decreasing the
weight of the exhaust heat energy recovery apparatus.
[0041] Preferably, a wall surface of the expander is kept warm.
[0042] In this manner, the use of the Brayton cycle apparatus in
which the wall surface of the expander is kept warm enables heat
energy to be converted to kinetic energy more efficiently, and
enables the exhaust hest energy to be recovered efficiently.
[0043] The present invention further provides a Brayton cycle
apparatus including a scroll expander formed by combining an
orbital expansion scroll with a fixed expansion scroll, a
compressor for operating in cooperation with the orbiting action of
the orbital expansion scroll to compress a working fluid, a
compressed working fluid flow passage for supplying the working
fluid from the compressor to the scroll expander, and a heat source
for heating the working fluid in the scroll expander by heat
transfer.
[0044] More specifically, the Brayton cycle apparatus is not
limited to a structure in which the working fluid is heated by a
compressed working fluid passage for supplying the working fluid
from the compressor to the scroll expander and may have a structure
for heating the working fluid in the scroll expander using heat
transferred from the heat source.
[0045] In this case, heating the working fluid in the scroll
expander using heat transferred from the heat source drives the
Brayton cycle apparatus of the present invention. As a result, the
pressure of the heat source itself causes no problem, the back
pressure of the heat source is unaffected, and heat energy is
efficiently converted to kinetic energy. As a result, even when the
Brayton cycle apparatus of the present invention is applied to, for
example, an internal combustion engine, the apparatus recovers the
exhaust heat energy efficiently without increasing the exhaust back
pressure.
[0046] Further, the working fluid is not heated by the compressed
working fluid passage. This simplifies the structure of the
compressed working fluid passage itself. This further enables the
working fluid to be heated by heat transfer using the structure of
the scroll expander so that the Brayton cycle apparatus is further
simplified and downsized.
[0047] Preferably, the compressor is a positive-displacement
compressor.
[0048] When the positive-displacement compressor is used in this
manner, the working fluid in the scroll expander is heated in the
manner described above. As a result, even when the Brayton cycle
apparatus of the present invention is applied to, for example, an
internal combustion engine, the apparatus recovers the exhaust heat
energy efficiently without increasing the exhaust back
pressure.
[0049] The present invention further provides a Brayton cycle
apparatus including an orbital partitioning wall having a first
surface on which an orbital compression scroll is formed and a
second surface on which an orbital expansion scroll is formed, a
scroll compressor formed by combining the orbital compression
scroll with a fixed compression scroll, a scroll expander formed by
combining the orbital expansion scroll with a fixed expansion
scroll, a compressed working fluid passage for supplying working
fluid from the scroll compressor to the scroll expander, and a heat
source for heating the working fluid in the scroll expander by heat
transfer.
[0050] More specifically, the Brayton cycle apparatus is not be
limited to the structure in which the working fluid is heated on
the compressed working fluid passage for supplying the working
fluid from the scroll compressor to the scroll expander and may
have a structure for heating the working fluid in the scroll
expander by heat transfer from the heat source.
[0051] Unlike a conventional gas turbine Brayton cycle apparatus in
the prior art, the Brayton cycle apparatus uses the scroll
compressor and the scroll expander and simplifies the structure.
The simplified structure downsizes the apparatus. In the Brayton
cycle apparatus, the working fluid is moved, compressed, and
expanded inside the compressor and the expander in partitioned
spaces. Thus, the efficiency of conversion from heat energy to
kinetic energy is high.
[0052] Further, heating the working fluid by heat transferred from
the heat source drives the Brayton cycle apparatus of the present
invention. As a result, the pressure of the heat source itself
causes no problem, and the back pressure of the heat source is
unaffected.
[0053] The Brayton cycle apparatus of the present invention
converts heat energy to kinetic energy efficiently without
increasing the back pressure of the heat source. As a result, even
when the Brayton cycle apparatus is applied to, for example, an
internal combustion engine, the apparatus recovers the exhaust heat
energy efficiently without increasing the exhaust back
pressure.
[0054] Further, the working fluid is not heated in the compressed
working fluid passage. This simplifies the structure of the
compressed working fluid passage itself and further enables the
working fluid to be heated by heat transfer using the structure of
the scroll expander so that the Brayton cycle apparatus is further
simplified and downsized.
[0055] Preferably, the compressed working fluid passage is a
through-hole formed in the orbital partitioning wall. The
through-hole communicates an internal space of the case of the
scroll compressor with an internal space of the case of the scroll
expander that is formed to sandwich the orbital partitioning wall
together with the scroll compressor.
[0056] The through-hole of the orbital partitioning wall also
functions as the compressed working fluid passage. Thus, the
compressed working fluid passage has an extremely simple structure.
As a result, the entire Brayton cycle apparatus is further
simplified and downsized.
[0057] Preferably, the heat source comes in contact with the case
of the scroll expander. The heat source heats the working fluid in
the scroll expander through the case of the scroll expander or the
fixed expansion scroll fixed to the case.
[0058] In this case, the fixed expansion scroll is used to heat the
working fluid through heat transfer. As a result, the Brayton cycle
apparatus is further simplified and downsized.
[0059] The present invention provides an exhaust heat energy
recovery apparatus that uses a Brayton cycle apparatus for heating
a working fluid fed to an expander by heat transferred from a flow
passage wall of an exhaust flow passage of an internal combustion
engine.
[0060] In this case, the Brayton cycle apparatus is used to heat
the working fluid by heat transfer to collect exhaust heat energy
of the internal combustion engine. Thus, the apparatus recovers the
exhaust heat energy efficiently without increasing the exhaust back
pressure of the internal combustion engine.
[0061] Further, the exhaust heat energy recovery apparatus heats
the working fluid fed to the expander by heat transferred from the
flow passage wall of the exhaust flow passage of the internal
combustion engine. As a result, the entire exhaust heat energy
recovery apparatus is simplified and downsized.
[0062] Preferably, the exhaust heat energy recovery apparatus
includes a scroll expander and a heat source for heating the
working fluid in the scroll expander through heat transfer. The
exhaust of the internal combustion engine is used as the heat
source. Thus, the entire exhaust heat energy recovery apparatus is
further simplified and downsized.
BRIEF DESCRIPTION OF THE DRAWINGS
[0063] FIG. 1 is a schematic view showing the structure of a
Brayton cycle apparatus according to a first embodiment of the
present invention;
[0064] FIG. 2 is a diagram showing the appearance of a heat
insulation apparatus included in the Brayton cycle apparatus of
FIG. 1;
[0065] FIG. 3 is a diagram showing the appearance of the heat
insulation apparatus of FIG. 2;
[0066] FIG. 4 is a plan view showing a compressor case included in
the apparatus of FIG. 1;
[0067] FIG. 5 is a plan view showing an expander case included in
the apparatus of FIG. 1;
[0068] FIG. 6 is a perspective view showing the compressor case of
FIG. 4;
[0069] FIG. 7 is a perspective view showing the expander case of
FIG. 5;
[0070] FIG. 8 is a diagram showing the structure of an orbital
partitioning wall included in the apparatus of FIG. 1;
[0071] FIG. 9 is a perspective view showing the orbital
partitioning wall of FIG. 8;
[0072] FIG. 10 is a diagram describing an internal structure of a
scroll compressor included in the apparatus of FIG. 1;
[0073] FIG. 11 is a diagram showing an internal structure of a
scroll expander included in the apparatus of FIG. 1;
[0074] FIG. 12 is a PV (pressure-volume) diagram of a Brayton cycle
of the apparatus of FIG. 1;
[0075] FIG. 13 is a diagram showing the positional relationship
between a fixed compression scroll and an orbital compression
scroll during driving of the Brayton cycle apparatus of FIG. 1;
[0076] FIG. 14 is a diagram showing the positional relationship
between a fixed expansion scroll and an orbital expansion scroll
during driving of the Brayton cycle apparatus of FIG. 1;
[0077] FIG. 15 is a schematic diagram showing the structure of a
Brayton cycle apparatus and an exhaust heat energy recovery
apparatus according to a second embodiment of the present
invention;
[0078] FIG. 16 is a schematic diagram showing the structure of heat
releasing fins of a compressor case included in the apparatus of
FIG. 15;
[0079] FIG. 17 is a schematic diagram showing the structure of heat
absorbing fins of an expander case included in the apparatus of
FIG. 15;
[0080] FIG. 18 is a schematic diagram showing the structure of a
Brayton cycle apparatus according to a third embodiment of the
present invention;
[0081] FIG. 19 is a diagram showing the appearance of a heat
insulation apparatus included in the Brayton cycle apparatus of
FIG. 18;
[0082] FIG. 20 is a diagram describing the appearance of the heat
insulation apparatus of FIG. 19;
[0083] FIG. 21 is a plan view showing a compressor case included in
the apparatus of FIG. 18;
[0084] FIG. 22 is a plan view showing an expander case included in
the apparatus of FIG. 18;
[0085] FIG. 23 is a perspective view showing the compressor case of
FIG. 21;
[0086] FIG. 24 is a perspective view showing the expander case of
FIG. 22;
[0087] FIG. 25 is a perspective view of an orbital partitioning
wall included in the apparatus of FIG. 18;
[0088] FIG. 26 is a diagram showing the structure of the orbital
partitioning wall of FIG. 25;
[0089] FIG. 27 is a diagram showing the positional relationship
between a fixed compression scroll and an orbital compression
scroll during driving of the Brayton cycle apparatus of FIG.
18;
[0090] FIG. 28 is a diagram showing the positional relationship
between a fixed expansion scroll and an orbital expansion scroll
during driving of the Brayton cycle apparatus of FIG. 18;
[0091] FIG. 29 is a graph comparing heat energy conversion
efficiency between different heating methods used in the apparatus
of FIG. 18;
[0092] FIG. 30 is a schematic diagram showing the structure of a
Brayton cycle apparatus according to a fourth embodiment of the
present invention; and
[0093] FIG. 31 is a diagram describing the structure of crank
mechanisms according to another example of the present
invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0094] A first embodiment of the present invention will now be
described. FIG. 1 shows a schematic structure of a Brayton cycle
apparatus 1. A heat insulation apparatus 2 included in the Brayton
cycle apparatus 1 is shown in FIGS. 2 and 3. FIG. 2(A) is a front
view showing the heat insulation apparatus 2, FIG. 2(B) is a rear
view, FIG. 3(A) is a right side view, and FIG. 3(B) is a left side
view of the same.
[0095] The heat insulation apparatus 2 includes a scroll compressor
4 and a scroll expander 6. The scroll compressor 4 includes a
compressor case 8 shown in the plan view of FIG. 4. A fixed
compression scroll 10 is formed in an internal space 9 of the
compressor case 8. A compressed working fluid outlet port 9a is
arranged in the compressor case 8 at a location corresponding to a
central portion of the fixed compression scroll 10. A working fluid
inlet port 9b is arranged at peripheral portion of the fixed
compression scroll 10. FIG. 6 is a perspective view showing the
compressor case 8.
[0096] The scroll expander 6 includes an expander case 12 shown in
the plan view of FIG. 5. A fixed expansion scroll 14 is formed in
an internal space 13 of the expander case 12. A compressed working
fluid inlet port 13a is arranged in the expander case 12 at a
location corresponding to a central portion of the fixed expansion
scroll 14. A working fluid outlet port 13b is arranged at a
peripheral portion of the fixed expansion scroll 14. FIG. 7 is a
perspective view showing the expander case 12.
[0097] A circular orbital recession 8b is arranged inside a contact
surface 8a of the compressor case 8. In the same manner, a circular
orbital recession 12b is arranged inside a contact surface 12a of
the expander case 12. When the contact surfaces 8a and 12a come in
contact with each other as shown in FIG. 2, the compressor case 8
is fastened with the expander case 12 by bolts Bt. The two orbital
recessions 8b and 12b define an accommodating chamber inside the
heat insulation apparatus 2. The accommodating chamber accommodates
an orbital partitioning wall 18. The orbital partitioning wall 18,
which is shown in FIG. 8, in the accommodating chamber orbits while
sliding in the accommodating chamber or orbits in a narrow gap
formed between the orbital partitioning wall 18 and the cases.
[0098] An orbital compression scroll 20 is formed to project from a
compressor-side surface 18a of the orbital partitioning wall 18
shown in FIG. 8(A). An orbital expansion scroll 22 is formed to
project from an expander-side surface 18b of the orbital
partitioning wall 18 shown in FIG. 8(B). FIG. 9 is a perspective
view of the orbital partitioning wall 18.
[0099] Three crank mechanisms 24, each of which is formed in to be
disk-shaped are rotatably attached to the peripheral portion of the
orbital partitioning wall 18 by crank pins 24b. The three crank
mechanisms 24 are respectively accommodated in three crank
accommodating units 8c, which are arranged in the compressor case
8. Each crank mechanism 24 has a crankshaft 24a arranged in its
central portion. The crankshaft 24a is inserted in a crankshaft
reception hole 8d arranged in the center of the crank accommodating
unit 8c and is supported on the compressor case 8 in a rotatable
manner. With the crank mechanisms 24 being supported on the
compressor case 8 in this manner, the entire orbital partitioning
wall 18 is supported on the compressor case 8 in a manner enabling
orbiting.
[0100] In the assembled state for the heat insulation apparatus 2,
two of the three crankshafts 24a project outside the heat
insulation apparatus 2 as shown in FIGS. 1 and 2. The first
crankshaft 24a receives a cranking torque when activating the
Brayton cycle apparatus 1 from outside the heat insulation
apparatus 2. The second crankshaft 24a outputs a torque generated
by the Brayton cycle apparatus 1 out of the heat insulation
apparatus 2. The number of crankshafts 24a projecting outside the
heat insulation apparatus 2 may be changed from one to two. In this
case, the single crankshaft 24a may function to both input the
cranking torque and output the generated torque.
[0101] The orbital compression scroll 20 arranged on one surface
(the compressor-side surface 18a (front surface)) of the orbital
partitioning wall 18 with the above-described structure is combined
with the fixed compression scroll 10 of the compressor case 8 (FIG.
4 and FIG. 6), and the orbital expansion scroll 22 arranged on the
other surface (the expander-side surface 18b (rear surface)) is
combined with the fixed expansion scroll 14 of the expander case 12
(FIG. 5 and FIG. 7). The compressor case 8, the expander case 12,
and the orbital partitioning wall 18 are then fastened together by
the bolts Bt to form the heat insulation apparatus 2.
[0102] FIG. 10 shows the internal structure of the scroll
compressor 4 included in the heat insulation apparatus 2 with this
structure. FIG. 10 shows the orbital compression scroll 20 arranged
on the compressor-side surface 18a (front surface) of the orbital
partitioning wall 18 and the compressor case 8 that is combined
with the orbital compression scroll 20. When the scroll compressor
4 is arranged so that the compressor case 8 (the orbital
compression scroll 20) is located at the upper side and the
expander case 12 (the orbital expansion scroll 22) is located at
the lower side, the part of the compressor case 8 located above the
orbital partitioning wall 18 is indicated by single-dashed lines.
The orbital compression scroll 20 is shown in black.
[0103] FIG. 11 shows the internal structure of the scroll expander
6 included in the heat insulation apparatus 2. FIG. 11 shows the
orbital expansion scroll 22 arranged on the expander-side surface
18b (rear surface) of the orbital partitioning wall 18 and the
expander case 12 that is combined with the orbital expansion scroll
22 as viewed through the orbital partitioning wall 18 from the side
of the scroll compressor 4. The parts of the fixed expansion scroll
14 and the orbital expansion scroll 22 located below the orbital
partitioning wall 18 are indicated by broken lines.
[0104] Referring to FIGS. 10 and 11, the crankshafts 24a rotate
clockwise as viewed in the drawings from the side of the compressor
case 8 so that the orbital partitioning wall 18 orbits clockwise.
As a result, the scroll compressor 4 realizes a heat-insulation
compression stroke in the PV (pressure-volume) diagram of a Brayton
cycle of FIG. 12 and the scroll expander 6 realizes a
heat-insulation expansion stroke in the PV diagram.
[0105] The orbital state will now be described with reference to
FIG. 13 and FIG. 14. FIG. 13 shows the orbital partitioning wall 18
viewed from the side of the compressor case 8 and the part of the
compressor case 8 located above the orbital partitioning wall 18 in
an overlapped state to show the positional relationship between the
fixed compression scroll 10 and the orbital compression scroll 20.
In the same manner, FIG. 14 shows the orbital partitioning wall 18
viewed from the side of the compressor case 8 and the part of the
expander case 12 located below the orbital partitioning wall 18 in
an overlapped manner to show the positional relationship between
the fixed expansion scroll 14 and the orbital expansion scroll 22.
The orbital compression scroll 20 and the orbital expansion scroll
22, which are positioned on the front and rear surfaces of the
orbital partitioning wall 18 produces the same orbiting action.
Thus, the orbiting shown in FIG. 13 and the orbiting shown in FIG.
14 occur simultaneously at the front and rear surfaces of the
orbital partitioning wall 18.
[0106] The orbital partitioning wall 18 orbits clockwise as viewed
from the side of the scroll compressor 4 as described above. Thus,
the position of the orbital compression scroll 20 with respect to
the fixed compression scroll 10 changes sequentially from the
states (1) to (8) shown in FIG. 13. As a result, an initial volume
Va1 of a working fluid (atmospheric gas in this case) is introduced
into the internal space 9 of the compressor case 8 through the
working fluid inlet port 9b, and the working fluid flows toward the
center of the compressor case 8 while gradually reducing its
volume. When the volume of the working fluid reaches a final volume
Va2 (Va1>Va1) at the central portion of the compressor case 8,
the compressed working fluid outlet port 9a opens so that the
compressed working fluid is fed from the compressed working fluid
outlet port 9a to the heating device 30 (FIG. 1).
[0107] During the orbiting of the orbital compression scroll 20,
orbiting simultaneously occurs in the scroll expander 6. The
position of the orbital expansion scroll 22 with respect to the
fixed expansion scroll 14 changes sequentially from the states (1)
to (8) shown in FIG. 14. As a result, an initial volume Vb2 of the
working fluid heated in the heating device 30 is introduced from
the compressed working fluid inlet port 13a into the internal space
13 of the expander case 12, and flows toward the peripheral side of
the expander case 12 while gradually increasing its volume. When
the volume of the working fluid reaches a final volume Vb1
(Vb1>Vb2) at the peripheral portion of the expander case 12, the
working fluid is released from restriction imposed by the fixed
expansion scroll 14 and the orbital expansion scroll 22, and is
discharged outside the expander case 12 from the working fluid
outlet port 13b.
[0108] The dimensions of the fixed expansion scroll 14 and the
orbital expansion scroll 22 in the axial direction are greater than
the dimensions of the fixed compression scroll 10 and the orbital
compression scroll 20 in the axial direction, and the scrolls are
designed to satisfy the relationship Va1<Vb1 and Va2<Vb2.
[0109] The heat insulation apparatus 2 and the heating device 30
with the above-described structures are combined together to
complete the Brayton cycle apparatus 1 shown in FIG. 1. The heating
device 30 uses a double pipe and includes a heat source flow
passage 30a, which functions as an inner passage, and an outer
passage 30b, which is arranged to surround the flow passage 30a.
The heating device 30 has the working fluid flow through the outer
passage 30b. The working fluid flowing through the outer passage
30b exchanges heat with fluid flowing through the heat source flow
passage 30a through the pipe wall (flow passage wall) of the heat
source flow passage 30a. When an exhaust pipe of an internal
combustion engine is used as the heat source flow passage 30a,
exhaust heat energy of the internal combustion engine is recovered.
In this case, the exhaust flows through the heat source flow
passage 30a and the heat of the exhaust is transferred to the
working fluid (air) flowing through the outer passage 30b.
[0110] The values of the volumes Va1, Va2, Vb1, and Vb2 above are
designed to maximize the heat conversion efficiency of the Brayton
cycle apparatus 1 by considering the working fluid temperature at
the working fluid inlet port 9b, the heat exchanger efficiency in
the heating device 30, the working fluid temperature at the
compressed working fluid inlet port 13a, and the heat insulation
efficiency in the scroll compressor 4 and the scroll expander
6.
[0111] The first embodiment has the advantages described below.
[0112] (1) Unlike the gas turbine Brayton cycle apparatus of the
prior art, the Brayton cycle apparatus 1 of the preferred
embodiment uses the scroll compressor 4 and the scroll expander 6.
This simplifies and downsizes the structure.
[0113] In particular, in the heat insulation apparatus 2, the
working fluid is moved, compressed, and expanded inside the scroll
compressor 4 and the scroll expander 6 in spaces partitioned and
sealed by the combination of the fixed scrolls 10 and 14 and the
orbital scrolls 20 and 22. Thus, the efficiency in conversion from
heat energy to kinetic energy is high.
[0114] The external energy source is only required to transfer heat
to the working fluid via the pipe wall of the flow passage 30a and
exchange heat with the working fluid. This downsizes the external
energy source. Further, the pressure of the energy source itself
causes no problem, and the back pressure of the energy source
including the exhaust is unaffected.
[0115] As a result, the Brayton cycle apparatus 1 of the present
embodiment converts heat energy to kinetic energy efficiently
without increasing the back pressure of the energy source. Thus,
when the Brayton cycle apparatus 1 of the present embodiment is
applied to an internal combustion engine, the apparatus recovers
the exhaust heat energy efficiently without increasing the exhaust
back pressure of the internal combustion engine.
[0116] (2) The orbital compression scroll 20 of the scroll
compressor 4 and the orbital expansion scroll 22 of the scroll
expander 6 are respectively arranged at opposite sides of the
orbital partitioning wall 18, which is orbited by the crankshafts
24a. The compressor case 8, in which the fixed compression scroll
10 is formed, is set on the orbital compression scroll 20 side of
the orbital partitioning wall 18 to come in contact with the
orbital partitioning wall 18 in a slidable manner or to face the
orbital partitioning wall 18 with a narrow gap therebetween. The
orbital compression scroll 20 and the fixed compression scroll 10
are combined to form the scroll compressor 4. The expander case 12,
in which the fixed expansion scroll 14 is formed, is set on the
orbital expansion scroll 22 side of the orbital partitioning wall
18 to come in contact with the orbital partitioning wall 18 in a
slidable manner or to face the orbital partitioning wall 18 with a
narrow gap therebetween. The orbital expansion scroll 22 and the
fixed expansion scroll 14 are combined to form the scroll expander
6.
[0117] The scroll compressor 4 and the scroll expander 6 are formed
in this manner so that the Brayton cycle apparatus 1 is further
simplified and downsized.
[0118] (3) As described above, the orbital partitioning wall 18
covers the expander case 12. Thus, the orbital partitioning wall 18
is exposed to the high-temperature working fluid that is introduced
into the scroll expander 6. However, the compressor case 8 is
enabled to contact the orbital partitioning wall 18 from the side
opposite to the expander case 12. As a result, heat transferred
from the scroll expander 6 to the orbital partitioning wall 18 is
removed by the compressor case 8 and released into the
atmosphere.
[0119] The heat releasing effect of the compressor case 8 prevents
the orbital partitioning wall 18 from being heated to a high
temperature. As a result, the orbital partitioning wall 18 is
prevented from being deformed by heat, and the dimensional accuracy
of the orbital partitioning wall 18 is maintained. This prevents
the working fluid from leaking from the heat insulation apparatus 2
and prevents the friction coefficient during orbiting of the
orbital partitioning wall 18 from becoming large. As a result, high
energy conversion efficiency is maintained.
[0120] Thus, the orbital partitioning wall 18 and the scroll
compressor 4 in particular may be made of a light alloy with a low
heat resistance. This contributes to further decreasing the weight
of the Brayton cycle apparatus 1.
[0121] (4) The scroll compressor 4 uses the atmospheric gas (air)
drawn through the working fluid inlet port 9b as the working fluid,
and the scroll expander 6 releases the expanded working fluid from
the working fluid outlet port 13b into the atmosphere. In this
manner, the atmospheric gas is used as the working fluid. This
eliminates the need for an apparatus for releasing heat of the
working fluid and further simplifies and downsizes the structure of
the Brayton cycle apparatus 1.
[0122] A second embodiment of the present invention will now be
described. In the present embodiment, a Brayton cycle apparatus 51
with the structure shown in FIG. 15 is used to collect exhaust heat
energy of an internal combustion engine Eng that is mounted on a
vehicle. A heat insulation apparatus 52 is formed by a scroll
compressor 54 and a scroll expander 56. The internal structures of
the scroll compressor 54 and the scroll expander 56 are the same as
the structures of the scroll compressor 4 and the scroll expander 6
described in the first embodiment.
[0123] The present embodiment differs from the first embodiment in
the following points. More specifically, a large number of heat
releasing fins 58b, which are formed as projections, are arranged
on an end surface 58a of a compressor case 58 as shown in FIG. 15
and FIG. 16. The heat releasing fins 58b are used to discharge from
the compressor case 58 heat, which is transferred from the internal
orbital partitioning wall 18 to the compressor case 58. More
specifically, the heat releasing fins 58b improve the releasing
efficiency of the heat received from the high-temperature scroll
expander 56 by the orbital partitioning wall 18 through the
compressor case 58.
[0124] Further, a large number of heat absorbing fins 62b, which
are formed as projections, are also arranged on an end surface 62a
of an expander case 62 as shown in FIG. 15 and FIG. 17. A cover 62c
is arranged on the end surface 62a of the expander case 62. The
cover 62c covers a compressed working fluid inlet port 63a and the
heat absorbing fins 62b to define a heat absorption chamber 62d.
The working fluid heated by a heating device 80 is introduced into
the heat absorption chamber 62d. Thus, the working fluid introduced
into the heat absorption chamber 62d heats the heat absorbing fins
62b. The compressed working fluid inlet port 63a that opens into
the heat absorption chamber 62d absorbs the heated working fluid.
The working fluid introduced into the heat absorption chamber 62d
heats the working fluid inside the expander case 62 through the end
surface 62a of the wall of the heat absorption chamber 62d. Thus, a
pressure decrease caused by expansion of the working fluid in the
scroll expander 56 is small. As a result, even when the expansion
coefficient of the scroll expander 56 is high, the working fluid
can be set in an atmospheric pressure state and discharged from the
working fluid outlet port 63b. This enables the Brayton cycle
apparatus 51 to collect the exhaust heat energy more
efficiently.
[0125] The heating device 80 includes two passages, namely, a
passage 80c for having the working fluid pass through the entire
length of a double pipe 80b and a passage 80d for having the
working fluid pass through only part of the double pipe 80b. The
passage distribution state of the compressed working fluid supplied
from the scroll compressor 54 is adjustable using a distribution
valve 80e. The distribution ratio of the passages 80c and 80d in
the present embodiment is adjusted in a manner that the working
fluid supplying temperature detected by a temperature sensor 81
arranged at an opening of the compressed working fluid inlet port
63a becomes equal to a predetermined reference temperature. More
specifically, the distribution ratio of the distribution valve 80e
is adjusted in a manner that the temperature of the working fluid
becomes equal to a reference temperature that is appropriate for
starting expansion in the scroll expander 56 when the working fluid
reaches the compressed working fluid inlet port 63a after heat is
absorbed by the heat absorbing fins 62b.
[0126] Crankshafts 74a of the Brayton cycle apparatus 51 are
rotated when the internal combustion engine Eng starts driving the
Brayton cycle apparatus 51. However, after the driving of the
Brayton cycle apparatus 51 starts, the crankshafts 74a rotate
independently of the output of the internal combustion engine Eng
by using heat energy of the exhaust that passes through the heating
device 80. Thus, the crankshafts 74a need to be disconnected from
the internal combustion engine Eng. For this purpose, an
electromagnetic clutch 92 is arranged between an output shaft 64 of
the internal combustion engine Eng and the crankshafts 74a of the
Brayton cycle apparatus 51.
[0127] The distribution ratio control of the distribution valve 80e
and the engagement/disengagement control of the electromagnetic
clutch 92 are executed by an electronic control unit (ECU) 94 based
on the driving state of the internal combustion engine Eng.
[0128] For example, the electromagnetic clutch 92 is set in a
disengaged state before the internal combustion engine Eng is
started. At the timing when the internal combustion engine exhaust
temperature reaches a sufficiently high temperature after the
internal combustion engine Eng is started, the electromagnetic
clutch 92 is engaged so that the crankshafts 74a of the Brayton
cycle apparatus 51 are rotated based on an output of the internal
combustion engine Eng. The ECU 94 drives a valve actuator 80f and
adjusts the distribution valve 80e in a manner that the working
fluid temperature detected by the temperature sensor 81 is adjusted
to, for example, 350.degree. C.
[0129] Afterwards, the ECU 94 disengages the electromagnetic clutch
92. As a result, the crankshafts 74a of the Brayton cycle apparatus
51 rotate independently to rotate an apparatus for recovering the
exhaust heat energy, or a generator 96 in this case. As a result,
the exhaust heat energy is recovered as electric energy and used as
a vehicle power supply or stored in a battery.
[0130] With the above-described structure, the expander case 62,
which directly comes in contact with the high-temperature working
fluid, is made of a heat-resistant material (e.g. an iron alloy
such as cast iron). The compressor case 58, through which the
working fluid flows with a relatively low temperature, is made of a
high heat-conductive material (particularly a light alloy such as
an aluminum alloy). The orbital partitioning wall 18 is made of a
high heat-conductive material so that the orbital partitioning wall
18 is cooled by transferring heat to the compressor case 58.
[0131] The second embodiment described above has the advantages
described below.
[0132] (1) The heat releasing fins 58b are formed on the compressor
case 58. Thus, the compressor case 58 can easily release heat into
the atmosphere. This strengthens advantage (3) described in the
first embodiment.
[0133] (2) The cover 62c covers the end surface 62a of the expander
case 62 and defines the heat absorption chamber 62d. As described
above, the working fluid expanded in the scroll expander 56 is
heated by the wall of the expander case 62 having the end surface
62a. Further, the heat absorbing fins 62b are formed on the end
surface 62a. The heat absorbing fins 62b enhance heat conductivity
of the end surface 62a, and enable the Brayton cycle apparatus 51
to convert heat energy to kinetic energy further efficiently
without complicating the structure of the Brayton cycle apparatus
51.
[0134] (3) The exhaust pipe is formed by the double pipe 80b. The
heating device 80 is formed as a heat exchanger for exchanging heat
between the high-temperature gas (the exhaust of the internal
combustion engine Eng in this case) and the working fluid. The
Brayton cycle apparatus 51 recovers the exhaust heat energy as
kinetic energy. Thus, the Brayton cycle apparatus 51 converts the
exhaust heat energy to kinetic energy more efficiently without
increasing the exhaust back pressure of the internal combustion
engine Eng.
[0135] (4) A light alloy may be used as a material for the
compressor case 58 and the orbital partitioning wall 18 as
described above. This reduces the weight of the entire Brayton
cycle apparatus 51. When the Brayton cycle apparatus 51 is applied
to an internal combustion engine that is mounted on a vehicle, the
Brayton cycle apparatus 51 improves fuel efficiency of the
engine.
[0136] (5) Advantages (1), (2), and (4) of the first embodiment are
obtained.
[0137] A third embodiment of the present invention will now be
described. FIG. 18 is a schematic diagram showing the structure of
a Brayton cycle apparatus 101. A heat insulation apparatus 102
included in the Brayton cycle apparatus 101 is shown in FIGS. 19
and 20. FIG. 19(A) is a front view showing the heat insulation
apparatus 102, FIG. 19(B) is a rear view, FIG. 20(A) is a right
side view, and FIG. 20(B) is a left side view of the same.
[0138] In the same manner as the first embodiment, a working fluid
inlet port 109b projects from a peripheral portion of a scroll
compressor 104 and a working fluid outlet port 113b projects from a
peripheral portion of a scroll expander 106.
[0139] Unlike the first embodiment, a compressed working fluid
outlet port 9a is not arranged in a compressor case 108 and a
compressed working fluid inlet port 13a is not arranged in an
expander case 112 as shown in FIGS. 21 to 24. FIG. 21 is a plan
view showing the compressor case 108, FIG. 22 is a plan view
showing the expander case 112, FIG. 23 is a perspective view
showing the compressor case 108, and FIG. 24 is a perspective view
showing the expander case 112.
[0140] Instead of the compressed working fluid outlet port 9a and
the compressed working fluid inlet port 13a, a through-hole 118c is
formed in a central portion of an orbital partitioning wall 118 as
shown in FIGS. 25 and 26. FIG. 25 is a perspective view showing the
orbital partitioning wall 118, FIG. 26(A) is a plan view of the
orbital partitioning wall 118 showing a compressor-side surface
118a of the orbital partitioning wall 118, and FIG. 26(B) is a rear
view of the orbital partitioning wall 118 showing an expander-side
surface 118b of the orbital partitioning wall 118.
[0141] In the scroll compressor 104, the orbital partitioning wall
118 orbits as shown in the states (1) to (8) in FIG. 27. An orbital
compression scroll 120 of the orbital partitioning wall 118 moves
relative to a fixed compression scroll 110 of the compressor case
108 so that the working fluid introduced from the working fluid
inlet port 109b into the scroll compressor 104 is compressed and
reaches the through-hole 118c formed in the central portion of the
orbital partitioning wall 118. FIG. 27 shows the orbital
partitioning wall 118 viewed from the side of the compressor case
108 and the compressor case 108 located above the orbital
partitioning wall 118 in an overlapped manner to describe the
positional relationship between the fixed compression scroll 110
and the orbital compression scroll 120. Accordingly, the left and
right sides shown in FIG. 27 are reversed from the state shown in
FIG. 21.
[0142] The working fluid in a compressed state passes through the
through-hole 118c so that the working fluid is immediately
introduced into the scroll expander 106 from the scroll compressor
104 as indicated by a broken line Ap in FIG. 18.
[0143] In the scroll expander 106, the orbital partitioning wall
118 orbits as shown in (1) to (8) in FIG. 28. An orbital expansion
scroll 122 of the orbital partitioning wall 118 moves relative to a
fixed expansion scroll 114 of the expander case 112 so that the
working fluid introduced through the through-hole 118c into the
scroll expander 106 expands and reaches the working fluid outlet
port 113b.
[0144] FIG. 28 shows the orbital partitioning wall 118 viewed from
the side of the compressor case 108 and the part of the expander
case 112 located below the orbital partitioning wall 118 in an
overlapped manner to show the positional relationship between the
fixed expansion scroll 114 and the orbital expansion scroll
122.
[0145] The expander case 112 comes in contact with or is joined
with a flow passage 130a (FIG. 18) as a heat source. The expander
case 112 exchanges heat with a fluid flowing through the flow
passage 130a through a pipe wall (flow passage wall) of the flow
passage 130a. Thus, the working fluid expands while being heated by
the heat transferred to the working fluid that comes in contact
with the expander case 112 or the fixed expansion scroll 114.
[0146] The orbital partitioning wall 118 with this structure orbits
clockwise in FIGS. 27 and 28 to realize a heat-insulation
compression stroke, an isobaric heating stroke, and a
heat-insulation expansion stroke in the PV diagram of the Brayton
cycle shown in FIG. 12.
[0147] In the above-described structure, the expander case 112
comes in contact with the high-temperature flow passage 130a and is
heated to a high temperature by the heat transfer from the flow
passage 130a. As a result, the working fluid is heated by the
expander case 112 and the fixed expansion scroll 114. Thus, the
expander case 112 and the fixed expansion scroll 114 are made of a
heat-resistant material (e.g. an iron alloy such as cast iron). The
expander case 112 and the fixed expansion scroll 114 may be made of
a light alloy such as an aluminum alloy. Because the temperature of
the working fluid in the compressor case 108 is relatively low, the
compressor case 108 is made of a high heat-conductive material
(particularly a light alloy such as an aluminum alloy). The orbital
partitioning wall 118 is made of a high heat-conductive material so
that the orbital partitioning wall 18 may be cooled by transferring
heat to the compressor case 58.
[0148] With the above-described structure, heat energy transferred
from the flow passage 130a to the expander case 112 is converted to
rotation energy of crankshafts 124a.
[0149] FIG. 29 shows a graph comparing the heat energy conversion
efficiency experiments in the present embodiment case, in which the
expander case 112 is heated, with the heat energy conversion
efficiency experiments in the first embodiment case, in which the
expander case 112 is not heated and the working fluid is introduced
into the scroll expander 106 after the working fluid is heated
separately. To correctly indicate the difference in the torque gain
in the scroll expander 106 between the different heating methods,
this graph compares the output torque of the crankshafts 124a when
the expander case 112 is heated with an output torque of the
crankshafts 124a when the working fluid introduced into the
expander case 112 is heated in the state in which the scroll
expander 106 is disconnected from the Brayton cycle apparatus 101.
The horizontal axis of the graph indicates a temperate increase
difference .DELTA.T, which is the difference between a temperature
increase of the expander case 112 and a temperature increase of the
working fluid occurring via heating. The vertical axis of the graph
indicates a torque gain (Nm).
[0150] As shown in the graph, the heat energy conversion efficiency
is higher when the expander case 112 made of an aluminum alloy is
heated than when the working fluid is heated. When the expander
case 112 is made of cast iron, clearance for the mechanism of the
scroll expander 106 may be reduced and the heat energy conversion
efficiency is further increased.
[0151] The third embodiment has the advantages described below.
[0152] (1) Advantages (1) to (4) of the first embodiment are
obtained.
[0153] (2) The Brayton cycle apparatus 101 of the present
embodiment heats the working fluid in the scroll expander 106 using
the heat transferred from the heat source (the flow passage 130a)
without using a heating device for separately heating the working
fluid.
[0154] Thus, the compressed working fluid passage has a simple
structure. The compressed working fluid passage is actually
realized by the through-hole 118c formed in the orbital
partitioning wall 118.
[0155] Further, the expander case 112 and the fixed expansion
scroll 114, which are the components of the scroll expander 106,
are used to transfer heat to the working fluid and heat the working
fluid. As a result, the Brayton cycle apparatus 101 is further
simplified and downsized.
[0156] A fourth embodiment of the present invention will now be
described. As shown in FIG. 30, a Brayton cycle apparatus 201 of
the present embodiment differs from the structure of the first
embodiment shown in FIG. 1 in that a heat insulator 201a is
arranged to cover the expander case 12 in the heat insulation
apparatus 2 and keep the expander case 12 warm. The other parts of
the Brayton cycle apparatus 201 are the same as the structure in
the first embodiment. Thus, the components of the Brayton cycle
apparatus 201 that are the same as the components in the first
embodiment are denoted by the same reference numerals.
[0157] The fourth embodiment has the advantages described
below.
[0158] (1) Advantages (1) to (4) of the first embodiment are
obtained.
[0159] (2) The heat insulator 201a keeps the wall surface of the
expander case 12 warm. This prevents heat from being released from
the expander case 12 outside through heat transfer from the
expander case 12 when the working fluid is expanded in the scroll
expander 6 in a heat-insulated state.
[0160] In this manner, the wall surface of the expander case 12 is
kept warm to prevent heat energy from leaking from the scroll
expander 6. As a result, the heat energy is converted to kinetic
energy more efficiently.
[0161] The above embodiments may be modified in the following
forms.
[0162] (a) The Brayton cycle apparatus shown in FIG. 1, FIG. 18, or
FIG. 30 may be used as an exhaust heat energy recovery apparatus
for an internal combustion engine instead of the Brayton cycle
apparatus used in the second embodiment.
[0163] In the above embodiments, the Brayton cycle apparatus used
to collect exhaust heat energy from an internal combustion engine
uses the scroll compressor and the scroll expander. Another
compressor, such as a screw compressor, a vane compressor, or a
turbo compressor, may be used instead of the scroll compressor. A
turbine compressor may be used instead of the scroll expander.
[0164] A positive-displacement compressor and a
positive-displacement expander may be used instead of the scroll
compressor and the scroll expander. The Brayton cycle apparatus may
be formed by combining a positive-displacement compressor for
compressing a working fluid and a scroll expander. In this case,
the scroll expander may operate in cooperation with the operation
of the positive-displacement compressor.
[0165] (b) The orbital partitioning wall 18 is supported by the
three crank mechanisms 24 as shown in FIG. 8. However, the present
invention should not be limited to this structure. The orbital
partitioning wall 18 may be supported by two crank mechanisms 24 or
may be supported by four or more crank mechanisms 24. Although each
crank mechanism 24 is circular, each crank mechanism 24 may include
a balancer 100 as shown in FIG. 31 to improve the vibration
reducing effect during driving of the Brayton cycle apparatus. The
same applies to the orbital partitioning wall 118 in the third
embodiment.
[0166] (c) Although the heat releasing fins 58b and the heat
absorbing fins 62b are formed as projections as shown in FIGS. 16
and 17, the heat releasing fins 58b and the heat absorbing fins 62b
may be formed as flat plates or bent plates.
[0167] (d) The heat releasing fins 58b shown in FIGS. 15 and 16 may
be arranged on the compressor case 108 in the third embodiment.
This structure enables the heat of the compressor case 108 to be
easily released into the atmosphere and strengthens advantage (3)
described in the first embodiment.
[0168] In the third embodiment, the expander case 112 comes in
contact with or joined together with the flow passage 130a, which
functions as a heat source, as shown in FIG. 18 to exchange heat
through the pipe wall (flow passage wall) of the flow passage 130a.
However, the expander case 112 may be formed to have a flow passage
through which the exhaust flows, and the exhaust may be guided to
this flow passage.
[0169] In the third embodiment, a peripheral portion of the
expander case 112 excluding parts that are in contact with or
joined with the flow passage 130a may be covered by a heat
insulator to keep the expander case 112 warm.
[0170] (e) In the above embodiments, the working fluid inlet port
and the working fluid outlet port are open to the atmosphere and
the atmospheric gas is used as the working fluid. However, the
passage of the working fluid may be closed, and a gas other than
the atmospheric gas may be used as the working fluid. In this case,
it is preferable that a heat releasing apparatus be arranged.
[0171] (f) In the above embodiments, the orbital compression scroll
and the orbital expansion scroll are formed to sandwich the orbital
partitioning wall to operate the expander in cooperation with
movement of the compressor. The synchronous movement intends to
mean that the compressor is linked to the expander in a manner that
the compressor and the expander move in a unified manner. Thus,
operating the expander in cooperation with the movement of the
compressor is equivalent to operating the compressor in cooperation
with the operation of the expander. Unlike the above embodiments,
this compressor does not have to be directly connected to the
expander. Particularly in the first, second, and fourth
embodiments, a shaft or a gear may be arranged between the
compressor and the expander to operate the expander in cooperation
with the operation of the compressor.
* * * * *