U.S. patent application number 12/070291 was filed with the patent office on 2008-08-21 for exhaust heat recovery apparatus.
This patent application is currently assigned to DENSO Corporation. Invention is credited to Seiji Inoue, Kimio Kohara, Masashi Miyagawa, Kenshirou Muramatsu, Yasutoshi Yamanaka.
Application Number | 20080196401 12/070291 |
Document ID | / |
Family ID | 39646268 |
Filed Date | 2008-08-21 |
United States Patent
Application |
20080196401 |
Kind Code |
A1 |
Muramatsu; Kenshirou ; et
al. |
August 21, 2008 |
Exhaust heat recovery apparatus
Abstract
An exhaust heat recovery apparatus includes an evaporation unit,
a condensation unit, an evaporation-side communication part and a
condensation-side communication part. The evaporation unit is
disposed in an exhaust gas passage through which an exhaust gas
flows and performs heat exchange between the exhaust gas and an
operation fluid flowing therein, thereby evaporating the operation
fluid. The condensation unit is disposed in a coolant passage
through which an engine coolant flows and performs heat exchange
between the operation fluid and the engine coolant, thereby
condensing the operation fluid. The evaporation-side communication
part connects the evaporation unit and the condensation unit for
introducing evaporated operation fluid to the condensation unit.
The condensation-side communication part connects the condensation
unit and the evaporation unit for introducing condensed operation
fluid to the evaporation unit. The condensation-side communication
part is provided with a throttle part.
Inventors: |
Muramatsu; Kenshirou;
(Nishio-city, JP) ; Miyagawa; Masashi;
(Ichinomiya-city, JP) ; Yamanaka; Yasutoshi;
(Kariya-city, JP) ; Inoue; Seiji; (Nukata-gun,
JP) ; Kohara; Kimio; (Nagoya-city, JP) |
Correspondence
Address: |
HARNESS, DICKEY & PIERCE, P.L.C.
P.O. BOX 828
BLOOMFIELD HILLS
MI
48303
US
|
Assignee: |
DENSO Corporation
Kariya-city
JP
|
Family ID: |
39646268 |
Appl. No.: |
12/070291 |
Filed: |
February 18, 2008 |
Current U.S.
Class: |
60/320 |
Current CPC
Class: |
F01N 5/02 20130101; Y02T
10/12 20130101; Y02T 10/16 20130101; F28D 15/0266 20130101; F28D
21/0003 20130101; F28D 15/06 20130101 |
Class at
Publication: |
60/320 |
International
Class: |
F01N 3/02 20060101
F01N003/02 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 19, 2007 |
JP |
2007-037482 |
Claims
1. An exhaust heat recovery apparatus comprising: an evaporation
unit to be disposed in an exhaust gas passage through which an
exhaust gas exhausted. from an engine flows, for performing heat
exchange between the exhaust gas and an operation fluid flowing
therein, thereby evaporating the operation fluid; a condensation
unit to be disposed in a coolant passage through which an engine
coolant flows, for performing heat exchange between the engine
coolant and the operation fluid that has been evaporated in the
evaporation unit, thereby condensing the operation fluid; an
evaporation-side communication part connecting the evaporation unit
and the condensation unit for introducing the operation fluid from
the evaporation unit to the condensation unit; a condensation-side
communication part connecting the condensation unit and the
evaporation unit for introducing the operation fluid from the
condensation unit to the evaporation unit; and a throttle part
disposed in the condensation-side communication part.
2. The exhaust heat recovery apparatus according to claim 1,
wherein the throttle part includes a fixed throttle.
3. The exhaust heat recovery apparatus according to claim 2,
wherein the fixed throttle is provided by partly reducing a passage
area of the condensation- side communication part.
4. The exhaust heat recovery apparatus according to claim 1,
wherein the throttle part includes a variable throttle that is
configured to vary an opening degree of an orifice through which
the operation fluid flows in accordance with a temperature of the
operation fluid.
5. The exhaust heat recovery apparatus according to claim 4,
wherein the variable throttle is configured such that the opening
degree is reduced in accordance with an increase in the temperature
of the operation fluid.
6. An exhaust heat recovery apparatus comprising: an evaporation
unit to be disposed in an exhaust gas passage through which an
exhaust gas exhausted from an engine flows, for performing heat
exchange between the exhaust gas and an operation fluid flowing
therein, thereby evaporating the operation fluid; a condensation
unit to be disposed in a coolant passage through which an engine
coolant flows, for performing heat exchange between the engine
coolant and the operation fluid that has been evaporated in the
evaporation unit, thereby condensing the operation fluid; an
evaporation-side communication part connecting the evaporation unit
and the condensation unit and defines a passage for introducing the
operation fluid from the evaporation unit to the condensation unit;
and a condensation-side communication part connecting the
condensation unit and the evaporation unit and defines a passage
for introducing the operation fluid from the condensation unit to
the evaporation unit, wherein the condensation-side communication
part includes a throttle portion that has a reduced passage area.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is based on Japanese Patent Application No.
2007-37482 filed on Feb. 19, 2007, the disclosure of which is
incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The present invention relates to an exhaust heat recovery
apparatus, which is used for a vehicle such as an automobile.
BACKGROUND OF THE INVENTION
[0003] It is known to recovery heat of exhaust gas discharged from
an exhaust system of a vehicular engine using the principle of heat
pipe and to use the recovered heat for other purposes such as for
warming the engine. For example, Japanese Unexamined Patent
Application Publication No. 62-268722 describes an exhaust heat
recovery apparatus for heating an engine coolant using heat of an
exhaust gas from an engine. Specifically, an evaporation unit that
has heat pipes is disposed in an engine exhaust pipe through which
the exhaust gas flows and a condensation unit that has heat pipes
is disposed in an engine coolant circuit through which the engine
coolant flows.
[0004] As another example, Japanese Unexamined Patent Application
Publication No. 4-45393 describes a looped heat pipe heat
exchanger. The disclosed heat exchanger includes a looped closed
circulation passage filled with an internal heat-transfer fluid, an
evaporation unit disposed on the circulation passage for
evaporating the internal heat-transfer fluid therein by receiving
external heat, and a condensation unit disposed on the circulation
passage at a position higher than the evaporation unit for
performing heat exchange between the evaporated internal
heat-transfer fluid and an external heat-transfer fluid.
[0005] FIG. 6 shows an example of an exhaust heat recovery
apparatus. In the exhaust heat recovery apparatus shown in FIG. 6,
an evaporation unit J1 and a condensation unit J2, as heat
exchanging units, are disposed adjacent to each other in a
horizontal direction. Ends of heat pipes J3 of the evaporation and
condensation units J1, J2 are coupled to headers (communication
parts) J5, so that the heat pipes J3 of the evaporation unit J1 are
in communication with the heat pipes J3 of the condensation unit J2
through the headers J5.
[0006] In such exhaust heat recovery apparatuses, the temperature
of the engine coolant is immediately increased by recovering the
heat of exhaust gas, especially, in a cold starting of the engine,
such as in winter. Therefore, fuel efficiency and heating operation
can be improved. On the other hand, in an engine high-load
condition, such as in hot summer, it is necessary to restrict the
recovery of the heat of the exhaust gas so as to avoid overheating
of the engine.
[0007] For example, it is proposed to provide the exhaust heat
recovery apparatus with a diaphragm-type valve unit for stopping
the circulation of the operation fluid. The diaphragm-type valve
unit is constructed of a diaphragm that is movable in response to
the pressure of the operation fluid and a valve body that is driven
by the diaphragm. The valve unit restricts the heat from being
excessively recovered.
SUMMARY OF THE INVENTION
[0008] The present invention is made in view of the foregoing
matter, and it is an object of the present invention to provide an
exhaust heat recovery apparatus, which is capable of restricting
excess recovery of heat with a simple structure.
[0009] According to an aspect of the present invention, an exhaust
heat recovery apparatus includes an evaporation unit, a
condensation unit, an evaporation-side communication part, a
condensation-side communication part and a throttle part. The
evaporation unit is to be disposed in an exhaust gas passage
through which an exhaust gas exhausted from an engine flows, for
performing heat exchange between the exhaust gas and an operation
fluid flowing therein, thereby evaporating the operation fluid. The
condensation unit is to be disposed in a coolant passage through
which an engine coolant flows, for performing heat exchange between
the engine coolant and the operation fluid that has been evaporated
in the evaporation unit, thereby condensing the operation fluid.
The evaporation-side communication part connects the evaporation
unit and the condensation unit for introducing evaporated operation
fluid from the evaporation unit to the condensation unit. The
condensation-side communication part connects the condensation unit
and the evaporation unit for introducing condensed operation fluid
from the condensation unit to the evaporation unit. The throttle
part is disposed in the condensation-side communication part.
[0010] The throttle part is configured to restrict an exhaust heat
from being excessively recovered. Accordingly, the excess recovery
of heat is restricted by a simple structure.
[0011] For example, the throttle part is constructed of a fixed
throttle having an orifice. An upper limit of the quantity of heat
recovered in the exhaust heat recovery apparatus can be determined
by setting an opening degree of an orifice of the throttle part and
the amount of operation fluid enclosed in the exhaust heat recovery
apparatus.
[0012] As another example, the throttle part is provided by a
variable throttle that is capable of varying an opening degree of
an orifice through which the operation fluid in accordance with a
temperature of the operation fluid.
[0013] According to a second aspect of the present invention, an
exhaust heat recovery apparatus includes an evaporation unit, a
condensation unit, an evaporation-side communication part, a
condensation-side communication part. The evaporation unit is to be
disposed in an exhaust gas passage through which an exhaust gas
flows, for performing heat exchange between the exhaust gas and an
operation fluid flowing therein, thereby evaporating the operation
fluid. The condensation unit is to be disposed in a coolant passage
through which an engine coolant flows, for performing heat exchange
between the engine coolant and the operation fluid that has been
evaporated in the evaporation unit, thereby condensing the
operation fluid. The evaporation-side communication part connects
the evaporation unit and the condensation unit and defines a
passage for introducing the operation fluid from the evaporation
unit to the condensation unit. The condensation-side communication
part connects the condensation unit and the evaporation unit, and
defines a passage for introducing the operation fluid from the
condensation unit to the evaporation unit. The condensation-side
communication part includes a throttle portion that has a reduced
passage area.
[0014] Accordingly, the excess recovery of heat is restricted by
partly reducing the passage area of the condensation-side
communication part.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] Other objects, features and advantages of the present
invention will become more apparent from the following detailed
description made with reference to the accompanying drawings, in
which like parts are designated by like reference numbers and in
which:
[0016] FIG. 1 is a schematic cross-sectional view of an exhaust
heat recovery apparatus according to a first embodiment of the
present invention;
[0017] FIGS. 2A and 2B are conceptual views for showing operations
of an exhaust heat recovery apparatus as an comparative
example;
[0018] FIGS. 2C and 2D are conceptual views for showing operations
of the exhaust heat recovery apparatus according to the first
embodiment;
[0019] FIG. 3A is an enlarged schematic cross-sectional view of an
evaporation-side communication part of a exhaust heat recovery
apparatus, in an operation fluid low-temperature condition,
according to a second embodiment of the present invention;
[0020] FIG. 3B is an enlarged schematic cross-sectional view of the
evaporation-side communication part of the exhaust heat recovery
apparatus, in an operation fluid high-temperature condition,
according to the second embodiment of the present invention;
[0021] FIG. 4 is an enlarged schematic cross-sectional view of a
condensation-side communication part of an exhaust heat recovery
apparatus according to a third embodiment of the present
invention;
[0022] FIG. 5 is an enlarged schematic cross-sectional view of a
condensation-side communication part of an exhaust heat recovery
apparatus according to another embodiment of the present invention;
and
[0023] FIG. 6 is a schematic cross-sectional view of an exhaust
heat recovery apparatus of a related art.
DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS
First Embodiment
[0024] Referring to FIG. 1, an exhaust heat recovery apparatus of a
first embodiment of the present invention is employed in a vehicle
that is driven by an engine (e.g., internal combustion engine), for
recovering exhaust heat of an exhaust gas from an exhaust system of
the engine and using the heat for facilitating an engine warming up
or the like.
[0025] The exhaust heat recovery apparatus generally includes an
evaporation unit 1 and a condensation unit 2. The evaporation unit
1 is disposed in a first housing 100 that is in communication with
an exhaust gas passage (not shown) through which the exhaust gas
exhausted from the engine flows. In the present embodiment, for
example, the first housing 100 is disposed in an exhaust pipe
through which the exhaust gas flows. The evaporation unit 1
performs heat exchange between the exhaust gas and an operation
fluid flowing therein, thereby to evaporate the operation
fluid.
[0026] The condensation unit 2 is disposed outside of the exhaust
pipe. The condensation unit 2 is disposed in a second housing 200
that is in communication with a coolant passage (not shown) of the
engine, through which an engine coolant flows. The condensation
unit 2 performs heat exchange between the operation fluid that has
been evaporated in the evaporation unit 1 and the engine coolant,
thereby to condense the operation fluid. The second housing 200 has
a coolant inlet port 201 and a coolant outlet port 202. The coolant
inlet port 201 is coupled to the coolant passage at a position
downstream of the engine for introducing the coolant into the
second housing 200. The coolant outlet port 202 is coupled to the
coolant passage at a position upstream of the engine for
introducing the coolant from the second housing 200 to the coolant
passage.
[0027] In the present embodiment, for example, the first housing
100 and the second housing 200 are disposed adjacent to each other.
Also, a clearance is provided between the first housing 100 and the
second housing 200.
[0028] The evaporation unit 1 has a plurality of evaporation-side
heat pipes 3a and evaporation-side fins 4a joined to outer surfaces
of the heat pipes 3a. The fins 4a are, for example, corrugate fins.
Each of the heat pipes 3a has a generally flat tubular shape. The
heat pipe 3a is orientated such that its longitudinal axis extends
in a vertical direction V, such as, an up and down direction in
FIG. 1. Also, the heat pipe 3a is orientated such that a major axis
of a cross-section defined in a direction perpendicular to the
longitudinal axis of the pipe 3a is substantially parallel to a
flow direction of the exhaust gas, such as in a direction
perpendicular to a paper surface of FIG. 1. The heat pipes 3a are
stacked parallel to each other in a pipe stacking direction H, such
as in a horizontal direction.
[0029] The evaporation unit 1 has evaporation-side headers 5a at
both ends of the heat pipes 3a. The headers 5a extend in the pipe
stacking direction H to be in communication with all the heat pipes
3a. One of the headers 5a, which is in communication with upper
ends of the heat pipes 3a, is referred to as a first
evaporation-side header 51a, and the other header 5a, which is in
communication with lower ends of the heat pipes 3a, is referred to
as a second evaporation-side header 52a.
[0030] The condensation unit 2 includes condensations-side heat
pipes 3b and condensation-side fins 4b joined to outer surfaces of
the heat pipes 3b. The fins 4b are, for example, corrugate fins.
The heat pipes 3b are generally flat tubes. Each of the heat pipes
3b is orientated such that its longitudinal axis extends in the
vertical direction V, such as, in the up and down direction in FIG.
1. Also, the heat pipe 3b is orientated such that a major axis of a
cross-section defined in a direction perpendicular to the
longitudinal axis of the pipe 3b is substantially parallel to the
flow direction of the exhaust gas of the evaporation unit 1, such
as in the direction perpendicular to the paper surface of FIG. 1.
The heat pipes 3b are stacked parallel to each other in the pipe
stacking direction H, such as in the horizontal direction.
[0031] The condensation unit 2 includes condensation-side headers
5b at both ends of the heat pipes 3b. The headers 5b extend in the
pipe stacking direction H to be in communication with all the heat
pipes 3b. One of the headers 5b, which is in communication with
upper ends of the heat pipes 3b, is referred to as a first
condensation-side header 51b, and the other header 5b, which is in
communication with lower ends of the heat pipes 3b, is referred to
as a second condensation-side header 52b.
[0032] The evaporation-side headers 5a are in communication with
the condensation-side headers 5b through communication parts 6,
which have substantially tubular shapes. Thus, a closed, looped
path is formed by the heat pipes 3a, 3b, the headers 5a, 5b and the
communication parts 6. The path is filled with the operation fluid
that is capable of being evaporated and condensed, such as water,
alcohol or the like. The operation fluid circulates through the
evaporation unit 1 and the condensation unit 2.
[0033] One of the communication parts 6, which is located on an
upper side and connects the first evaporation-side header 51a and
the first condensation-side header 51b, is referred to as a
evaporation-side communication part 61. The operation fluid that
has been evaporated in the evaporation unit 1 is introduced to the
condensation unit 2 through the evaporation-side communication part
61.
[0034] The other communication part 6, which is located on a lower
side and connects the second evaporation-side header 52a and the
second condensation-side header 52b, is referred to as a
condensation-side communication part 62. The operation fluid that
has been condensed in the condensation unit 2 is introduced to the
evaporation unit 1 through the condensation-side communication part
62.
[0035] The condensation-side communication part 62 has a fixed
throttle 7a as a throttle part. In the present embodiment, a
throttle member 70 is disposed in the condensation-side
communication part 62, and the fixed throttle 7a is provided by the
throttle member 70. That is, the throttle member 70 is disposed
such that a passage area (e.g., a cross-sectional area) of a
passage through which the condensed operation fluid flows is partly
reduced in the condensation-side communication part 62.
[0036] The throttle member 70 forms an orifice having a reduced
cross-section. For example, the throttle member 70 has a shape so
that a cross-sectional area of the orifice gradually reduces from
an upstream end toward a middle portion and gradually increases
from the middle portion toward a downstream end, with respect to
the flow of the condensed operation fluid. The throttle member 70
has a first tapered tubular wall 701 whose inner diameter reduces
from an upstream position toward a downstream position with respect
to the flow of the operation fluid, and a second tapered tubular
wall 702 continuously extends from a downstream end of the first
tapered tubular wall 702. An inner diameter of the second tapered
tubular wall 702 increases from an upstream position toward a
downstream position with respect to the flow of the operation
fluid.
[0037] Next, an operation of the exhaust heat recovery apparatus
will be described. FIGS. 2A and 2B are conceptual views for showing
operations of an exhaust heat recovery apparatus without having a
throttle part as a comparative example. FIGS. 2C and 2D are
conceptual views for showing operations of the exhaust heat
recovery apparatus of the present embodiment.
[0038] FIGS. 2A and 2C show conditions where the quantity Qin of
heat of the exhaust gas introduced in the exhaust heat recovery
apparatus is a first value Q1. FIGS. 2B and 2D show conditions
where the quantity Qin of heat of the exhaust gas is a second value
Q2 that is greater than the first value Q1. In FIGS. 2A to 2D, the
plurality of evaporation-side heat pipes 3a is simply illustrated
by a singe heat pipe 3a, for convenience of explanation. Likewise,
the plurality of condensation-side heat pipes 3b is simply
illustrated by a single heat pipe 3b. Further, the illustration of
the fins 4a, 4b and the first and second housings 100, 200 are
omitted in FIGS. 2A to 2D.
[0039] The operation fluid evaporated in the evaporation unit 1
flows in the condensation unit 2 through the evaporation-side
communication part 61. In the condensation unit 2, the operation
fluid is condensed and liquefied. The liquefied operation fluid
flows in the evaporation unit 1 through the condensation-side
communication part 62.
[0040] Due to the balance of the evaporation of the operation fluid
in the evaporation unit 1 and the condensation of the operation
fluid in the condensation unit 2, a water level difference h of the
operation fluid is generated between the evaporation unit 1 and the
condensation unit 2. The operation fluid is returned to the
evaporation unit 1 from the condensation unit 2 due to the water
level difference h. In this way, the operation fluid is circulated
in the exhaust heat recovery apparatus.
[0041] In the exhaust heat recovery apparatus shown in FIG. 2A,
pressure loss .DELTA.P1 of a return flow of the operation fluid and
the water level difference h satisfy the following relation:
.DELTA.P1=.rho.gh
[0042] In the above equation, p denotes the density of the
operation fluid in a liquid phase, and g denotes the gravitational
acceleration. Here, the density p of the operation fluid and the
gravitational acceleration g are constant. Thus, when the quantity
Qin of the heat of the exhaust gas is constant, the water level
difference h is determined by the pressure loss .DELTA.P1. Qout
denotes the quantity of heat transferred to the coolant in the
condensation unit 2.
[0043] As shown in FIG. 2B, when the quantity Qin of the heat of
the exhaust gas increases, the amount of the return flow of the
operation fluid increases. With this, the flow speed of the
operation fluid increases. Therefore, the pressure loss A.DELTA.P1
of the return flow of the operation fluid increases, and hence the
water level difference h increases.
[0044] In the present embodiment shown in FIG. 2C, since the
condensation-side communication part 62 is provided with the fixed
throttle 7a, pressure loss .DELTA.P' of the return flow of the
operation fluid is determined by the sum of the pressure loss
.DELTA.P1 and pressure loss .DELTA.P2 due to the fixed throttle 7a
(i.e., .DELTA.P'=.DELTA.P1+.DELTA.P2). In this case, a water level
difference h2 between the evaporation unit 1 and the condensation
unit 2 is greater than the water level difference h of the exhaust
heat recovery apparatus shown in FIG. 2A by the amount of the
pressure loss .DELTA.P2 of the fixed throttle 7a.
[0045] Then, when the quantity Qin of the heat of the exhaust gas
increases as shown in FIG. 2D, the pressure loss .DELTA.P' of the
return flow of the operation fluid increases. With this, the water
level difference h2, which is necessary for returning the operation
fluid, is increased. When it becomes difficult to keep the water
level difference h2 necessary for returning the operation fluid,
the amount of the operation fluid returned to the evaporation unit
1 is limited. Thus, the quantity of heat recovered in the exhaust
heat recovery apparatus plateaus.
[0046] In the present embodiment, the fixed throttle 7a is provided
in the condensation-side communication part 62. The upper limit of
the quantity of heat recovered in the exhaust heat recovery
apparatus is determined by previously setting an opening degree of
the fixed throttle 7a, such as the passage area of the orifice of
the fixed throttle 7a, and the amount of the operation fluid filled
in the exhaust heat recovery apparatus.
[0047] Thus, the structure for restricting the excess heat recovery
is simplified, as compared with an exhaust heat recovery apparatus
having a diaphragm-type valve unit constructed of a diaphragm, a
valve body and the like. (Second embodiment) A second embodiment of
the present invention will be described with reference to FIGS. 3A
and 3B. Components similar to the first embodiment will be
designated by the same reference numerals, and a description
thereof is not repeated.
[0048] In the second embodiment, the condensation-side
communication part 62 is provided with a variable throttle 7b as
the throttle part, in place of the fixed throttle 7a of the first
embodiment. The variable throttle 7b is configured to vary the
opening degree of an orifice defined therein, that is, the
cross-sectional area of the passage of the operation fluid, in
accordance with the temperature of the operation fluid.
[0049] FIG. 3A shows a condition of the variable throttle 7b when
the temperature of the operation fluid is low, and FIG. 3B shows a
condition of the variable throttle 7b when the temperature of the
operation fluid is high. The variable throttle 7b is configured
such that the opening degree is reduced in accordance with an
increase in the temperature of the operation fluid.
[0050] In the present embodiment, the variable throttle 7b is made
of a material that is deformable in accordance with the ambient
temperature. For example, the material of the variable throttle 7b
can be a bi-metal, a shape-memory alloy, or the like. Further, in
the present embodiment, the variable throttle 7b is configured such
that the passage of the operation fluid is not fully closed, even
when the temperature of the operation fluid flowing through the
condensation-side communication part 62 is increased.
[0051] Next, an operation of the exhaust heat recovery apparatus of
the second embodiment will be described. When the quantity Qin of
the heat of the exhaust gas increases, the quantity of heat
recovered in the exhaust heat recovery apparatus increases. In the
present embodiment, the variable throttle 7b is provided in the
condensation-side communication part 62. When the quantity Qin of
the heat of the exhaust gas increases, the temperature of the
operation fluid increases. Thus, the opening degree of the variable
throttle 7b reduces with the increase of the temperature of the
operation fluid, and hence the pressure loss .DELTA.P2 increases.
As such, an increase in the quantity of the heat recovered in the
exhaust heat recovery apparatus is limited at a certain point. When
the quantity Qin of the heat of the exhaust gas further increases,
the opening degree of the variable throttle 7b further reduces, and
hence the pressure loss .DELTA.P2 further increases. As a result,
the amount of the return flow of the operation fluid reduces, and
thus the quantity of heat recovered in the exhaust heat recovery
apparatus reduces.
[0052] In the present embodiment, the condensation-side
communication part 62 is provided with the variable throttle 7b
that varies the opening degree in accordance with the increase in
the temperature of the operation fluid. Therefore, the quantity of
heat recovered in the exhaust heat recovery apparatus is reduced in
accordance with the increase in temperature of the operation fluid.
Because the quantity of heat recovered in the exhaust heat recovery
apparatus is limited when an engine load is high, such as in
summer, in which the temperature of the operation fluid is high, it
is less likely that the engine will be overheated.
Third Embodiment
[0053] A third embodiment of the present invention will be
described with reference to FIG. 4. Components similar to the first
embodiment will be designated by the same reference numerals, and a
description thereof is not repeated.
[0054] As shown in FIG. 4, the exhaust heat recovery apparatus of
the present embodiment has a variable throttle 7c in the
condensation-side communication part 62, as the throttle part. The
variable throttle 7c includes an orifice 71, a valve body 72 for
opening and closing the orifice 71, and a temperature sensitive
deformable member 73. An end of the deformable member 73 is
connected to an end wall of the vale body 72 on a side opposite to
the orifice 71. An opposite end of the deformable member 73 is
connected to a support member 74 that is disposed in the
condensation-side communication part 62.
[0055] The deformable member 73 is deformable in response to the
temperature. For example, the deformable member 73 is configured to
be thermally expanded when the temperature of the operation fluid
passing through the condensation-side communication part 62 exceeds
a predetermined temperature. The deformable member 73 is, for
example, made of thermo-wax, thermo-metal, or the like, which has a
coefficient of thermal expansion greater than that of the metal of
the condensation-side communication part 62.
[0056] When the temperature of the operation fluid passing through
the condensation-side communication part 62 increases, the valve
body 72 is moved in a direction to reduce the opening degree of the
orifice 71. On the other hand, when the temperature of the
operation fluid passing through the condensation-side communication
part 62 reduces, the valve body 72 is moved in a direction to
increase the opening degree of the orifice 71. In the present
embodiment, the valve body 72 does not fully close the orifice 71,
even when the temperature of the operation fluid passing through
the condensation-side communication part 62 is increased.
[0057] Since the condensation-side communication part 62 is
provided with the variable throttle 7c that varies the opening
degree of the orifice 71 in accordance with the increase in the
temperature of the operation fluid, the quantity of heat recovered
in the exhaust heat recovery apparatus is reduced in accordance
with the increase in temperature of the operation fluid. As such,
the effects similar to the second embodiment will be provided.
Other Embodiments
[0058] In the first embodiment, the throttle member 70 forms the
orifice the inner diameter of which gradually reduces from the
upstream position toward the middle position and gradually
increases from the middle position toward the downstream position
with respect to the flow of the operation fluid. However, the shape
of the orifice of the throttle member 70 is not limited to the
above. For example, the throttle member 70 may have a cylindrical
shape and may have a substantially constant passage area.
[0059] In the first embodiment, the fixed throttle 7a is provided
by the throttle member 70. However, the fixed throttle 7a can be
formed by partly reducing a passage area (e.g., inner diameter) of
the condensation-side communication part 62, as shown in FIG. 5. In
this case, the number of components is reduced. Further, the
pressure loss .DELTA.P2 of the fixed throttle 7a is determined by
arranging an inner diameter d and a length L of the fixed throttle
7a.
[0060] In the second and third embodiments, the variable throttles
7b, 7c are disposed to directly contact the operation fluid, and
the opening degrees of the variable throttles 7b, 7c are
mechanically controlled in accordance with the temperature of the
operation fluid. Alternatively, a temperature sensor can be
separately employed to detect the temperature of the operation
fluid passing through the condensation-side communication part 62,
and the variable throttle 7b, 7c can be configured such that the
opening degrees thereof are electrically controlled based on the
temperature detected by the temperature sensor.
[0061] In the above embodiments, the condensation-side
communication part 62 is exemplarily orientated horizontally.
However, the orientation of the condensation-side communication
part 62 is not limited to the above. The condensation-side
communication part 62 can be inclined relative to a horizontal
direction.
[0062] Additional advantages and modifications will readily occur
to those skilled in the art. The invention in its broader term is
therefore not limited to the specific details, representative
apparatus, and illustrative examples shown and described.
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