U.S. patent application number 11/641518 was filed with the patent office on 2007-06-21 for waste heat collecting apparatus.
This patent application is currently assigned to DENSO Corporation. Invention is credited to Shinichi Hamada, Satoshi Inoue, Seiji Inoue, Kimio Kohara, Masashi Miyagawa, Yasutoshi Yamanaka.
Application Number | 20070137851 11/641518 |
Document ID | / |
Family ID | 37895900 |
Filed Date | 2007-06-21 |
United States Patent
Application |
20070137851 |
Kind Code |
A1 |
Hamada; Shinichi ; et
al. |
June 21, 2007 |
Waste heat collecting apparatus
Abstract
A waste heat collecting apparatus has a loop-type heat pipe,
which has a vaporizing portion arranged in an area for exhaust gas
passage and a condensing portion provided in a water tank, through
which coolant foran engine flows. Working fluid is circulated from
the vaporizing portion to the condensing portion and back to the
vaporizing portion. A valve device is provided at a downstream side
of the condensing portion, wherein the valve device is operated to
open or close a fluid passage for the working fluid depending on an
inner pressure of the heat pipe.
Inventors: |
Hamada; Shinichi;
(Anjo-city, JP) ; Miyagawa; Masashi;
(Ichinomiya-city, JP) ; Inoue; Seiji; (Nukata-gun,
JP) ; Kohara; Kimio; (Nagoya-city, JP) ;
Yamanaka; Yasutoshi; (Kariya-city, JP) ; Inoue;
Satoshi; (Kariya-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: |
37895900 |
Appl. No.: |
11/641518 |
Filed: |
December 19, 2006 |
Current U.S.
Class: |
165/274 ;
123/41.2; 165/104.21 |
Current CPC
Class: |
F28D 15/06 20130101;
F28D 15/0266 20130101; F01N 5/02 20130101; Y02T 10/12 20130101 |
Class at
Publication: |
165/274 ;
123/041.2; 165/104.21 |
International
Class: |
F01P 9/02 20060101
F01P009/02; F28D 15/00 20060101 F28D015/00; F28F 27/00 20060101
F28F027/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 20, 2005 |
JP |
2005-366895 |
Dec 27, 2005 |
JP |
2005-375667 |
Jul 26, 2006 |
JP |
2006-203780 |
Nov 21, 2006 |
JP |
2006-314684 |
Claims
1. A waste heat collecting apparatus for an automotive vehicle
comprising: a loop-type heat pipe having; a vaporizing portion
arranged in an area for exhaust gas passage for vaporizing working
fluid filled in the heat pipe with heat contained in exhaust gas
from an engine; a condensing portion for condensing working fluid,
which is vaporized in the vaporizing portion, by coolant for the
engine; and a connecting passage for connecting the condensing
portion with the vaporizing portion, a valve device provided in the
connecting passage between the condensing portion and the
vaporizing portion for opening or closing the connecting passage,
wherein the valve device has a driving portion and a valve body
connected with the driving portion for opening or closing the
connecting passage, the driving portion being operated by at least
one of the operating parameters, which comprises inner pressure of
the working fluid in the heat pipe, temperature of the working
fluid in the heat pipe, and temperature of the coolant, and wherein
the valve device is provided at a downstream side of the condensing
portion or an upstream side of the vaporizing portion.
2. A waste heat collecting apparatus according to claim 1, wherein
the valve device has a hysteresis for an opening and closing
operation of the valve body.
3. A waste heat collecting apparatus according to claim 2, wherein
the driving portion is operated by the inner pressure of the
working fluid in the heat pipe, the valve body closes the
connecting passage when the inner pressure is higher than a first
predetermined pressure, and the valve body opens the connecting
passage when the inner pressure is lower than a second
predetermined pressure, wherein the first predetermined pressure is
higher than the second predetermined pressure.
4. A waste heat collecting apparatus according to claim 3, wherein
the first predetermined pressure is 0.1 MPa, and the second
predetermined pressure is 0.05 MPa.
5. A waste heat collecting apparatus according to claim 3, wherein
water is used as the working fluid for the heat pipe, the first
predetermined pressure is 0.1 MPa, and the second predetermined
pressure is 0.6 kPa.
6. A waste heat collecting apparatus according to claim 1, wherein
the valve device has a bypass aperture such that a small amount of
the working fluid is circulated from the condensing portion to the
vaporizing portion even when the valve body is moved to its closed
position.
7. A waste heat collecting apparatus according to claim 1, further
comprising: a heat insulating portion provided between the
vaporizing portion and the condensing portion for insulating the
condensing portion from the vaporizing portion.
8. A waste heat collecting apparatus according to claim 7, wherein
the heat insulating portion is formed by multiple air spaces formed
at a heat insulating plate, which is provided between the
vaporizing portion and the condensing portion.
9. A waste heat collecting apparatus according to claim 1, wherein
the connecting passage is arranged at such a portion, which is
outside of the area for the exhaust gas passage.
10. A waste heat collecting apparatus according to claim 1, wherein
the connecting passage is arranged in the area for the exhaust gas
passage.
11. A waste heat collecting apparatus according to claim 10,
further comprising: a heat insulating wall provided at an upstream
side of the connecting passage with respect to the exhaust gas
flow.
12. A waste heat collecting apparatus according to claim 1, wherein
the vaporizing portion has multiple tubes arranged in the area for
the exhaust gas passage, such that longitudinal direction of the
tubes is arranged in a vertical direction, the condensing portion
is arranged at an upper side of the vaporizing portion and arranged
in a coolant passage through which the coolant for the engine
flows, and the connecting passage is a return pipe, a longitudinal
length of which is almost equal to that of the tubes (111) of the
vaporizing portion.
13. A waste heat collecting apparatus according to claim 12,
wherein the vaporizing portion comprises multiple tube lines, each
having multiple tubes, wherein the tube lines are arranged in a
direction of the exhaust gas flow, and the return pipe is arranged
at a downstream side of the multiple tube lines.
14. A waste heat collecting apparatus according to claim 1, wherein
the vaporizing portion comprises; multiple tubes arranged in an
area for the exhaust gas passage, such that longitudinal direction
of the tubes is arranged in a vertical direction, a first header
portion for collecting the working fluid from the tubes, and a
second header portion for distributing the condensed working fluid,
which is condensed at the condensing portion, into the tubes, the
condensing portion is arranged in a coolant passage through which
the coolant for the engine flows, and the condensing portion is
respectively connected to the first and second header portions
through the connecting passage.
15. A waste heat collecting apparatus according to claim 1, wherein
the driving portion of the valve device has a diaphragm, which is
displaced depending on the inner pressure of the working fluid for
the heat pipe.
16. A waste heat collecting apparatus according to claim 1, wherein
the driving portion of the valve device has a thermo-wax portion,
which is displaced depending on the temperature of the working
fluid for the heat pipe or the temperature of the coolant for the
engine.
17. A waste heat collecting apparatus according to claim 16,
wherein the valve device has the thermo-wax portion expanded or
contracted depending on the temperature of the coolant, the valve
body comprises a bellows having one opened end connected to the
thermo-wax portion, wherein the other end of the bellows is closed,
and a communication port is provided in the valve device so that a
part of the coolant enters into the inside space of the
bellows.
18. A waste heat collecting apparatus according to claim 1, wherein
the connecting passage has a fluid flow-in passage for allowing the
working fluid vaporized at the vaporizing portion to flow into the
condensing portion, and a fluid flow-out passage for returning the
condensed working fluid condensed at the condensing portion to the
vaporizing portion, the fluid flow-in and flow-out passages are
arranged closer to each other, and the fluid flow-in passage is
arranged at a position higher in a vertical direction than a liquid
level of the working fluid in the vaporizing portion, which
corresponds to a liquid level of the working fluid when the heat
collecting apparatus is not in its operation.
19. A waste heat collecting apparatus according to claim 1, wherein
the connecting passage is formed by a single pipe, which is
arranged at a position higher in a vertical direction than a liquid
level of the working fluid in the vaporizing portion, which
corresponds to a liquid level of the working fluid when the heat
collecting apparatus is not in its operation.
20. A waste heat collecting apparatus according to claim 19,
wherein a partitioning wall provided in the pipe for separating a
space of the pipe into an upper space for the working fluid and a
lower space for the condensed working fluid, so that the condensed
working fluid is not directly contacted with the working fluid.
21. A waste heat collecting apparatus according to claim 1, wherein
the valve device is arranged at a position higher in a vertical
direction than a liquid level of the working fluid in the
vaporizing portion, which corresponds to a liquid level of the
working fluid when the heat collecting apparatus is not in its
operation.
22. A waste heat collecting apparatus according to claim 1, wherein
a reverse flow preventing means is provided in the condensing
portion, so that a reverse flow of the condensed working fluid to
the vaporizing portion is suppressed.
23. A waste heat collecting apparatus according to claim 22,
wherein the reverse flow preventing means is formed by a plate
member, which is inclined in a flow direction of the working
fluid.
24. A waste heat collecting apparatus according to claim 22,
wherein the reverse flow preventing means is formed as a
restricting portion, so that an inner diameter of a fluid passage
for the working fluid is made smaller.
25. A waste heat collecting apparatus having a loop-type heat pipe
comprising: a vaporizing portion arranged in an area for exhaust
gas passage for vaporizing working fluid filled in the heat pipe
with heat contained in exhaust gas from an engine, wherein the
vaporizing portion having multiple tubes vertically extending, and
a lower and an upper header tank portion provided at both
longitudinal ends of the multiple tubes; a water tank provided at
an upper side of the vaporizing portion, through which coolant for
the engine flows; a condensing portion provided in an inside of the
water tank for condensing working fluid, which is vaporized in the
vaporizing portion, by means of heat exchange with the coolant
flowing through the water tank, wherein an upstream end of the
condensing portion is connected with the upper header tank portion
and a downstream end of the condensing portion is operatively
connected to the lower header tank portion; a condensed water
return portion provided between the downstream end of the
condensing portion and the lower header tank portion; and a valve
device provided in the water tank for opening or closing a fluid
passage between the downstream end of the condensing portion and
the condensed water return portion, wherein the valve device has a
driving portion and a valve body connected with the driving portion
for opening or closing the fluid passage, and the driving portion
is operated by an inner pressure of the working fluid in the heat
pipe.
26. A waste heat collecting apparatus having a loop-type heat pipe
comprising: a vaporizing portion arranged in an area for exhaust
gas passage for vaporizing working fluid filled in the heat pipe
with heat contained in exhaust gas from an engine, wherein the
vaporizing portion having multiple tubes vertically extending, and
a lower and an upper header tank portion provided at both
longitudinal ends of the multiple tubes; a water tank provided at a
horizontal side of the vaporizing portion, through which coolant
for the engine flows; a condensing portion provided in an inside of
the water tank for condensing working fluid, which is vaporized in
the vaporizing portion, by means of heat exchange with the coolant
flowing through the water tank, wherein an upstream end of the
condensing portion is connected with the upper header tank portion
and a downstream end of the condensing portion is operatively
connected to the lower header tank portion; and a valve device
provided in the water tank at a downstream side of the condensing
portion for opening or closing a fluid passage between the
downstream end of the condensing portion and the lower header tank
portion, wherein the valve device has a driving portion and a valve
body connected with the driving portion for opening or closing the
fluid passage, and the driving portion is operated by an inner
pressure of the working fluid in the heat pipe.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is based on Japanese Patent Application
Nos. 2005-366895 filed on Dec. 20, 2005, 2005-375667 filed on Dec.
27, 2005, 2006-203780 filed on Jul. 26, 2006, and 2006-314684 filed
on Nov. 21, 2006, the disclosures of which are incorporated herein
by reference.
FIELD OF THE INVENTION
[0002] The present invention relates to a waste heat collecting
apparatus for collecting waste heat from an internal combustion
engine to utilize the collected heat for heating engine coolant,
wherein the waste heat collecting apparatus has a loop-type heat
pipe. The invention is preferably applied to an automotive vehicle
having the internal combustion engine.
BACKGROUND OF THE INVENTION
[0003] A heat exchanger of a heat pipe type is known in the art,
for example, as disclosed in Japanese Patent Publication No.
H4-45393. A conventional heat exchanger of this prior art has a
loop-type heat pipe, wherein a flow control valve is provided in a
fluid passage (condensed coolant passage) connecting a condensing
portion with a vaporizing portion for controlling an amount of
working fluid flowing through the fluid passage.
[0004] In the above conventional heat exchanger, a bypass passage
is provided, which is bifurcated from another fluid passage (vapor
flow passage) connecting the vaporizing portion to the condensing
portion. A driving portion of the flow control valve is provided in
the bypass passage, such that the driving portion is operated
depending on vapor pressure (higher than a predetermined pressure),
which is applied to the driving portion from the vapor flow passage
(the vaporizing portion). The flow control valve further has a
driven portion on a side of the condensing portion for closing the
condensed coolant passage in association of the operation of the
driving portion.
[0005] The driving portion is formed as a diaphragm motor, which is
composed of a diaphragm having a valve body connected to the
diaphragm. The driven portion is formed as an emergency closing
valve for closing the condensed coolant passage, which is composed
of a link moved in association with displacement of the diaphragm
and a cable. A communication pipe is further provided between the
diaphragm motor and the emergency closing valve for discharging
vapor entered the diaphragm motor to the emergency closing
valve.
[0006] Opening degree of the flow control valve is adjusted
depending on temperature of the working fluid in the condensing
portion. As a result, an amount of heat transfer to another working
fluid is adjusted, and an inner pressure of the heat pipe is
controlled at a value, which is within a desired range.
[0007] In the case that the flow control valve is kept opened due
to any abnormal condition, and the vapor pressure exceeds a
predetermined pressure as a result of excessive vaporization at the
vaporizing portion, the driving portion is operated so that the
condensed coolant passage is closed by the driven portion which is
operated in association with the driving portion. Accordingly, the
circulation of the working fluid is forcibly stopped to prevent an
abnormal increase of the vapor pressure higher than the
predetermined pressure. A blowout of the heat pipe is thereby
prevented.
[0008] According to the above conventional heat exchanger, however,
the driving portion is provided in the vapor flow passage, whereas
the driven portion is provided in the condensed coolant passage. It
is necessary, therefore, to provide the link and wire for
operatively associating both of them. Furthermore, the
communicating pipe is necessary for discharging the vapor (which
has entered the diaphragm motor) to the emergency closing valve. As
above, the structure of the heat exchanger is complicated as a
whole.
[0009] In addition, when the operation for the heat pipe is stopped
due to the closing of the emergency closing valve, the inner
pressure of the heat pipe is decreased and thereby the emergency
closing valve is opened again in a short period. An inter-rock
means is, for example, necessary for the link and/or cable in order
to avoid the above re-open of the emergency closing valve. This is
also one of reasons that the structure of the heat exchanger
becomes complicated.
SUMMARY OF THE INVENTION
[0010] The present invention is made in view of the foregoing
problems, and has an object to provide a waste heat collecting
apparatus having a loop-type heat pipe, according to which
collection of the excessive heat is avoided with a simple
structure.
[0011] According to one of features of the present invention, a
waste heat collecting apparatus has a loop-type heat pipe. The
loop-type heat pipe has a vaporizing portion arranged in an area
for exhaust gas passage for vaporizing working fluid filled in the
heat pipe with heat contained in exhaust gas from an engine; a
condensing portion for condensing working fluid, which is vaporized
in the vaporizing portion, by engine coolant for the engine; and a
connecting passage for connecting the condensing portion with the
vaporizing portion.
[0012] The waste heat collecting apparatus further has a valve
device provided in the connecting passage between the condensing
portion and the vaporizing portion for opening or closing the
connecting passage, wherein the valve device has a driving portion
and a valve body connected with the driving portion for opening or
closing the connecting passage.
[0013] The driving portion is operated by at least one of the
operating parameters, which comprises [0014] inner pressure of the
working fluid in the heat pipe, [0015] temperature of the working
fluid in the heat pipe, and [0016] temperature of the coolant,
[0017] wherein the valve device is provided at a downstream side of
the condensing portion or an upstream side of the vaporizing
portion.
[0018] According to another feature of the invention, a waste heat
collecting apparatus having a loop-type heat pipe comprises: a
vaporizing portion arranged in an area for exhaust gas passage for
vaporizing working fluid filled in the heat pipe with heat
contained in exhaust gas from an engine, wherein the vaporizing
portion having multiple tubes vertically extending, and a lower and
an upper header tank portion provided at both longitudinal ends of
the multiple tubes; a water tank provided at an upper side of the
vaporizing portion, through which coolant for the engine flows; and
a condensing portion provided in an inside of the water tank for
condensing working fluid, which is vaporized in the vaporizing
portion, by means of heat exchange with the coolant flowing through
the water tank, wherein an upstream end of the condensing portion
is connected with the upper header tank portion and a downstream
end of the condensing portion is operatively connected to the lower
header tank portion.
[0019] The waste heat collecting apparatus further comprises: a
condensed water return portion provided between the downstream end
of the condensing portion and the lower header tank portion; and a
valve device provided in the water tank for opening or closing a
fluid passage between the downstream end of the condensing portion
and the condensed water return portion, wherein the valve device
has a driving portion and a valve body connected with the driving
portion for opening or closing the fluid passage, and the driving
portion is operated by an inner pressure of the working fluid in
the heat pipe.
[0020] According to a further feature of the invention, a waste
heat collecting apparatus having a loop-type heat pipe comprises: a
vaporizing portion arranged in an area for exhaust gas passage for
vaporizing working fluid filled in the heat pipe with heat
contained in exhaust gas from an engine, wherein the vaporizing
portion having multiple tubes vertically extending, and a lower and
an upper header tank portion provided at both longitudinal ends of
the multiple tubes; a water tank provided at a horizontal side of
the vaporizing portion, through which coolant for the engine flows;
a condensing portion provided in an inside of the water tank for
condensing working fluid, which is vaporized in the vaporizing
portion, by means of heat exchange with the coolant flowing through
the water tank, wherein an upstream end of the condensing portion
is connected with the upper header tank portion and a downstream
end of the condensing portion is operatively connected to the lower
header tank portion.
[0021] The waste heat collecting apparatus further comprises a
valve device provided in the water tank at a downstream side of the
condensing portion for opening or closing a fluid passage between
the downstream end of the condensing portion and the lower header
tank portion, wherein the valve device has a driving portion and a
valve body connected with the driving portion for opening or
closing the fluid passage, and the driving portion is operated by
an inner pressure of the working fluid in the heat pipe.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] The above and 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 the drawings:
[0023] FIG. 1 is a schematic view showing a waste heat collecting
system installed in an automotive vehicle according to a first
embodiment of the present invention;
[0024] FIG. 2 is a cross sectional view showing a waste heat
collecting apparatus according to the first embodiment;
[0025] FIG. 3 is a cross sectional view taken along a line III-III
in FIG. 2;
[0026] FIG. 4 is a cross sectional view showing a valve device for
the first embodiment in a valve opened condition;
[0027] FIG. 5 is a cross sectional view showing the valve device
for the first embodiment in a valve closed condition;
[0028] FIG. 6 is a diagram showing a relation of an inner pressure
of a heat pipe with respect to a temperature of engine coolant and
heat quantity of exhaust gas;
[0029] FIG. 7 is a diagram showing an operation of valve opening
and closing for the valve device;
[0030] FIG. 8A is a time chart showing a change of the inner
pressure of the heat pipe after a start of an engine operation;
[0031] FIG. 8B is a time chart showing a change of the temperature
of the engine coolant after the start of the engine operation;
[0032] FIG. 8C is a time chart showing a change of the heat
quantity of the exhaust gas after the start of the engine
operation;
[0033] FIG. 9 is a cross sectional view showing a valve device
according to a second embodiment;
[0034] FIG. 10 is a cross sectional view showing a valve device
according to a third embodiment;
[0035] FIG. 11 is a cross sectional view showing a waste heat
collecting apparatus according to a fourth embodiment;
[0036] FIG. 12 is a cross sectional view showing a waste heat
collecting apparatus according to a fifth embodiment;
[0037] FIG. 13 is a cross sectional view showing a modified waste
heat collecting apparatus according to the fifth embodiment;
[0038] FIG. 14 is a cross sectional view showing a waste heat
collecting apparatus according to a sixth embodiment;
[0039] FIG. 15 is a cross sectional view showing a waste heat
collecting apparatus according to a seventh embodiment;
[0040] FIG. 16 is an enlarged schematic view showing a reverse flow
preventing portion of the seventh embodiment;
[0041] FIG. 17 is an enlarged schematic view showing a modification
of the reverse flow preventing portion;
[0042] FIG. 18 is an enlarged schematic view showing a restricting
portion; and
[0043] FIG. 19 is a cross sectional view showing a waste heat
collecting apparatus in an inclined position.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
First Embodiment
[0044] A waste heat collecting apparatus. 100 according to a first
embodiment of the present invention is applied to an automotive
vehicle having an engine 10 for producing a driving power for the
vehicle. The waste heat collecting apparatus 100 is provided in an
exhaust pipe 11 and a waste heat collecting circuit 30. More
detailed structure will be explained with reference to FIGS. 1 to
5, wherein FIG. 1 is a schematic view showing the waste heat
collecting apparatus 100 installed in the vehicle, FIG. 2 is a
cross sectional view of the waste heat collecting apparatus 100,
FIG. 3 is a cross sectional view taken along a line III-III in FIG.
2, FIG. 4 is a cross sectional view showing a valve device 150
provided in the waste heat collecting apparatus in a valve opened
condition, and FIG. 5 is a cross sectional view showing the valve
device 150 in a valve closed condition.
[0045] As shown in FIG. 1, the engine 10 is a water cooled type
internal combustion engine, and has the exhaust pipe 11 for
emitting exhaust gas which is produced after combustion of fuel in
the engine 10. A catalytic converter 12 is provided in the exhaust
pipe 11 for purifying the exhaust gas. The engine 10 further has a
radiator circuit 20 through which engine coolant is circulated, the
waste heat collecting circuit 30 which is formed separately from
the radiator circuit and through which the engine coolant is
circulated, and a heater circuit 40 through which the engine
coolant is also selectively circulated for heating air to be blown
into a passenger room of the vehicle.
[0046] A radiator 21 is provided in the radiator circuit 20 for
cooling down the engine coolant, circulated by a water pump 22, by
means of heat exchange with external air. A bypass passage 23 is
provided in the radiator circuit 20 for bypassing the radiator 21.
An amount of the engine coolant flowing into the radiator 21 as
well as an amount of the engine coolant flowing through the bypass
passage 23 is adjusted by a thermostat 24. In an operation of
warming up the engine 10, the amount of the engine coolant flowing
through the bypass passage 23 is increased to facilitate the
warm-up of the engine 10. Namely, super cooling of the engine
coolant is prevented in the engine warming-up operation.
[0047] One end of the waste heat collecting circuit 30 is
bifurcated from the radiator circuit 20 on an outlet side of the
engine 10, whereas the other end thereof is connected to an inlet
side of the engine 10, wherein the engine coolant is circulated
through the waste heat collecting circuit 30 by the water pump 22.
A water tank 140 (a condensing portion 130) of the waste heat
collecting apparatus 100 is provided in the waste heat collecting
circuit 30, which is described below.
[0048] One end of the heater circuit 40 is connected to another
outlet port of the engine 10 and the other end thereof is connected
to the waste heat collecting circuit 30 at a downstream side of the
waste heat collecting apparatus 100. A heater core 41 is provided
in the heater circuit 40, and the engine coolant is also circulated
through the heater circuit 40 by the water pump 22. The heater core
41 is arranged in a unit casing (not shown) of an air-conditioning
unit, and heats the air blown by a blower fan (not shown) by means
of heat exchange with hot water (the engine coolant).
[0049] As shown in FIGS. 2 and 3, the waste heat collecting
apparatus 100 is composed of a loop-type heat pipe 101 having a
vaporizing portion 110, the condensing portion 130, the valve
device 150, and a condensed water returning portion 160, which are
connected in this order. An insertion portion (not shown) is
provided in the heat pipe 110. The heat pipe 101 is evacuated
(depressurized) through the insertion portion, and the insertion
portion is tightly closed after working fluid is filled into the
heat pipe 101. The working fluid in this embodiment is water. The
boiling temperature of the water is 100.degree. C. at normal
atmosphere (1 atm). However, since the heat pipe 101 is
depressurized (e.g. 0.1 atm), the boiling temperature of the
working fluid in the heat pipe 101 becomes 5 to 10.degree. C.
Alcohol, fluorocarbon, Freon gas and so on may be used as the
working fluid.
[0050] The condensing portion 130 as well as the valve device 150
is arranged in the water tank 140. Each part of the waste heat
collecting apparatus 100 is made of stainless material having high
corrosion resistance. And those parts are integrally fixed
(soldered) to each other by soldering material clad on fixing
portions, after those parts are assembled.
[0051] The vaporizing portion 110 is composed of multiple tubes
111, multiple fins 112, a lower plate member 113, an upper plate
member 114, and a lower tank plate 115. As shown in FIGS. 2 and 3,
each of the tubes 111 is formed into a flat tube shape, and its
longitudinal direction is arranged to be a vertical direction.
Multiple tubes 111 are arranged in a horizontal direction (a
right-left direction in FIG. 2 or 3) at an equal distance (with a
tube pitch "TP"). As more exactly shown in FIG. 3, the tubes 111
are composed of three lines of tubes, each of which extends in the
right-left direction in FIG. 3. Both longitudinal ends of the tubes
111 are respectively fixed to the lower and upper plate members 113
and 114, each of which has multiple apertures. Multiple plate-type
fins 112 made of thin plate material are disposed between the tubes
111, so that the fins 112 are fixed to (contacted with) outer
surfaces of the tubes 111.
[0052] The lower tank plate 115 is provided so as to oppose to the
lower plate member 113 and the lower ends of the tubes 111, so that
a lower header portion is formed between the lower tank plate 115
and the lower plate member 113. A lower passage 116 of the lower
header portion formed between the lower tank plate 115 and the
lower plate member 113 is communicated with each lower end of the
tubes 111, so that the condensed working fluid is distributed to
each of the tubes 111.
[0053] A heat insulating plate 121 is provided, in a similar manner
to the lower tank plate 115, so as to oppose to the upper plate
member 114 and the upper ends of the tubes 111, so that an upper
header portion is formed between the heat insulating plate 121 and
the upper plate member 114. The heat insulating plate 121 is formed
into a wave form, as shown in FIG. 2. An upper passage 117 of the
upper header portion formed between the heat insulating plate 121
and the upper plate member 114 is communicated with each upper end
of the tubes 111, so that the working fluid from each of the tubes
111 is collected in the upper passage 117. A pair of side plates
118 is provided at both horizontal sides (the right and left sides)
of the waste heat collecting apparatus 100 as a reinforcing and
fixing member.
[0054] Multiple passages for exhaust gas are formed in a space
surrounded by the upper and lower plate members 114 and 113 and the
pair of side plates 118 (hereinafter also referred to as exhaust
gas passage). As shown in FIGS. 2 and 3, the exhaust gas flows in a
direction perpendicular to the sheet of FIG. 2 through the exhaust
gas passage.
[0055] The water tank 140 is composed of a lower water tank plate
141 of a flat shape and an upper water tank member 142 having a
U-shape in its cross section. An inside space defined by the lower
water tank plate 141 and the upper tank member 142 extends in a
direction, which coincides with the directions of three lines of
the tubes 111. The water tank 140 is formed at an upper side of the
upper passage 117.
[0056] An inlet pipe 143 for the engine coolant is provided at a
left end of the water tank 140, and an outlet pipe 144 is provided
at a right end of the water tank 140. The condensing portion 130 is
arranged in the inside of the water tank 140.
[0057] In the condensing portion 130, a fluid passage is formed,
which is similar to a so-called drawn-cup type heat exchanger,
wherein multiple tubes 133 formed of pairs of tube plates 131 and
132 are built up. The condensing portion 130 is composed of
multiple passage portions 133a and a pair of tank portions 133b and
133c at both longitudinal ends of the passage portions 133a. Each
of the tank portions 133b and 133c is communicated in a direction
of building up the tubes 133 (in a vertical direction).
[0058] A vapor inlet pipe 134 is provided in the tank portion 133b,
wherein one end (a lower end) of the vapor inlet pipe 134 is
communicated with the upper passage 117 and the other end (an upper
end) thereof is opened to an upper space of the tank portion 133b.
The upper passage 117 is communicated with the inside space of the
tank portion 133b through the vapor inlet pipe 134 and further
communicated with the tank portion 133c through the passage
portions 133a of the tubes 133. As above, the upper header portion
(117) of the vaporizing portion 110 is communicated with the
condensing portion 130 through the vapor inlet pipe 134. The pipe
134 is also referred to as a connecting passage for connecting the
vaporizing portion 110 with the condensing portion 130.
[0059] Multiple air spaces 120 are formed between the heat
insulating plate 121 of the wave form and the flat-shaped lower
water tank plate 141, wherein the air spaces 120 function as an
heat insulating portion between the vaporizing portion 110 and the
condensing portion 130.
[0060] The condensed water returning portion 160 is formed by a
return pipe 161 and a heat insulating wall 162. The return pipe 161
is a single pipe having a circular cross section, a longitudinal
length of which is almost equal to that of the tubes 111. One end
(an upper end) of the return pipe 161 upwardly extends through the
upper passage 117 and is communicated with an inside of the tank
portion 133c of the condensing portion 130, whereas the other end
(a lower end) thereof is communicated with the lower passage 116 of
the vaporizing portion 110. The return pipe 161 is arranged in the
space of the vaporizing portion 110 (namely, in the area of the
exhaust gas passages), such that the return pipe 161 is separated
from the neighboring tube 111 with a distance equal to the tube
pitch "TP", as shown in FIG. 3. As seen from FIG. 3, the return
pipe 161 is arranged in the line of the tubes 111, which are at the
most downstream side of the exhaust gas flow. Not only one return
pipe but multiple return pipes (less than the number of the tubes
111) may be provided. The return pipe 161 is also referred to as a
connecting passage for connecting the condensing portion 130 with
the vaporizing portion 110.
[0061] The heat insulating wall 162 is arranged at an upstream side
of the return pipe 161. The heat insulating wall 162 is formed into
a semi-circular shape, as shown in FIG. 3. However, the heat
insulating wall 162 may be formed into a circular shape, so that it
fully covers the return pipe 161.
[0062] The valve device 150 is arranged in the tank portion 133c
and forms a connecting passage for connecting the passage portion
133a with the return pipe 161. The valve device 150 is a diaphragm
type valve control device for controlling a valve opening degree in
accordance with the inner fluid pressure in the heat pipe 101.
[0063] The valve device 150 is inserted into the tank portion 133c
from an upper side of the water tank 140, so that an outer
peripheral portion of its lower end extends through the tank
portion 133c and the water tank plate 141. The outer peripheral
portion of the lower end is brought into contact with the heat
insulating plate 121, and surrounds the opening end (upper end) of
the return pipe 161. The valve device 150 is arranged at a
downstream side of the working fluid in the condensing portion
130.
[0064] As shown in FIGS. 4 and 5, the valve device 150 is composed
of a housing body 150A having an upper casing 151 and a lower
casing 152, a diaphragm 153, a spring 154 and a valve body 155.
[0065] The housing body 150A is formed into a cylindrical shape and
has a large diameter portion at its intermediate portion. An air
port 151a is provided at a top end of the upper casing 151 for
communicating the inside of the housing body 150A with the ambient
air. A water inlet port 152a is provided at a side wall of the
lower casing 152, through which the condensed water flows into the
inside of the housing body 150A. A water outlet port 152b is
provided at a lower end of the lower casing 152, through which the
condensed water flows out from the housing body 150A. The water
outlet port 152b is connected to the upper end of the return pipe
161. A valve seat (a gate portion) 152c having an aperture 152d is
formed in the inside of the lower casing 152, between the water
inlet and outlet ports 152a and 152b.
[0066] The diaphragm 153 is disposed between the upper and lower
casings 151 and 152 for applying a driving force to the valve body
155. The spring 154 is arranged between the upper casing 151 and
the diaphragm 153 for biasing the diaphragm 153 downwardly (in a
direction indicated by an arrow in FIG. 4). The diaphragm 153 is
upwardly or downwardly moved in accordance with a force balanced
between a downward force (the ambient pressure "Pa" introduced into
the inside of the upper casing 151 through the air port 151a and
the spring force "F") and an upward force (the inner pressure "Pi"
of the working fluid introduced into the inside of the lower casing
152 from the heat pipe 101 through the water inlet port 152a
[0067] The valve body 155 is formed of a flat disc and arranged to
oppose to the lower side of the gate portion 152c. The valve body
155 is integrally connected to the diaphragm 153 via a connecting
rod 155a. Accordingly, the valve body 155 is moved upwardly or
downwardly together with the diaphragm 153 in order to close or
open the aperture 152d of the gate portion 152c.
[0068] When the inner pressure "Pi" of the working fluid is
increased to exceed a first predetermined value "Pi-1" at a
predetermined temperature (e.g. 70.degree. C.) of the engine
coolant, the valve device closes its passage (the aperture 152d is
closed by the valve body 155). On the other hand, when the inner
pressure "Pi" is decreased to become lower than a second
predetermined value "Pi-2", which is lower than the first
predetermined value "Pi-1", the valve device opens its passage (the
aperture 152d is opened by the valve body 155). The first
predetermined value "Pi-1" is also referred to as a valve closing
pressure, and the second predetermined value "Pi-2" is also
referred to as a valve opening pressure.
[0069] The characteristic feature of valve opening and closing for
the valve device 150 will be further explained with reference to
FIGS. 6 and 7. FIG. 6 shows a relation between the temperature of
the engine coolant and the inner pressure "Pi" of the heat pipe
101, with respect to the heat quantity of the exhaust gas. As shown
in FIG. 6, the inner pressure "Pi" of the heat pipe 101 is
increased as the temperature of the engine coolant is increased.
The inner pressure "Pi" of the heat pipe 101 is also increased as
the heat quantity of the exhaust gas is increased. The heat
quantity of the exhaust gas varies depending on the operational
condition of the engine, so that the heat quantity becomes higher
at a high-load engine operation whereas the heat quantity becomes
lower at a low-load engine operation.
[0070] As shown in FIG. 7, the valve opening and closing operation
of the valve device 150 has a hysteresis. Namely, the valve device
150 closes its passage at the first predetermined pressure "Pi-1"
for the inner pressure, which is attained by the heat quantity
during a middle-load engine operation at the temperature of
70.degree. C. of the engine coolant. And the valve device 150 opens
its passage at the second predetermined pressure "Pi-2" for the
inner pressure, which is attained by the heat quantity during a
low-load engine operation (e.g. an engine idling operation) at the
temperature of 70.degree. C. of the engine coolant. As explained
above, the water is used as the working fluid for the heat pipe 101
in this embodiment. The first predetermined pressure "Pi-1" is
selected as a value of 0.1 Mpa, whereas the second predetermined
pressure "Pi-2" is selected as a value of 0.05 MPa.
[0071] The temperature of the saturated vapor for the water
corresponds to 100.degree. C. at the inner pressure "Pi" of 0.1
MPa. In most cases, the engine coolant is controlled at around
100.degree. C. by the radiator 21. Therefore, when the inner
pressure "Pi" is higher than 0.1 MPa, an operation for collecting
the waste heat from the exhaust gas by the engine coolant is
stopped by closing the valve device 150, as explained below.
[0072] The temperature of the saturated vapor for the water
corresponds to 80.degree. C. at the inner pressure "Pi" of 0.05
MPa. The operation for collecting the waste heat from the exhaust
gas by the engine coolant is actively carried out by opening the
valve device 150, when the inner pressure "Pi" is between 0.05 MPa
and 0.1 MPa (the temperature of the engine coolant is between 80 to
100.degree. C.).
[0073] According to the waste heat collecting apparatus 100 of the
above embodiment, the vaporizing portion 110 is arranged in the
exhaust pipe 11 at a downstream side of the catalytic converter 12,
and the inlet and outlet pipes 143 and 144 of the water tank 140
are connected to the waste heat collecting circuit 30.
[0074] An operation of the waste heat collecting apparatus 100 will
be explained.
[0075] When the engine operation is started, the water pump 22 is
activated by the engine 10, so that the engine coolant starts its
circulation in the radiator circuit 20, the waste heat collecting
circuit 30, and the heater circuit 40. The exhaust gas combusted in
the engine 10 flows through the catalytic converter 12 in the
exhaust pipe 11 and is emitted to the atmosphere, wherein the
exhaust gas passes through the vaporizing portion 110 (the exhaust
gas passage defined by the plate members 113, 114, 118) of the
waste heat collecting apparatus 100. The engine coolant circulating
in the waste heat collecting circuit 30 flows through the water
tank 140 (the condensing portion 130 of the waste heat collecting
apparatus 100).
[0076] After the engine operation has been started, the temperature
of the engine coolant increases as shown in FIG. 8B, the inner
pressure "Pi" of the heat pipe 101 is gradually increased as shown
in FIG. 8A, and the heat quantity of the exhaust gas varies
depending on the engine load as shown in FIG. 8C. Accordingly, the
inner pressure "Pi" of the heat pipe varies in accordance with the
various engine operational conditions, such as a vehicle
acceleration, a vehicle deceleration, a vehicle stop, and so on (as
indicated by projecting points in FIG. 8A).
[0077] When the inner pressure "Pi" of the heat pipe 101 is lower
than the valve closing pressure "Pi-1", the valve body 155 opens
the aperture 152d, as already explained with reference to FIG. 7.
Therefore, the working fluid (water) in the heat pipe 101 receives
the heat at the vaporizing portion 110 from the exhaust gas flowing
through the exhaust pipe 11, to start the vaporization. The working
fluid (steam) upwardly flows in the tubes 111, and flows into the
condensing portion 130 (the tank portion 133b and the passage
portion 133a) through the upper passage 117 and the vapor inlet
pipe 134. The steam flowing into the condensing portion 130 is then
cooled down by the engine coolant flowing from the waste heat
collecting circuit 30 into the water tank 140, and condensed to the
condensed water. The condensed water flows into the lower passage
116 of the vaporizing portion 110 through the water inlet port 152a
of the valve device 150, the aperture 152d opened by the valve body
155, the water outlet port 152b, and the return pipe 161. The
condensed water flowing through the return pipe 161 is prevented by
the heat insulating wall 162 from vaporizing by the heat from the
exhaust gas.
[0078] As above, the heat from the exhaust gas is transmitted to
the working fluid, and transferred from the vaporizing portion 110
to the condensing portion 130. The heat is emitted as the
condensation latent heat, when the steam is condensed to the water
at the condensing portion 130, so that the engine coolant flowing
through the waste heat collecting circuit 30 is heated.
[0079] Accordingly, the operation for warming up the engine 10 is
facilitated. A friction loss in the engine 10 is thereby reduced.
Furthermore, an increase of fuel amount, which is otherwise
necessary for improving a smooth starting operation as well as a
quick warming operation for the engine, can be suppressed. As a
result, a fuel consumption ratio is improved. In addition, a
heating performance by the heater core 41 is improved.
[0080] When the inner pressure "Pi" of the heat pipe 101 exceeds
the valve closing pressure "Pi-1", as indicated by a point "A" in
FIG. 8A, the valve body 155 temporarily closes the aperture 152d.
The condensed water is thereby prevented from flowing into the
return pipe 161, so that the circulation of the working fluid in
the heat pipe 101 is stopped. Namely, the collection of the waste
heat is stopped. Then, the inner pressure "Pi" of the heat pipe 101
is decreased. When the inner pressure "Pi" becomes lower than the
valve opening pressure "Pi-2", as indicated by a point "B" in FIG.
8A, the valve body 155 again opens the aperture 152d, to re-start
the operation of the waste heat collection.
[0081] When the temperature of the engine coolant exceeds
70.degree. C. after the point "B" (at a time point of "t1" in FIG.
8B), and when the inner pressure "Pi" becomes higher than the valve
closing pressure "Pi-1", as indicated by a point "C" in FIG. 8A,
the valve body 155 again closes the aperture 152d. As a result, the
inner pressure "Pi" is decreased due to the stop of the operation
of the heat pipe 101. So long as the engine is in its operation,
the heat quantity of the exhaust gas does not become lower than
that at the engine idling operation. This means that the inner
pressure "Pi" of the heat pipe 101 does not become lower than the
valve opening pressure "Pi-2" like the point "B". Therefore,the
aperture 152d is not opened by the valve body after the time point
"t1", and the operation for the waste heat collection is
continuously stopped.
[0082] When the engine operation is stopped, there exists no longer
the heat quantity of the exhaust gas, and the temperature of the
engine coolant is also decreased. The inner pressure "Pi" of the
heat pipe 101 is thereby decreased to be lower than the valve
opening pressure "Pi-2", and the valve body 155 opens the aperture
152d.
[0083] As above, according to the waste heat collecting apparatus
100 of the embodiment, the valve device 150 is arranged at the
downstream side of the condensing portion 130, wherein the valve
device 150 is composed of the diaphragm 153 for sensing the inner
pressure "Pi" of the heat pipe 101 and the valve body 155 for
moving integrally with the diaphragm 153 to open or close the
passage for the heat pipe 101. Accordingly, the structure of the
valve device 150 is simpler. Furthermore, since the operation for
the waste heat collection is stopped depending on the inner
pressure "Pi", which is decided in accordance with the temperature
of the engine coolant and the heat quantity of the exhaust gas, an
overheating of the engine coolant by the exhaust gas can be
avoided. Namely, an overheat of the engine can be avoided.
[0084] In addition, the valve device 150 is provided with a
hysteresis characteristic for opening and closing operation. Namely
the aperture 152d is closed when the inner pressure "Pi" of the
heat pipe 101 is higher than the valve closing pressure "Pi-1",
whereas the aperture 152d is opened when the inner pressure "Pi" of
the heat pipe 101 is lower than the valve opening pressure "Pi-2",
wherein the pressure "Pi-2" is lower than the pressure "Pi-1".
Accordingly, a hunting operation of the valve device 150 (a hunting
between the valve closing position and valve opening position of
the valve body 155) can be prevented, even when a small variation
for the inner pressure "Pi" of the heat pipe 101 occurs. As a
result, a stable operation for the waste heat collection and a
stable stopping operation of the waste heat collection can be
realized.
[0085] The waste heat collecting apparatus 100 of the present
invention can be applied to a hybrid vehicle. In the hybrid
vehicle, the engine operation is often temporally stopped even
during the vehicle is running. Therefore,the temperature of the
engine coolant may be decreased during the running of the vehicle.
The inner pressure "Pi" of the heat pipe 101 varies in a more
complicated manner compared with a general vehicle, so that the
start and stop of the waste heat collecting operation are repeated
more often than the general vehicle. However, according to the
present invention, the overheat of the engine coolant is likewise
prevented and the overheat of the engine for the hybrid vehicle can
be surely prevented.
[0086] According to the above embodiment, multiple tubes 111 are
provided in the vaporizing portion 110, so that a heat receiving
area is increased to facilitate the vaporization of the working
fluid at the vaporizing portion 110. The heat transferring amount
from the vaporizing portion 110 to the condensing portion 130 is
thereby increased.
[0087] In addition, the heat insulating portion 120 is provided
between the vaporizing portion 110 and the condensing portion 130,
so that the vaporizing portion 110 is prevented from being cooled
down by the engine coolant flowing through the condensing portion
130. Therefore, the condensing operation in the vaporizing portion
110 is suppressed. A proper heat transfer can be realized, even
when the condensing portion 130 is provided closely to and at the
upper side of the vaporizing portion 110. The heat insulating
portion 120 is formed by the multiple air spaces formed between the
heat insulating plate 121 and the water tank plate 141. As a
result, the heat insulating portion 120 can be formed by a simple
manner.
[0088] In addition, the longitudinal length of the return pipe 161
is made to be almost equal to that of the tubes 111, so that the
condensing portion 130 can be assembled to the vaporizing portion
110 in a compact manner. Furthermore, the return pipe 161 is
arranged in the space for the vaporizing portion 110 (the exhaust
gas passage area) together with multiple tubes 111, so that the
return pipe 161 can be assembled together with the multiple tubes
111. As a result, a manufacturing process for the waste heat
collecting apparatus 100 can be made simpler.
[0089] In addition, the heat insulating wall 162 is provided at the
upstream side of the return pipe 161, so that the heat transfer
from the exhaust gas to the condensed water flowing through the
return pipe 161 is suppressed. Therefore, the vaporization of the
working fluid (the condensed water) in the return pipe 161 can be
suppressed, to achieve a smooth return flow of the condensed
water.
[0090] In addition, the return pipe 161 is arranged at the
downstream side of the exhaust gas flow, namely at the line of the
tubes 111 which is arranged at the downstream side among other
lines of tubes 111. The temperature of the exhaust gas (the heat
quantity of the exhaust gas) becomes lower, as the exhaust gas
flows in the downstream direction. Accordingly, the vaporization of
the condensed water in the return pipe 161 can be also suppressed
in this meaning.
[0091] As above, the waste heat collecting apparatus 100 can be
obtained, which has a high performance for the heat transfer, which
is compact in size, and which can avoid an excessive collection of
the waste heat.
[0092] According to the above embodiment, the valve closing
pressure of the valve body 155 for the valve device 150 is selected
as the value of 0.1 MPa, whereas the valve opening pressure thereof
is selected as the value of 0.05 MPa. However, the other values may
be selected for the valve closing and opening pressures. For
example, the valve opening pressure may be selected as the value of
0.6 kPa, while the valve closing pressure is selected as the same
value of 0.1 MPa. In the case that the valve opening pressure is
selected as the value of 0.6 kPa, the temperature of the saturated
vapor for the water corresponds to 0.degree. C. Since the water may
not be frozen above that temperature (above that pressure), this
value (0.6 kPa) can be regarded as one of fundamental conditions
for performing the heat transfer operation. In case of 0.6 kPa for
the valve opening pressure, the range for the waste heat collecting
operation can be enlarged to its maximum value.
Second Embodiment
[0093] FIG. 9 shows a second embodiment of the invention. The valve
device 150 of the second embodiment differs from that of the first
embodiment in that a bypass aperture 152e (having a smaller opening
than that of the aperture 152d) is provided at the valve seat 152c.
According to such a modification, even when the aperture 152d is
fully closed by the valve body 155, a small amount of the condensed
water may return from the condensing portion 130 to the vaporizing
portion 110 through the return pipe 161 via the bypass aperture
152e.
[0094] In the case that the engine 10 is operating at its
high-load, but the radiator 21 has an additional coverage for the
cooling operation, the waste heat collecting operation is carried
out by the circulation of the working fluid through the bypass
aperture 152e. The size of the bypass aperture 152e is decided
depending on the additional coverage at the radiator 21, such that
the overheat of the engine 10 can be avoided even when the certain
amount of the working fluid is circulated through the bypass
aperture 152e.
[0095] As above, the small amount of the working fluid can be
circulated through the bypass aperture 152e even when the aperture
152d is fully closed by the valve body 155. Since the working fluid
flows from the condensing portion 130 to the vaporizing portion
110, the vaporizing portion can be cooled, to thereby improve a
heat resisting performance of the waste heat collecting apparatus
100.
Third Embodiment
[0096] FIG. 10 shows a third embodiment of the invention. The valve
device 150 of the first embodiment is replaced by a valve device
170 of a thermo-wax type, wherein the valve device 170 opens and
closes the passage depending on the temperature of the engine
coolant.
[0097] The valve device 170 is composed of a thermo-wax portion
171, a connecting rod 172, and a bellows 173. A wax is filled into
the thermo-wax portion 171, which is expanded or contracted
depending on the temperature of the coolant. One end (upper end) of
the connecting rod 172 is connected with the thermo-wax portion
171, and the other end (lower end) thereof is connected to a lower
end of the bellows 173. The connecting rod 172 is moved downwardly
or upwardly depending on the expansion or contraction of the
wax.
[0098] The lower end portion of the bellows 173 acts as a valve
body for the valve device 170. The bellows 173 is made of a metal
and extendable in a longitudinal direction. One end (upper end) of
the bellows 173 has an open end and the other end (lower end) is
closed. The thermo-wax portion 171 is connected to the open end of
the bellows 173 to close the upper end. A pair of communication
ports 174 is provided at the upper portion of the bellows 173
(close to the thermo-wax portion 171), for communicating the inside
of the bellows 173 with the outside thereof.
[0099] The valve device 170 is arranged in the tank portion 133c of
the condensing portion 130, such that the thermo-wax portion 171 is
arranged at the upper outer side of the tank portion 133c, and the
communication ports 174 are opening to the space outside of the
tank portion 133c. The lower end of the bellows 173 is arranged to
oppose to a valve seat formed in the water tank plate 141, at which
the tank portion 133c is connected to the return pipe 161.
[0100] The upper portion of the thermo-wax portion 171 is exposed
to the coolant in the water tank 140. The coolant flows into the
inside of the bellows 173 through the communication ports 174, so
that the lower portion of the thermo-wax portion 171 as well as the
connecting rod 172 are exposed to the coolant.
[0101] When the temperature of the engine coolant is low, the wax
of the thermo-wax portion 171 is contracted and the connecting rod
172 is moved in the upward direction. The lower end of the bellows
173 (acting as the valve body) is also moved upwardly together with
the connecting rod 172 so that the valve device 170 opens its
passage. Namely, the condensing portion 130 is communicated with
the return pipe 161 to carry out the waste heat collecting
operation by the apparatus 100.
[0102] When the temperature of the engine coolant is increased, the
wax of the thermo-wax portion 171 is expanded and the connecting
rod 172 is moved in the downward direction. The lower end of the
bellows 173 (acting as the valve body) is also moved downwardly
together with the connecting rod 172. The valve device 170 closes
its passage when the temperature of the engine coolant exceeds a
predetermined temperature. Accordingly,the communication between
the condensing portion 130 and the return pipe 161 is cut off to
stop the waste heat collecting operation by the apparatus 100.
[0103] As above, according to the third embodiment, the start or
stop of the waste heat collecting operation is carried out
depending on the temperature of the engine coolant, so that the
control for the temperature of the coolant becomes easier.
Furthermore, since the coolant flows into the inside of the bellows
173 through the communication ports 174, the whole portion of the
thermo-wax portion 171 is exposed to the coolant. As a result, the
valve opening and closing operation of the valve device 170 is not
affected by the temperature of the working fluid. Therefore, a more
accurate control of the valve opening and closing operation
depending on the temperature of the coolant can be realized.
Fourth Embodiment
[0104] FIG. 11 shows a fourth embodiment of the invention. In the
waste heat collecting apparatus 100 according to the fourth
embodiment, a position of the condensing portion 130 relative to
the vaporizing portion 110 is modified, when compared with the
first embodiment. The same reference numerals are used in the
fourth embodiment to designate the same or similar parts and
devices of the first embodiment.
[0105] The multiple tubes 133 of the condensing portion 130 are
arranged to be parallel to the tubes 111 of the vaporizing portion
110. Namely, the tubes 133 are vertically arranged and the
condensing portion 130 is arranged at a horizontal side portion of
the vaporizing portion 110.
[0106] In the fourth embodiment, each of the tubes 111 of the
vaporizing portion 110 is composed of a pair of plate members and
corrugated fins 112 are disposed between the neighboring tubes 111.
A lower header portion 113A of a cylindrical shape is provided at
the lower ends of the respective tubes 111 to form the lower
passage 116. In the same manner, an upper header portion 114A of a
cylindrical shape is provided at the upper ends of the respective
tubes 111 to form the upper passage 117.
[0107] The pair of side plates 118 is provided at both horizontal
sides of the vaporizing portion 110. An upper and a lower plate
119a, 119b are provided at both vertical sides of the vaporizing
portion 110. The exhaust gas passage (of a rectangular shape) is
formed by those plates 118, 119a and 119b.
[0108] A right hand end 117a of the upper passage 117 (the upper
header portion 114A) is directly connected to the tank portion 133b
of the condensing portion 130. Therefore, the vapor inlet pipe 134
of the first embodiment is not necessary in the fourth
embodiment.
[0109] The valve device 150 is provided at the lower end of the
condensing portion 130 and fluidically connected to the lower tank
portion 133c (the downstream side tank). The water outlet port 152b
of the valve device 150 is directly connected to a right hand end
116a of the lower passage 116 (the lower header portion 113A).
[0110] Although not shown in FIG. 11, an inlet pipe and outlet
pipe, which correspond to the inlet and outlet pipes 143 and 144
for the coolant, are provided at the condensing portion 130, so
that the heat exchange between the working fluid flowing through
the tubes 133 and the coolant flowing through the condensing
portion 130 (but the outside of the tubes 133) is carried out in
the same manner to the first embodiment. The right hand and left
hand ends 117a and 116a of the upper and lower header tank portions
117 and 116 are also referred to as a fluid connecting portion.
[0111] According to the fourth embodiment, as above, the
longitudinal direction of the tubes 133 of the condensing portion
130 is arranged in the same direction (the vertical direction) of
the tubes 111 of the vaporizing portion 110, and the condensing
portion 130 is arranged at the horizontal side of the vaporizing
portion 110. Accordingly, the upper tank portion 133b of the
condensing portion 130 can be arranged to oppose to the upper
header portion 114A of the vaporizing portion 110, whereas the
lower tank portion 133c of the condensing portion 130 (more
exactly, the valve device 150 in the embodiment of FIG. 11) can be
arranged to oppose to the lower header portion 113A of the
vaporizing portion 110. As a result, the vapor inlet pipe 134 and
the return pipe 161 of the first embodiment can be eliminated in
the fourth embodiment.
Fifth Embodiment
[0112] FIG. 12 shows a fifth embodiment of the invention. In the
waste heat collecting apparatus 100 according to the fifth
embodiment, the fluid connecting portion for fluidically connecting
the vaporizing portion 110 with the condensing portion 130 is
modified, and the position of the valve device 150 is modified, in
comparison with the fourth embodiment. The same reference numerals
are used in the fifth embodiment to designate the same or similar
parts and devices of the fourth embodiment.
[0113] The fluid connecting portion is composed of a fluid flow-in
passage 163 and a fluid flow-out passage 164, as shown in FIG. 12,
wherein the fluid connecting portion is circled by a dotted line.
The fluid flow-in passage 163 is a passage portion for allowing the
working fluid (steam) vaporized at the vaporizing portion 110 to
flow into the condensing portion 130. For that purpose, the fluid
flow-in passage 163 connects one of the tubes 111 of the vaporizing
portion 110, which is arranged at a side close to the condensing
portion 130, with one of the tubes 133 of the condensing portion
130, which is arranged at a side close to the vaporizing portion
110.
[0114] The fluid flow-out passage 164 is a passage portion for
returning the condensed water condensed at the condensing portion
130 to the lower passage 116 of the vaporizing portion 110. For
that purpose, the fluid flow-out passage 164 connects the water
outlet port 152b of the valve device 150 with the tube 111 of the
vaporizing portion 110, which is arranged at the side close to the
condensing portion 130.
[0115] The fluid flow-in and flow-out passages 163 and 164 are
arranged closer to each other, in a range in which the passages 163
and 164 are connectable to the tube 111. The fluid flow-in passage
163 is arranged at such a position, which is higher in a vertical
direction than a liquid level D of the working fluid (water) in the
vaporizing portion 110. The liquid level D here corresponds to a
level of the working fluid during the non-operation of the waste
heat collecting apparatus 100, wherein the working fluid is not
vaporized by the exhaust gas and substantially all of the working
fluid is condensed to the water and stored in the vaporizing
portion 110.
[0116] The valve device 150 is also arranged at the position, which
is higher in the vertical direction than the liquid level D. As the
fluid flow-out passage 164 is connected to the valve device 150,
the fluid flow-out passage 164 is likewise arranged at the position
higher than the liquid level D in the vertical direction. A lower
end of the condensing portion 130 is designed to be aligned with
the valve device 150. Accordingly, the lower end of the condensing
portion 130 is higher than the lower end of the condensing portion
110 in the vertical direction.
[0117] The waste heat collecting apparatus 100 of the fifth
embodiment has the same operation and effects to the fourth (i.e.
the first) embodiment. In addition, the fluid flow-in and flow-out
passages 163 and 164 are arranged closer to each other, so that
heat stress generated at the passage portions 163 and 164 can be
reduced.
[0118] In the passage portions 163 and 164 for connecting the
vaporizing portion 110 and the condensing portion 130 with each
other, heat stress (i.e. thermal deformation) is generated by the
temperature difference between the exhaust gas passing through the
vaporizing portion 110 and the engine coolant flowing through the
condensing portion 130. The heat stress becomes larger, as a
distance between the passage portions 163 and 164 becomes longer.
However, the distance between the passage portions 163 and 164 can
be made shorter by arranging them closer to each other. As a
result, the heat stress generated at the passage portions 163 and
164 can be reduced.
[0119] The fluid flow-in passage 163 is arranged at the position
higher than the liquid level D, so that the fluid flow-in passage
163 may not be filled with the water, and thereby the steam
vaporized at the vaporizing portion 110 may not be held within the
space of the vaporizing portion 110.
[0120] As the valve device 150 is also arranged at the position
higher than the liquid level D, the function of the valve device
150 may not be blocked by frost of the water. In other words, in
the case that the valve device 150 was arranged at a position lower
than the liquid level D, the valve device 150 may be frozen
together with the water when the waste heat collecting apparatus
100 is not operated in a low-temperature environment. When the
valve device 150 is frozen, the on-off operation thereof can not be
carried out, and the circulation of the working fluid in the waste
heat collecting apparatus 100 is thereby blocked until the
surrounding portion of the valve device 150 has been defrosted.
Namely, the waste heat collecting apparatus 100 can not start its
operation.
[0121] According to the above embodiment, however, the above
problem does not occur, because the valve device 150 is arranged at
the position higher than the liquid level D so that it may not be
frozen together with the water.
[0122] According to the above embodiment, the valve device 150 is
arranged at the position higher than the liquid level D, and the
lower end of the condensing portion 130 is arranged at the position
higher than the lower end of the condensing portion 110 in the
vertical direction. Accordingly, all of the water (the working
fluid) in the apparatus 100 can be substantially pooled in the
vaporizing portion 110 (no water is held in the condensing portion
130), during the waste heat collecting apparatus 100 is not
operated. This means that the amount of the water to be charged
into the apparatus 100 can be made smaller. Furthermore, the size
of the condensing portion 130 can be made smaller, even in
consideration of such a situation, in which all of the condensed
water should be held in the condensing portion 130 during the
operation of the apparatus 100 in which the valve device 150 is
closed.
[0123] FIG. 13 shows a modification of the fifth embodiment. In
this modification, the condensing portion 130 is arranged at an
upper side of the vaporizing portion 110, wherein positions of the
passage portions 163 and 164 as well as the valve device 150 are
changed. As shown in FIG. 13, the condensing portion 130 is rotated
in an anti-clockwise direction by 90 degrees, when compared with
that in FIG. 12.
[0124] The fluid flow-in passage 163 is a passage for connecting
the upper passage 117 of the vaporizing portion 110 with one of the
tubes 133 of the condensing portion 130, which is arranged at a
side close to the vaporizing portion 110. The fluid flow-out
passage 164 is a long slender passage portion for connecting the
water outlet port 152b of the valve device 150 with the lower
passage 116 of the vaporizing portion 110. The passage portions 163
and 164 are arranged closer to each other. According to the above
modification, the fluid flow-in passage 163 as well as the valve
device 150 is arranged at the position higher than the liquid level
D, so that the same effects of the fifth embodiment of FIG. 12 can
be obtained.
Sixth Embodiment
[0125] FIG. 14 shows a sixth embodiment of the invention, in which
the fluid connecting portion is formed by one fluid pipe 165.
[0126] The fluid pipe 165 is extended such that the water outlet
port 152b of the valve device 150 is communicated with the tube 111
of the vaporizing portion 110, which is arranged at the side close
to the condensing portion 130. An upper portion of the fluid pipe
165 is communicated with the tube 133 of the condensing portion
130, which is arranged at the side close to the vaporizing portion
110. The fluid pipe 165 is also arranged at the position higher
than the liquid level D.
[0127] A partitioning wall 166 is formed in the inside of the fluid
pipe 165 for separating the space of the pipe 165 into an upper
space and a lower space. As a result, the tube 111 of the
vaporizing portion 110 is communicated with the tube 133 of the
condensing portion 130 through the upper space formed in the fluid
pipe 165 by the partitioning wall 166. In the similar manner, the
water outlet port 152b of the valve device 150 is communicated with
the tube 111 of the vaporizing portion 110 through the lower space
formed in the fluid pipe 165 by the partitioning wall 166.
[0128] According to the above sixth embodiment, the fluid flow-in
and flow-out passage portions (corresponding to the passages 163
and 164 in FIG. 12) are formed in the single fluid pipe 165. The
distance between the fluid flow-in and flow-out passage portions is
substantially zero. Accordingly, the heat stress can be further
reduced.
[0129] In addition, the partitioning wall 166 is provided in the
fluid pipe 165. Accordingly, a direct contact between the steam
vaporized at the vaporizing portion 110 and the condensed water
condensed at the condensing portion 130 is prevented by the
partitioning wall 166. It is, therefore, avoided that the steam
from the vaporizing portion 110 is cooled down (condensed) by the
condensed water before entering into the condensing portion
130.
[0130] However, the partitioning wall 166 may not be provided, in
the case that a degree of affection caused by the direct contact
between the steam and the condensed water is relatively small.
Seventh Embodiment
[0131] A seventh embodiment of the invention is shown in FIGS. 15
to 18, in which a reverse flow preventing means is provided in the
condensing portion 130, so that a reverse flow of the condensed
water to the vaporizing portion 110 is suppressed.
[0132] The reverse flow preventing means is provided at an upstream
side of an intermediate passage portion 133a of the tubes 133. The
upstream side is indicated by a circle E in FIG. 15.
[0133] The reverse flow preventing means is, for example, formed as
multiple plate members (like a window roof) 133d, as shown in FIG.
16. The plate member 133d is provided at an inner wall of the
intermediate passage portion 133a, such that it is inclined in a
direction of a flow of the steam, which enters into the tube 133
from the vaporizing portion 110. Multiple plate members 133d are
provided to oppose to each other. The multiple plate members 133d
may be alternately provided at the inner wall of the intermediate
passage portion 133a, in the direction of the steam flow, as shown
in FIG. 17. The reverse flow preventing means may be formed as a
restricting portion 133e, so that an inner diameter of the
intermediate passage portion 133a is made smaller, as shown in FIG.
18.
[0134] As already explained in the first embodiment of the
invention, the valve device 150 is closed, when the inner pressure
"Pi" of the working fluid in the heat pipe 101 is increased to
exceed the first predetermined value (the valve closing pressure)
"Pi-1", as a result that the vaporization has been continuously
carried out in the vaporizing portion 110. The re-circulation of
the condensed water in the heat pipe 101 (from the condensing
portion 130 to the vaporizing portion 110) is stopped.
[0135] In such a situation, the vaporizing portion 110 is in a
condition of a so-called "empty-heating", so that the temperature
of the vaporizing portion 110 may be increased to an extremely high
value. When, in the above situation, the waste heat collecting
apparatus 100 is inclined (e.g. by an angle .theta. in FIG. 19)
because of a vehicle travel on a punishing road, or a vibration is
applied to the apparatus 100 during the vehicle travel, the
condensed water in the condensing portion 130 may be re-circulated
to the vaporizing portion 110.
[0136] In the case that the condensed water was re-circulated to
the vaporizing portion 110, which is in the condition of the
"empty-heating", as in an arrow indicated in FIG. 19, the
vaporizing portion 110 would be rapidly cooled down, so that the
heat stress may occur. Furthermore, the re-circulated water may be
vaporized at once to increase the pressure in the vaporizing
portion 110. The heat transfer may be completed in the vaporizing
portion, which deteriorates the strength as well as the function of
the heat collecting apparatus 100.
[0137] According to the seventh embodiment of the invention,
however, the above drawbacks can be overcome by the reverse flow
preventing means.
Other Modifications
[0138] The valve device 150 (170) is provided at the downstream
side of the condensing portion 130 in the above embodiments.
However, the valve device may be provided at an upstream side of
the vaporizing portion 110.
[0139] The valve device 150 (170) is operated to open or close its
passage depending on operating parameters of the waste heat
collecting apparatus, such as the inner pressure "Pi" of the
working fluid of the heat pipe 101, or the temperature of the
coolant for the engine in the above embodiments. However, the valve
device may be operated to open or close the passage depending on a
temperature of the working fluid for the heat pipe 101. For
example, a thermo-wax type valve device, which is similar to the
valve device 170 in FIG. 10, is used, wherein a thermo-wax portion
(171) is exposed to the working fluid for the heat pipe instead of
the coolant for the engine, so that the thermo-wax portion is
operated depending on the temperature of the working fluid.
[0140] The heat insulating portion 120 is formed by multiple air
spaces formed by the heat insulating plate 121 in the above
embodiments. However, a heat insulating material may be disposed
between the vaporizing portion 110 and the condensing portion
130.
[0141] The return pipe 161 is arranged in the area of the exhaust
gas passage in the first embodiment. However, the return pipe may
be arranged at such a portion outside of the exhaust gas passage,
so that the heat insulating wall 162 may be eliminated.
* * * * *