U.S. patent application number 11/400815 was filed with the patent office on 2006-10-19 for heat pipe.
This patent application is currently assigned to DENSO Corporation. Invention is credited to Shinichi Hamada, Seiji Inoue, Kimio Kohara, Yasutoshi Yamanaka.
Application Number | 20060231235 11/400815 |
Document ID | / |
Family ID | 37107358 |
Filed Date | 2006-10-19 |
United States Patent
Application |
20060231235 |
Kind Code |
A1 |
Yamanaka; Yasutoshi ; et
al. |
October 19, 2006 |
Heat pipe
Abstract
A heat pipe able to switch between operation and suspension of
heat transport when used for a bottom heat type and able to prevent
the condensed working medium from dropping to the evaporator side
and a waste heat recovery system using the same are provided. A
heat pipe having an evaporator set at one end of a tubular closed
container and using heat of an outside high temperature part to
cause the inside working medium to evaporate and a condenser set at
the other end side of the closed container and radiating heat to an
outside low temperature part to cause the evaporated working medium
to condense, wherein the evaporator is arranged below the condenser
and has a holding means holding the liquefied working medium
condensed by the condenser along with an increase in the amount of
heat received by the evaporator to prevent return to the
evaporator.
Inventors: |
Yamanaka; Yasutoshi;
(Kariya-city, JP) ; Hamada; Shinichi; (Anjo-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: |
37107358 |
Appl. No.: |
11/400815 |
Filed: |
April 7, 2006 |
Current U.S.
Class: |
165/51 ;
165/104.21 |
Current CPC
Class: |
Y02T 10/12 20130101;
F28D 15/06 20130101; Y02T 10/166 20130101; Y02T 10/16 20130101;
F28D 15/0275 20130101; F01N 5/02 20130101; F02G 5/02 20130101 |
Class at
Publication: |
165/051 ;
165/104.21 |
International
Class: |
F01N 5/02 20060101
F01N005/02; F28D 15/02 20060101 F28D015/02 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 12, 2005 |
JP |
2005-114984 |
Apr 27, 2005 |
JP |
2005-130275 |
Claims
1. A heat pipe comprising an evaporator provided at one end of a
tubular closed container, and using heat of an outside high
temperature part to cause the inside working medium to evaporate
and a condenser provided at the other end side of the closed
container and radiating heat to an outside low temperature part to
cause the evaporated working medium to condense, wherein the
evaporator is arranged below the condenser and has a holding means
holding the liquefied working medium condensed by the condenser
along with an increase in the amount of heat received by the
evaporator to prevent return to the evaporator.
2. A heat pipe comprising an evaporator provided at one end of a
tubular closed container, and using heat of an outside high
temperature part to cause the inside working medium to evaporate
and a condenser provided at the other end side of the closed
container and radiating heat to an outside low temperature part to
cause the evaporated working medium to condense, wherein the
evaporator is arranged below the condenser and has a holding means
holding the liquefied working medium condensed by the condenser
when a temperature of said low temperature part becomes a
predetermined value or more to prevent return to the
evaporator.
3. A heat pipe as set forth in claim 1, wherein said holding means
is made a valve element provided between the evaporator and the
condenser, and opening and closing a return passage of the
liquefied working medium.
4. A heat pipe as set forth in claim 3, wherein said valve element
has a passage through which a steam working medium evaporated by
the evaporator circulates and a dam part preventing outflow of the
liquefied working medium to the passage side.
5. A heat pipe as set forth in claim 4, wherein a height of the dam
part is set higher by a predetermined amount than the level of the
liquefied working medium prevented from flowing out to the passage
side.
6. A heat pipe as set forth in claim 3, wherein the valve element
is driven by heat expansion and heat shrinkage of thermal wax
provided at the condenser.
7. A heat pipe as set forth in claim 1, wherein the holding means
is made an area enlarging part enlarging the area of the surface of
the inside wall of the condenser.
8. A heat pipe as set forth in claim 7, wherein the area enlarging
part is a wick.
9. A waste heat recovery system using a heat pipe, wherein an
evaporator of a heat pipe as set forth in claim 1 is arranged in an
exhaust pipe for circulation of exhaust gas of an internal
combustion engine, a condenser is arranged in a cooling water
passage for circulation of cooling water of the internal combustion
engine, and the heat pipe is used for transporting waste heat of
the exhaust gas to the cooling water.
Description
TECHNICAL FIELD
[0001] The present invention relates to a heat pipe suitable for
recovering the waste heat of exhaust gas of for example a vehicular
internal combustion engine and using it for heating cooling water
of the internal combustion engine and a waste heat recovery system
using the same.
BACKGROUND ART
[0002] In the past, as a vehicular heating system using a heat
pipe, for example, the one shown in Japanese Utility Model
Publication (A) No. 59-16211 is known. This arranges an evaporator
of the heat pipe (loop type) in an exhaust passage of the engine,
arranges a condenser of the heat pipe at an air outlet side of a
heating use heater core, uses the heat pipe to directly transport
exhaust heat to the heating use air, and thereby tries to secure
heating performance in a short time after engine startup.
[0003] In this vehicular heating system, the heat pipe is provided
at its middle part with a valve means. When the heating use air
temperature obtained by the temperature sensor becomes a
predetermined value, the valve means is closed and heat transport
by the heat pipe is stopped.
[0004] However, in the art described in the above Japanese Utility
Model Publication (A) No. 59-16211, when arranging the evaporator
of the heat pipe at the bottom side and the condenser at the top
side, that is, when used as the so-called "bottom heat" type, if
the drops of water condensed by the condenser at the time the heat
transport operation stops drop to the evaporator side due to
vibration etc. during vehicle operation, rapid evaporation occurs,
so the internal pressure of the heat pipe rapidly rises and the
heat pipe is liable to rupture or the repeated pressure fluctuation
is liable to cause the heat pipe to break. This phenomenon is
particularly remarkable in a wickless bottom heat type heat
pipe.
DISCLOSURE OF THE INVENTION
[0005] An object of the present invention, in consideration of the
above problem, is to provide a heat pipe able to switch between
operation and suspension of heat transport when used for a bottom
heat type and able to prevent the condensed working medium from
dropping to the evaporator side and a waste heat recovery system
using the same.
[0006] The present invention achieves the above object by employing
the following technical means.
[0007] In a first aspect of the present invention, there is
provided a heat pipe having an evaporator (110A) set at one end of
a tubular closed container (111) and using heat of an outside high
temperature part (11) to cause the inside working medium to
evaporate and a condenser (110B) set at the other end of the closed
container (111) and radiating heat to an outside low temperature
part (30) to cause the evaporated working medium to condense,
wherein the evaporator (110A) is arranged below the condenser
(110B) and has a holding means (112) holding the liquefied working
medium condensed by the condenser (110B) along with an increase in
the amount of heat received by the evaporator (110A) to prevent
return to the evaporator (110A).
[0008] Due to this, since return of the liquefied working medium
along with an increase in the amount of heat received by the
evaporator (110A) is prevented by the holding means (112), it
becomes possible to switch between operation and suspension of heat
transport by the simple configuration of the holding means (112) in
a heat pipe (110) when used as a bottom heat type.
[0009] Here, the liquefied working medium at the time of suspension
of heat transport is held by the holding means (112), so the
liquefied working medium can be prevented from dropping down into
the evaporator (110A) due to outside vibration etc. That is, since
rapid evaporation at the evaporator (110A) side can be prevented,
there is no longer the risk of the inside pressure of the heat pipe
(110) rapidly rising and the heat pipe (110) rupturing or repeated
pressure fluctuation causing the heat pipe (110) to break.
[0010] In a second aspect of the present invention, there is
provided a heat pipe where the evaporator (110A) is arranged under
the condenser (110B) and has a holding means (112) which holds the
liquefied working medium condensed by the condenser (110B) when the
temperature of the outside low temperature part (30) becomes a
predetermined value or more so as to prevent return to the
evaporator (110A), whereby an effect similar to the first aspect
can be obtained.
[0011] The holding means (112), in a third aspect of the present
invention, may be made a valve element (112) provided between the
evaporator (110A) and the condenser (110B) and opening and closing
a return passage (111a) of the liquefied working medium.
[0012] In a fourth aspect of the present invention, the valve
element (112) has a passage (112b) through which a steam working
medium evaporated by the evaporator (110A) circulates and a dam
part (112a) preventing outflow of the liquefied working medium to
the passage (112b) side.
[0013] Due to this, even after the valve element (112) is closed,
the steam working medium from the evaporator (110A) passes through
the passage (112b) and reaches the condenser (110B) where it is
condensed, so a rise in the inside pressure in the evaporator
(110A) can be prevented. Further, the dam part (112a) of the valve
element (112) can reliably hold the liquefied working medium and
prevent inflow from the passage (112b) to the evaporator
(110A).
[0014] In a fifth aspect of the present invention, the height of
the dam part (112a) is set higher by a predetermined amount than
the level of the liquefied working medium prevented from flowing
out to the passage (112b) side.
[0015] Due to this, the valve element (112) of the fourth aspect
may be made a specific aspect enabling the liquefied working medium
to be prevented from dropping down into the evaporator (110A) due
to outside vibration etc.
[0016] In a sixth aspect of the present invention, the valve
element (112) is driven by heat expansion and heat shrinkage of the
thermal wax (113) provided at the condenser (110B).
[0017] Due to this, the valve element (112) can be opened and
closed in accordance with the temperature of the low temperature
part (30) corresponding to the condenser (110B). That is, when
desiring to keep the temperature of the low temperature part (30)
down to a predetermined temperature, the valve element (112) can be
closed at a predetermined temperature and heat transport of the
heat pipe (110) can be stopped.
[0018] Further, in a seventh aspect of the present invention, the
holding means may be made an area enlarging part enlarging the area
of the surface of the inside wall of the condenser (110B).
[0019] Specifically, in an eighth aspect of the present invention,
the area enlarging part preferably uses a wick.
[0020] A ninth aspect of the present invention relates to a waste
heat recovery system using a heat pipe (110) of the first aspect,
wherein an evaporator (110A) of a heat pipe (110) is arranged in an
exhaust pipe (11) for circulation of exhaust gas of an internal
combustion engine (10), a condenser (110B) is arranged in a cooling
water passage (30) for circulation of cooling water of the internal
combustion engine (10), and the heat pipe (110) is used for
transporting waste heat of the exhaust gas to the cooling
water.
[0021] Further, the reference numerals in parentheses of the above
means show the correspondence with the specific means described in
the embodiments later.
[0022] Below, the present invention will be better understood from
the attached drawings and the description of the preferred
embodiments of the present invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] FIG. 1 is a schematic view showing the state of the waste
heat recovery system mounted in a vehicle.
[0024] FIG. 2 is a side view of a waste heat recovery system in a
first embodiment.
[0025] FIG. 3 is a cross-sectional view in a part A-A of FIG.
2.
[0026] FIG. 4 is a cross-sectional view showing a valve element in
a heat pipe in a first embodiment (valve opening state).
[0027] FIG. 5 is a cross-sectional view showing a valve element in
a heat pipe in a first embodiment (valve closing state).
[0028] FIG. 6 is a perspective view of a valve element seen from
the B direction in FIG. 4.
[0029] FIG. 7 is a graph showing an operating state and a suspended
state of a heat transport function of a heat pipe with respect to
the cooling water temperature.
[0030] FIG. 8 is a cross-sectional view showing a valve element in
a heat pipe in a second embodiment (valve opening state).
[0031] FIG. 9 is a cross-sectional view showing a valve element in
a heat pipe in a second embodiment (valve closing state).
[0032] FIG. 10 is a graph showing an amount of heat conduction to
engine cooling water according to a waste heat recovery system in a
second embodiment.
BEST MODE FOR WORKING THE INVENTION
[0033] (First Embodiment)
[0034] A waste heat recovery system 100 in a first embodiment of
the present invention is applied to a vehicle (automobile) having
an engine 10 as a drive source for operation. First, a specific
configuration is explained below using FIG. 1 to FIG. 6. Further,
FIG. 1 is a schematic view showing the state of the waste heat
recovery system 100 mounted in a vehicle, FIG. 2 is a side view
showing a waste heat recovery system 100, FIG. 3 is a
cross-sectional view in a part A-A of FIG. 2, FIG. 4 and FIG. 5 are
cross-sectional views showing a valve element 112 in a heat pipe
110, and FIG. 6 is a perspective view showing a valve element 112
seen from the B direction in FIG. 4.
[0035] As shown in FIG. 1, the engine 10 is a water cooled type
internal combustion engine which has an exhaust pipe (corresponding
to the high temperature part in the present invention) 11 from
which exhaust gas after fuel is burned is exhausted. The exhaust
pipe 11 is provided with a catalytic converter 12 for purifying the
exhaust gas.
[0036] Further, the engine 10 has a radiator circuit 20 in which
engine cooling water (hereinafter, cooling water) is circulated to
cool the engine 10 and a heater circuit 30 using cooling water
(warm water) as a heat source to heat the air-conditioning air.
[0037] The radiator circuit 20 is provided with a radiator 21. The
radiator 21 cools the cooling water circulated by the water pump 22
by heat exchange with the outside air. Further, the radiator
circuit 20 is provided with a bypass passage (not shown) through
which the cooling water is circulated bypassing the radiator 21. A
thermostat (not shown) is used to adjust the amount of the cooling
water circulating through the radiator 21 and the amount of cooling
water circulating through the bypass passage. In particular, at the
time of engine warmup, the amount of cooling water at the bypass
passage side is increased and engine warmup is promoted. That is,
overcooling of the cooling water by the radiator 21 is
prevented.
[0038] The heater circuit (corresponding to the low temperature
part in the present invention and cooling water passage) 30 is
provided with a heater core 31 as a heating use heat exchanger. The
water pump 22 is used for circulation of the cooling water (warm
water). The heater core 31 is arranged in an air-conditioning case
of a not shown air-conditioning unit. Air-conditioning air blown by
a blower is heated by heat exchange with the warm water.
[0039] The waste heat recovery system 100, as shown in FIG. 2 and
FIG. 3, is comprised of a plurality of (here, three) heat pipes 110
at the outsides of which fins 120 are provided. One end of each
heat pipe 110 (evaporator 110A) is arranged in an exhaust pipe part
130, while the other end (condenser 110B) is arranged in the water
tank 140. The members forming the waste heat recovery system 100
(explained below) are comprised of a stainless steel material
provided with a high corrosion resistance. The members are
assembled, then are soldered together by solder material provided
at the abutting parts and engaging parts.
[0040] Each heat pipe 110 has a container 111, valve element 112,
and thermostat 113. Inside of the container 111, a working medium
is sealed. The container (corresponding to the closed container in
the present invention) 111 is comprised of a straight round tube
which is used in a posture with its longitudinal direction oriented
in the vertical direction. The top end side of the container 111 is
opened. This opening is closed by fastening a thermostat 113 there.
The thermostat 113 is a temperature sensing part in which thermal
wax expanding and shrinking in accordance with the temperature is
sealed. Further, the valve element 112 is the characterizing part
in the present embodiment. Details will be explained later.
[0041] Further, each heat pipe 110 is provided with a not shown
inlet. The inside of the heat pipe 110 is evacuated to a vacuum
(reduced in pressure) from this inlet, then a working medium is
sealed in them, then the inlet is sealed. The working medium used
here is water. Water has a boiling point of usually (at one
atmosphere) 100.degree. C., but since the tube 110 is reduced in
pressure (for example, to 0.04 atmosphere), the boiling point
becomes 30 to 40.degree. C. Further, the working medium used may
also be, in addition to water, alcohol, a fluorocarbon, freon,
etc.
[0042] Each heat pipe 110 of this configuration forms an evaporator
110A at the bottom side, a condenser 110B at the top side, and an
insulating part 110C between the two 110A, 110B and functions as a
bottom heat type.
[0043] A plurality of the heat pipes 110 are arranged. The outside
walls of the parts of the heat pipes 110 corresponding to the
evaporator 110A and condenser 110B have plate type fins 120 formed
from a thin sheet material joined to them. Further, the evaporators
110A formed by the heat pipes 110 are arranged in the exhaust pipe
part 130 forming a square cross-section duct, while the condensers
110B are arranged in a water tank 140 forming a box shaped vessel.
Further, the water tank 140 has an inlet pipe 141 and outlet pipe
142 connected to the inside of the water tank 140 joined to it at
facing sides.
[0044] Further, the characterizing part of this embodiment is the
provision of a valve seat 111b inside each heat pipe 110 and a
valve element 112 connected from the thermostat 113 and able to sit
on the valve seat 111b.
[0045] As shown in FIG. 4 to FIG. 6, the valve seat 111b is
positioned between the evaporator 110A and condenser 110B of the
heat pipe 110 (container 111) (insulating part 110C), sticks out
from the inside wall surface 111a of the container 111 to the axial
center, and thereby forms a ring shape in the circumferential
direction at the inside wall surface 111a.
[0046] The valve element 112 (corresponding to the holding part in
the present invention) is based on a disk shaped member. At the
outer circumference, it has a vertical wall part (corresponding to
the dam part of the present invention) 112a forming a ring in
cross-sectional shape extending in the vertical direction in the
circumferential. Further, at the axial center side from the
vertical wall part 112a, a plurality of hole parts (corresponding
to the passage in the present invention) 112b are formed passing
through the disk shaped part and forming fan shapes. Further, the
disk shaped part is integrally provided at its axial center with a
shaft 112c which is connected to a thermostat 113 at the top side.
The shaft 112c abuts against the thermal wax in the thermostat 113
and is biased to the thermal wax side by a not shown spring member.
Therefore, conditional on the temperature of the outside of the
thermostat 113 (corresponding to the temperature of the low
temperature part of the present invention, specifically, the
temperature of the cooling water circulating through the water tank
140) not satisfying the predetermined temperature (corresponding to
the predetermined value in the present invention, for example,
90.degree. C.), shrinkage of the thermal wax causes the shaft 112c
to be biased by the spring member to the thermostat 113 side and
the bottom end of the vertical wall part 112a of the valve element
112 and the valve seat 111b to separate (valve opening state) (FIG.
4).
[0047] Further, conditional on the temperature of the outside of
the thermostat 113 being the predetermined temperature or more, the
shaft 112c is pushed by expansion of the thermal wax (expansion
force of thermal wax overcoming biasing force of spring member) to
the opposite thermostat side and the bottom end of the vertical
wall part 112a of the valve element 112 sits on the valve seat 111b
(valve closing state) (FIG. 5).
[0048] When the valve element 112 sits on the valve seat 111b, the
inside wall surface 111a, valve seat 111b, and vertical wall part
112a form a space M opening upward. This space M, as explained
later, forms a space in which condensed water condensed by the
condenser 110B is held. The volume of the space M is set to be at
least the maximum amount of the condensed water. In other words,
the top end position of the vertical wall part 112a is set to
become higher by a predetermined amount than the level of the
maximum amount of the condensed water.
[0049] The waste heat recovery system 100 is formed in the above
way. The exhaust pipe part 130 is interposed in the exhaust pipe 11
forming the part becoming the downstream side of the catalytic
converter 12. Further, the two pipes 141 and 142 of the water tank
140 are connected to the heater circuit 30 (FIG. 1).
[0050] Next, the operation based on the above configuration and the
mode of action and effects of the same will be explained with
addition of FIG. 7. FIG. 7 is a graph showing the operating state
and suspended state of the heat transport function of a heat pipe
110 with respect to the cooling water temperature.
[0051] Along with the startup of the engine 10, the water pump 22
is activated. The cooling water circulates through the radiator
circuit 20 and the heater circuit 30. The exhaust gas of the fuel
burned by the engine 10 passes through the catalytic converter 12,
flows through the exhaust pipe 11 and exhaust pipe part 130, passes
the outside of the evaporator 110A of each heat pipe 110 in the
waste heat recovery system 100, and is discharged to the
atmosphere. Further, the cooling water circulating through the
heater circuit 30 circulates through the inside of the water tank
140 and passes outside of the condenser 110B of each heat pipe
110.
[0052] In the waste heat recovery system 100, after the engine 10
is started and until the cooling water temperature reaches a
predetermined temperature, as shown in FIG. 4, the water (working
medium) in each heat pipe 110 receives heat from the exhaust gas
flowing through the exhaust pipe part 130 and boils and vaporizes
at the evaporator 110A to become steam. This rises through the
inside of the heat pipe 110, passes through the hole parts 112b of
the valve element 112 and between the vertical wall part 112a and
the inside wall surface 111a to flow into the condenser 110B. The
steam flowing into the condenser 110B is cooled by the cooling
water flowing through the inside of the water tank 140, becomes
condensed water at the inside wall surface 111a, descends due to
gravity, and returns along the inside wall surface 111ato the
evaporator 110A. The inside wall surface 111a forms a return
passage by which the condensed water flows down and is
returned.
[0053] In this way, the heat of the exhaust gas is transmitted to
the water and transported from the evaporator 110A to the condenser
110B. When the steam is condensed by the condenser 110B, it is
discharged as latent heat of condensation, whereby the cooling
water flowing through the heater circuit 30 is heated (waste heat
recovery operation). Further, part of the heat of the exhaust gas
is transferred from the evaporator 110A to the condenser 110B due
to heat conduction through the outside wall of the heat pipe
110.
[0054] Therefore, when the outside air temperature is relatively
low or the cooling water temperature reaches a predetermined
temperature after the engine 10 is started etc., waste heat
recovery is executed by the heat pipe 110 (left side of time axis
in FIG. 7), the cooling water is positively heated, and warmup of
the engine 10 is promoted, so the friction loss of the engine 10 is
reduced, the increase in fuel for improving the low temperature
starting ability is suppressed, etc. and the fuel economy
performance is improved. Further, the heating performance of the
heater core 31 having the cooling water as a heat source is
improved.
[0055] On the other hand, when the heat transport of the heat pipe
110 (or operating conditions of the engine 10 etc.) results in the
cooling water temperature reaching a predetermined temperature or
more, as shown in FIG. 5, the thermostat 113 causes the shaft 112c
to be pushed to the opposite thermostat side (white arrow in FIG.
5) and the vertical wall part 112a of the valve element 112 to sit
on the valve seat 111b. This being the case, the condensed water
condensed at the condenser 110B is held at the space M forming the
outer circumference of the valve element 112 and return of the
condensed water to the evaporator 110A is obstructed. After this,
when evaporation at the evaporator 110A proceeds, the steam passes
through the hole parts 112b of the valve element 112 and flows into
the condenser 110B, then is condensed at the condenser 110B.
Further, when evaporation at the evaporator 110A proceeds, the
water in the evaporator 110A completely evaporates and becomes
steam, whereupon heat transport is stopped. That is, waste heat
recovery is suspended (right side of time axis in FIG. 7, and
heating of the cooling water is suspended (waste heat recovery
suspended).
[0056] Therefore, if waste heat recovery is continued along with
the elapse of time after startup of the engine 10 and while the
cooling water temperature is rising, the cooling water temperature
overly rises, the heat radiating ability of the radiator 20 is
exceeded, and overheating results. By switching to suspension of
waste heat recovery, this inconvenience is prevented.
[0057] Here, in the present embodiment, by providing each heat pipe
110 with a valve element 112 closed by the thermostat 113 and
forming a space M at the outer circumference of the valve element
112 at the time of valve closing, the condensed water from the
condenser 110B is held and return to the evaporator 110A is
inhibited. In this way, in each heat pipe 110 used as a bottom heat
type, operation and suspension of heat transport can be switched by
this simple configuration.
[0058] Further, the condensed water at the time of suspension of
heat transport is held at the space M by the valve element 112, but
since the position of the top end of the vertical wall part 112a is
set sufficiently higher than the level of the held condensed water
(higher by predetermined amount), it is possible to prevent
condensed water from dropping down to the evaporator 110A due to
vibration etc. of the vehicle. That is, rapid evaporation at the
evaporator 110A side can be prevented, so there is no longer any
risk of the inside pressure of the heat pipe 110 rapidly rising and
the heat pipe 110 rupturing or of repeated pressure fluctuations
causing the heat pipe 110 to break.
[0059] Further, since the valve element 112 is provided with hole
parts 112b, even after the valve element 112 is closed, steam from
the evaporator 110A passes through the hole parts 112b, reaches the
condenser 110B, and is condensed, so a rise in the inside pressure
of the evaporator 110A can be prevented.
[0060] Further, since the valve element 112 is opened and closed by
the thermostat 113, heat transport of the heat pipe 110 can be
suspended based on the cooling water temperature.
[0061] (Second Embodiment)
[0062] A second embodiment of the present invention is shown in
FIG. 8 to FIG. 10. The second embodiment is comprised of the first
embodiment simplified in the configuration of the valve element
112A. That is, in the art described in Patent Document 1 in the
section on the Background Art, a temperature sensor or valve means
is used for operating and suspending heat transport by the heat
pipe. Further, in actuality, control means for opening and closing
the valve means in accordance with the temperature from the
temperature sensor also becomes necessary and therefore the cost
becomes higher. This solves the problem and prevents condensed
water from dropping down at the time of suspension of heat
transport.
[0063] The container 111A of the heat pipe 110 is a sealed vessel
closed from the top end side as well. The thermostat 113 is
eliminated. Further, the valve element 112A is comprised of a disk
shaped part formed with a vertical wall part 112a and hole parts
112b. The shaft 112c is eliminated. That is, the valve element 112A
is arranged in a free state above the valve seat 111b without
support from other members.
[0064] Further, the amount of water sealed in the heat pipe 110 is
adjusted in advance to an amount completely evaporating in the
evaporator 110A when the exhaust gas temperature (amount of waste
head), which rises in accordance with the load of the engine 10,
exceeds a predetermined exhaust gas temperature.
[0065] In the present embodiment, after the engine 10 is started,
when the exhaust gas temperature accompanying the engine load
becomes a predetermined exhaust gas temperature or less, the steam
evaporated at the evaporator 110A rises, passes through the hole
parts 112b of the valve element 112A, and reaches the condenser
110B. At this time, due to the upward flow of steam (steam flow
rate), the valve element 112A is lifted up further than the valve
seat 111b (valve opening state of FIG. 8).
[0066] The steam flowing into the condenser 110B is cooled by the
cooling water flowing through the inside the water tank 140,
becomes condensed water at the inside wall surface 111a, descends
due to gravity, and is returned along the inside wall surface
111ato the evaporator 110A. Therefore, due to the heat transport
function of the heat pipe 110, the cooling water is positively
heated (left side of abscissa in FIG. 10, waste heat recovery
operation).
[0067] On the other hand, when the exhaust gas temperature
accompanying engine load exceeds a predetermined exhaust gas
temperature (along with an increase in the amount of heat received
by the evaporator 110A), the water of the evaporator 110A
completely evaporates and there is no longer any upward flow of
steam, so the valve element 112A sits on the valve seat 111b (valve
closing state of FIG. 8). Therefore, the condensed water condensed
at the condenser 110B, like in the first embodiment, is held in the
space at the outer circumference of the valve element 112A, the
return of the condensed water to the evaporator 110A is inhibited,
and heat transport is stopped (right side of abscissa in FIG. 10,
waste heat recovery suspended).
[0068] After this, when the engine 10 stops being operated, the
exhaust gas is no longer supplied to the evaporator 110A, so the
evaporator 110A rapidly falls in temperature. Further, since the
cooling water has a large heat capacity, it holds the high
temperature (approximately 80.degree. C.) for a while, this cooling
water side (condenser 110B) becomes the evaporator of the heat pipe
110, the exhaust gas side (evaporator 110A) becomes the condenser,
and the original operation is reversed. Further, the condensed
water held in the space M gradually evaporates, passes through the
hole parts 112b of the valve element 112A, and condenses at the
exhaust gas side (evaporator 110A), whereby the heat pipe 110
returns to the original state.
[0069] In the present embodiment, even if the cooling water
temperature does not sufficiently rise, once the engine 10 engages
in a high load operation and the exhaust gas temperature becomes
higher than a predetermined exhaust gas temperature, there is the
problem that the valve element 112A ends up sitting on the valve
seat 111b and return to the original state becomes difficult until
the engine 10 is turned off once, but compared with the first
embodiment, there is the merit of being far cheaper.
[0070] Further, in the present embodiment, the vertical wall part
112a is provided at the outer circumference of the valve element
112A, but even if provided around the hole parts 112b, the water
holding function can be similarly secured.
[0071] (Other Embodiments)
[0072] In the second embodiment, the valve element 112A was used as
the holding means of the condensed water, but instead of this it is
also possible to use an area enlarging part enlarging the area of
the inside wall surface of the condenser 110B. Specifically, the
area enlarging part may be made a wick comprised of metal mesh,
metal felt, foam metal, sintered metal, etc. An effect similar to
the second embodiment can be obtained.
[0073] Further, the heat pipe 110 (container 111) was shaped as a
round tube, but the invention is not limited to this and may also
be made an angular tube, flat tube, multi-hole tube, etc.
[0074] Further, the explanation was given of a high temperature
part comprised of the exhaust pipe 11, a low temperature part
comprised of the heater circuit 30, and the heat of the exhaust gas
being transported to the cooling water, but it is also possible to
use the waste heat of the heat generating equipment for heating a
predetermined location.
[0075] Note that the present invention was explained in detail
based on specific embodiments, but a person skilled in the art can
make various changes, modifications, etc. without departing from
the claims and concept of the present invention.
* * * * *