U.S. patent application number 12/319423 was filed with the patent office on 2009-09-03 for external combustion engine.
This patent application is currently assigned to DENSO CORPORATION. Invention is credited to Takashi Kaneko, Yasunori Niiyama, Shuzo Oda, Shinichi Yatsuzuka.
Application Number | 20090217667 12/319423 |
Document ID | / |
Family ID | 41012131 |
Filed Date | 2009-09-03 |
United States Patent
Application |
20090217667 |
Kind Code |
A1 |
Niiyama; Yasunori ; et
al. |
September 3, 2009 |
External combustion engine
Abstract
An external combustion engine suppressing boiling of cooling
water in a cooler. A heater 12 uses waste heat of a heat engine 1
as a heat source to heat a working medium to make it evaporate. A
cooler 13 uses cooling fluid cooling the heat engine 1 as a cooling
source to cool steam of the working medium and make it condense. A
heated part temperature reducing means is provided for reducing a
temperature Th of the heated part 12a when the amount of heat
radiated from the cooling fluid to the outside becomes smaller than
the amount of heat transferred from the working medium to the
cooling fluid. Due to this, it is possible to suppress the rise of
the temperature Tw of the cooling fluid in the cooler 13, so it is
possible to suppress boiling of the cooling water in the cooler
13.
Inventors: |
Niiyama; Yasunori;
(Kuwana-city, JP) ; Kaneko; Takashi; (Nagoya-city,
JP) ; Yatsuzuka; Shinichi; (Nagoya-city, JP) ;
Oda; Shuzo; (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: |
41012131 |
Appl. No.: |
12/319423 |
Filed: |
January 7, 2009 |
Current U.S.
Class: |
60/670 |
Current CPC
Class: |
F01K 15/02 20130101;
F01K 23/065 20130101; F01K 27/005 20130101 |
Class at
Publication: |
60/670 |
International
Class: |
F01K 23/06 20060101
F01K023/06 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 28, 2008 |
JP |
2008-047523 |
Claims
1. An external combustion engine provided with a pipe-shaped
container in which a working medium is sealed flowably in a liquid
state, a heater having a heated part communicating with one end of
the container and heating the working medium at the heated part to
make it evaporate, a cooler arranged at a middle of the container
and cooling the steam of the working medium produced by the heater
to make it condense, and an output part communicated with the other
end of the container and converting the displacement of the liquid
part of the working medium produced due to the change in volume of
the working medium accompanying evaporation and condensation of the
working medium to mechanical energy for output, the heater being
designed to use waste heat of a heat engine as a heat source to
heat the working medium and make it evaporate, the cooler being
designed to use a cooling fluid cooling the heat engine as a
cooling source to cool the steam of the working medium and make it
condense, and the engine provided with a heated part temperature
reducing means for reducing the temperature of the heated part when
the amount of heat radiated from the cooling fluid to the outside
becomes smaller than the amount of heat transferred from the
working medium to the cooling fluid.
2. An external combustion engine as set forth in claim 1, wherein
said heated part temperature reducing means has a pump means for
circulating the cooling fluid to the cooler.
3. An external combustion engine as set forth in claim 2, wherein
said heated part temperature reducing means controls the pump means
based on at least one of the amount of waste heat of the heat
engine, the temperature of the heated part, and the temperature of
the cooling fluid.
4. An external combustion engine as set forth in claim 2, wherein
said pump means is driven by electric power.
5. An external combustion engine as set forth in claim 2, wherein
said pump means is coupled with an output part so as to be driven
by output from the output part.
6. An external combustion engine as set forth in claim 2, wherein
the length of the flow path of the cooling fluid becomes shorter by
providing a bypass flow path for circulating the cooling fluid
bypassing the heat engine, and the bypass flow path is provided
with a pump means and a radiating means for radiating the heat of
the cooling fluid to the outside.
7. An external combustion engine as set forth in claim 6, wherein
said radiating means is provided with a heat storing material for
storing the heat discharged from the cooling fluid.
8. An external combustion engine as set forth in claim 1, wherein
said heated part temperature reducing means has cooling means for
cooling the heater from the outside.
9. An external combustion engine as set forth in claim 8, wherein
said cooling means is a means for blowing air to the heater.
10. An external combustion engine as set forth in claim 8, wherein
said cooling means is a means for spraying water to the heater.
11. An external combustion engine as set forth in claim 1, wherein
said heated part temperature reducing means has judging means for
judging when the amount of heat radiated from the cooling fluid to
the outside becomes smaller than the amount of heat transferred
from the working medium to the cooling fluid based on at least the
temperature of the heated part.
12. An external combustion engine as set forth in claim 11, wherein
said judging means deems that the amount of heat radiated from the
cooling fluid to the outside has become smaller than the amount of
heat transferred from the working medium to the cooling fluid when
the heat engine has stopped and the temperature of the heated part
exceeds the boiling point of the cooling fluid.
13. An external combustion engine as set forth in claim 11, wherein
said judging means calculates the temperature of the heated part
based on the pressure inside the heated part.
14. An external combustion engine as set forth in claim 11, wherein
said judging means calculates the temperature of the heated part
based on the radiant heat radiated from the heater.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to an external combustion
engine using evaporation and condensation of a working medium to
cause displacement of a liquid part of the working medium and
converting displacement of the liquid part of the working medium to
mechanical energy for output.
[0003] 2. Description of the Related Art
[0004] In the past, in this type of external combustion engine,
also called a "liquid piston steam engine", a pipe-shaped container
is sealed with a working medium flowable in a liquid state, a
heater arranged at one end of the container (heated part) is used
to heat part of the liquid state working medium to cause it to
evaporate, and a cooler arranged at the middle of the container
(cooled part) is used to cool the steam of the working medium to
cause it to condense. By this evaporation and condensation of this
working medium, the liquid part of the working medium is cyclically
made to displace (so-called "self-excited vibration"), then this
self-excited vibration of the working medium is taken out at an
output part communicated with the other end of the container. (For
example, see Japanese Patent Publication (A) No. 2004-84523).
[0005] In this regard, Japanese Patent Application No. 2007-174065
(hereinafter referred to as the "prior application") proposes
applying a liquid piston steam engine to an electric power
generation system mounted in a vehicle. In this prior application,
the exhaust gas of the engine for driving the vehicle, in this case
a water-cooled type internal combustion engine (E/G), is utilized
as the heat source of the heater so as to heat the working medium.
The waste heat of the water-cooled type internal combustion engine
is therefore recovered and utilized to generate electric power in
this electric power generation system.
[0006] Further, in this prior application, the cooling water of the
water-cooled type internal combustion engine is circulated to the
cooler of the liquid piston steam engine so as to combine the
cooling water circulation circuit of the water-cooled type internal
combustion engine and the cooling water circulation circuit of the
liquid piston steam engine and thereby streamline the
configuration.
[0007] According to this prior application, when the vehicle
ignition switch (I/G) is turned off and the water-cooled type
internal combustion engine stops, exhaust gas is no longer
produced. For this reason, in the liquid piston steam engine, right
after the water-cooled type internal combustion engine stops, the
excess heat stored in the heater causes the heated part to become
high in temperature, but after that the temperature of the heated
part gradually falls so the working medium can no longer be
sufficiently heated and the liquid piston steam engine stops
operating.
[0008] However, in general, in the cooling water circulation
circuit of a water-cooled type internal combustion engine, the
water pump for circulating the cooling water is driven by the power
of the water-cooled type internal combustion engine, so if the
water-cooled type internal combustion engine stops, the water pump
also stops so the circulation of the cooling water ends up stopping
and the amount of heat radiated from the cooling water becomes
extremely small.
[0009] Furthermore, as shown in FIG. 7, after the water-cooled type
internal combustion engine stops, if the amount of heat transferred
from the heater having the excess heat to the cooling water in the
cooler is larger than the amount of heat radiated from the cooling
water, the temperature of the cooling water inside the cooler ends
up rising.
[0010] If, as a result, the temperature of the cooling water in the
cooler ends up rising to the boiling point or more, the cooling
water in the cooler will boil and therefore the internal pressure
of the cooling water circulation circuit will end up abnormally
rising. In the worst case, there is the problem that the various
pipes and devices in the cooling water circulation circuit will
break and leakage of cooling water will end up being caused.
[0011] Note that this problem is liable to similarly occur not only
after the water-cooled type internal combustion engine stops, but
also in rapid transition of the water-cooled type internal
combustion engine from the high load state to the low load state.
That is, the water pump is driven by the power of the water-cooled
type internal combustion engine, so in rapid transition of the
water-cooled type internal combustion engine from the high load
state with a large amount of waste heat to the low load state where
the amount of circulation of the cooling water is small, the amount
of circulation of the cooling water becomes insufficient and the
cooling water in the cooler ends up rising in temperature.
[0012] Further, this problem is liable to similarly occur not only
when applying a liquid piston steam engine to an electric power
generation system mounted in a vehicle, that is, when using the
exhaust gas of a water-cooled type internal combustion engine
(engine for driving a vehicle) as a heat source to heat and
evaporate a working medium and using the cooling water cooling the
water-cooled type internal combustion engine as a cooling source to
cool and condense the steam of the working medium, but also when
using the waste heat of various heat engines as a heat source to
heat and evaporate a working medium and using the cooling fluid
cooling the heat engine as a cooling source to cool and condense
the steam of the working medium.
SUMMARY OF THE INVENTION
[0013] The present invention, in consideration of the above point,
has as its object to suppress the boiling of the cooling water in
the cooler.
[0014] To achieve the above object, in the aspect of the invention
described in claim 1, there is provided an external combustion
engine provided with
[0015] a pipe-shaped container (11) in which a working medium is
sealed flowably in a liquid state,
[0016] a heater (12) having a heated part (12a) communicating with
one end of the container (11) and heating the working medium at the
heated part (12a) to make it evaporate,
[0017] a cooler (13) arranged at a middle of the container (11) and
cooling the steam of the working medium produced by the heater (12)
to make it condense, and
[0018] an output part (14) communicated with the other end of the
container (11) and converting the displacement of the liquid part
of the working medium produced due to the change in volume of the
working medium accompanying evaporation and condensation of the
working medium to mechanical energy for output,
[0019] the heater (12) being designed to use waste heat of a heat
engine (1) as a heat source to heat the working medium and make it
evaporate,
[0020] the cooler (13) being designed to use a cooling fluid
cooling the heat engine (1) as a cooling source to cool the steam
of the working medium and make it condense, and
[0021] the engine provided with a heated part temperature reducing
means for reducing the temperature (Th) of the heated part (12a)
when the amount of heat radiated from the cooling fluid to the
outside becomes smaller than the amount of heat transferred from
the working medium to the cooling fluid.
[0022] Due to this, it is possible to suppress the rise of
temperature (Tw) of the cooling fluid in the cooler (13), so it is
possible to suppress boiling of the cooling water at the cooler
(13).
[0023] In the aspect of the invention as set forth in claim 2,
there is provided an external combustion engine as set forth in
claim 1, wherein the heated part temperature reducing means has a
pump means (21, 31) for circulating the cooling fluid to the cooler
(13).
[0024] In the aspect of the invention as set forth in claim 3,
there is provided an external combustion engine as set forth in
claim 2, wherein the heated part temperature reducing means
controls the pump means (21, 31) based on at least one of the
amount of waste heat of the heat engine (1), the temperature (Th)
of the heated part (12a), and the temperature (Tw) of the cooling
fluid.
[0025] In the aspect of the invention as set forth in claim 4,
there is provided an external combustion engine as set forth in
claim 2 or 3, wherein the pump means (21) is driven by electric
power.
[0026] In the aspect of the invention as set forth in claim 5,
there is provided an external combustion engine as set forth in
claim 2, wherein the pump means (21) is coupled with an output part
(14) so as to be driven by output from the output part (14).
[0027] In the aspect of the invention as set forth in claim 6,
there is provided an external combustion engine as set forth in any
one of claims 2 to 5, wherein the length of the flow path of the
cooling fluid becomes shorter by providing a bypass flow path (20)
for circulating the cooling fluid bypassing the heat engine (1),
and
[0028] the bypass flow path (20) is provided with a pump means (21)
and a radiating means (22) for radiating the heat of the cooling
fluid to the outside.
[0029] According to this, the length of the flow path of the
cooling fluid becomes shorter, so the drive force of the pump means
(21) can be reduced.
[0030] In the aspect of the invention as set forth in claim 7,
there is provided an external combustion engine as set forth in
claim 6, wherein the radiating means (22) is provided with a heat
storing material for storing the heat discharged from the cooling
fluid. According to this, the heat storing material makes it
possible to effectively utilize the heat.
[0031] In the aspect of the invention as set forth in claim 8,
there is provided an external combustion engine as set forth in
claim 1, wherein the heated part temperature reducing means has
cooling means (40, 41) for cooling the heater (12) from the
outside.
[0032] In the aspect of the invention as set forth in claim 9,
there is provided an external combustion engine as set forth in
claim 8, wherein the cooling means (40) is a means for blowing air
to the heater (12).
[0033] In the aspect of the invention as set forth in claim 10,
there is provided an external combustion engine as set forth in
claim 8, wherein the cooling means (41) is a means for spraying
water to the heater (12).
[0034] In the aspect of the invention as set forth in claim 11,
there is provided an external combustion engine as set forth in any
one of claims 1 to 10 wherein the heated part temperature reducing
means has judging means (S100, S300) for judging when the amount of
heat radiated from the cooling fluid to the outside becomes smaller
than the amount of heat transferred from the working medium to the
cooling fluid based on at least the temperature (Th) of the heated
part (12a).
[0035] In the aspect of the invention as set forth in claim 12,
there is provided an external combustion engine as set forth in
claim 11, wherein the judging means (S100, S300) deems that the
amount of heat radiated from the cooling fluid to the outside has
become smaller than the amount of heat transferred from the working
medium to the cooling fluid when the heat engine (1) has stopped
and the temperature (Th) of the heated part (12a) exceeds the
boiling point of the cooling fluid.
[0036] Note that "when the temperature (Th) of the heated part
(12a) exceeds the boiling point of the cooling fluid" in the
present invention does not mean only when the temperature (Th) of
the heated part (12a) strictly exceeds the boiling point of the
cooling fluid and means also when the temperature (Th) of the
heated part (12a) exceeds a temperature near the boiling point of
the cooling fluid.
[0037] In the aspect of the invention as set forth in claim 13,
there is provided an external combustion engine as set forth in
claim 11 or 12, wherein the judging means (S300) calculates the
temperature (Th) of the heated part (12a) based on the pressure
inside the heated part (12a).
[0038] In the aspect of the invention as set forth in claim 14,
there is provided an external combustion engine as set forth in
claim 11 or 12, wherein the judging means (S300) calculates the
temperature (Th) of the heated part (12a) based on the radiant heat
radiated from the heater (12).
[0039] Note that the reference numerals after the means described
in this section and the claims show the correspondence with
specific means described in the later explained embodiments.
BRIEF DESCRIPTION OF THE DRAWINGS
[0040] These and other objects and features of the present
invention will become clearer from the following description of the
preferred embodiments given with reference to the attached
drawings, wherein:
[0041] FIG. 1 is a schematic view of the overall configuration of a
vehicle electric power generation system in a first embodiment of
the present invention;
[0042] FIG. 2 is a flow chart showing an outline of the control
processing executed by an electronic control unit of a first
embodiment;
[0043] FIG. 3 is a flow chart showing an outline of the control
processing executed by an electronic control unit at the time of a
cooling mode of FIG. 2;
[0044] FIG. 4 is a timing chart showing an example of control in
the first embodiment;
[0045] FIG. 5 is a schematic view of the overall configuration of a
vehicle electric power generation system in a second embodiment of
the present invention;
[0046] FIG. 6 is a schematic view of the overall configuration of a
vehicle electric power generation system in a third embodiment of
the present invention; and
[0047] FIG. 7 is a graph showing the problem in the prior
application.
[0048] In the figures, 1 indicates a water-cooled type internal
combustion engine (heat engine), 11 a container, 12 a heater, 12a a
heated part, 13 a cooler, 14 an output part, 20 a bypass flow path,
21 an auxiliary water pump (pump means), and 22 an auxiliary
radiator (radiating means).
DESCRIPTION OF THE PREFERRED EMBODIMENTS
First Embodiment
[0049] Below, a first embodiment of the present invention will be
explained. This embodiment applies the external combustion engine
according to the present invention (liquid piston steam engine) to
an electric power generation system mounted in a vehicle. FIG. 1 is
a schematic view of the overall configuration of a vehicle electric
power generation system according to the present embodiment.
[0050] First, a liquid piston steam engine 10 will be simply
explained. The liquid piston steam engine 10 may be roughly divided
into a pipe-shaped container 11 in which a working medium (in this
example, water) is sealed flowably in a liquid state, a heater 12
heating the working medium to make it evaporate, a cooler 13
cooling the steam of the working medium evaporated by the heater 12
to make it condense, and an output part 14 converting the
displacement of the liquid part of the working medium caused by the
change in volume of the working medium accompanying evaporation and
condensation of the working medium to mechanical energy for
output.
[0051] In this embodiment, a plurality of containers 11 (in the
example of FIG. 1, three) are arranged in parallel to form a
so-called multi-cylinder type liquid piston steam engine, but it is
also possible to provide just one container 11 to form a so-called
single-cylinder type liquid piston steam engine.
[0052] The heater 12 is a heat exchanger exchanging heat with
exhaust gas of the engine driving the vehicle, in this case a
water-cooled type internal combustion engine (heat engine) 1, and
is arranged at one end of the container 11. Inside the heater 12 is
formed a space communicated with the container 11. This space forms
a heated part 12a using the exhaust gas of the water-cooled type
internal combustion engine 1 as a heat source to heat the working
medium.
[0053] The cooler 13 circulates cooling water cooling the
water-cooled type internal combustion engine 1 (cooling fluid)
through it so as to cool the steam of the working medium and is
arranged so that the middle of the container 11 runs through it.
Therefore, the middle of the container 11 forms a cooled part
cooling the working medium.
[0054] The output part 14 converts the reciprocating displacement
of the liquid part of the working medium (linear motion) to rotary
motion and outputs it from an output shaft 14a. For example, it may
be comprised by an expansion mechanism made of a piston,
crankshaft, etc. Further, a linear motor may also be used to switch
to linear motion.
[0055] The output shaft 14a of the output part 14 has a motor
generator 15 coupled with it. This motor generator 15 can generate
electric power by the output from the output part 14 and charge a
storage battery 16 when the liquid piston steam engine 10 is
operating and can receive electric power from the storage battery
16 and drive the output shaft 14a of the output part 14 when the
liquid piston steam engine 10 has stopped.
[0056] For example, when the liquid piston steam engine 10 is
started up, the motor generator 15 functions as a starter for
starting the liquid piston steam engine 10. In this embodiment, an
existing battery (not shown) mounted in the vehicle is used as the
storage battery 16, but a specialized storage battery separate from
the existing battery may also be used.
[0057] Next, the circuit for circulating the cooling water cooling
the water-cooled type internal combustion engine 1 (hereinafter
referred to as a "cooling water circulation circuit") will be
explained. The cooling water circulation circuit may be roughly
divided into a radiator circuit 2 radiating the heat of the cooling
water flowing out from the water-cooled type internal combustion
engine 1 to the outside (outside air) and a heater circuit 3
heating the air-conditioning air inside the passenger compartment
by the heat of the cooling water flowing out from the water-cooled
type internal combustion engine 1.
[0058] The radiator circuit 2 has a radiator 4 cooling the cooling
water by heat exchange between the cooling water and the outside
air. An electric blower fan 5 blowing air to the radiator 4 is
driven by the electric power supplied from the above-mentioned
battery.
[0059] In the heater circuit 3, a heater core 6 of a vehicle
air-conditioning system is arranged. This heater core 6 is a
heating use heat exchanger heating the air-conditioning air inside
the passenger compartment by heat exchange between the cooling
water and the air-conditioning air inside the passenger
compartment. The heater circuit 3 merges with the radiator circuit
2 at the cooling water inlet side of the water-cooled type internal
combustion engine 1.
[0060] In the cooling water inlet side of the water-cooled type
internal combustion engine 1, a water pump 7 for circulating the
cooling water to the radiator circuit 2 and heater circuit 3 is
arranged. This water pump 7 is driven by the power of the
water-cooled type internal combustion engine 1.
[0061] At the upstream side from the part merging with the heater
circuit 3 in the radiator circuit 2, a thermostat 8 regulating the
ratio of the flow rate of the cooling water circulating through the
radiator circuit 2 and the flow rate of the cooling water
circulating through the heater circuit 3 is arranged.
[0062] In the heater circuit 3, a cooler 13 of the liquid piston
steam engine 10 is arranged between the water-cooled type internal
combustion engine 1 and the heater core 6. Further, in the heater
circuit 3, a bypass flow path 20 is provided between the cooling
water inlet side and cooling water outlet side of the cooler
13.
[0063] This bypass flow path 20 is a bypass for making the cooling
water flowing out from a cooling water outlet part of the cooler 13
bypass the water-cooled type internal combustion engine 1 and
heater core 6 etc. and flow toward a cooling water inlet part of
the cooler 13 and is provided so as to shorten the length of the
flow path of the cooling water in the heater circuit 3.
[0064] In the bypass flow path 20, an auxiliary water pump (pump
means) 21 circulating cooling water to the bypass flow path 20 and
an auxiliary radiator (radiating means) 22 cooling the cooling
water flowing through the bypass flow path 20 by heat exchange
between the cooling water and the outside air are arranged.
[0065] The auxiliary water pump 21 is an electric water pump driven
by electric power supplied from the storage battery 16. The
electric blower fan 23 blowing air to the auxiliary radiator 22 is
also driven by the electric power supplied from the storage battery
16. The auxiliary water pump 21 and the electric blower fan 23 of
the auxiliary radiator 22 are controlled by a not shown electronic
control unit.
[0066] The details will be explained later, but these bypass flow
path 20, auxiliary water pump 21, auxiliary radiator 22, electric
blower fan 23, and electronic control unit configure a heated part
temperature reducing means reducing the temperature Th of the
heated part 12a (hereinafter referred to as the "heated part
temperature") when the amount of heat radiated from the cooling
water to the outside (the outside air) becomes smaller than the
amount of heat transferred from the working medium to the cooling
water. Note that the specific configuration of the heated part
temperature reducing means is not limited to this and can be
modified in various ways as explained later.
[0067] In the heater circuit 3, electric type shutoff valves 24 to
27 opening and closing the cooling water flow path are arranged.
Specifically, these are arranged between a branch part 3a of the
bypass flow path 20 and the heater core 6, between a merged part 3b
of the bypass flow path 20 and the water-cooled type internal
combustion engine 1, at the inlet part of the bypass flow path 20,
and at an outlet part of the bypass flow path 20.
[0068] The operations of these shutoff valves 24 to 27 are also
controlled by the electronic control unit. In this embodiment, the
above-mentioned water pump 7 and electric blower fan 5 of the
radiator 4 are controlled by the electronic control unit.
[0069] The electronic control unit is comprised of a known
microcomputer including a CPU, ROM, RAM, etc. and its peripheral
circuits and performs various computations and processing based on
a control program stored in the ROM to control the operations of
the various equipment connected to the output side.
[0070] At the input side of this electronic control unit, detection
signals from a heated part temperature sensor 28 detecting the
heated part temperature Th, a cooling water temperature sensor 29
detecting the cooling water temperature Tw at the cooling water
outlet side of the water-cooled type internal combustion engine 1,
and a cooling water flow rate sensor 30 detecting the cooling water
flow rate Fw at the cooling water outlet side of the water-cooled
type internal combustion engine 1 are input.
[0071] The heated part temperature sensor 28 is arranged at the
heated part 12a. The cooling water temperature sensor 29 and
cooling water flow rate sensor 30 are arranged in the heater
circuit 3 at the cooling water outlet side of the water-cooled type
internal combustion engine 1.
[0072] It is possible to use a thermocouple as the heated part
temperature sensor 28. Instead of using the heated part temperature
sensor 28 to detect the heated part temperature Th, it is also
possible to provide a pressure sensor for detecting the internal
pressure of the heated part 12a and have the electronic control
unit calculate the heated part temperature Th based on the internal
pressure of the heated part 12a. Further, it is also possible to
provide a radiant heat sensor detecting the radiant heat radiated
from the heater 12 and have the electronic control unit calculate
the heated part temperature Th based on the radiant heat radiated
from the heater 12.
[0073] Next, the operation of the present embodiment in the above
configuration will be explained. The operation of the vehicle
electric power generation system may be roughly divided into the
normal operation mode performed at the time of operation of the
water-cooled type internal combustion engine 1 and the cooling mode
performed after the water-cooled type internal combustion engine 1
stops.
[0074] The normal operation mode recovers the waste heat of the
exhaust gas of the water-cooled type internal combustion engine 1
and generates electric power. The first and second cooling modes
cool the liquid piston steam engine 10 after the water-cooled type
internal combustion engine 1 stops.
[0075] In the normal operation mode, in the liquid piston steam
engine 10, the heater 12 uses the exhaust gas of the water-cooled
type internal combustion engine 1 as a heat source to heat and
evaporate the working medium. Due to this, high temperature, high
pressure steam of the working medium is stored at one end of the
container 11 and the liquid part of the working medium is pushed
out and displaced to the other end of the container 11 (output part
14 side).
[0076] Here, at the time of operation of the water-cooled type
internal combustion engine 1, the water pump 7 is driven and
cooling water is circulated in the heater circuit 3. For this
reason, when the steam of the working medium 14 stored at one end
of the container 11 reaches the middle of the container 11
(location where cooler 13 is arranged), the steam of the working
medium is cooled and condensed by the cooling water circulating
through the cooler 13. Due to this, the liquid part of the working
medium pushed out by the steam of the working medium to the output
part 14 is pushed back to the heater 12 side.
[0077] This operation is repeatedly performed until stopping the
operations of the heater 12 and cooler 13. During that time, the
working medium inside the container 11 cyclically displaces
(so-called self-excited vibration). The self-excited vibration of
the working medium (linear motion) is converted at the output part
14 to rotary motion of the output shaft 14a and output. Due to
this, electric power is generated at the motor generator 15 and the
storage battery 16 is charged.
[0078] The cooling mode may further be roughly divided into a first
cooling mode and a second cooling mode. In the first cooling mode,
the excess heat stored in the heater 12 is used to operate the
liquid piston steam engine 10 and take out output from the output
part 14. This output is used by the motor generator 15 to generate
electric power. At this time, the cooling water is made to flow
through only the bypass flow path 20 and is prevented from flowing
to the water-cooled type internal combustion engine 1 and heater
core 6 side by the electronic control unit operating the shutoff
valves 24 to 27.
[0079] Furthermore, the electric power generated by the motor
generator 15 is used to drive the auxiliary water pump 21 to
circulate cooling water in the cooler 13. At the same time, the
electric blower fan 23 of the auxiliary radiator 22 is also driven
by the electric power generated by the motor generator 15. Due to
this, the cooler 13 cools the working medium, the excess heat of
the heater 12 is gradually robbed, and the heated part temperature
Th gradually falls.
[0080] In the second cooling mode, the electric power supplied from
the storage battery 16 is used to drive the motor generator 15
whereby the output shaft 14a of the output part 14 is driven to
forcibly displace the working medium in the container 11. At the
same time as this, the auxiliary water pump 21 and the electric
blower fan 23 of the auxiliary radiator 22 are also driven by the
electric power supplied from the storage battery 16.
[0081] Due to this, the cooler 13 cools the working medium and the
cooled working medium enters the heated part 12a and cools the
heater 12, so the excess heat of the heater 12 is further robbed
and the heated part temperature Th further falls.
[0082] The switching control of the normal operation mode and first
and second cooling modes will be explained next based on FIG. 2 and
FIG. 3. FIG. 2 is a flow chart showing the outlines of the control
processing executed by the electronic control unit. This control
processing is started when a not shown vehicle start switch
(ignition switch) is turned on.
[0083] First, at step S100, it is judged if the water-cooled type
internal combustion engine 1 is operating. Note that step S100 and
the later explained step S300 correspond to the judging means in
the present invention.
[0084] When it is judged at step S100 that the water-cooled type
internal combustion engine 1 is operating (ON), the routine
proceeds to step S200 where the above-mentioned normal operation
mode is executed. When it is judged at step S100 that the
water-cooled type internal combustion engine 1 has stopped (OFF),
the routine proceeds to step S300 where it is judged if the heated
part temperature Th exceeds a first predetermined temperature
Tb.
[0085] Here, as the first predetermined temperature Tb, for example
the boiling point of the cooling water or a temperature near the
boiling point may be set. As the temperature near the boiling point
of the cooling water, the temperature when the internal pressure of
the cooling water circulation circuit becomes the upper limit
pressure in the pressure resistant performance may be set.
[0086] When it is judged at step S300 that the heated part
temperature Th exceeds the first predetermined temperature Tb, the
routine proceeds to step S400 where the above-mentioned cooling
mode is shifted to. When it is judged at step S300 that the heated
part temperature Th is the first predetermined temperature Tb or
less, the control processing is ended without performing the
cooling mode.
[0087] FIG. 3 is a flow chart showing the outline of the control
processing executed by the electronic control unit at the time of
the cooling mode. In the cooling mode, first, at step S410, it is
judged if the heated part temperature Th exceeds a second
predetermined temperature To. Here, as the second predetermined
temperature To, the lower limit temperature at which output can be
taken out from the liquid piston steam engine 10 is set.
[0088] That is, the liquid piston steam engine 10 can no longer
maintain the self-excited vibration of the working medium and can
no longer take out output when the heated part temperature Th
becomes less than a certain temperature. Therefore, the lower limit
of the heated part temperature Th enabling the self-excited
vibration of the working medium to be maintained and output to be
taken out is set as the second predetermined temperature To. Note
that the second predetermined temperature To is a temperature
higher than the first predetermined temperature Tb (To>Tb).
[0089] When it is judged at step S410 that the heated part
temperature Th exceeds the second predetermined temperature To, the
routine proceeds to step S420 where the above-mentioned first
cooling mode is performed. The first cooling mode is performed
until it is judged at step S410 that the heated part temperature Th
is the second predetermined temperature To or less.
[0090] When it is judged at step S410 that the heated part
temperature Th is the second predetermined temperature To or less,
the routine proceeds to step S430 where the above-mentioned second
cooling mode is shifted to. The second cooling mode is performed
until it is judged at step S440 that the heated part temperature Th
is the first predetermined temperature Tb or less.
[0091] Furthermore, when it is judged at step S440 that the heated
part temperature Th is the first predetermined temperature Tb or
less, the second cooling mode is ended and the cooling mode itself
is ended.
[0092] FIG. 4 is a timing chart showing an example of the control
in the present embodiment. Note that the amount of heat radiated in
FIG. 4 means the amount of heat recovered from the heater 12 and
radiated to the outside (the outside air). Further, the cooling
water temperature in FIG. 4 means the temperature of the cooling
water in the cooler 13.
[0093] As will be understood from FIG. 4, according to the present
embodiment, when the water-cooled type internal combustion engine 1
has stopped and the heated part temperature Th exceeds the first
predetermined temperature Tb (for example, the boiling point of the
cooling water), the first and second cooling modes are performed,
so even if the water-cooled type internal combustion engine 1
stops, cooling water continues to be circulated to the cooler 13 of
the liquid piston steam engine 10 until the heated part temperature
Th falls to the first predetermined temperature Tb or less.
[0094] For this reason, after the water-cooled type internal
combustion engine 1 stops, the heater 12 with the excess heat is
quickly cooled and the heated part temperature Th quickly falls. As
a result, after the water-cooled type internal combustion engine 1
stops, it is possible to keep the excess heat stored in the heater
12 of the liquid piston steam engine 10 from causing the
temperature of the cooling water in the cooler 13 to rise.
[0095] That is, the present embodiment deems that the amount of
heat radiated from the cooling water to the outside (the outside
air) has become smaller than the amount of heat transferred from
the working medium to the cooling water and reduces the temperature
Th of the heated part 12a by the above-mentioned heated part
temperature reducing means when the water-cooled type internal
combustion engine 1 has stopped and the heated part temperature Th
exceeds the first predetermined temperature Tb (for example, the
boiling point of cooling water).
[0096] For this reason, it is possible to keep the temperature of
the cooling water in the cooler 13 from rising to the boiling point
or more and thereby the cooling water from ending up boiling. As a
result, it is possible to prevent the problem of the boiling of the
cooling water from causing the internal pressure of the cooling
water circulation circuit to abnormally rise, the various pipes and
devices of the cooling water circulation circuit to break, and
cooling water to leak.
[0097] Further, in the first cooling mode, the excess heat of the
heater 12 is used to take out output from the liquid piston steam
engine 10, so all or part of the drive power of the auxiliary water
pump 21 and electric blower fan 23 of the auxiliary radiator 22 in
the first and second cooling modes can be met by the output from
the liquid piston steam engine 10. For this reason, in the first
and second cooling modes, it is possible to reduce the amount of
electric power supplied from the storage battery 16 and possible to
save energy.
[0098] Further, in the first and second cooling modes, the cooling
water bypasses the water-cooled type internal combustion engine 1
and heater core 6 etc. and flows through the bypass flow path 20,
so the length of the flow path of the cooling water is shortened,
so it is possible to reduce the drive power of the auxiliary water
pump 21 and possible to further save energy.
[0099] Further, as shown in FIG. 4, in the first and second cooling
modes, if reducing the drive power of the auxiliary water pump 21
along with the fall in the heated part temperature Th, it is
possible to further save energy. This is true not only for the
drive power of the auxiliary water pump 21, but also the drive
power of the electric blower fan 23 of the auxiliary radiator
22.
[0100] Note that in the present embodiment, in the first cooling
mode, the output taken out from the output part 14 is used by the
motor generator 15 to generate electric power, but as a
modification, it is also possible not to generate electric power by
the motor generator 15 even if taking out output from the output
part 14 in the first cooling mode.
[0101] That is, when not generating electric power by the motor
generator 15 despite taking out output from the output part 14, the
output part 14 becomes load-less, so the operating frequency of the
liquid piston steam engine 10 rises.
[0102] For this reason, in this modification, it is possible to
raise the operating frequency of the liquid piston steam engine 10
in the first cooling mode, so the amount of heat robbed from the
heated part 12a by the working medium is increased, the cooling of
the working medium in the cooler 13 is promoted, and the heated
part temperature Th can be reduced in a short time. As a result,
the time during which the cooling mode is performed can be
shortened.
Second Embodiment
[0103] In the above first embodiment, the auxiliary water pump 21
and the electric blower fan 23 of the auxiliary radiator 22 are
driven by the electric power supplied from the storage battery 16,
but in the second embodiment, as shown in FIG. 5, the auxiliary
water pump 31 and the electric blower fan 32 of the auxiliary
radiator 22 are coupled with the output shaft 14a of the output
part 14.
[0104] Due to this, the auxiliary water pump 31 and the electric
blower fan 32 of the auxiliary radiator 22 are directly driven by
the output from the output part 14.
[0105] In the present embodiment as well, advantageous effects
similar to the first embodiment can be obtained.
Third Embodiment
[0106] In the above embodiments, after the water-cooled type
internal combustion engine 1 stops, cooling water is circulated
through the cooler 13 to suppress boiling of the cooling water at
the cooler 13, but in the third embodiment, as shown in FIG. 6,
after the water-cooled type internal combustion engine 1 stops, the
heater 12 is cooled from the outside to suppress boiling of the
cooling water at the cooler 13.
[0107] FIG. 6 is a schematic view of the configuration of a vehicle
electric power generation system in the present embodiment. The
heater 12 of the liquid piston steam engine 10 is arranged in the
middle of an exhaust pipe 40 through which the exhaust gas of the
water-cooled type internal combustion engine 1 flows.
[0108] In this embodiment, as the cooling means for cooling the
heater 12 from the outside, an air duct (not shown) introducing air
blown by the electric blower fan 5 of the radiator 4 to the heater
12, an electric blower fan 40 directly blowing air to the heater
12, and a water spray mechanism 41 spraying water on the heater 12
are provided.
[0109] In this embodiment, the electric blower fan 40 is designed
to be driven by the electric power supplied from the storage
battery 16. The water spray mechanism 82 has a not shown water tank
and an injector 41a injecting water inside the water tank toward
the heater 12. The electric blower fan 40 and injector 41a are
controlled by the above-mentioned electronic control unit.
[0110] The cooling of the heater 12 by these means is started when
the water-cooled type internal combustion engine 1 stops and the
heated part temperature Th exceeds a first predetermined
temperature Tb and is stopped when the heated part temperature Th
falls to the first predetermined temperature Tb or more. Due to
this, it is possible to obtain advantageous effects similar to the
above first embodiment.
[0111] As will be understood from the above explanation, in the
present embodiment, the above-mentioned heated part temperature
reducing means is comprised by a cooling means for cooling the
heater 12 from the outside. Note that as the cooling means for
cooling the heater 12 from the outside, it is not necessarily
required to provide all of the above-mentioned air duct, electric
blower fan 40, and water spray mechanism 41. It is sufficient to
provide even one of these.
Other Embodiments
[0112] Note that in the above first and second embodiments, an
electric blower fan 23 for blowing air to the auxiliary radiator 22
is arranged, but the electric blower fan 23 may also be eliminated.
In this case, a heat storing material may be arranged at the
auxiliary radiator 22. Due to this, it is possible to avoid a drop
in the heat radiating performance accompanying elimination of the
electric blower fan 23 and possible to effectively utilize the heat
recovered by the cooling water.
[0113] Further, in the above embodiments, an auxiliary water pump
21 and an auxiliary radiator 22 are arranged in the bypass flow
path 20, but it is also possible to eliminate the bypass flow path
20 and arrange the auxiliary water pump 21 and auxiliary radiator
22 in the main circuit of the heater circuit 3.
[0114] Further, in the above embodiments, the cooler 13 of the
liquid piston steam engine 10 is arranged in the heater circuit 3,
but it is also possible to arrange the cooler 13 of the liquid
piston steam engine 10 in the radiator circuit 2. In this case, in
the first and second cooling modes, heat can be radiated from the
cooling water by the radiator 4 of the heater circuit 3, so the
auxiliary radiator 22 can be eliminated.
[0115] Further, in the above embodiments, the heated part
temperature Th is reduced to suppress boiling of the cooling water
at the cooler 13 only after the water-cooled type internal
combustion engine 1 is stopped, but in the same way as the above
embodiments, it is also possible to reduce the heated part
temperature Th to suppress boiling of the cooling water at the
cooler 13 when the water-cooled type internal combustion engine 1
rapidly transits from a high load state to a low load state.
[0116] That is, in the above embodiments, the water pump 7 is
driven by power of the water-cooled type internal combustion engine
1, so in rapid transition of the water-cooled type internal
combustion engine 1 from the high load state with a large amount of
waste heat to a low load state with little amount of circulation of
the cooling water, the amount of circulation of the cooling water
is liable to become insufficient and the cooling water is liable to
end up boiling at the cooler 13.
[0117] Further, in the above embodiments, the water pump 7 was
driven by power of the water-cooled type internal combustion engine
1, but if using a water pump 7 comprised of an electric water pump
and using electric power supplied from the storage battery 16 to
drive this water pump 7 after the water-cooled type internal
combustion engine 1 stops, it is possible to suppress boiling of
the cooling water at the cooler 13 in the same way as the above
embodiments.
[0118] In this case, it is possible to eliminate the bypass flow
path 20, auxiliary water pump 21, auxiliary radiator 22, electric
blower fan 40, water spray mechanism 41, etc. in the above
embodiments.
[0119] Further, in the above embodiments, the external combustion
engine was configured to use the exhaust gas of an engine driving a
vehicle, in this case a water-cooled type internal combustion
engine 1, as the heat source to heat and evaporate the working
medium and to use the cooling water of the water-cooled type
internal combustion engine 1 as the cooling source to cool and
condense the steam of the working medium, but the invention is not
limited to this. The external combustion engine may also be
configured to use the waste heat of various heat engines as the
heat source to heat and evaporate the working medium and use the
various cooling fluids cooling the heat engines (for example oil
etc.) as the cooling source to cool and condense the steam of the
working medium.
[0120] Further, the above embodiments only show examples of the
configuration of the liquid piston steam engine 10. For example, it
is of course possible to change the configuration of the liquid
piston steam engine 10 as shown in Japanese Patent Publication (A)
No. 2004-84523.
[0121] While the invention has been described with reference to
specific embodiments chosen for purpose of illustration, it should
be apparent that numerous modifications could be made thereto by
those skilled in the art without departing from the basic concept
and scope of the invention.
* * * * *