U.S. patent application number 10/172490 was filed with the patent office on 2003-07-03 for heat engine.
Invention is credited to Conrad, Wayne Ernest.
Application Number | 20030121259 10/172490 |
Document ID | / |
Family ID | 56290295 |
Filed Date | 2003-07-03 |
United States Patent
Application |
20030121259 |
Kind Code |
A1 |
Conrad, Wayne Ernest |
July 3, 2003 |
Heat engine
Abstract
A heat engine body comprising a container defining a sealed
region within which a working fluid is circulated when the heat
engine body is in use, the sealed region having spaced apart first
and second ends which are in fluid flow communication via a working
fluid passageway, the first end is at a different temperature than
the second end when the heat engine body is use, and a heat
exchanger comprising at least one member defining a plurality of
openings having louvers which are configured and arranged to cause
at least a portion of a fluid to flow through the openings as the
fluid flows through the heat exchanger.
Inventors: |
Conrad, Wayne Ernest;
(Hampton, CA) |
Correspondence
Address: |
Orange & Chari
Suite 4900
P.O. Box 190
66 Wellington Street West
Toronto
ON
M5K 1H6
CA
|
Family ID: |
56290295 |
Appl. No.: |
10/172490 |
Filed: |
June 17, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10172490 |
Jun 17, 2002 |
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PCT/CA00/1502 |
Dec 18, 2000 |
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PCT/CA00/1502 |
Dec 18, 2000 |
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09570523 |
May 16, 2000 |
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09570523 |
May 16, 2000 |
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09523139 |
Mar 10, 2000 |
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6345666 |
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60182106 |
Feb 11, 2000 |
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60182105 |
Feb 11, 2000 |
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60182050 |
Feb 11, 2000 |
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Current U.S.
Class: |
60/508 |
Current CPC
Class: |
F02G 1/0435 20130101;
F28F 1/24 20130101; F02G 1/0445 20130101; F02G 2255/20 20130101;
F28D 7/103 20130101; H02K 7/1884 20130101; F02G 1/055 20130101;
F25B 9/14 20130101; F02G 2243/02 20130101; F28F 1/105 20130101;
H02K 35/02 20130101; F05C 2225/08 20130101; F02G 1/057
20130101 |
Class at
Publication: |
60/508 |
International
Class: |
F01B 001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 17, 1999 |
CA |
2,292,684 |
Claims
I claim:
1. A heat engine body comprising: (a) a container defining a sealed
region within which a working fluid is circulated when the heat
engine body is in use, the sealed region having spaced apart first
and second ends which are in fluid flow communication via a working
fluid passageway, the first end is at a different temperature than
the second end when the heat engine body is in use; and, (b) a heat
exchanger comprising at least one member defining a plurality of
openings having associated louvres which are configured and
arranged to cause at least a portion of a fluid to flow through the
openings as the fluid flows through the heat exchanger.
2. The heat engine body as claimed in claim 1 wherein the louvres
are configured and arranged to cause a portion of a fluid flowing
through the heat exchanger to flow from the first opposed side to
the second opposed side through at least some of the openings and
then from the second opposed side to the first opposed side through
at least some of the openings.
3. The heat engine body as claimed in claim 1 wherein the louvers
are configured and arranged to cause at least a portion of a fluid
flowing through the openings to swirl as the fluid flows through
the heat exchanger.
4. The heat engine body as claimed in claim 1 wherein the heat
exchanger comprises a plurality of longitudinally spaced apart
fins.
5. The heat engine body as claimed in claim 1 wherein the heat
exchanger comprises a plurality of longitudinally spaced apart fins
which are mounted to a wall of the heat engine body and at least
some of the fins have a hub adjacent the wall and an annular body
portion extending away from the hub, and the openings are provided
in the annular body portion.
6. The heat engine body as claimed in claim 1 wherein the heat
exchanger comprises a plurality of longitudinally spaced apart fins
which are mounted to a wall of the heat engine body and at least
some of the fins have a hub adjacent the wall and a plurality of
blades extending away from the hub, the blades defining the
openings through which the fluid flows.
7. The heat engine body as claimed in claim 1 wherein the heat
exchanger comprises a helical fin.
8. The heat engine body as claimed in claim 1 wherein the heat
exchanger comprises a helical fin which is mounted to a wall of the
heat engine body and has a hub adjacent the wall and an annular
body portion extending away from the hub, and the openings are
provided in the annular body portion.
9. The heat engine body as claimed in claim 1 wherein the heat
exchanger comprises a helical fin which is mounted to a wall of the
heat engine body and has a hub adjacent the wall and a plurality of
blades extending away from the hub, the blades defining the
openings through which the fluid flows.
10. The heat engine body as claimed in claim 1 wherein the heat
exchanger comprises a longitudinally extending member, the openings
are oriented generally parallel to the direction of travel of the
fluid and the louvres extend outwardly from the longitudinally
extending member to impinge the fluid.
11. The heat engine body as claimed in claim 1 wherein the heat
exchanger comprises at least one fin which is constructed from
metal and are prepared by stamping.
12. The heat engine body as claimed in claim 1 wherein the heat
exchanger comprises at least one fin which has a deformable collar
for lockingly engaging the inner surface to which the fin is
attached.
13. The heat engine body as claimed in claim 1 wherein the heat
exchanger comprises at least one fin which is mechanically mounted
to a wall of the heat engine body by a pressure which is exerted
between the at least one fin and the wall which is sufficient to
ensure that the rate of heat transfer between the fin and the wall
is maintained over the normal operating temperature of the
wall.
14. The heat engine body as claimed in claim 1 wherein at least
some of the louvres have at least one opening provided therein and
the louvre is configured and arranged to cause a portion of the
fluid to pass at least twice through the louvre as the fluid flows
through the heat exchanger.
15. The heat engine body as claimed in claim 1 wherein at least
some of the louvres have a first side, a second side and at least
one opening which is configured and arranged to cause a portion of
the fluid to flow unidirectionally from the first side of a louvre
to the second side of the louvre as the fluid flows through the
heat exchanger.
16. The heat engine body as claimed in claim 1 wherein at least
some of the louvres have at least one opening and the at least one
opening has associated sublouvres provided therein and the
sublouvres are configured and arranged to cause a portion of the
fluid to pass at least twice through the louvre as the fluid flows
through the heat exchanger.
17. The heat engine body as claimed in claim 1 wherein at least
some of the louvres have a first side, a second side and at least
one opening and the at least one opening has associated sublouvres
provided therein and the sublouvres are configured and arranged to
cause a portion of the fluid to flow unidirectionally from the
first side of a louvre to the second side of the louvre as the
fluid flows through the heat exchanger.
18. A heat engine body comprising: (a) a container defining a
sealed region within which a working fluid is circulated when the
heat engine is in use, the sealed region having first and second
ends which are in fluid flow communication via a working fluid
passageway, the first end is at a different temperature than the
second end when the heat engine is in use; and, (b) the heat engine
having a plurality of fins which are prepared by stamping.
19. A heat exchanger means capable of being mounted in an fluid
flow passage which is located between first and second walls, the
walls having a first end and a spaced apart second end, the heat
exchanger means comprising fin means having first and second
opposed sides and first directing means for generating a main flow
of fluid through the fin means as the fluid flows from the first
end to the second end and secondary directing means for generating
a secondary fluid flow which passes through at least some of the
first directing means whereby the heat transfer between the fluid
and the heat exchanger means is enhanced.
20. A heat engine body comprising: (a) inner and outer spaced apart
longitudinally extending walls, at least one of the inner and outer
walls being of a thin walled construction, the inner wall
surrounding a cavity, each of the inner and outer wall having
longitudinally spaced apart first and second ends, the first end is
at a different temperature than the second end when the heat engine
is in use, the first and second ends in fluid flow communication
via a passageway, the first and second ends and the passageway
defining a sealed region within which a working fluid is circulated
when the heat engine body is in use; and, (b) positioning members
for dimensionally stabilizing the one of the inner and outer wall
which is of a thin walled construction.
Description
FIELD OF THE INVENTION
[0001] This invention relates to a heat engine.
BACKGROUND OF THE INVENTION
[0002] The heat engine is an alternate engine to the internal
combustion engine. Various designs for heat engines have been
developed in the past. Despite its potential for greater
thermodynamic efficiency compared to internal combustion engines,
heat engines have been used in only limited applications in the
past due to several factors including the complexity of the
designs, the weight of the engine per unit of horse power output as
well as the difficulty in starting a heat engine.
SUMMARY OF THE INVENTION
[0003] In accordance with the instant invention, an improved design
for a heat engine is disclosed. In one embodiment, the heat engine
is made from lightweight sheet metal. By using a plurality of
cylindrical containers, one nested inside the other for the
displacer, the combustion and cooling chambers as well as to create
an air flow path between the heating and cooling chambers, a rugged
durable lightweight construction is achieved.
[0004] In another embodiment, the heat engine utilizes a power
piston which is biased to a first position. By biasing the piston,
several advantages are obtained. First, the heat engine may be self
starting provided the power piston is biased so as to be initially
positioned in the cooling chamber. A further advantage is that by
using an electrical means (eg. a solenoid, an electromagnet or the
like) and preferably a magnetic drive member (eg. an electromagnet)
to move the displacer, preferably in response to the position of
the power piston, a complicated mechanical linkage between the
power piston and the displacer is not required thus simplifying the
design. Further, by using an electrical linkage, the phase angle
between the displacer and the power piston may be adjusted.
[0005] The heat engine of the instant invention may be combined
with a fuel source (eg. butane), a linear generator and an
electrically operated light emitting means to create a flashlight
or other portable light source. It will be appreciated that due to
the simplicity of the design of the instant invention, the heat
engine as well as the linear generator are each adapted to be
scaled up or down so as to produce greater or lessor amounts of
power. Accordingly, in another embodiment, the heat engine together
with a linear generator and a fuel source may be used as a
generator. It will further be appreciated that by connecting a
linear generator to a source of electricity (eg. standard
electrical outlet) the electricity from a power grid may be used to
run the linear generator as a motor whereby the power piston
effectively drives the displacer. In such a case, the heat engine
may be used as a refrigerator or a cryogenic cooler. In such an
embodiment, the heating and cooling chambers of the heat engine are
effectively reversed and no combustion chamber is required.
[0006] In accordance with one aspect of the instant invention,
there is provided a heat engine comprising an outer container
comprising an outer longitudinally extending wall and first and
second longitudinally spaced apart ends, the outer wall surrounding
an outer cavity; an inner container spaced from the outer container
and comprising an inner longitudinally extending wall constructed
from sheet metal and surrounding an inner cavity having first and
second longitudinally spaced apart ends, the inner longitudinally
extending wall having first and second longitudinally spaced apart
ends, the first end of the cavity is at a different temperature
than the second end of the cavity when the heat engine is in use,
the first and second ends of the inner cavity being in fluid flow
communication via a passageway, the first and second ends of the
inner cavity and the passageway defining a sealed region within
which a working fluid is circulated when the heat engine is in use;
a plurality of longitudinally spaced apart positioning members
extending between the inner and outer containers; a displacer
movably mounted in the inner cavity; and, a piston movably mounted
in the inner cavity.
[0007] In accordance with another aspect of the instant invention,
there is provided a heat engine comprising inner and outer spaced
apart longitudinally extending walls, each of the inner and outer
walls being of a thin walled construction, the inner wall
surrounding a cavity, each of the inner and outer wall having
longitudinally spaced apart first and second ends, the first end is
at a different temperature than the second end when the heat engine
is in use, the first and second ends in fluid flow communication
via a passageway, the first and second ends and the passageway
defining a sealed region within which a working fluid is circulated
when the apparatus is in use; a displacer movably mounted in the
cavity between the first and second ends for movement between a
first position and a second position; a piston movably mounted in
the second end for movement between a first position and a second
position; and, support members for maintaining the dimensional
integrity of each of the ends of the inner wall.
[0008] In accordance with another aspect of the instant invention,
there is provided a heat engine comprising an outer container
means; a thin walled inner container means positioned inside the
outer container means, the inner container means having first and
second longitudinally spaced apart ends; fluid conduit means for
connecting the first and second ends in fluid flow communication;
positioning means for dimensionally stabilizing the inner and outer
container means; displacer means movably mounted in the inner
container means; and, piston means movably mounted in the inner
container means.
[0009] In accordance with another aspect of the instant invention,
there is provided a heat engine comprising inner and outer spaced
apart longitudinally extending walls, each wall having an inner
surface and an outer surface, the inner wall surrounding a cavity,
each of the inner and outer wall having longitudinally spaced apart
first and second ends, the first end is at a different temperature
than the second end when the heat engine is in use, the first and
second ends in fluid flow communication via a passageway, the first
and second ends and the passageway defining a sealed region within
which a working fluid is circulated when the heat engine is in use;
a displacer movably mounted in the cavity between the first and
second ends for movement between a first position and a second
position; a piston movably mounted in the second end for movement
between a first position and a second position; and, a heat
exchanger mounted on a portion of the outer surface of the outer
wall, the heat exchanger comprising at least one cooling fin
extending around the outer wall and having first and second opposed
sides and constructed to permit a cooling fluid to flow there
through.
[0010] In accordance with another aspect of the instant invention,
there is provided a heat engine comprising an outer member
comprising an outer longitudinally extending wall having an outer
surface and first and second longitudinally spaced apart ends, the
outer wall surrounding an outer cavity; an inner member spaced from
the outer member and comprising an inner longitudinally extending
wall surrounding an inner cavity having first and second
longitudinally spaced apart ends, the inner longitudinally
extending wall having first and second longitudinally spaced apart
ends, the first end of the cavity is at a different temperature
than the second end of the cavity when the heat engine is in use,
the first and second ends of the inner cavity being in fluid flow
communication via a passageway, the first and second ends of the
inner cavity and the passageway defining a sealed region within
which a working fluid is circulated when the heat engine is in use;
a displacer movably mounted in the inner cavity; a piston movably
mounted in the inner cavity; and, a plurality of cooling fin
members longitudinally spaced apart along on a portion of the outer
surface of the outer wall for cooling the outer surface, the
cooling fin members having first and second opposed sides, at least
some of the cooling fin members having a plurality of passages
whereby cooling fluid flows, through the passages as the cooling
fluid cools the cooling fin members.
[0011] In accordance with another aspect of the instant invention,
there is provided a, heat engine comprising outer container means
having an outer surface; inner container means having a
longitudinally extending axis and positioned inside the outer
container means, the inner container means having first and second
longitudinally spaced apart ends; fluid conduit means for
connecting the first and second ends in fluid flow communication;
heat exchanger means mounted on the outer surface of the outer
container means for generating a flow of cooling fluid through the
heat exchanger means and cooling at least a portion of the outer
container means; displacer means movably mounted in the inner
container; and, piston means movably mounted in the inner
container.
[0012] In accordance with another aspect of the instant invention,
there is also provided a heat engine comprising inner and outer
spaced apart longitudinally extending walls, each wall having an
inner surface and an outer surface, the inner wall surrounding a
cavity, each of the inner and outer wall having longitudinally
spaced apart first and second ends, the first end is at a different
temperature than the second end when the heat engine is in use, the
first and second ends in fluid flow communication via a passageway,
the first and second ends and the passageway defining a sealed
region within which a working fluid travels when the engine is in
use; a displacer movably mounted in the cavity between the first
and second ends for movement between a first position and a second
position; a piston movably mounted in the second end for movement
between a first position and a second position; and, a heat
exchanger mounted in a portion of the sealed region through which
the working fluid travels, the heat exchanger comprising at least
one fin extending around the inner wall having first and second
opposed sides and constructed to direct the working fluid to flow
there through to enhance heat transfer between the working fluid
and the heat exchanger.
[0013] In accordance with the instant invention, there is also
provided a heat engine comprising an outer member comprising an
outer longitudinally extending wall having an outer surface and
first and second longitudinally spaced apart ends, the outer wall
surrounding an outer cavity; an inner member spaced from the outer
member and comprising an inner longitudinally extending wall
surrounding an inner cavity having first and second longitudinally
spaced apart ends, the inner longitudinally extending wall having
first and second longitudinally spaced apart ends, the first end of
the cavity is at a different temperature than the second end of the
cavity when the heat engine is in use, the first and second ends of
the inner cavity being in fluid flow communication via a
passageway, the first and second ends of the inner cavity and the
passageway defining a sealed region; a displacer movably mounted in
the inner cavity; a piston movably mounted in the inner cavity;
and, a plurality of members longitudinally spaced apart along on a
portion of the inner wall for transferring heat between a fluid and
the inner wall, the spaced apart members having first and second
opposed sides, at least some of the spaced apart members having a
plurality of passages whereby the fluid flows through the passages
as heat is transferred between the fluid and the spaced apart
members.
[0014] In accordance with another aspect of the instant invention,
there is provided a heat engine within which a working fluid is
circulated, the heat engine comprising outer container means having
an outer surface; inner container means having a longitudinally
extending axis and positioned inside the outer container means, the
inner container means having first and second longitudinally spaced
apart ends; fluid conduit means for connecting the first and second
ends in fluid flow communication; heat exchanger means comprising
fin means mechanically mounted in the heat exchanger means for
contacting the working fluid and assisting in transferring heat
between the heat engine and the working fluid; displacer means
movably mounted in the inner container; and, piston means movably
mounted in the inner container.
[0015] In accordance with another aspect of the instant invention,
there is provided a heat engine comprising inner and outer spaced
apart longitudinally extending walls, each wall having an inner
surface and an outer surface, the inner wall surrounding a cavity,
each of the inner and outer wall having longitudinally spaced apart
first and second ends, the first end is at a different temperature
than the second end when the heat engine is in use, the first and
second ends in fluid flow communication via a passageway, the first
and second ends and the passageway defining a sealed region; and, a
heat exchanger mounted on a portion of one of the walls, the heat
exchanger comprising at least one fin extending around the portion
of the wall and having first and second opposed sides and a
plurality of main directing members, the fin configured and
arranged to produce a main flow of fluid which flows through the
fin and to produce a secondary fluid flow which passes through the
main directing members whereby the heat transfer between the fluid
and the heat exchanger is enhanced.
[0016] In accordance with another aspect of the instant invention,
there is provided a heat exchanger capable of being mounted in an
fluid flow passage which is located between first and second walls,
the walls having a first end and a spaced apart second end, the
heat exchanger comprising at least one fin extending between the
first and second walls, the at least one fin having first and
second opposed sides and a plurality of main directing members, the
at least one fin configured and arranged to produce a main flow of
fluid which flows through the at least one fin as the fluid flows
through the passage from the first end to the second end and to
produce a secondary fluid flow which passes through the main
directing members whereby the heat transfer between the fluid and
the at least one fin is enhanced.
[0017] In accordance with another aspect of the instant invention,
there is provided a heat engine comprising outer container means
having an outer surface; inner container means having a
longitudinally extending axis and positioned inside the outer
container means, the inner container means having first and second
longitudinally spaced apart ends; fluid conduit means for
connecting the first and second ends in fluid flow communication;
and, heat exchanger means mounted on at least one of the container
means and having fin means and a first end and a second end, the
fin means having first and second opposed sides and first directing
means for generating a main flow of fluid through the fin means as
the fluid flows from the first end to the second end and secondary
directing means for generating a secondary fluid flow which passes
through at least some of the first directing means whereby the heat
transfer between the fluid and the heat exchanger means is
enhanced.
[0018] In accordance with another aspect of the instant invention,
there is provided a heat exchanger means capable of being mounted
in an fluid flow passage which is located between first and second
walls, the walls having a first end and a spaced apart second end,
the heat exchanger means comprising fin means having first and
second opposed sides and first directing means for generating a
main flow of fluid through the fin means as the fluid flows from
the first end to the second end and secondary directing means for
generating a secondary fluid flow which passes through at least
some of the first directing means whereby the heat transfer between
the fluid and the heat exchanger means is enhanced.
[0019] In accordance with another aspect of the instant invention,
there is provided a heat engine comprising an outer longitudinally
extending wall, an inner longitudinally extending wall spaced from
the outer longitudinally extending wall to define a first
passageway, each wall having an inner surface and an outer surface,
the inner wall surrounding a cavity, each of the inner and outer
walls having longitudinally spaced apart first and second ends, a
heat source mounted at the first end and spaced from the inner wall
to define a second passageway, the first and second ends in fluid
flow communication via the first and second passageways, the first
and second ends and the first and second passageways defining a
sealed region within which a working fluid is circulated; a
displacer movably mounted in the cavity; a piston movably mounted
in the second end; a first heat exchanger mounted in the first
passageway comprising at least one fin having first and second
opposed sides and constructed to direct the working fluid as it
flows through the first heat exchanger to enhance heat transfer
between the working fluid and the first heat exchanger; and, a
second heat exchanger mounted in the second passageway comprising
at least one fin having first and second opposed sides and
constructed to direct the working fluid as it flows through the
second heat exchanger to enhance heat transfer between the working
fluid and the second heat exchanger.
[0020] In accordance with the instant invention, there is also
provided a heat engine comprising a container defining a sealed
region within which a working fluid is circulated when the heat
engine is in use, the sealed region having first and second
portions, the first portion is at a different temperature than the
second portion when the heat engine is in use, the first and second
portions being in fluid flow communication via a working fluid
passageway; a displacer movably mounted in the sealed region; a
piston movably mounted in the sealed region; a combustion chamber
positioned to provide heat to one of the first and second portions
of the sealed region; and, a heat exchanger having a combustion air
passageway for providing air for combustion to the combustion
chamber and an exhaust gas passageway for withdrawing exhaust gas
from the combustion chamber, a portion of the working fluid
passageway is contained in the heat exchanger, a portion of the
combustion air passageway is thermally connected to a portion of
the exhaust air passageway and a portion of the working fluid
passageway is thermally connected to a portion of the exhaust air
passageway, at least one of the passageways having fin portions
having first and second opposed sides and constructed to direct a
fluid to flow through the second heat exchanger to enhance heat
transfer between the fluid and the heat exchanger.
[0021] In accordance with the instant invention, there is also
provided a heat engine comprising container means defining a sealed
region within which a working fluid is circulated when the heat
engine is in use, the sealed region having first and second
portions, the first portion is at a different temperature than the
second portion when the heat engine is in use; combustion means for
providing heated exhaust gas for heating the first portion;
combustion air conduit means for providing air for combustion to
the combustion means; fluid conduit means for connecting the first
and second ends in fluid flow communication; exhaust gas conduit
means for conveying exhaust gas from the combustion means; and,
heat exchanger means comprising fin means for transferring heat
between the exhaust gas and at least one of the air for combustion
and the working fluid.
[0022] In accordance with another aspect of the instant invention,
there is provided a heat engine comprising a container defining a
sealed region within which a working fluid is circulated when the
heat engine is in use, the sealed region having a heating chamber
and a cooling chamber, the heating and cooling chambers being in
fluid flow communication via a working fluid passageway; a
combustion chamber thermally connected to the heating chamber; a
displacer movably mounted in the sealed region; a piston movably
mounted in the sealed region; at least one cooling fin having first
and second opposed sides and positioned exterior of the cooling
chamber; and, a heat exchanger having a combustion air passageway
for providing air for combustion to the combustion chamber, at
least some of the cooling fins are positioned in the heat exchanger
whereby heat withdrawn from the cooling chamber is a used to
preheat the air for combustion.
[0023] In accordance with another aspect of the instant invention,
there is also provided a heat engine comprising container means
having first and second portions; fluid conduit means for
connecting the first and second portions in fluid flow
communication, the first portion is at a higher temperature than
the second portion when the heat engine is in use; combustion means
for receiving air for combustion and providing heat to the first
portion; and, heat exchanger means for transferring heat from the
second portion of the container means to the air for combustion,
the heat exchanger means comprising fin means positioned in the
heat exchanger means.
[0024] In accordance with another aspect of the instant invention,
there is also provided a heat engine comprising container means
having first and second portions; fluid conduit means for
connecting the first and second portions in fluid flow
communication, the first portion is at a higher temperature than
the second portion when the heat engine is in use; combustion means
for receiving air for combustion and providing heat to the first
portion; heat exchanger means for transferring heat from the second
portion of the container means to the air for combustion; and, fan
means for providing forced convection in the heat exchanger
means.
[0025] In accordance with another aspect of the instant invention,
there is provided al heat engine comprising inner and outer spaced
apart longitudinally extending walls, each wall having an inner
surface and an outer surface, the inner wall surrounding a cavity,
each of the inner and outer wall having longitudinally spaced apart
first and second ends, the first end is at a different temperature
than the second end when the heat engine is in use, the first and
second ends in fluid flow communication via a passageway, the first
and second ends and the passageway defining a sealed region within
which a working fluid travels when the engine is in use; a
displacer movably mounted in the cavity between the first and
second ends for movement between a first position and a second
position; a piston movably mounted in the second end for movement
between a first position and a second position; a combustion
chamber housing having a wall and positioned to provide heat to the
first end of the inner wall; and, at least one fin mounted in the
combustion chamber, the at least one fin having first and second
opposed sides and constructed to direct combustion gas to flow
there through to enhance heat transfer between the combustion gas
and the combustion chamber housing.
[0026] In accordance with another aspect of the instant invention,
there is also provided a heat engine comprising a container
defining a sealed region within which a working fluid is circulated
when the heat engine is in use, the sealed region having first and
second portions, the first portion is at a different temperature
than the second portion when the heat engine is in use, the first
and second portions being in fluid flow communication via a working
fluid passageway; a displacer movably mounted in the sealed region;
a piston movably mounted in the sealed region; a combustion chamber
housing positioned to provide heat to one of the first and second
portions of the sealed region; and, a heat exchanger positioned in
the combustion chamber housing comprising a plurality of fin
portions having first and second opposed sides and constructed to
direct combustion gas to flow through the heat exchanger to enhance
heat transfer between the combustion gas and the heat
exchanger.
[0027] In accordance with the instant invention, there is also
provided a heat engine within which a working fluid is circulated,
the heat engine comprising container means defining a sealed region
within which a working fluid is circulated when the heat engine is
in use, the sealed region having first and second portions, the
first portion is at a different temperature than the second portion
when the heat engine is in use; combustion means for providing
combustion gas for heating the first portion; and, heat exchanger
means comprising fin means mounted in the heat exchanger means for
contacting the combustion gas and assisting in transferring heat
from the combustion gas to the working fluid.
[0028] In accordance with the instant invention, there is also
provided a comprising a container defining a sealed region within
which a working fluid is circulated when the apparatus is in use,
the sealed region having spaced apart first and second ends which
are in fluid flow communication via a working fluid passageway, the
first end is at a different temperature than the second end when
the apparatus is in use; a displacer movably mounted in the sealed
region between the first and second ends for movement between a
first position and a second position; a piston movably mounted in
the second end for movement between a first position and a second
position; and, a heat exchanger comprising at least one member
defining a plurality of openings having associated louvres which
are configured and arranged to cause at least a portion of a fluid
flowing through the openings to swirl as the fluid flows through
the heat exchanges.
[0029] In accordance with the instant invention, there is also
provided a comprising a container defining a sealed region within
which a working fluid is circulated when the apparatus is in use,
the sealed region having spaced apart first and second ends which
are in fluid flow communication via a working fluid passageway, the
first end is at a different temperature than the second end when
the apparatus is in use; a displacer, movably amounted in the
sealed region between the first and second ends for movement
between a first position and a second position; a piston movably
mounted in the second end for movement between a first position and
a second position; and, a heat exchanger comprising at least one
member having first and second opposed sides and a plurality of
openings having associated louvres which are configured and
arranged to cause a portion of a fluid flowing through the heat
exchanger to flow from the first opposed side to the second opposed
side through at least some of the openings and then from the second
opposed side to the first opposed side through at least some of the
openings.
[0030] In accordance with another aspect of the instant invention,
there is provided an apparatus comprising a container defining a
sealed region within which a working fluid is circulated when the
heat engine is in use, the sealed region having a first chamber and
a second chamber, the first and second chambers being in fluid flow
communication via a working fluid passageway; a heat transfer
member selected from the group consisting of a heat source or heat
sink thermally connected to the first chamber; a displacer movably
mounted in the sealed region between a first position and a second
position to define a displacer cycle profile; a piston movably
Mounted in the sealed region between a first position and a second
position to define a piston cycle profile; and, at least one
magnetic drive member drivingly connected to one of the displacer
and the piston.
[0031] A similar arrangement may be used for the piston. It will be
appreciated that magnetic drive members may be used on only one of
the piston and the displacer but are preferably used for both the
piston and the displacer. Thus, in accordance with another aspect
of the instant invention, there is provided an apparatus comprising
a container defining a sealed region within which a working fluid
is circulated when the heat engine is in use, the sealed region
having a first chamber and a second chamber, the first and second
chambers being in fluid flow communication via a working fluid
passageway; a heat transfer member selected from the group
consisting of a heat source or heat sink thermally connected to the
first chamber; a displacer movably mounted in the sealed region
between a first position and a second position to define a
displacer cycle profile; a piston movably mounted in the sealed
region between a first position and a second position to define a
piston cycle profile; and, a plurality of magnets, at least one of
which is mounted on one of the displacer and the piston and at
least another of which is positioned and arranged to interact with
the magnet affixed to the one of the displacer and the piston,
whereby the one of the displacer and the piston is held in position
by magnetic fields as it travels between its first and second
positions.
[0032] The apparatus may use any of the constructions discussed
above. In one embodiment, a magnet is affixed to the displacer and
a plurality of spaced apart positioning magnets, one of which has a
variable magnetic field, interact with the magnet affixed to the
displacer and the apparatus further comprises a signal generating
magnet and a signal generating coil and one of the signal
generating magnet and the signal generating coil is positioned on
the piston for movement relative to the other of the signal
generating magnet and the signal generating coil wherein the
control member comprises the signal generating magnet and the
signal generating coil and the movement of the piston generates a
signal that is sent to the positioning magnet having the variable
magnetic field thereby driving the displacer. Preferably, the
control member includes an adjustable signal generator for
modulating the signal sent to the positioning magnet having the
variable magnetic field to adjust the cycle profile of the
displacer.
[0033] In accordance with another aspect of the instant invention,
there is provided an apparatus comprising a container defining a
sealed region within which a working fluid is circulated when the
heat engine is in use, the sealed region having a first chamber and
a second chamber, the first and second chambers being in fluid flow
communication via a working fluid passageway; a heat transfer
member selected from the group consisting of a heat source or heat
sink thermally connected to the first chamber; a displacer movably
mounted in the sealed region between a first position and a second
position to define a displacer cycle profile; a piston movably
mounted in the sealed region between a first position and a second
position to define a piston cycle profile; and, a solenoid
drivingly connected to the displacer.
[0034] In accordance with another aspect of the instant invention,
there is provided an apparatus comprising a container defining a
sealed region within which a working fluid is circulated when the
heat engine is in use, the sealed region having a heating chamber
and a cooling chamber, the heating and cooling chambers being in
fluid flow communication via a working fluid passageway; a heat
source thermally connected to the heating chamber; a displacer
movably mounted in the sealed region between a first position and a
second position to define a displacer cycle profile; a piston
movably mounted in the sealed region between a first position and a
second position to define a piston cycle profile; a drive member
drivingly, connected to the displacer; and, an electric generator
comprising a at least one coil and at least one magnet, the magnet
is drivenly connected to the piston and the at least one coil is
positioned exterior to the sealed region.
[0035] In accordance with one aspect of the instant invention,
there is provided an apparatus comprising a heat engine comprising
a container defining a sealed region within which a working fluid
is circulated when the heat engine is in use, the sealed region
having a heating chamber and a cooling chamber, the heating and
cooling chambers being in fluid flow communication via a working
fluid passageway, a variable heat source thermally connected to the
heating chamber whereby the variable heat source provides variable
heat levels to the working fluid, a displacer movably mounted in
the sealed region between a first position and a second position to
define a displacer cycle profile and, a piston movably mounted in
the sealed region between a first position and a second position to
define a piston cycle profile; an power output member drivenly
connected to the heat engine and having an output for supplying
work; and, a feedback member responsive to power demand from the
power output member to modulate the amount of heat provided by the
heat source to the working fluid.
[0036] In accordance with another aspect of the instant invention,
there is provided a heat engine comprising a working container
defining a sealed region within which a working fluid is circulated
when the heat engine is in use, the sealed region having a first
chamber and a second chamber, the first and second chambers in
fluid flow communication via a working fluid passageway; a
displacer movably mounted in the sealed region; and, a piston
movably mounted in the sealed region, at least one of the displacer
and the piston comprising a sealed member having first and second
longitudinally spaced apart ends and an outer wall extending
between the first and second longitudinally spaced apart ends
whereby the outer wall and the spaced apart ends surround an inner
cavity which is sealed from the working fluid.
DESCRIPTION OF THE DRAWINGS
[0037] For a better understanding of the present invention, and to
explain more clearly how it may be carried into effect, reference
will now be made by way of example to the accompanying drawings
which show preferred embodiments of the present invention, in
which:
[0038] FIG. 1 is a partially cut away perspective view of a heat
engine according to the instant invention;
[0039] FIG. 2a is a cross section along the line 2-2 of FIG. 1 of a
heat engine configured as a flashlight with the heat exchanger for
the fresh air for combustion removed, with the displacer positioned
adjacent the heater cup and the power piston positioned at the end
of the power stroke;
[0040] FIG. 2b is a cross section along the line 2-2 of FIG. 1
configured as a flashlight with the heat exchanger for the fresh
air for combustion removed, with the displacer positioned distal to
the heater cup and the power piston positioned at the beginning of
the power stroke;
[0041] FIG. 2c is a cross section along the line 2-2 of FIG. 1 of
an alternate embodiment with the displacer positioned adjacent the
heater cup and the power piston positioned at the end of the power
stroke;
[0042] FIG. 2d is a cross section along the line 2-2 of FIG. 1 of
an alternate embodiment with the displacer positioned distal to the
heater cup and the power piston positioned at the beginning of the
power stroke;
[0043] FIG. 2e is a cross section along the line 2-2 of FIG. 1 of a
further alternate embodiment configured as a flashlight with the
displacer positioned adjacent the heater cup and the power piston
positioned at the end of the power stroke;
[0044] FIG. 3 is an enlargement of the heating and regeneration
zones of the cross section of FIG. 2c;
[0045] FIG. 4 is an enlargement of the cooling zone and linear
generator of FIG. 2c;
[0046] FIG. 5 is an exploded view of the displacer and
electromagnet of FIG. 2;
[0047] FIG. 6a is a perspective view of the heat exchanger for the
heating zone and the regeneration zone;
[0048] FIG. 6b is a perspective view of the air flow through an
alternate version of the heat exchanger for the heating zone;
[0049] FIG. 6c is an cross section along the line 6-6 in FIG. 6b
showing the air flow through the heat exchanger for the heating
zone of FIG. 6b;
[0050] FIG. 6d is an enlargement showing the air flow through the
heat exchanger for the regeneration zone of FIG. 6a;
[0051] FIG. 6e is a perspective view of an alternate embodiment of
the heat exchanger for the heating zone and the regeneration
zone;
[0052] FIG. 6f is a cross section along the line 6'-6' in FIG.
6e;
[0053] FIG. 7 is a perspective view of the working components of
FIG. 2a with the inner and outer cylinders removed;
[0054] FIG. 8 is a schematic drawing of the control circuit for the
electromagnet of FIG. 5;
[0055] FIG. 9 is a partially cut away perspective view of a heat
engine according to a second embodiment of the instant invention
which employs a magnetic drive system wherein the electronic
control shown in FIGS. 9 and 10 has been removed;
[0056] FIG. 10 is a cross section along the line 10-10 of FIG. 9
with the heat exchanger for the fresh air for combustion removed,
with the displacer positioned adjacent the heater cup and the power
piston positioned at the end of the power stroke;
[0057] FIG. 11 is a cross section along the line 10-10 of FIG. 9
with the heat exchanger for the fresh air for combustion removed,
with the displacer positioned distal to the heater cup and the
power piston positioned at the beginning of the power stroke;
[0058] FIG. 12 is a perspective view of a louvred fin;
[0059] FIG. 12a is a perspective view of another louvred fin;
[0060] FIG. 12b is a cross section of a cylindrical tube with the
louvred fin of FIG. 12a attached thereto;
[0061] FIG. 12c is a perspective view of an alternate louvred
fin;
[0062] FIG. 12d is a perspective view of an alternate louvred
fin;
[0063] FIG. 12e is a perspective view of a portion of a heat
exchanger with louvred fins and cyclonic flow in the circulating
fluid as the fluid travels axially through the heat exchanger;
[0064] FIG. 12f is a perspective view of a portion of a heat
exchanger with louvred fins and cross flow in the circulating fluid
as the fluid travels axially through the heat exchanger;
[0065] FIG. 13 is a perspective view of a radial blade;
[0066] FIG. 14 is a perspective view of a further embodiment of a
spacer ring;
[0067] FIG. 15 is a perspective view of a further embodiment of a
spacer ring;
[0068] FIG. 16 is a perspective view of a helical fin;
[0069] FIG. 17 is an enlarged view of the helical fin of FIG. 16
with an alternate louvre;
[0070] FIG. 18a is an enlarged perspective view of a louvre of the
helical fin of FIG. 16 showing the sublouvres;
[0071] FIG. 18b is an enlarged perspective view of a louvre of the
helical fin of FIG. 16 showing alternate sublouvres;
[0072] FIG. 19 is a cross section along the line 11-11 of FIG. 11a
of a further alternate embodiment of the heat engine;
[0073] FIG. 20 is a cross section along the line 11-11 of FIG. 11a
of a further alternate embodiment of the heat engine;
[0074] FIG. 21 is an assembly for a power piston or a displacer
wherein the power piston of displacer is constructed from two
containers that are welded together;
[0075] FIG. 22 is an assembly for a power piston or a displacer
wherein the power piston of displacer is constructed from two
containers that are threadedly engaged;
[0076] FIG. 23 is an assembly for a power piston or a displacer
wherein the power piston of displacer is constructed from a first
and second containers wherein the second container is press fitted
into the opening of the first container; and,
[0077] FIGS. 24a and b are graphs of the movement of the power
piston compared to the movement of the displacer in one embodiment
of the invention.
DESCRIPTION OF PREFERRED EMBODIMENT
[0078] The heat engine described herein contains several novel
design innovations including the construction of the heat engine
from sheet metal or the like, the construction and positioning of
the heat exchangers (including the regenerator), the drive system
for the displacer and the power piston so as to allow different
cycles for the displacer and the power piston, the feedback system
for controlling the amount of heat (energy) provided to the working
fluid and the ability to synchronize the frequency of several
generators to allow their series or parallel connection to a
load.
[0079] In the preferred embodiments of FIGS. 1-4, 7, 9-11, 19 and
20 the heat engine includes a linear generator as the power output
member. It will be appreciated that the heat engine may be
drivingly connected to any other electric generator known in the
art. In an alternate preferred embodiment, the heat engine includes
a mechanical linear to rotary converter which are known in the art
as the power output member. It will be appreciated that the design
innovations of this disclosure may be used with either any power
output member known in the art. Thus the piston may be linked by
any means known in the art, eg., to provide linear or rotary
mechanical power. Accordingly, similar parts have been referred to
by the same reference numeral in all embodiments.
[0080] In accordance with the embodiments of FIGS. 2a, 2b, 2e and
7, a light bulb is incorporated into the housing of the heat engine
and so as to provide a portable flashlight. The heat engine is
drivingly connected to a linear generator which is used to create
current to power one or more incandescent light bulbs, fluorescent
light bulbs, LEDs, gas plasma discharge light sources or the like.
It will be appreciated that the heat engine may be powered by any
heat source known in the art. In a preferred embodiment, the
flashlight housing includes a fuel reservoir which, upon
combustion, provides heat to power the heat engine. Accordingly,
the flashlight comprises four main components namely a heat source,
a heat engine, a linear generator and a light emitting device (eg.
a light bulb). It will also be appreciated that the linear
generator may be used to provide power for any required purpose and
that the heat engine and the linear generator may be configured as
an electric generator or may be connectable to an electric motor or
any other application that requires electricity (i.e. the load). In
any such application, the component to which the linear generator
provides electricity may be housed with the heat engine and the
linear generator of the may be a separate discrete component.
[0081] As shown in the drawings attached hereto, the components are
shown set out in a linear array (i.e. they are positioned
sequentially along longitudinal axis A of the flashlight). However,
it will be appreciated that the components may be set up in various
configurations. For example, the fuel reservoir need not be
positioned directly in line with the heat engine. Similarly, the
light bulb or other powered component need not be positioned along
longitudinal axis A of the flashlight but may be positioned at any
desired point by adjusting the shape of the outer housing and
providing a sufficient length of wire to connect the light bulb or
other powered component to the linear generator. Alternately, the
housing of the heat engine and the linear generator may have an
electrical outlet for receiving a standard electric plug.
[0082] The following description is based on the flashlight model
which has a single light bulb. However, the device, complete with
an on board heat source (eg. a reservoir filled with a combustible
fuel and a combustion chamber), creates a self contained, light
weight light source which may be in the form of a flash light, a
portable camping light, a lamp or the like. In this application,
the flashlight has been described as if it were standing vertically
on a table with bulb 48 positioned at the bottom. References to
upper and lower, vertical or horizontal in this application are for
reasons of convenience based upon this orientation of the
flashlight in the drawings. It will be appreciated that the heat
engine and the linear generator may be used when the housing of the
apparatus is in any particular orientation.
[0083] Thin Walled Construction
[0084] According to one aspect of the instant invention, a novel
construction of a heat engine is provided which uses thin walled
structures to house the working or moving components of the heat
engine (i.e. displacer 46 and power piston 50) within a working
container having first and second ends. The working fluid is
circulated between the first end of the working container which is
warmer than the second end. In contrast to earlier designs wherein
the working container is prepared from a block of metal which is
machined to produce a space within which the working fluid
circulates or which is forged, this design uses sheet metal and the
like to form a container. Positioning members are provided to
dimensionally stabilize the walls of the container thereby
providing a durable structure. Due to the construction materials
used, the heat engine is light weight and has good thermal
efficiency since the thin walled construction allows for faster
heat transfer to and from the working fluid and significantly
reduced heat retention by the components of the heat engine.
[0085] In a more preferred embodiment, the working container is an
inner container which is housed within an outer housing and the
positioning members extend between the outer housing and the
working container at a plurality of locations along the length of
the working container. The positioning members may be provided only
at the longitudinally opposed ends of the inner container. For
example, the positioning means may be affixed to the opposed ends
of the inner and/or outer containers and extend generally parallel
to the longitudinal axis of the heat engine to draw the opposed
ends together (eg. a bolt and a butterfly nut), in which case they
function as clamping means to draw the opposed ends together and
seal the inner cavity. Preferably, the positioning means extends
generally transverse to the longitudinal axis of the heat engine.
In such a case, if the passageway through which the working fluid
travels between the first and second ends of the inner container is
positioned in the space between the outer housing and the inner
container, then the positioning members are configured to allow
fluid flow there through. The positioning members may also function
as heat exchangers and/or a regenerator thereby reducing the number
of components required for constructing a heat engine. More
preferably, the outer housing is also of a thin walled
construction.
[0086] As in the embodiment of FIG. 1, the container may be open
topped wherein the combustion chamber is positioned at least
partially within and preferably wholly within the inner container
and is used to dimensionally stabilize the top of the inner
container. The combustion chamber is constructed from materials
which will maintain their structural integrity at combustion
temperatures and therefore, the combustion chamber may be prepared
by standard construction techniques for turbine engine components
(eg. stamping components out of a super nickel alloy to maximize
heat transfer by minimizing the wall thickness).
[0087] FIGS. 1, 2a, 9-11, 19 and 20 exemplify this construction.
Referring to FIG. 2a, a flashlight 10 is shown with each of the
components set out in a longitudinally extending array inside outer
wall 12. Outer wall 12 has a first end 14 and a second end 16. A
start or ignition button 18 is provided, preferably on the
longitudinally outer wall 12.
[0088] As shown in FIGS. 2a-2d, flashlight 10 comprises a heating
zone 22, a regeneration zone 24, a cooling zone 26 and an
electrical generation zone 28. Flashlight 10 is provided with a
housing to include the components for each of these four zones. The
housing comprises outer wall 12 and inner wall 30 which are
preferably co-axially positioned about longitudinal axis A (see
FIG. 1). While the housing which is shown in the drawings comprises
nested cylinders, it will be appreciated that the housing may
comprise inner and outer containers that may be of any shape and
need not be coaxially mounted. Further, the housing may allow any
configuration of the components provided the electrical generation
means is drivenly connected to the heat engine.
[0089] Outer wall 12 has an outer surface 32 and an inner surface
34. Inner wall 30 has an outer surface 36 and an inner surface 38.
Inner surface 34 of outer wall 12 and outer surface 36 of inner
wall 30 are spaced apart to define an outer cavity which may be
used as annular fluid flow path 40 within which regenerator 42 is
preferably positioned. The construction techniques of this design
may be used in configurations of heat engines that do not include a
regenerator or which do not position the regenerator in an annular
passageway exterior to the inner cavity within which the displacer
is positioned.
[0090] In the preferred embodiment of FIGS. 2a and 2b, positioned
inside inner wall 30 are heater cup 44, displacer 46, driver 48 for
moving displacer 46, power piston 50 and the linear generator
comprising a plurality of magnets 52, ferrite beads 54 and coils
56. Light bulb 58 is mounted at second end 16 of outer wall 12.
Alternately, piston 50 may be a portion of the linear generator
(see eg. FIG. 10).
[0091] As shown in FIG. 3, heater cup 44 has an inner surface 60
and an outer surface 62. Outer surface 62 is spaced from inner
surface 38 of inner wall 30 so as to define a fluid flow path 64.
Fluid flow path 64 is a first passageway that is in fluid flow
communication with fluid flow path 40 by means of a plurality of
spaced apart openings 66 which are provided in inner wall 30.
Accordingly, fluid flow path 64 and openings 66 define a passageway
connecting the interior of the upper portion of inner wall 30 (i.e.
heating chamber 160) with fluid flow path 40. In the embodiment of
FIG. 1, inner wall 30 terminates prior to top 90 of heater cup 44
thereby providing an annular space 64 through which the upwardly
flowing working fluid passes as it travels from heating chamber 140
to annular fluid flow path 40. A plurality of positioning members
to dimensionally stabilize the end of inner wall 30 adjacent heater
cup 44 are provided in fluid flow paths 64 and 40. These
positioning members may be in the form of rings that extend
continuously around outer surface 62 and engage inner surface 38 of
inner wall 30 to prevent inner wall from contracting inwardly when
the heat engine is operating. These positioning members may also be
constructed to assist in the transfer of heat to the working fluid.
Examples of such positioning members are protrusions 106 (see FIG.
3), contact with wall of burner cup 44 (see FIG. 2a), spacer rings
164, 476 (see FIGS. 14 and 15), louvred fins 428, 440, 468 (see
FIGS. 12, 12a, 12c, 12d and 13) and helical louvred fin 448 (see
FIG. 16). In another alternate embodiment, inner and outer walls 30
and 12 may be two containers that are prepared by die stamping and
then connected together at their open (top) ends by placing one
container inside the other and spin welding the top ends together
to form a double walled vessel. The portions of the containers that
are spun welded together define an intermediate portion and
openings 66 may be provided therein to allow heating chamber 140 to
be in fluid flow communication with fluid flow path 40 (see eg.
FIG. 3).
[0092] In the embodiment of FIGS. 2a and 2b, inner wall 30 has a
swedged portion 204 at which point inner wall 30 has an increased
diameter thereby bringing inner and outer walls 30 and 12 into
engagement. This method of assembly is advantageous if inner wall
30 is prepared from a preformed cylindrical tube.
[0093] This engagement, for example over the length of the
electrical generator zone 28, maintains the co-axial alignment of
the cylinders. In the embodiment of FIG. 4, outer wall 12 has a
uniform diameter along its length and accordingly is maintained in
a spaced apart relationship from inner wall 30 by, for example, a
sealant which is inserted in gap 166 below openings 158 or by
spacer rings 164. As shown in FIG. 15, spacer rings 164 may be
generally annular members having a generally U shaped profile in
cross section. As such, ring 164 has a pair of opposed edges 262
extending from upper end 264 to trough portion 266 to define an
open area 268. Preferably, opposed edges 262 extend outwardly at a
sufficient angle a to central axis B which extends through ring 164
so that upper ends 264 are compressed towards each other when ring
164 is inserted between outer and inner walls 12 and 30 thus
providing a tight sliding fit to mechanical lock the cylinders
together. A plurality of rings 164 which are spaced apart in gap
166 provides sufficient mechanical connection between outer and
inner walls 12 and 30 so as to coaxially align them.
[0094] As is exemplified by FIG. 1, providing any such positioning
members between spaced apart inner and outer walls creates a
sandwiched construction wherein the inner and outer walls become
mutually self supporting. By including a plurality of such spaced
apart members, longitudinally spaced apart portions of, for
example, outer wall 12 and inner wail 30 (e.g. positioned adjacent
each of heater cup 44 and piston 50), may be in contact with each
other and transmit stresses (either inwardly directed or outwardly
directed forces) between the inner wall and the outer wall. By
maintaining the relative position of the inner and outer walls, the
positioning members allow the mechanical strength of the inner and
outer walls to be combined.
[0095] For example, in the embodiment of FIG. 1, at the lower end
of the heat engine, a plurality of rings 164 are provided. At the
upper end, inner wall 30 is dimensionally stabilized by louvred
fins which are provided in both passageways 64 and 88 to thereby
hold inner wall 30 and outer wall 12 at fixed positions with
respect to heater cup 44.
[0096] In the embodiments of FIGS. 2a-2d, a gap 166 exists between
inner and outer walls 30 and 12 below the upper extent of travel of
piston 50. The gap between inner and outer walls 30 and 12 is
sealed so as to cause the working fluid to enter cooling chamber
160 and act on piston 50. Preferably, the gap is sealed immediately
below openings 158 so as to prevent working fluid from entering gap
166 which would function as a dead zone in the heat engine. This
gap may be sealed in several ways. For example, one or more rings
164 may be provided to seal gap 166. In an alternate embodiment, a
sealant (eg. epoxy) may be applied to fill all or a portion of gap
166. In the alternate embodiment of FIG. 2e, inner wall 30 is
swedged outwardly immediately below openings 158 such that inner
and outer walls 30 and 12 are positioned adjacent each other in the
cooling zone. The positioning of inner and outer walls 30 and 12
adjacent each other or the use of epoxy are additional examples of
positioning members as they utilize the interplay between the inner
and outer walls 30 and 12 to stabilize inner and outer walls 30 and
12.
[0097] In a preferred embodiment, inner wall 30 and outer wall 12
are each of a "thin walled" construction. For example, each of
inner wall 30 and outer wall 12 may be made from a metal such as
aluminum, stainless steel, super metal alloys and the like, and are
preferably made from stainless steel and the like. The wall
thickness of cylinders 12 and 30 may vary from about 0.001 to about
0.250 inches, preferably from about 0.005 to about 0.125 inches,
more preferably from about 0.01 to about 0.075 inches and, most
preferably from about 0.02 to about 0.05 inches. Similarly, the
walls of displacer 46 as well as the walls of piston 50 may be made
from the same or similar materials. In larger heat engines (eg.
those over 12 inches in diameter), the wall thickness is preferably
selected so as to be greater than one sixtieth of the diameter of
inner wall 30 and preferably about one thirtieth of the diameter of
inner wall 30 when the wall is constructed for super nickel alloys
and other similar materials whose strength is will not be
significantly compromised at 600.degree. C.
[0098] Accordingly, the main components of the heat engine may be
constructed from sheet metal or the like using the same materials
and in a manner that is similar to the containers which are used
for soft drink cans or the like. In this preferred embodiment,
inner and outer walls 30 and 12 are formed from prefabricated
components (prepared eg. by stamping or drawing) which are then
assembled together to form the heat engine. For example, inner and
outer walls 30 and 12 may be prepared from sheet metal by roll
forming the sheet metal and then laser welding the sheet metal to
form a longitudinally extending tube. Alternately, metal may be
drawn through a die to form a cylindrical tube. Openings 66 and 158
in inner wall 30 may then be made by stamping, drilling, laser
cutting or the like. A circular bottom plate may be obtained from
sheet metal by stamping and then roll formed or welded to the tube
to produce an opened top container into which the power piston and
the displacer may be placed. Alternately, a prefabricated open
topped container may be formed by stamping metal using a high speed
carbide die. This is in contrast to existing techniques for forming
engines wherein a block of metal is cast and subsequently bored or
the like to prepare the engine body thus resulting in an engine
which is much heavier than is structurally required for a heat
engine.
[0099] Similarly, displacer 46 may be manufactured from roll formed
sheet metal which is then laser welded together. Bottom 146 and top
136 may then be affixed to the side walls by roll forming, welding,
brazing, the use of an adhesive or the like. Divider plates 144 may
be added as required in the manufacturing operation. Once sealed,
displacer 46 provides a rugged construction which will withstand
the heat and stresses applied to displacer 46 in the heat engine. A
power piston may be constructed in a similar fashion.
[0100] As shown in FIGS. 21-23, displacer 46 or power piston 50 may
be constructed from two open topped containers 498 which are joined
together, such as at the mid point of displacer 46 by welding along
seam line 500. Each container comprises longitudinally extending
side walls 502 and an end wall 504. Side walls and end walls 502
and 504 may be integrally formed such as by high speed carbide die
stamping or, alternately, side walls 502 may be prepared by
drawings metal through a die to form a preformed longitudinally
extending cylindrical tube and end wall 504 may be affixed thereto
by roll forming or the like. It will be appreciate that welding
seam 500 may be provided at any position along side walls 502. By
providing end walls 504 to dimensionally stabilize the opposed ends
of displacer 46, and by sealing side walls and end walls 502 and
504 of displacer 46 so as to contain a sealed cavity 506, the
overall exterior structure of displacer 46 is sufficiently strong
to act as a displacer (or a power piston) in a heat engine.
[0101] FIG. 22 shows an alternate embodiment wherein cap 508 is
provided with walls 510 which have a thread 512 provided on the
inner surface thereof. The distal portion of walls 502 from end 504
are recessed inwards slightly and have a mating thread 514 provided
thereon. Accordingly, displacer 46 (or a power piston 50) may be
constructed by providing an open topped vessel and screwing a cap
508 thereon.
[0102] A further alternate construction is shown in FIG. 23. In
this case, a cap 516 is provided. Cap 516 has walls 518. Portion
520 of walls 518 are recessed inward slightly so as to provide a
seat for the distal end of walls 502 to be received thereon. The
diameter of the outer surface of walls 520 is slightly larger than
the diameter of the inner surface of walls 502 so that portions 520
lockingly engage the inner surface of walls 502. In this way, a
sealed displacer 46 (or power piston 50) may be provided. It will
be appreciated that in the embodiments of FIGS. 22 and 23, one
opposed end of walls 502 is stabilized by end wall 504 and the
other opposed end of walls 502 is stabilized by cap 508, 518.
[0103] In order to reduce thermal transfers due to radiation and
convection within displacer 46, displacer 46 may be divided into a
plurality of chambers 142 by a plurality of divider plates 144 as
is shown in FIGS. 1 and 3.
[0104] Pressurization
[0105] The durability of displacer 46 and/or the power piston may
be further improved by pressurizing the interior of displacer 46 or
the power piston. The degree to which displacer 46 and/or the power
piston is pressurized is preferably based on the degree of
pressurization of the working fluid in the heat engine. Preferably,
displacer 46 and the power piston has a pressure from about -2 to
about 10 atm, more preferably from about 1 to about 10 and, most
preferably, from about 2 to about 4 atm greater than the pressure
of the working fluid in the heat engine. In a similar manner, the
structural integrity of walls 12 and 30 may be similarly enhanced
by pressurizing the interior of the heat engine once it has been
constructed. Preferably, the interior of the heat engine (i.e.
where the working fluid circulates) is pressurized to a pressure
from about 1 to about 20, more preferably from about 4 to about 10
atm. Thus, if the pressure of the working fluid is 4 atm, then the
displacer may be at a pressure from 2 to 14 atm.
[0106] The working fluid may be any working fluid known in the art.
For example, the working fluid may be selected from air and helium,
and, is preferably helium. Helium has a high thermal conductivity
which allows the heat engine to be operated at a higher operating
frequency thus increasing the power output per unit volume of
interior working space of the heat engine (i.e. the volume within
which the working fluid circulates).
[0107] Dual Flow Heat Exchanger
[0108] In another aspect of this design, the heat engine includes a
heat exchanger which uses the heat exchange fins described herein
for transferring heat between the exhaust gas and at least one of
the air for combustion and the working fluid and, preferably, for
transferring heat between the exhaust gas and both the air for
combustion and the working fluid. To this end, the heat exchanger
comprises a first heat exchanger mounted in a first passageway
comprising at least one fin having first and second opposed sides
and constructed to direct the working fluid as it flows through the
first heat exchanger to enhance heat transfer between the working
fluid and the first heat exchanger; and, a second heat exchanger
mounted in a second passageway comprising at least one fin having
first and second opposed sides and constructed to direct the
working fluid as it flows through the second heat exchanger to
enhance heat transfer between the working fluid and the second heat
exchanger. Optionally, the heat exchanger comprises a third heat
exchanger mounted in the exhaust gas passageway and comprises at
least one fin having first and second opposed sides and constructed
to direct the exhaust gas as it flows there through to enhance heat
transfer between the exhaust gas and the third heat exchanger.
[0109] Referring to the embodiment of FIG. 3, heater cup 44 is a
combustion chamber which surrounded by a heat exchanger 67
comprising inner burner shield 68 having inner surface 74 and outer
surface 76, outer burner shield 70 having inner surface 78 and
outer surface 80 and air preheat shield 72 having inner surface 82
and outer surface 84 (see, eg., FIGS. 1 and 3,). Outer surface 84
of air preheat shield 72 is preferably at a temperature which may
be comfortably handled by a user. It can be seen that when a flame
is present, bottom 138 of burner cup 44 becomes hot and this heat
is transferred to the working fluid. Wall 62 of the burner cup 44
is heated both by direct radiation from the flame and by contact
with the hot exhaust gas 316 which come from the flame.
[0110] Inner surface 74 is spaced from outer surface 32 of outer
wall 12 to define a first pass 86 for the exhaust gases. As the
exhaust gas travels through first pass 86 (a combustion gas
passageway), the working fluid in flow path 64 is heated.
Similarly, inner surface 78 of outer burner shield 70 is spaced
from outer surface 76 of inner burner shield 68 so as to define a
second pass 88 for the exhaust gases (a combustion gas passageway).
Inner surface 82 of air preheat shield 72 is spaced from outer
surface 80 of outer burner shield 70 so as to define a preheat air
flow path 102 (a combustion air passageway). The lower portions of
outer burner shield 70 and air preheat shield 72 define entry port
104 to preheat air flow path 102. As the exhaust gas travels
through second pass 88, the air for combustion in preheat air flow
path 102 is heated. Depending upon the temperature of the exhaust
gas and the thermal efficiency which is desired, a fewer number of
passes or a greater number of passes may be utilized.
[0111] Heater cup 44 defines a combustion chamber 92. Inner burner
shield 68 may be spaced from top 90 of heater cup 44 so as to
define a manifold 94 through which the exhaust gases travel prior
to entering first pass 86. At the bottom of first pass 86, an
annular member 96 is positioned so as to force the exhaust gases to
travel through second pass 88, if a second pass is desired, prior
to entering second manifold 98 where the exhaust gases are
redirected through cylindrical exit ports 100. Alternately, as
shown in FIG. 1, outer burner shield 70 may have a transverse
portion 97 to close the bottom of first pass 86.
[0112] Inner burner shield 68, outer burner shield 70 and air
preheat shield 72, may be affixed together by any means known in
the art. In the preferred embodiment of FIG. 3, the three shields
and annular member 96 are constructed so as to be press fitted
together. To this end, inner surfaces 74, 78 and 82 are each
provided with a plurality of discrete protrusions which are spaced
apart around each of the inner surfaces. The protrusions abut
against the outer surface which is positioned immediately inwardly
thereof so as to provide a seating means for positioning each
shield with respect to the next inner member. For example, inner
surface 74 of inner burner shield 68 is provided with a plurality
of protrusions 106 which engage, at discrete locations, outer
surface 32 of outer wall 12. The protrusions thereby allow inner
burner shield 68 to be press fitted onto outer wall 12 and to
remain seated at a spaced distance from outer surface 32 to define
the fluid flow path. Similarly, annular member 96 may be installed
by press fitting onto outer wall 12 prior to shields 68, 70 and 72
being installed. In the preferred embodiment of FIG. 1, a plurality
of positioning members comprising one or more of spacer rings 164,
476, louvred fins 428, 440, 468 and helical louvred fin 448 are
provided to dimensionally stabilize shields 68, 70 and 72 are
provided in first and second passes 86 and 88 and preheat air flow
path 102. These positioning members may also be constructed to
assist in the transfer of heat.
[0113] In the preferred embodiment, a fuel, preferably an organic
fuel, is combusted in heater cup 44 so as to provide heat for the
heat engine. As shown in FIG. 3, the fuel may be a gaseous fuel
(eg. butane). However, it will be appreciated that liquid or solid
fuel (eg. paraffin) may be used. However, the heat engine may use
any heat source (eg. a non-combustion exothermic chemical reaction
that is preferably reversible) and in such a case, heat exchanger
67 may not be required.
[0114] In an alternate embodiment, the heat engine may be run in
reverse with chamber 160 which is positioned adjacent piston 50
operating at a higher temperature than chamber 140. In such a case,
heater cup 44 is replaced with a heat sink and a heat exchanger 67
may be provided to withdraw heat from chamber 140. Such a heat
exchanger would not require a preheat air flow path but is
otherwise preferably of a similar design.
[0115] Fuel Reservoir
[0116] As shown in FIG. 7, a fuel reservoir 108 is provided. Fuel
reservoir may be of any size which is sufficient to render
flashlight 10 portable. For example, fuel reservoir 108 may
comprise a storage tank having a volume from about 25 ml to 1 litre
or more. One litre of fuel weighs about the equivalent of about 6 D
cell batteries. Commercially available flashlights typically use up
to 8 such batteries. The total weight of a portable long life
flashlight may be from about 300 g (for a unit with about 25-50 ml
of fuel and a life of about 100 hours) to about 2 kg (for a unit
with about 1 litre of fuel and a life of about 2000 hours). Conduit
110 extends from reservoir 108 to annular burner 112. Conduit 110
extends through shield 68, 78 and 72 and has openings 114 through
which fresh air for combustion may be drawn, via preheat air flow
path 102, for mixing with the fuel prior to combustion in burner
112. A valve 116 is provided in conduit 110 so as to selectively
connect reservoir 108 and burner 112 in fluid flow communication
when it is desired to power flashlight 10. In an alternate
embodiment, the heat engine may be connected to an external fuel
source via conduit 110 and the fuel flow control valve may be
provided as part of the external fuel source (eg. a regulator on a
fuel tank).
[0117] Burner
[0118] Burner 112 may be of any type known in the art. The burner
together with the burner cup define the heat source. Preferably,
the burner is adapted to provide a varying level of heat to the
heat engine (eg. by having a fuel valve that is operable between a
number of positions) so as to be a variable heat source. It will be
appreciated that the heat source may be a chemical reaction (eg.
from a fuel cell and the amount of heat provided may be obtained by
altering the rate of reaction) or solar.
[0119] Preferably, burner 112 has a top 118 a bottom 120 and a
circumferential sidewall having a plurality of recesses 124
provided therein through which the mixture of air and fuel may pass
and be combusted (see FIGS. 3 and 7). Each recess 124 is defined by
a pair of opposed radial walls 126 and an inner circumferential
wall 128. The air fuel mixture may be ignited by a piezo electric
member positioned in housing 220 in which button 18 is mounted and
an electric spark may be transmitted to position adjacent burner
112 by means of wire 222 and spark plug 224. Buttons to open fuel
valves, and to hold them open, are known in the art and any such
device may be incorporated into this design.
[0120] In operation, when button 18 is depressed into housing 220,
drive rod 228 (which is affixed to button 18 by eg. screw 229)
causes connecting rod 226 (which is pivotally mounted to drive rod
228 by pivot 230) to move laterally transmitting this lateral force
to valve 116 via drive rod 232 (which is pivotally connected to
connecting rod 226 by pivot 234 and to valve 116 by pivot 238)
causing valve 116 to pivot about pivot 236 to the open position.
This allows pressurized fuel to pass through conduit 110 drawing
air for combustion through openings 114 into conduit 110. The mixed
fuel and air passes through burner 112 where it is ignited by any
means known in the art such as spark plug 224. The combustion of
the fuel produces heated exhaust gases which pass through heater
cup 44. In the embodiment of FIG. 3, the exhaust gases exit
flashlight 10 by means of first manifold 94, first pass 86, second
pass 88, second manifold 98 and exit port 100. Button 18 may be
locked in this "on position" by a locking means in housing 220.
Alternately, the fuel valve may be controlled by a thermomechanical
member, an electrothermomechanical member or electric control.
[0121] Displacer Control
[0122] According to another aspect of the instant invention, the
upstroke and downstroke of the displacer are different. Preferably,
the heat engine includes means for operating displacer 46 and
piston 50 to provide the working fluid with greater residence time
in cooling chamber 140 than in heating chamber 160. This may be
accomplished by controlling displacer 46 so that upstroke and the
downstroke portions of the displacer cycle vary, eg., by varying
the rate of movement of displacer 46 during the upstroke as
compared to the downstroke or by pausing displacer 46 during its
cycle to provide the additional residence time in cooling chamber
140. Such movement of displacer 46 provides improved
thermodynamically efficient heat transfer to and from the working
fluid. By allowing an additional 40%, preferably 30% and more
preferably 20% of time for the air in the cold region, improved
thermodynamic efficiency can be achieved. Exemplary means for
operating the displacer include the use of a solenoid or a magnetic
drive system. This may be achieved by attenuating the pulse width
and phase delay of the signal sent to the driver by means of a
phase delay circuit 326 (see, eg. FIG. 10).
[0123] For example, referring to FIGS. 24a and b, the displacement
of displacer 46 and piston 50 from the central positions of their
cycle is plotted against time. In FIG. 24a, the phase angle between
displacer 46 and piston 50 is 180.degree. and the rate of expansion
and the rate of compression by each of displacer 46 and piston 50
are the same. Traditionally in heat engines, the movement of the
displacer 46 and piston 50 are physically linked together by a
mechanical coupling and can not be varied. According to one aspect
of the instant invention, the phase angle between displacer 46 and
piston 50 may be varied. In addition, the rate of expansion and the
rate of compression of one, and preferably both, of displacer 46
and piston 50 may be varied. The compression and expansion of the
working fluid, and the phase angle between displacer 46 and piston
50, may be varied to optimize the cooling capacity of a heat engine
under different thermal loads and different thermal conditions. By
way of example, in FIG. 24b, the phase angle between displacer 46
and piston 50 is 180.degree. but the rate of expansion and the rate
of compression by piston 50 are different. In this example, rapid
compression is followed by a slower rate of compression then by a
rapid rate of expansion followed by a slower rate of expansion. The
expansion and compression rates are independent and are each
individually adjusted to maximize heat transfer between the working
fluid and the heat engine. The actual cycle profile will vary for
different configurations of the heat engine. An advantage of the
instant invention is that the electronic control of piston 50
permits the cycle profile to be easily adjusted to meet different
configurations of the heat engine as well as different uses of the
heat engine (eg. electricity production, refrigeration,
cryocooling). In this way, the compression and expansion of the
working fluid may be controlled to be conducted at
thermodynamically optimum rates and the heat engine may be used not
only to generate work using a heat source but to generate cooling
using work input to a linear generator operating as a piston.
[0124] For example, in the case of refrigeration or cryocooling, at
least one drive member may be drivingly connected to the displacer
and the piston to produce a displacer cycle profile and a piston
cycle profile which causes the working fluid to undergo differing
rates of expansion and compression in the first chamber than in the
second chamber whereby the movement of the working fluid transfers
heat from the heat sink (eg. the inside of a chamber to be cooled
or conduits for providing cooling to another location) to the
working fluid in the first chamber and then from the second chamber
to the heat dissipation members. The at least one drive member may
be a motor drivingly connected to the piston and a second drive
member (eg. coils 328) to move the displacer. Preferably, the at
least one drive member is operated to cause the working fluid to
undergo a slower rate of expansion in the first chamber then the
rate of compression of the working fluid in the first chamber and
to undergo a slower rate of compression in the second chamber then
the rate of expansion of the working fluid in the second
chamber.
[0125] Referring to FIGS. 2a-2d, the heat engine has a first
portion 240 in which displacer 46 is movably mounted and a second
portion 242 in which power piston 50 is movably mounted. The
portion within which displacer 46 is movable is the hot end of the
heat engine and the portion within which the power piston is
movable is the cool end of the heat engine. Driver 48 has an
internal circumferential wall 130 defining an opening 132 into
which displacer rod 134 is received. Displacer 46 is mounted for
movement within inner wall 30 between the alpha position shown in
FIG. 2b wherein displacer 46 is withdrawn from heater cup 44 and
the omega position as shown in FIG. 2a in which displacer 46 is
distal to driver 48 and advanced towards heater cup 44. As shown in
FIGS. 2a and 2c, when displacer 46 is positioned in the omega
position, there is a chamber 244 between displacer 46 and driver
48. In this position, displacer rod 134 is substantially removed
from opening 132. As shown in FIGS. 2b and 2d, when displacer 46 is
in the alpha position, effectively all of displacer rod 134 is
received in opening 132 leaving heating chamber 140 (defined by top
136 of displacer 46, bottom 138 of heater cup 44 and inner surface
38 of inner wall 30) between displacer 46 and heater cup 44.
[0126] Heating chamber 140 is heated by the combustion occurring in
heater cup 44. As displacer 46 moves upwardly to the position shown
in FIG. 2a, the heated working fluid in heating chamber 140 is
forced upwardly through fluid flow path 64 where it is heated by
the heated heater cup 44, and through opening 66 into fluid flow
path 40 (a portion of the working fluid passageway) where it is
heated by the exhaust gasses, thus increasing the pressure of the
working gas. When displacer 46 is in the distal position shown in
FIGS. 2a and 2c, effectively all of the working fluid has been
forced out of heating chamber 140. To this end, it is preferred
that bottom 138 of heater cup 44 and top 136 of displacer 46 are
constructed so as to intimately fit adjacent each other so as to
force as much of the working fluid out of the heating chamber 140
as possible. Preferably, as shown in FIG. 2a, bottom 138 is curved
so as to transfer heat to the working fluid. Alternately, as shown
in FIG. 3, bottom 138 may be flat and, accordingly, top 136 of
displacer 46 may also be flat.
[0127] Inner circumferential wall 130 of driver 48 provides a guide
for displacer rod 134 so as to maintain the longitudinal alignment
of displacer 46 along axis A as displacer 46 moves between the
alpha and omega positions. Displacer rod 134 and inner
circumferential wall 130 may be dimensioned and constructed so as
to allow relatively frictionless movement of displacer rod 134 into
and out of opening 132. In order to further assist in the reduction
of frictional forces, bottom 146 of displacer 46 may have a
recessed circumferential wall 148. A teflon bushing 150 or the like
may be mounted around recessed circumferential wall 148 for
engagement with inner surface 38 of inner wall 30 as displacer 46
moves. Further, a second teflon bushing or the like 152 may be
provided on inner circumferential wall 130.
[0128] Driver 48 may be any means known in the art which is
drivingly connected to displacer 46 to cause displacer 46 to move
in a cycle that is complementary to the cycle of power piston 50 so
as to optimize the thermal efficiency of the heat engine. This may
be achieved by moving displacer 46 in response to an external
stimulus such as an electrical impulse caused by the movement of
power piston 50. Preferably, driver 48 is a solenoid or an
electromagnet and, more preferably, an electromagnet. If driver 48
is a solenoid, current may be provided to the solenoid by means of
wire 154 (see FIG. 2e). Accordingly, when current is supplied to
the solenoid, displacer 46 will move due the current (i.e. the
external force) supplied thereto. If driver 48 is an electromagnet,
then, displacer 46 and/or displacer rod 134 includes a permanent
magnet for moving displacer 46 due to a magnetic field produced by
the electromagnet. Accordingly, when current is supplied to the
coils of the electromagnet, the coils may be charged in a reverse
polarity to the portion of displacer rod 134 in opening 132 thus
forcing displacer rod 134 outwardly from opening 132 thus driving
the working fluid from heating chamber 140. When the current is
reversed in the coils, displacer rod 134 is attracted to driver 48
and accordingly displacer rod 134 is pulled downwardly into opening
132 (thus drawing the working fluid into heating chamber 140).
[0129] In a preferred embodiment, displacer 46 is biased,
preferably to the alpha position shown in FIG. 2b. This may be
achieved, for example, by means of spring 156 as shown in FIGS. 2c
and 3. In such a case, driver 48 may act only to move displacer 46
to the omega position (i.e. towards heater cup 44) thus pushing
heated working fluid to cooling chamber 160. When the working fluid
is cooled to a sufficient degree, the current to driver 48 may be
switched off allowing the biasing means (eg. spring 156) to move
the displacer to the alpha position thus drawing the working fluid
into heating chamber 140. When the working fluid is heated, the
current to driver 48 may be switched on thus moving displacer 46
against spring 156 to the omega position. In one embodiment, driver
48 may be powered at all times once the heat engine is running.
[0130] It will be appreciated that driver 48 need not completely
extend to inner wall 38 of inner wall 30. For example, driver 48
may have a smaller diameter than inner wall 30 and be mounted
thereto by, eg., brackets. If the outer wall of driver 48 contacts
inner wall 38 as shown in FIGS. 2a-2e, then chamber 244 is
preferably in fluid flow communication with cooling chamber 160,
such as by passage 260, to prevent a reduced pressure region from
forming in chamber 244. Thus, when displaced moves to the extended
position shown in FIG. 2a, cooled working fluid in cooling chamber
160 may travel through passage 260 into chamber 244 to maintain an
equilibrium pressure between chambers 244 and 160. Further, when
displacer 46 moves to the retracted position as shown in FIG. 2b,
cooled fluid is pushed from chamber 244 by displacer 46 into
cooling chamber 160 via passage 260 and then to heating chamber
140.
[0131] Inner wall 30 is provided with a passageway, eg. a plurality
of openings 158 adjacent the top of cooling zone 26. Openings 158
define an entry port for the working fluid to enter second portion
242 of the heat engine after passing through air flow path 40. As
shown in FIG. 5, the lower portion of driver 48 may have a
chamfered surface 168. The chamfered surface assists in directing
the working fluid into and out of cooling chamber 160. Power piston
50 is not physically connected to displacer 46 but is moved due to
the change of pressure in cooling chamber 160. Accordingly, when
displacer rod 134 moves displacer 46 to the withdrawn position
shown in FIGS. 2a and 2c, working fluid is forced through flow path
40, through opening 158 into cooling chamber 160. The action of the
working fluid on top 162 of piston 50 forces piston 50 downwardly
into open area 246. As the working fluid cools in cooling chamber
160, the pressure of the working fluid decreases thus drawing
piston 50 upwardly and reducing the volume of the working zone of
the heat engine (i.e. chambers 140, 160, 244 and fluid flow paths
64 and 40). When displacer 46 moves away from heater cup 44 to the
position shown in FIGS. 2b and 2d, eg. in response to driver 48 or
the spring, the working fluid is drawn from cooling chamber 160
through openings 158 through flow path 40 through openings 66,
through flow path 64 into heating chamber 140.
[0132] In the alternate embodiment of FIGS. 9-11, 19 and 20, driver
48 comprises a magnetic field that is imposed on displacer 46. As
exemplified in these Figures, displacer 46 has a magnet 286 affixed
to it, preferably on bottom 146. Displacer magnet 286 and displacer
46 affixed thereto are held concentrically in place and their range
of motion limited by two magnets 284 and 288 which are preferably
circular and which repel the displacer magnet 286. Thus displacer
46 sits on a magnetic bearing caused by the mutual repulsion of
magnet 288 to displacer magnet 286 and the mutual repulsion of
magnet 284 to displacer magnet 286. The repulsive magnetic field
between magnets 286 and 288 serves to store kinetic energy from the
upstroke of displacer 46 and limits the travel of displacer 46. The
stored kinetic energy from the upstroke of displacer 46 is returned
to displacer 46 on the downstroke.
[0133] Linear Generator
[0134] In another aspect of the design, the apparatus includes a
linear generator. Preferably, piston 50 comprises part of the
linear generator. The linear generator in electrical generation
zone 28 may be of any construction known in the art. The following
description is of the preferred embodiment of the linear generator
which is shown in FIGS. 2a, 2b, 2c, 2d and 4. In these embodiments,
the linear generator is positioned in a sealed chamber. In the
embodiment of FIGS. 2a and 2b, the upper end of the linear
generator is isolated from the working fluid by piston 50 and the
lower end is sealed by closure member 195. In the embodiments of
FIGS. 2c, 2d and 4, the upper end of the linear generator is
isolated from the working fluid by top 162 and the lower end is
sealed by closure member 195. As shown in FIGS. 2a and 2b, piston
50 is a sealed member having a top 162, a bottom 170 and sidewalls
172. Drive rod 174 may accordingly be affixed to bottom 170 by any
means known in the art. In the embodiment of FIGS. 2c, 2d and 4,
piston 50 comprises top 162 and sidewalls 172. In this embodiment,
drive rod 174 is affixed to inner surface 176 of top 162, by any
means known in the art, such as by threaded engagement therewith.
As shown in FIG. 4, inner surface 176 may be provided with a
splined shaft 178 which is received in a mating recess in drive rod
174.
[0135] A plurality of magnets 52 are fixedly attached to drive rod
174 by any means known in the art, such as by use of an adhesive or
by mechanical means (eg. the interior opening through which drive
rod passes in magnet 152 may be sized to produce a locking fit with
drive rod 174 or drive rod 174 may be threaded and magnet 152 may
be positioned between spacers that are threadedly received on drive
rod 174). A mating number of coils 56 of electrically conductive
wire are provided at discrete locations along the length of
electrical generation zone 28. Coils 56 are affixed to inner wall
34 of outer wall 12 by any means known in the art, such as by means
of an adhesive or by mechanical means (eg. coils 56 may be provided
in a housing which is affixed to inner wall 34 by welding or by
brackets). Thus coils 56 are stationary as drive rod with magnets
52 affixed thereto is moved by power piston 50. It will be
appreciated that coils 56 may be affixed in a stationary manner by
any other means known in the art. In an alternate embodiment, coils
56 may be affixed to drive rod 174 and magnets 52 may be
stationary.
[0136] An annular ferrite bead 54 is positioned centrally within
each set of coils 56. Each ferrite bead 54 has a central opening
through which drive rod 174 passes. One of the coils 56 has wires
180 extending outwardly there from. The remainder of the coils 56
have wires 182 extending outwardly there from (see FIG. 7). It will
be appreciated by those skilled in the art that only one ferrite
bead 54 and one coil 156 may be provided. It will further be
appreciated that the output wires from any of the coils 56 may be
grouped together in parallel or series as may be desired.
[0137] As power piston 50 moves into area 246 away from driver 48
in response to working fluid impinging upon top 162, magnets 52
move longitudinally along axis A so as to cause current to flow in
coils 56 (see FIG. 2b). When piston 50 moves upwardly due to the
cooling of the working fluid in cooling chamber 160, magnets 52 are
then driven in the reverse direction causing current to again flow
in coils 56.
[0138] In the preferred embodiment, each magnet 152 moves between a
pair of ferrites 154. In particular, referring to FIG. 4, magnet
52a is movably mounted in the linear generator between ferrite 54a
and ferrite 54b. As drive rod 174 moves with piston 50, magnet 52a
moves from a position adjacent ferrite 54a as shown in FIG. 4 to a
position adjacent ferrite 54b. Similarly, magnet 52b moves from a
position adjacent ferrite 54b to a position adjacent ferrite 54c.
In this way, it will be seen that at the end of each stroke of
piston 50, ferrite 54b is acted upon at any one time by only one
magnet 152. Similarly, magnet 52a will first act upon ferrite 54a
and then upon ferrite 54b. In this way, ferrite 54b is sequentially
exposed to, eg., a north field from magnet 52a and then a south
field from magnet 52b.
[0139] One advantage of the instant design is that there is a
higher rate of change of flux per unit time due to ferrites 154
first being acted upon by one field and then the opposed field.
Further, since ferrite 154 is acted upon by opposed poles of
different magnets, the magnetic field induced on ferrite on 54b by
magnet 52a will completely collapse as magnet 52a moves to the
position shown in FIG. 4 and ferrite 54b is acted upon by magnet
52b.
[0140] An alternate construction of a linear generator is shown in
FIGS. 9-11, 19 and 20. In these embodiments, the magnets are
positioned within inner wall 30 and the coils are positioned
exterior thereto (eg. on outer surface 36 of inner wall 30 or on
outer surface 32 of outer wall 12). Power piston 50 consists of a
plurality of spaced apart magnets, eg. four magnets 270, 272, 274
and 276 and three non-magnetic spacers 278, 280 and 282. The
non-magnetic spacers may be made of plastic which surrounds and
encases the magnets. It will be appreciated that the assembly of
magnets and spacers may be connected to the power piston of FIGS.
2a or 2c by a drive rod 174. Preferably, the assembly comprises
piston 50.
[0141] Power piston 50 of FIGS. 9-11, 19 and 20 is held
concentrically in place and its range of motion limited by two
magnets 284 and 190 which are preferably circular permanent magnets
and which repel magnets 270 and 276 respectively. Thus the power
piston 50 sits on a magnetic bearing caused by the mutual repulsion
of magnets 284 and 270, and magnets 190 and 276. The repulsive
magnetic field between magnets 276 and 190 serves to store kinetic
energy from the downstroke of the power piston 50 and will return
this energy to the power piston 50 on the upstroke of power piston
50. Thus the magnets 276 and 190 act as a magnetic spring at the
bottom of the stroke, and, similarly, magnets 284 and 270 form a
repulsive magnetic field at the top of the power piston stroke
which also acts as a magnetic spring.
[0142] Heat Engine Cycle
[0143] The following is a description of the operation of the heat
engine based on the embodiment of FIGS. 9-11 wherein fin means are
provided in various fluid flow passageways to assist in heat
transfer. Heating chamber 140, cooling chamber 160 and passageways
64, 312 and 40 are a sealed region within which the working fluid
circulates. This heat engine cycle begins with displacer 46
positioned towards the cold end of the engine, that is, in the
alpha position. This causes most of the working fluid to be forced
into heating chamber 140. Wall 62 of burner cup 44 heats the inner
heat exchanger 310 which in turn heats the working fluid in passage
64. The hot exhaust gas 316 then pass through manifold 94 and then
pass through the exhaust outer heat exchanger 314 (to which the hot
exhaust gas imparts most of its heat energy) and exit as cooled
exhaust gas 332. The heat energy from the exhaust outer heat
exchanger 314 is then transferred through the heat engine outer
wall 12 and into the exhaust inner heat exchanger 312 which in turn
imparts this heat into the working fluid.
[0144] The beating of the working fluid causes the working fluid to
expand. The expansion takes place through heat exchangers 310 and
312, through the regenerator 42, through openings 158 and into
cooling chamber 160 where pressure begins to build against power
piston 50. This causes power piston 50 to move downwards towards
magnet 190 and causes the magnets 270, 272, 274 and 276 to induce
voltages and current in the generator coils 318, 320, 322 and 324
respectively. The coils provide power to an output. A portion of
the power is preferably used to operate the displacer (eg. coils
318) and the remaining is preferably provided to an output for
providing electrical power to an load.
[0145] The electrical energy from one or more of the coils, eg.
generator coil 318, provides power via wires 180 to the phase delay
circuit 326 which modifies the power signal from the generator coil
318 and then feeds it through wires 154 to the displacer control
coil 328 which acts as an adjustable drive member. Circuit 326 is a
signal modulator which may comprise, eg., either of a variable
capacitor and a fixed inductor or of a variable inductor and a
fixed capacitor. Phase delay circuit 326 may be any circuit that
will drive displacer 46 to move in a cycle that is out of phase to
the cycle of power piston 50. Circuit 326 modifies the power signal
from the generator coil 318 and then feeds it through wire 154 to
displacer control coil 328. This signal sent to the displacer
control coil 328 causes an upward force on the magnet 286 which in
turn causes magnet 286 and displacer 46 affixed thereto to move
upwards towards magnet 288.
[0146] The upstroke of displacer 46 causes the working fluid to
flow through the heat exchangers 312 and 310, through the
regenerator 42, through the openings 158 and into the cold end of
the engine 160. As the working fluid passes through the regenerator
42, most of the heat of the working fluid is transferred to the
regenerator 42. The remaining heat from the working fluid now
located in the cold end 160 of the engine is dissipated by heat
exchanger 330. Heat from the working fluid now located in cooling
chamber 160 is dissipated by heat exchanger 330 which preferably
comprises a plurality of cooling fins 331 which may be louvred fins
428, 440, 468 or helical louvred fin 448. This causes the working
fluid to contract and reduces the pressure within the engine. This
causes power piston 50 to move upwards under the influence of the
magnetic energy stored between magnets 276 and 190.
[0147] The upward motion of power piston 50 causes magnet 270 to
induce a reverse current pulse in the generator coil 318. This
reverse current pulse from generator coil 318 provides power to the
phase delay circuit 326 which modifies the power signal from the
generator coil 318 and then feeds it through wires 154 to the
displacer control coil 328. This signal sent to the displacer
control coil 328 causes a downward force on displacer magnet 286
which in turn causes displacer magnet 286 and displacer 46 affixed
thereto to move downwards towards magnet 284. The repulsive
magnetic field between displacer magnet 286 and magnet 288 serves
to impart the stored kinetic energy from the upstroke of the
displacer 46 to the downstroke. The repulsive magnetic field
between displacer magnet 286 and magnet 284 serves to store kinetic
energy from the downstroke of displacer 46 for the next upstroke.
The repulsion of displacer magnet 286 and magnet 284 also serves to
limit the travel of displacer 46.
[0148] In an alternate embodiment, phase delay circuit 326 may be
replaced by a controller that senses when the voltage from the
generator coil 318 is approaching zero which is the bottom of the
stroke of the power piston 50. At this point, the controller may
cut the signal to the displacer control coil 328 and begin a
reverse (negative) pulse which causes the displacer 46 to move
downwards towards magnet 270. Alternately, the controller may cut
the signal and allow displacer 46 to move downwardly under the
influence of a biasing member, eg. a spring or the magnetic fields
to which it is exposed.
[0149] If displacer is to be directly driven by piston 50 (eg.
without any phase angle modification) electrical energy from
generator coil 318 may provide power via wires 180 to displacer
control coil 328.
[0150] The downward movement of the displacer 46 causes the working
fluid to be forced from the cold end of the engine 160 through
openings 158, through regenerator 42 through the heat exchangers
312 and 310, and into the hot end of the engine near bottom 138 of
burner cup 44. As the working fluid passes through regenerator 42,
most of the heat stored in regenerator 42 is transferred into the
working fluid. The cycle then repeats itself.
[0151] In accordance with one aspect of this invention, the cycle
profile of the displacer and/or the piston may be adjusted. The
cycle profile describes the velocity of the displacer/piston as it
moves between the first and second positions and the dwell time of
the displacer/piston when it is in each of the first and second
positions. The cycle profile also includes the phase angle between
the piston and the displacer. The apparatus preferably includes a
feedback member responsive to power demand from the power output
member by a load to modulate the amount of heat provided by the
heat source to the working fluid. A preferred embodiment of the
feedback member comprises an adjustable signal generator drivenly
connected to one of the piston and the displacer (preferably the
displacer) to control the movement of the one of the piston and the
displacer. The adjustable signal generator may be manually
controlled but preferably comprises the piston and a signal
modulator whereby the piston generates a signal which is sent to
the signal modulator and the signal modulator modulates the signal
that is then sent to an adjustable drive member. Examples of such
configurations are shown in FIGS. 10, 19 and 20.
[0152] Thus the piston and, eg., the phase delay circuit 326,
variable inductor 370 or primary controller 372 comprise an
adjustable signal generator which is drivenly connected to an
adjustable drive member. The adjustable drive member may be a coils
328, driver 48 and may also include any other drive member known in
the art of heat engines for moving one of the displacer and the
piston (and preferably the displacer)
[0153] Self Starting
[0154] Piston 50 is preferably biased to the alpha position shown
in FIGS. 2b, 2c and 4 such as by means of a spring 184 (see FIG.
2b) or by a magnetic bushing (eg. 186, 190) as shown in FIGS. 2c
and 4. In particular, as shown in FIG. 4, a magnet 186 is attached
to distal end 188 of drive rod 174 from piston 50. Distal end 188
travels through an central opening in closure member 195 which may
be installed in outer wall 12 by a press fit. A second magnet 190
is affixed to inner surface 192 of closure member 194. To prevent
the magnets touching each other, an elastomeric member 196 may be
affixed to the distal end of magnet 190 from inner surface 192. End
198 of magnet 186 is of an opposite polarity to end 200 of magnet
190. Accordingly, magnets 190 and 186 will repel piston 50 to the
alpha position shown in FIG. 4. Piston 50 moves between the alpha
position and the omega position (shown in FIG. 2d) due to the
influence of the working fluid on top 162 of piston 50.
[0155] By biasing displacer 46 and piston 50 to the alpha
positions, the heat engine may be self starting. In particular,
when heat is applied to heating chamber 92 (eg. combustion is
initiated in heater cup 44), the working fluid in heating chamber
140 will commence expanding. The expansion of the working fluid
will cause some of the working fluid to pass out of heating chamber
140 into cooling chamber 160. The entrance of the working fluid
into cooling chamber 160 will cause piston 50 to move downwardly.
Provided piston 50 moves downwardly by a sufficient amount and/or
at a sufficient rate, an electrical current will be generated which
may be transmitted by wires 180 to driver 48. The signal will cause
driver 48 to move displacer 46 towards the omega position thus
initiating a first stroke of displacer 46 and evacuating additional
heated working fluid from heating chamber 140 into cooling chamber
160 thus further driving piston 50 downwardly to generate further
amounts of current.
[0156] The working fluid is isolated in the heat engine. To this
end, the opposed ends of inner wall 30 are sealed and fluid flow
path 40 is also sealed. Heater cup 44 is preferably used to seal
the end of inner wall 30 adjacent heating chamber 140. Piston 50 is
preferably used to seal the end of inner wall 30 adjacent cooling
chamber 160 such as by creating a seal with inner surface 38 of
inner wall 30 thus isolating the linear generator from the working
fluid.
[0157] It will be appreciated that the linear generator need not be
sealed. For example, air may be able to pass through the central
opening in closure member 195 as well as past coils 56 so as to
prevent significant pressure build up in the linear generator as
magnets 52 move.
[0158] Closure members 194 and 195 assist in the construction of
flashlight 10 as well as to protect coils 56 from the incursion of
foreign material which would damage the linear generator. Closure
members 194 and 195 may be affixed to the bottom of the one of the
cylinders by any means known in the art. For example, referring to
FIG. 2a, closure member 195 is integrally formed as part of outer
wall 30 whereas, for example, closure member 194 is welded to the
distal end of outer wall 12 from heater cup 44. In the embodiment
shown in FIG. 4, closure member 194 has an annular flange 202 which
is threadedly received on outer surface 32 of outer wall 12.
However, if the inner container, or the outer container, are
prepared by high speed die stamping, then closure members may be
integrally formed as part of the inner/outer container.
[0159] Referring to FIG. 8, wires 180 from the first set of coils
56 are electrically connected to wires 154 of driver 48. Wires 180
pass through controller 206 (which is preferably phase delay
circuit 326). Wires 180 and 154 as well as controller 206 (which
may be a phase delay circuit) may be positioned between inner and
outer walls 30 and 12 (i.e. in gaps 166 and fluid flow path
40).
[0160] Thermomechanical Control
[0161] A cross sectional view of a preferred embodiment of a heat
exchanger utilizing thermomechanical control is shown in FIGS.
9-11.
[0162] To start the engine, the start switch 18 is engaged. The
start switch 18 is operatively linked to the fuel switch lever 290
by means of linking member 291 which is preferably mechanical. Fuel
switch lever 290 is activated such that the fuel flow control valve
292 and the variable flow fuel control valve 294 are both
momentarily opened. Preferably fuel switch lever 290 is a
mechanical switch drivenly moveable by linking member 291 between
two positions and which is mechanically linked to fuel flow control
valve 292 and the variable flow fuel control valve 294. When the
lever switch 290 is released, the variable flow fuel control valve
294 closes and the fuel flow control valve 292 remains open. This
ensures starting fuel reserve 296 is full and fuel from the
starting fuel reserve 296 begins to flow. The fuel in the starting
fuel reserve is sufficient for a short period of operation (eg. 1-2
minutes). In the event that the burner 298 fails to ignite, then
the amount of fuel which may accidentally escape into the
environment is limited to the small harmless amount in the starting
fuel reserve 296. Hence the starting fuel reserve 296 and its
associated mechanisms acts as a safety device to prevent the
spillage or release of large quantities of fuel.
[0163] When start switch 18 is depressed, piezo crystal high
voltage power supply 300 produces high voltage which flows along
conductor 302 to the electrode 304 where a spark is created which
ignites the fuel in the burner 298 and causes a flame to form.
Optionally, the fuel switch lever 290 and the start switch 18 need
not be linked together but may be sequentially operated by the
user.
[0164] The flame immediately begins to heat burner cup 44 as well
as heating fuel flow control member 308 which, on heating, begins
to open the variable flow fuel control valve 294. Flow control
valve member 308 may be any member that will reconfigure itself on
heating so as to adjust the position of variable flow fuel control
valve 294. Examples of such members include members that deform on
heating (eg. a bimetal strip), significantly contract or elongate
with temperature changes (eg. muscle wire) or significantly alter
their spring constant with temperature changes thereby exerting
variable force based on temperature (eg. homeostat type
devices).
[0165] Fuel flow control member 308 is configured such that as the
temperature in combustion chamber 92 reaches the optimum operating
temperature, the variable flow fuel control valve 294 will be fully
open so that the heat engine will provide full power. If full power
is not required, the burner cup will begin to overheat because the
available thermodynamic energy is not being converted to mechanical
or electrical energy. The overheating will cause the variable flow
fuel control valve 294 to begin to close over its central maximum
flow point thereby reducing the fuel flow and thereby reducing the
temperature to the optimal range.
[0166] Thus a self regulating system is established wherein the
amount of fuel delivered by the variable flow fuel control valve
294 is controlled by the temperature of combustion chamber 92 which
always remains within its optimum operating range as controlled by
the bimetal fuel flow control member 308. Accordingly, for example,
feedback member is drivingly connected to the variable fuel flow
valve 294 and comprises a thermal sensor (flow control valve member
308) thermally connected to combustion chamber 92 whereby the
temperature of combustion chamber 92 varies inversely to the power
drawn from the linear generator by the load, the thermal sensor
senses the temperature of combustion chamber 92 and the feedback
member adjusts the flow rate of fuel supplied to the combustion
chamber to maintain the temperature of the combustion chamber
within a preset range
[0167] Thermoelectromechanical Control
[0168] A cross sectional view of the preferred embodiment of this
invention is shown in FIG. 19.
[0169] To start the engine, the start switch 18 is preferably
engaged as with the embodiment of FIGS. 9-11 to commence ignition
and the heating of heater cup 44. When the power piston 50 begins
to move and the generator coils 318, 320, 322 and 324 begin to
generate power, electricity flows through wires 334, 336 and 338
which are electrically connected to low resistance resistor 342 via
wire 340. Electricity flows from low resistance resistor 342 to
internal load resistor 344 via wire 346 and to external load 348
via wire 350.
[0170] Electricity from the generator coils 320, 322 and 324 also
flows through wires 352, 354 and 356, through wire 358, through the
low resistance resistor 360, through wires 362 and 364 to the
internal load resistor 344 and to the external load 348. The
internal load resistor 344 ensures that a small amount of current
is always being withdrawn from the generator. This ensures that a
small amount of current is always flowing through the low
resistance resistor 360 which supplies heat to fuel flow control
member 308 which opens the variable flow fuel control valve 294 by
means of lever 366. The current drawn by the internal load resistor
causes the low resistance resistor 360 to heat slightly which
causes the fuel flow control member 308 to be reconfigured (eg. to
bend or contract or deform) thereby opening the variable flow fuel
control valve 294 enough to maintain the fuel flow required for
standby operation.
[0171] When the current drawn by the external load 348 increases,
the amount of heat created by the low resistance resistor 360
increases which causes the fuel flow control member 308 to be
further configured (eg. to bend further) thereby opening the
variable flow fuel control valve 294 further so as to provide
enough fuel to provide the thermal energy required to generate the
power drawn by the load. Thus a fuel control system which
proportions the fuel flow to the load has been developed.
[0172] Upon ignition, the flame immediately begins to heat the
burner cup 44. As the temperature of burner cup 44 becomes
sufficient to cause the cyclic operation of the heat engine, the
electrical current produced by generator coils 318, 320, 322 and
324 begins to flow. As the current begins to flow through low
resistance resistor 360, through internal load resistor 344 via
wire 346, low resistance resistor 360 begins to heat and supplies
heat to fuel flow control member 308 which begins to open the
variable flow fuel control valve 294 by means of lever 366. As the
temperature of low resistance resistor 360 reaches its optimum
operating temperature, the variable flow fuel control valve 294
will be open fully for full power. If full power is not required,
the low resistance resistor 360 will become cooler thereby causing
the variable flow fuel control valve 294 to begin to close thereby
reducing the fuel flow. Conversely, if the load 348 draws more
power, variable fuel flow control valve 294 will again be opened
due to the increased heat of low resistance resistor 360 being
supplied to the fuel flow control member 308 which in turn opens
variable fuel flow control valve 294. Thus a self regulating system
is established wherein the amount of fuel delivered by the variable
flow fuel control valve 294 is controlled by the temperature of low
resistance resistor 360 whose temperature is proportional to the
power required by load 348. Alternately, if the system does not
include internal load resistor 344, and if the external load 348
requires no power, then the mechanism associated with low
resistance resistor 360 will cause variable fuel flow control valve
294 to shut off the fuel supply and cause the engine to stop once
fuel reservoir 296 is exhausted.
[0173] The internal load resistor 344 ensures that a small amount
of current is always being withdrawn from the generator. This
ensures that a small amount of current is always flowing through
the low resistance resistor 360 which supplies heat to the heat
reconfigurable member 368 which operates the variable inductor 370.
Heat reconfigurable member 368 may be any member that will
reconfigure itself on heating (eg. a bimetal strip, muscle wire or
homeostat type devices). The current drawn by internal load
resistor 344 causes the low resistance resistor 360 to heat
slightly which causes the heat reconfigurable member 368 to bend
thereby operating the variable inductor 370 (a signal modulator) so
as to maintain an optimal phase angle between the displacer 46 and
the power piston 50. When the current drawn by the external load
348 increases, the amount of heat created by the low resistance
resistor 360 increases which causes the heat reconfigurable member
368 to deform further thereby further changing the setting of the
variable inductor 370 thereby again changing the phase angle
relationship between the displacer 46 and the power piston 50. It
has been found that a given engine with a given displacer and power
piston phase angle relationship has an energy efficiency curve
which varies for different power levels or different burner/ambient
temperatures. Similarly, it has been found that by varying the
phase angle, relationship between the displacer and the power
piston, an efficient operating point can be established for any
power and/or burner/ambient temperatures. Thus a simple
displacer/power piston phase control system has been developed
which modifies the phase angle under varying load conditions to
maintain the efficiency of the system.
[0174] In an alternate embodiment, solid state electronics may be
used to control a transistor which drives resistor 360 and fuel
flow control member 308 of the variable fuel flow valve 294 and the
variable inductor 370.
[0175] Accordingly, for example, a feedback member is drivingly
connected to the variable fuel flow valve 294 and comprises a
circuit including resistor 360 electrically connected to the
circuit to draw current proportional to the power demand drawn from
the output (external load 348), and a thermal sensor (fuel flow
control member 308) thermally connected to resistor 360 whereby the
thermal sensor indirectly senses the power demand of a load applied
to the output and the feedback member adjusts the flow rate of fuel
supplied to combustion chamber 92 to maintain the temperature of
combustion chamber 92 within a preset range.
[0176] Electric Modulation Control
[0177] A cross sectional view of the preferred embodiment of this
invention is shown in FIG. 20.
[0178] When the start switch 18 is depressed, a signal is sent from
the primary controller 372 (a signal modulator) to the fuel flow
controller 374 by means of wire bundle 376. The signal to the fuel
flow controller 374 causes the fuel flow controller 374 to energize
a valve, eg. spring loaded normally closed solenoid fuel valve 382,
to open by means of wire pair 384. The opening of the spring loaded
normally closed solenoid fuel valve 382 allows fuel to flow from
the small staring fuel reservoir 296 along passage 110 and along to
the burner 298.
[0179] The primary controller 372 also supplies power to the high
voltage power supply 378 by means of the wire pair 380 which causes
high voltage to be generated which then passes along wire 302 to
the high voltage electrode 304 where sparks are created which
causes the vaporized fuel in the burner 298 to be ignited. The
resulting flame immediately begins to heat the bottom of the burner
cup 44.
[0180] The hot exhaust gasses and radiation from the flame heats
the temperature sensing means 386 (eg. a thermocouple) which is
connected to the fuel flow controller 374 by means of the wire pair
388. In response to the fuel flow controller 374 interpreting a
high temperature present, the fuel flow controller 374 energizes
another valve, eg. spring loaded normally closed solenoid fuel
valve 390, by means of wire pair 392. The fuel flow controller 374
also sends a signal to the primary controller 372 by means of wire
bundle 376 which in turn causes the primary controller 372 to
de-energize the high voltage power supply and stop the sparking at
electrode 304. The temperature in burner cup 44 is constantly
measured by the temperature measuring means 386 and monitored by
the fuel flow controller 374 by means of the connection through
wire pair 388. If at any point the temperature drops below a preset
temperature of for example 400.degree. F., the fuel flow controller
374 sends a signal to the primary controller 372 by means of wire
bundle 376. If the primary controller 372 registers the fact that
the fuel flow is on and the temperature has fallen below the preset
temperature of for example 400.degree. F., the primary controller
372 will re-energize the high voltage power supply 378 causing high
voltage to flow along wire 302 to electrode 304 where sparks will
again be created in order to relight the fuel in the burner 298 and
to re-establish the flame. The heat from the flame will again heat
the temperature measuring means 386 which is monitored by the fuel
flow controller 374 through wire pair 388.
[0181] Once the preset temperature of for example 400.degree. F. is
reached, the fuel flow controller 374 will send a signal to the
primary controller 372 by means of the wire bundle 376 which will
in turn cause the primary controller 372 to de-energize the high
voltage power supply and stop the sparking at electrode 304. If the
temperature is not re-established within a preset amount of time,
the fuel flow controller 374 preferably de-energizes spring loaded
normally closed solenoid valves 382 and 390 by de-energizing wires
384 and 392 respectively. Thus, a safety means for ensuring that
the burner is lit is incorporated in the design.
[0182] The electrical energy from one or more coils, eg. generator
coil 318, provides power to the rechargeable battery 394 by means
of the wire pair 180. The battery 394 in turn provides power to the
primary controller 372 to which it is attached. The primary
controller 372 senses the input to the battery from the generator
coil 318 which causes the primary controller 372 to send a signal
to the displacer control coil 328 by means of wire 154. This
positively polarized signal sent to the displacer control coil 328
causes an upward force on the magnet 286 which in turn causes the
magnet 286 and the displacer 46 affixed thereto to move upwards
towards magnet 288.
[0183] In addition to the basic cycle, the new heat engine
optionally incorporates means to modulate the fuel burn and
optimize energy efficiency. There are a plurality, eg. four,
solenoid fuel valves 390, 294, 396 and 398 which are connected to
the fuel flow controller 374 by means of wire pairs 392, 402, 404,
and 406 respectively. The primary controller 372 senses the current
flowing to the load 408 through wire pairs 410, 412, and 414 by
means of the hall effect current sensor 416 which is connected to
the primary controller 372 by means of wire pair 418. The power
from the generator coils flows out to the load 408 (eg. an outlet
or an electric apparatus) by means of wires 420 and 422. When the
primary controller 372 determines that the current flowing to the
load is, eg., between 0 to 25 percent of the maximum output power
of the heat engine and generator, it ensures that only solenoid
fuel valve 390 is energized by sending a signal along two of the
eight wires in the wire bundle 376 which connects the primary
controller 372 to the fuel flow controller 374. The fuel flow
controller 374 in turn energizes only the spring loaded normally
closed solenoid valves 382 and 390.
[0184] When the primary controller 372 determines that the current
flowing to the load is, eg., between 26 to 50 percent of the
maximum output power of the heat engine and generator, it sends a
signal to the primary fuel controller 374 along two of the wires in
the wire bundle 376. This signal causes the primary fuel controller
374 to energize an additional spring loaded normally closed
solenoid fuel valve 396 by means of the wire pair 402 which causes
the spring loaded normally dosed solenoid fuel valve 396 to open
thereby increasing the fuel flow to the burner 298.
[0185] When the primary controller 372 determines that the current
flowing to the load is, eg., between 51 to 75 percent of the
maximum output power of the heat engine and generator, it sends a
signal to the primary fuel controller 374 along two of the wires in
the wire bundle 376. This signal causes the primary fuel controller
374 to energize yet another spring loaded normally closed solenoid
fuel valve 398 by means of the wire pair 404 which causes the
spring loaded normally closed solenoid fuel valve 398 to open
thereby further increasing the fuel flow to the burner 298.
[0186] When the primary controller 372 determines that the current
flowing to the load is, eg., greater than 75 percent of the maximum
output power of the heat engine and generator, it sends a signal to
the primary fuel controller 374 along two of the wires in the wire
bundle 376. This signal causes the primary fuel controller 374 to
energize yet another spring loaded normally closed solenoid fuel
valve 400 by means of the wire pair 406 which causes the spring
loaded normally closed solenoid fuel valve 400 to open thereby
further increasing the fuel flow to the burner 298. Conversely, if
the power level decreases to the range below which the burner is
operating, the system closes excess spring loaded normally closed
solenoid fuel valves until the number of open valves and the load
are matched.
[0187] Under normal operating conditions the output voltage
controller 424 connect to the primary controller 372 by means of
wire 426 and the voltage controller connects the wire pairs 410,
412 and 414 from generator coils 320,322 and 324 in parallel and
the output frequency of the generator is equal to the displacer
frequency. If an overload occurs as sensed by current sensor 416,
the voltage controller preferably disconnects the load 408 thereby
protecting the generator. In the case where the output from the
generator is being rectified, the frequency of operation of the
displacer will also be varied so as to optimize efficiency of the
system.
[0188] Accordingly, for example, a feedback member comprises
controller 372 operatively connected to variable fuel flow valve
294 and current sensor 416 connected to the output (load 408)
whereby the current sensor senses the current drawn from the output
and the controller adjusts the flow rate of fuel supplied to the
combustion chamber based on the amount of current drawn from the
load.
[0189] Regenerator
[0190] In accordance with another aspect of this invention, a novel
construction for a regenerator is provided. As shown in FIG. 6a,
regenerator 42 is preferably also of a thin wall construction. In
particular, regenerator 42 may be manufactured from copper (which
may be coated with an inverting layer such as silicon monoxide
and/or silicon dioxide), aluminum (which is coated with an
inverting layer such as silicon monoxide and/or silicon dioxide),
stainless steel or a super nickel alloy and have a thickness from
about 0.0005 to about 0.005 inches, more preferably from about
0.001 to about 0.002 inches.
[0191] As shown in FIG. 6a, regenerator 42 may comprise one and
preferably a plurality of sections 208 which are joined together by
a plurality of longitudinally extending members 210. Longitudinally
extending members 210 are spaced apart on opposed sides of openings
212. Openings 212 define thermal breaks between sections 208 so as
to minimize the heat conducted from hot end 214 to cool end 216.
Accordingly, longitudinally extending members 210 are preferably as
thin as possible in the circumferential direction so as to minimize
the heat transferred between sections 208 while still maintaining
sufficient structural integrity of regenerator 42 so that
regenerator 42 may be handled as a single member. In the embodiment
of FIG. 1, regenerator 42 comprises a plurality of individual
sections 208.
[0192] Regenerator 42 may be made from sheet metal which is roll
formed. Then louvres (directing members) 218 and openings 212 are
preferably formed (eg. by stamping). Subsequently, the material is
formed into a cylindrical tube and may be spot welded together to
form regenerator 42. Sublouvres (secondary directing members) may
be provided as are shown in FIGS. 17, 18a and 18b. Alternately, as
shown in FIGS. 6e and 6f, regenerator 42 may be made from sheet
metal which is folded repeatedly to define a plurality of outwardly
extending portions 213. Preferably, outwardly extending portions
are tightly packed adjacent each other so that they extend
generally radially outwardly. The spacing between outwardly
extending portions varies the position where the material is folded
(point 213a) to the position where the material is again folded
(point 213b) and defines a generally V shaped opening having a mean
diameter "d" (see FIG. 6f). Flow channels 215 are positioned
between adjacent outwardly extending portions 213 in the generally
V shapped openings and extend longitudinally through regenerator
42. As shown in FIG. 6f, such a regenerator 42 is folded to define
an annular band which is preferably positioned immediately interior
of outer wall 12 and has a central opening 217 within which
displacer 46 travels. As discussed previously, inner wall 30 may be
provided to define the channel within which displacer 46 travels so
that regenerator is positioned between inner and outer walls 30 and
12.
[0193] Regenerator 42 is positioned in fluid flow path 40 between
outer and inner walls 12 and, 30 as exemplified in FIG. 2a, the
regenerator preferably extends along a substantial portion of fluid
flow path 40. As shown in FIG. 2a, regenerator 42 commences at
about the top 136 of displacer 46 when displacer 46 is positioned
distal to driver 48. Further, regenerator 42 preferably ends
adjacent opening 158 in inner wall 30. It will be appreciated that
the construction of regenerator 42 may be used as a heat exchanger
in other parts of a heat engine provided that section has
sufficient strength to support the regenerator material.
[0194] In order to improve the heat transfer between the working
fluid and regenerator 42, regenerator 42 may have a plurality of
louvres 218 provided therein. Louvres 218 may extend continuously
along the length of regenerator 42 or, as shown in FIGS. 6a and 6e,
louvres 218 may be provided in a series of groups 219. Exemplary
louvres 218 are shown in more detail in FIG. 6d. Regenerator 42
comprises a main body portion 248. Louvres may be formed such as by
stamping or other means known in the art. As shown in FIG. 6d, each
louvres 218 comprises an angled panel which extends outwardly from
main body portion 248 and has opposed flanges 250 extending between
front portion 256 of angled panel 252 and main body portion 248. As
shown in FIG. 6d, some of the louvres may have angled panels that
extend in a first direction (e.g. upwards in FIG. 6d) and another
set of louvres may extend in the opposite direction (e.g. downwards
as shown in FIG. 6d). The designs which are shown in FIGS. 12d, 17,
18a and 18b may be used for louvres 218.
[0195] In FIGS. 6b and 6c, a heat exchanger using a coil of the
material used to form regenerator 42 of FIG. 6a is shown.
Regenerator is preferably fixed in position such as by spot welding
regenerator 42 to one of outer and inner walls 12 and 30. Referring
to FIG. 6c, arrows represent the flow of fluid through louvres 218.
Louvres 218 direct the fluid to pass first from one side of main
body portion 248 to the opposed side and, subsequently, a portion
to flow from the opposed side back to the initial side of main body
portion 248. The continual flow of fluid through main body portion
248 (from one side to the other) produces an improved heat transfer
between the working fluid and regenerator 42. In particular, when
the working fluid is passing through the regenerator from heating
chamber 140 to cooling chamber 160, regenerator 42 accumulates heat
which is transferred back to the working fluid when the working
fluid travels from cooling chamber 160 to heating chamber 140.
[0196] It is to be appreciated that louvred fins may be used in
place of part or all of regenerator 42. Further, a section 208 of
the regenerator material may be used as a heat exchanger in
passageway 64 or in the upper portion of passageway 40 provided
that positioning members are provided to dimensionally stabilize
the upper end of inner and outer walls 30 and 12. For example, one
or more rings 476 may be provided adjacent the upper end of inner
wall 30.
[0197] Heat exchanger 258 may also be incorporated into the portion
of fluid flow path 40 which is positioned in heating zone 22 (see
FIG. 2a) as well as in the cooling zone 26. This heat exchanger
assists in transferring heat from the exhaust gases in first pass
86 of heat exchanger 67 to the working fluid as it travels from
heating chamber 140 to cooling chamber 160.
[0198] Heat exchanger 258 may be made from the same material as
regenerator 42. This is shown in particular in FIG. 6a. In FIG. 6b,
a heat exchanger 258 is shown comprising a plurality of layers of
the louvres material shown in FIG. 6a. The number of layers of
louvred main body portion 248 which is utilized as regenerator 42
or as heat exchanger 258 may vary depending upon the desired
thermal efficiency of heat exchanger 258 as well as regenerator 42.
For example, if the radial thickness of fluid flow path 40 is about
0.05 inches, then only a single layer heat exchanger 258 may be
required as is shown in FIG. 6a.
[0199] The construction of the regenerator shown in FIGS. 6e and 6f
may also be used as heat exchangers in the portion of fluid flow
path 40 which is positioned in heating zone 22 as well as in the
cooling zone 26. Theses heat exchangers may be made integrally as
one longitudinally extending member or they may be made in
individual longitudinally extending sections.
[0200] When the heat exchangers in heater zone 22, cooling zone 26
and the regenerator are formed constructed from different sections
of material, then the thickness "t" (see FIG. 6f) of each section
is preferably varied to improve the heat exchange characteristics
of the construction. As the temperature difference between the
fluid and the metal decreases, additional surface area is required
to maintain the heat transfer rate between the fluid and the metal.
Accordingly, progressively thinner material is preferably used in
sections having a lower steady state temperature so as to increase
the number of louvres per unit of space and thereby increase the
surface area available for heat transfer. As the fluid cools as it
travels through the sections from the heating zone to the cooling
zone, the gas volume decreases and the velocity decreases. This
decrease in velocity reduces the rate of heat transfer. By increase
the number of louvres per unit of space, the void volume is
decreased (the packing is increased) thereby preferably preventing
the velocity of the fluid from significantly varying as the fluid
changes temperature while minimizing the back pressure.
Accordingly, it is preferred to provide a number of sections of
differing thickness so that the spacing between the louvres may be
varied whereby the heat transfer rate may be maintained
substantially constant as the fluid changes temperature as it
travels between the heating and the cooling chambers.
[0201] For example, if the sections are separately formed, then
louvres 218 of the heat exchangers for the heating and cooling
zones are preferably spaced apart such that the mean diameter "d"
(see FIG. 6f) is from 1 to 20 times the metal thickness, more
preferably 2 to 10 times the metal thickness and most preferably
about 4-5 times the metal thickness. Accordingly, the mean diameter
"d" adjacent sections 213 is preferably 0.001 to 0.020 inches,
preferably 0.002 to 0.012 inches and more preferably 0.006 inches.
In addition, louvres 218 of the regenerator are preferably spaced
apart such that the mean diameter "d" is from 1 to 10 times the
metal thickness, more preferably 2 to 5 times the metal thickness
and most preferably about 3 times the metal thickness. Accordingly,
the mean diameter "d" adjacent sections 213 is preferably 0.0005 to
0.006 inches, preferably 0.001 to 0.004 inches and more preferably
0.002 inches. The regenerator itself may also be constructed of a
series of separate sections. In such a case. For example, the
regenerator may be constructed from three sections comprising a hot
section having a thickness "t" of, e.g., 0.004, an intermediate
section having a thickness "t" of, e.g., 0.003 and a cool section
having a thickness "t" of, e.g., 0.001.
[0202] When the heat exchangers in heater zone 22, cooling zone 26
and the regenerator are formed integrally, then the unit is
preferably constructed from a suitable metal that has a thickness
"t" which is suitable for all sections, e.g., from about 0.001 to
about 0.004 inches and preferably about 0.002 inches. Louvres 218
are preferably spaced apart such that the mean diameter "d" is from
1 to 10 times the metal thickness, more preferably 2 to 5 times the
metal thickness and most preferably about 3 to 4 times the metal
thickness. Accordingly, the mean diameter "d" adjacent sections 213
is preferably 0.002 to 0.020 inches, preferably 0.004 to 0.010
inches and more preferably 0.005 inches.
[0203] Fins
[0204] In accordance with another aspect of this invention, there
is provided a novel construction for heat exchangers. As discussed
above, means to assist in transferring heat between the structural
components of the heat engine and a fluid may be provided in any of
the air flow passages of the heat exchanger. For example, they may
be provided in passages 64, 40, 86, 88 and 102. At least one heat
exchange member or fin is preferably provided in each fluid flow
passage. In one embodiment, as exemplified by FIG. 14, the fins are
constructed to allow the flow of fluid through the fin as the fluid
flows axially through the heat exchanger. In another embodiment,
the fins are constructed and arranged to produce a directed fluid
flow as the fluid passes through the heat exchanger (e.g. see FIGS.
12, 12a, 13 and 16). A plurality of individual annular fins may be
provided. Alternately, one or more continuous helical fins as shown
in FIG. 16 may be provided. In either case, the fins define a
plurality of rows of fins in the heat exchanger that the fluid
encounters as it flows through the heat exchanger and thus the
fluid is acted on by the fins several times as it flows through the
heat exchanger. In a further embodiment, the fins are preferably
provided with directing members whereby the fin is configured and
arranges to produce a main flow of fluid which flows through the
fin and to produce a secondary fluid flow which passes through the
main directing members whereby the transfer of heat between the
fluid and the heat exchanger is enhanced. Examples of such
directing members are shown in FIGS. 16, 17, 18a and 18b. The
directing members may be configured and arranged to produce a
cyclonic or swirling flow of air (see FIG. 12e) or a cross-flow
pattern (see FIG. 12f).
[0205] In the preferred embodiment of the heat exchanger, as
exemplified by FIG. 1, the fins are positioned between two
concentric cylinders which are spaced apart to define an air flow
passage. A second air flow passage is positioned interior of the
inner of the two concentric cylinders or exterior of the outer of
the two concentric cylinders. The fins may be affixed to the wall
of the heat exchanger by any means known in the heat exchanger art
but are preferably mechanically affixed to one or both of the inner
wall and the outer wall and extend all the way across the air flow
passage. However, the instant fin design may be used in a passage
of any particular configuration for a heat exchanger. For example,
the heat exchanger could have a square cross-section defining a
first fluid flow passage with the fins longitudinally spaced apart
in the passage. A plurality of generally parallel tubes (for
containing a fluid at a second temperature) could extend
longitudinally through the fins to thereby define a heat exchanger
with a square cross-section.
[0206] Referring to FIG. 12, annular fin 428 has a top surface 430
and inner edge 432, an outer edge 434 and a lower surface 436. Top
and bottom surfaces 430 and 436 are opposed surfaces of fin 428.
Inner and outer edges 432 and 434 are curved and have a portion
which abuts against the longitudinally extending surface of a wall.
See for example surface 438 of FIG. 12b. Such rings may be used in
a fluid flow passage which exists between spaced apart cylindrical
tubes. For example, such rings may be inserted in passageways 64 or
102 (see FIG. 1). In order to provide a plurality of annular fins
428 in passageway 102, outer burner shield 70 could be placed
inside air preheat shield 72 to define passageway 102. Any desired
number of rings, preferably a plurality thereof, could be inserted
into passageway 102 one at a time with edges 432 and 434 pointing
towards entry port 104. Rings would then slide along the inner
walls of shields 70 and 72 until they were positioned in the
desired location. Annular fins 428 are preferably sized such that
edges 432 and 434 are drawn towards each other upon insertion into
passageway 102. The pressure between edges 432 and 434 mechanically
lock annular fins 428 in position. Preferably, the pressure which
is exerted between fin 428 and shields 70 and 72 is sufficient to
ensure that the rate of heat transfer between shields 70 and 72 and
annular fin 428 is maintained over the normal operating temperature
of shields 70 and 72. In this way, as the dimension of passageway
102 may change under different thermal conditions, sufficient
contact will be maintained between the annular fins and the walls
of passageway 102 to ensure that the desired rate of heat transfer
is maintained.
[0207] Another embodiment of such an annular fin is shown in FIG.
12a. In this embodiment annular fin 440 has opposed surfaces (i.e.
top surface 446 and the bottom surface) which is generally flat (so
as to be generally transverse to the longitudinal fluid flow path
through the heat exchanger) and an outer edge 444 which is curved
as in the case of annular fin 428 to define a collar. Inner edge
442 is not curved. Examples of such fins are shown in passage 102
of FIG. 1. The outer diameter of fin 440 is selected such that when
inserted into annular passage 102, the pressure which is exerted
between outer edge 444 and inner surface of outer burner shield 72
will deform the collar and lockingly hold annular fin 440 in
position. It will be appreciated that a curved edge (or collar) may
be provided instead only on the inner edge. For example, referring
to the fins shown in passageway 88 of FIG. 1, inner edge 442 may be
curved so as to have the collar like portion of fin 440 of FIG. 12a
so as to lockingly engage a wall positioned on the interior of the
ring (in this case, inner burner shield 68). The top surface of the
fin preferably extends horizontally to have a blunt nosed edge. In
this embodiment, the inner diameter of the annular fin is selected
so as to be slightly smaller than inner burner shield 68 so as to
lockingly engage inner burner shield 68 when inserted therein.
Accordingly, in accordance to one aspect of this invention, fins
which have air flow passages there through are provided to
lockingly engage one or both walls of an annular passage to thereby
maintain contact with the selected walls over the operating
temperature of the heat exchanger. The passages may be provided as
openings 456 in a fin or by passages 474 between blades 472 of a
fin (see FIG. 13).
[0208] As shown in FIG. 16, one or more helical fins 448 may be
provided instead of a plurality of individual annular fins such as
fins 428 or 440. Helical fin 448 is shown in FIG. 16 in an
embodiment where it is positioned in the annular passage between
outer and inner walls 12 and 30. In this embodiment, helical fin
448 has curved inner and outer edges 450 and 452 for locking
engagement with surfaces 36 and 34 respectively. It will be
appreciated that helical fin 448 need have only one curved edge
(either inner out outer) so as to lockingly engage only a single
wall 12 or 30.
[0209] When used in a heat exchanger, the fins are preferably
constructed to allow a fluid to flow there through to enhance the
heat transfer between the fluid and the heat exchanger. In the
embodiment of FIGS. 12 and 12a, fins 428 and 440 are designed to
extend fully across the annular gap between and inner and an outer
wall. Therefore, fin 428 is provided with a plurality of openings
456. In order to improve the heat transfer between the fluid and
the heat exchanger, comprising fin 428 and the surface of the walls
with which fin 428 is in contact, a plurality of directing members
458 may be provided. As the air travels longitudinally, in the
direction of axis A of FIG. 2a, the air encounters top or bottom
surface 430 or 436 of fin 428 and passes through openings 456, heat
is transferred between fin 428 and the fluid passing through the
heat exchanger.
[0210] As shown in FIGS. 12 and 12a, each of the direction members
458 extends upwardly in the same direction. Accordingly, as fluid
travels longitudinally (or axially) through the heat exchanger, the
fluid will be deflected by directing members 458 to swirl around in
a cyclonic type flow. Accordingly, for example, referring to the
embodiment of FIG. 12e, a plurality of fins 428 may be positioned
on outer surface 32 of outer wall 12. As fluid travels upwardly
through openings 456, directing members 458 will cause the air to
flow cyclonically around outer wall 32.
[0211] As exemplified by FIGS. 12c and 12d, some of the directing
members 458 extend upwardly from top surface 446 and some extend
downwardly. As shown in FIG. 12c, directing members 458 may extend
away from surface 446 in the same direction or, alternately, as
shown in FIG. 12d, they may extend towards each other. Preferably,
directing members 458 extend towards each other as shown in FIG.
12d.
[0212] Directing members 458 have a distal end 460 spaced
circumferentially from the position where directing member 458
contacts top surface 446. As air travels through opening 456, it
travels along the bottom surface of directing member 458 until it
encounters distal end 460. When the fluid encounters distal end
460, turbulent flow is created. As a result of the turbulent flow,
a portion of the fluid, preferably at least about 65%, continues to
travel upwardly through the heat exchanger while the remainder of
the fluid is caused to travel in a reverse manner through an
adjoining opening 456 to the lower surface of fin 440. Accordingly,
directing members 458 cause a portion of the fluid travelling
through the heat exchanger to pass at least twice, and preferably
three times, through a fin 440 as the fluid travels axially through
the heat exchanger. For example, as the fluid flows through the
heat exchanger, a portion of the fluid which has travelled through
a fin 440 from lower surface 436 to top surface 430 will travel in
the reverse direction from top surface 430 to lower surface 436.
This portion of the fluid may then be reentrained in the
longitudinal flow of fluid through the heat exchanger and travel
again from lower surface 436 to top surface 430 and continue on
flowing through the heat exchanger to encounter another fin 440.
This is shown in particular in FIG. 12f. This type of flow wherein
the directing members are configured and arranged to cause a
portion of the fluid which has passed through the a fin from the
first opposed side to the second opposed side to then pass from the
second opposed side to the first opposed side is referred to as
"cross-flow". This flow is advantageous as it causes a portion of
the fluid to be in contact with fin 440 for a greater period of
time thereby increasing the heat transfer between fin 440 and the
fluid.
[0213] Directing members may be formed in several ways. As shown in
FIGS. 12c and 12d, directing members 458 constitute a flange which
may be cut or stamped from surface 446. In such a case, only one
edge of directing member 458 may be in contact with the remainder
of the fin. An alternate construction of a directing member is
shown in FIGS. 17, 18a and 18b. In this case, directing member 462
is in contact with the fin over more than one surface. In
particular, as shown in FIGS. 17, 18a and 18b, directing member 462
has a transverse or radial side 464 which is in contact with top
surface 454 as well as opposed longitudinal edges 466 which are in
contact with top surface 454. The increased contact surface between
directing member 462 and the fin permit a greater amount of heat to
be transferred between directing member 462 and the fin thus
improving heat transfer between directing member 462 and the fluid
flowing through opening 456. Directing members 462 may be produced
by a stamping operation. Directing members 462 may be provided on
any of the fins described herein.
[0214] In an alternate embodiment, the fin may comprise an annular
member which comprises a radial blade. In particular, as shown in
FIG. 13, fin 468 may have a hub (which may be a curved inner edge
or collar 470) and a plurality of blades 472 which extend
outwardly, and preferably radially outwardly, there from (or a hub
and a plurality of blades which extend inwardly). Blades 472 are
preferably angled with respect to the plane of fin 468 so as to
direct air to flow in a prescribed pattern through the heat
exchanger. The spacing between adjacent blades 472 comprises a
passage 474 through which a fluid may flow. It will be appreciated
that blades 472 may be oriented in the same direction (as is the
case with directing members 458 in FIG. 12), thus causing a
swirling flow of the fluid in the heat exchanger as is represented
by FIG. 12e. It will be appreciated that some of blades 472 may
direct the fluid upwardly whereas others may direct the fluid
downwardly (in the same manner as directing members 458 of FIGS.
12c or 12d) to create a cross-flow as shown by FIG. 12f. It will
further be appreciated that, as with fin 440, radial blades 472
preferably extend substantially all and preferably all the way
across the annular space between the concentric cylinders so as to
direct as much air as possible to flow through passages 474.
[0215] In some circumstances, a limited amount of heat may need to
be transferred between the fluid and the fin. In such a case, the
fin may be provided with openings without any directing members. An
example of such a fin is shown in FIG. 14. In this case, the fin
comprises a ring 476 having a plurality of openings (for example
circular openings 478) provided in top surface 480. Once again,
inner and/or outer edge 482 and 484 may be curved as shown in FIG.
14.
[0216] In a further preferred embodiment, the directing members are
themselves provided with directing members so as to cause the fluid
to travel through the directing member as the fluid passes through
the heat exchanger. An example of such a directing member is shown
in FIG. 16. In this case, directing member 458 is provided with at
least one and preferably a plurality of openings 486 provided
therein. For example, referring to FIG. 17, directing member 462
has a plurality of openings 486 provided therein. Some of the fluid
will travel through openings 486 as the fluid travels through
openings 456 in the fin. Preferably, as shown in FIGS. 18a and 18b,
the directing member is a main directing member and has a plurality
of secondary directing members 488 or sublouvres provided thereon.
It will be appreciated that the secondary directing members may use
the construction techniques of fins 440 (eg. it may be a flanged or
stamped opening) or of fins 468 (eg. it may be a passage through a
blade). As in the case with the main directing members, a secondary
directing member is preferably associated with each secondary
opening 486. As shown in FIG. 18a, secondary directing members 488
may all be oriented in the same direction such that as the fluid
flows axially through the fin from lower surface 490 to upper
surface 492, the fluid passes only once (i.e. unidirectionally)
from lower or inner surface 494 of directing member 462 to upper or
outer surface 496 of directing member 462 (inner surface 494 and
outer surface 496 are opposed surfaces). In the alternate
embodiment of FIG. 18b, some of the secondary directing members 488
extend upwardly from upper surface 496 and some extend downwardly
from lower surface 494. As shown in FIG. 18b, directing members may
alternately extend upwardly and downwardly or they may be in any
other random pattern (as is also the case with main directing
members 458 in the embodiments of FIGS. 12c and 12d). In this case,
as the fluid travels axially through the heat exchanger from lower
surface 490 to upper surface 492 of the fin, a portion of the fluid
will be caused to pass at least twice through main directing member
462 due to turbulent flow created by secondary directing members
488 thus creating cross flow of fluid similar to that shown in FIG.
12f. It will be appreciated that openings and preferably openings
with associated secondary directing members 488 may also be
provided on blades 472. In another embodiment, blades 472 may be
provided as secondary directing members.
[0217] In accordance with another aspect of this invention, any of
these fin designs may be provided on the outer surface of outer
wall 12 as shown in FIG. 1 to assist in cooling chamber 160. These
fins may define the outer perimeter of the heat engine.
Alternately, as shown in FIG. 1, a further outer cylindrical sleeve
522 may be provided. This may be an extension of air preheat shield
72. Air flow path 524 is an extension of preheat air flow path 102
and is used to transfer heat from the cooling chamber to the air
for combustion. As shown in FIG. 1, the cooling fins of heat
exchanger 330 transfer heat from outer wall 12 to the air for
combustion. A fan is optionally provided for producing forced
convection flow through air flow path 524. The fan may be mounted
at any position to provide this flow. As shown in FIG. 1, the fan
is provided adjacent the entrance to air flow path 524. The fan
comprises a motor 526 and a fan blade 528 driven by the motor.
Preferably, both motor 526 and fan blade 528 are annular. They may
be mounted on one or both of the walls that define air flow path
524 (i.e., outer wall 12 and/or sleeve 522 in the embodiment of
FIG. 1). If fan 528 is annular, then it may be mounted on an
annular fan mount 530 which is drivenly connected to annular motor
526.
[0218] In accordance with another aspect of this invention, any of
these fin designs may be provided on the inner surface 60 of heater
cup 44 as shown in FIG. 1 to assist in transferring heat from the
combustion gas in combustion chamber 92 to the wall of heater cup
44 (the combustion chamber housing) as exemplified by reference
numeral 532 in FIG. 1).
[0219] It will be appreciated by those skilled in the art that
other modifications may be made to a heat engine and the flashlight
disclosed herein and all of these are within the scope of the
following claims. For example, the construction of regenerator 42
and the construction of the louvred heat exchanger may be used in
any application heat exchange application.
[0220] Any heat exchanger construction known in the art may be used
with the thin walled design provided herein to provide a heat
exchanger means between the hot exhaust gases produced in burner
cup 44 and the working fluid in the heat engine. In order to
increase the thermal efficiency of the heat engine, the air for
combustion may be preheated such as by use of the exhaust gas.
* * * * *