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BACKGROUND OF THE INVENTION
This invention relates to heat engines which are operated by the
utilization of variations in volume of materials which are expanded and
contracted when heated and cooled, and more particularly to a heat engine
utilizing a non-compressible material.
Known as heat engines in the art are steam engines, external combustion
engines, and internal combustion engines. Among them, the steam engines
are bulky because they need a boiler, a condenser, etc. The external
combustion engines are less developed because of technical difficulty.
Thus, the internal combustion engines are most extensively employed.
However, recently it has been pointed out that the internal combustion
engines are sources of public nuisance generating air pollution, noise,
and so forth. In order to overcome this drawback, a variety of methods to
improve internal combustion engines have been proposed; however, these
methods are still insufficient to completely eliminate the drawback. Since
most of the internal combustion engines use fossil fuels, especially
petroleum, the use of the internal combustion engines is liable to be
affected by changes in fuel supply which have been caused recently.
Accordingly, there is a strong demand for the development of novel heat
engines which can replace the internal heat engines.
Thus, the Stirling cycle engine has been reconsidered in the course of
developing these novel engines. This is an external combustion type gas
engine which has been put into practical use hitherto and has the
possibility of being practically used in some cases.
However, this engine needs considerably high technology in material and
mechanical construction, and still has problems to be solved in combining
it with load devices.
An ideal engine can satisfy a variety of requirements such as compactness,
high efficiency, great output, and high durability. In order to provide
such an ideal engine, it is necessary:
(1) to increase the engine rotational speed;
(2) to increase the pressure of a fluid sealed therein;
(3) to increase the compression ratio;
(4) to increase the temperature on the high temperature side; and
(5) to increase the efficiencies in heat exchange of the heater, the
reheater, and the cooler.
However, these requirements involve the following problems.
In order to increase the rotational speed, it is necessary to increase the
speed of movement of the gas. However, the heater, the reheater, and the
cooler impose obstructions in the gas passage. Therefore, if the
rotational speed is increased, the flow resistance is greatly increased,
and the engine power is decreased. If, in order to overcome this
difficulty, a gas, such as hydrogen or helium, which is of lower density
than air is used, the problem of sealing arises in addition to the problem
of increasing the pressure of the fluid sealed. Especially, sealing
hydrogen gas is very difficult because it can pass through metal, and the
problem of hydrogen embrittlement arises. The increase of the compression
ratio may be achieved by making as small as possible the volume of the
operating fluid when it is most compressed. However, in order to do so, it
is necessary to decrease the internal volumes of the heater, the reheater,
and the cooler and to decrease the internal volume of passages connecting
these elements, which will lead to insufficient heat exchange. This is a
problem to be solved prior to solving the problem of increasing the heat
exchange efficiency. The increase of the temperature on the high
temperature side is limited by the material to be used to approximately
800.degree. C. However, it is difficult to design the engine with small
size and increased heat exchange rate, in the case where it is continually
subjected to such a high temperature. In addition, the temperature
increase will raise the problem of lubrication oil treatment; that is, a
problem arises in the lubrication system.
SUMMARY OF THE INVENTION
Accordingly, an object of this invention is to eliminate all of the
above-described difficulties accompanying heat engines. More specifically,
the main object of the invention is to provide a novel heat engine which
has a simple construction and a high performance.
Another object of this invention is to provide a heat engine which operates
at relatively low temperature with little noise.
In order to achieve the foregoing objects, the present invention provides a
novel heat engine in which a non-compressive thermal operating substance
which is expanded and contracted by temperature change is employed in such
a manner that variations in volume of the thermal operating substance is
converted into the output of the engine.
According to this invention, briefly summarized, there is provided a heat
engine comprising means retaining a non-compressible thermal opening
substance which changes in volume in accordance with temperature change,
means forming a low temperature zone, means forming a high temperature
zone greater in temperature than said low temperature zone, means for
subjecting said thermal operating substance alternately to said high and
low temperature zone to cause alternate volumetric expansion and
contraction of the thermal operating substance, and power output means for
converting the volumetric expansion and contraction into a mechanical
displacement.
The features which are believed to be novel and characteristic of this
invention are set forth in the appended claims. The invention itself,
however, together with the further objects and advantages thereof, will be
best understood from the following detailed description of preferred
embodiments of the invention with reference to the accompanying drawings,
in which like reference characters denote the same parts and elements.
BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings:
FIG. 1 is a side view, in vertical section, illustrating the basic
principle of the heat engine according to this invention;
FIG. 2 is a longitudinal section of a first form of the heat engine
incorporating the principle of the invention;
FIG. 3 is a fragmentary perspective view showing a thermal operating
section of the engine shown in FIG. 2;
FIG. 4 is a cross section, on an enlarged scale, of a modification of a
cylinder unit used in the first form of the heat engine shown in FIGS. 2
and 3;
FIG. 5 is a fragmentary longitudinal section showing a modification of the
engine of FIG. 2;
FIG. 6 is a longitudinal section of a second form of the heat engine
according to this invention;
FIG. 7 is a longitudinal section of a third form of the heat engine
according to this invention, the figure also showing the possibility of
installing the engine in parallel;
FIG. 8 is a fragmentary perspective view showing a housing section of the
engine shown in FIG. 7;
FIG. 9 is a view explanatory of the manner of arranging two heat engines
and of converting reciprocating motion into rotary motion;
FIG. 10 is a fragmentary section showing a modification of the third form
illustrated in FIG. 7;
FIG. 11 is a fragmentary view illustrating a further modification of the
third form of the heat engine;
FIG. 12 is a perspective view showing an insert or core used in the engine
illustrated in FIG. 11;
FIG. 13 is a fragmentary view illustrating a still further modification of
the third form of the engine;
FIG. 14 is a fragmentary section showing a modification of a container and
a sealing piston used in the engine of FIG. 13;
FIG. 15 is a perspective view showing a modified example of the container
used in the engine of FIG. 13;
FIG. 16 is a view similar to FIG. 15 but showing another example of the
container;
FIG. 17 is a perspective view showing an example of a heat transfer
promoting member;
FIG. 18 is a view showing an example of coupling two heat engines in
tandem; and
FIG. 19 is a sectional view showing a coupling used in the example of FIG.
18.
DETAILED DESCRIPTION
As conducive to a full understanding of the principle of this invention,
some explanation of a thermal operating substance, which plays an
important role in the invention, will first be presented.
The thermal operating substance may be any non-compressible material whose
volume is changed according to temperature change; however, it is
preferable that it be a non-compressible material having a high
coefficient of cubic expansion. Such a material is a liquid or a solid.
The most suitable material is a synthetic resin such as polyethylene.
Paraffins are also suitable as the thermal operating substance. Mercury or
alcohols can also be employed. It should be noted that a mixture of any of
said material with other materials can also be used. With respect to the
coefficient of cubic expansion, the coefficient of volumetric change in
the vicinity of a transformation point is also considered. The volumetric
change of the thermal operating substance due to heating or cooling
thereof can be taken out with the aid of a material such as water or oil
whose volume cannot be easily changed.
Now, with respect to the aforementioned requirements (1) through (5), the
thermal operating substance will be considered in comparison with a gas.
The increase of the rotational speed results in an increase in the
displacement and a decrease in the time period of the displacement. Since
a gas is compressible, it is contracted when it imparts force to the load.
In addition, the gas used in a gas engine undergoes only an abrupt
expansion, or an explosion, for a short period in two strokes or four
strokes of each piston of the engine, and accordingly the gas engine is
provided with a flywheel or inertia wheel to utilize this explosion
uniformly over the period of the two or four strokes. In this connection,
the increase of the rotational speed has a significant meaning. The engine
is further provided with a speed change gear mechanism so as to maintain
the engine speed within a certain speed range.
On the other hand, being non-compressible, the liquid or solid can supply
force to the load throughout its entire process of volumetric change and
can impart a great force to the load even when the volumetric change
thereof is converted into a large amount of displacement. Accordingly, the
increase in the displacement and the decrease in the time period thereof
can be promoted by these two features, and a sufficient amount of work can
be obtained even with a small displacement and a long time period.
The increase in pressure of the fluid will give rise to the problem of
sealing the fluid. However, as the thermal operating substance and its
associated fluid medium are liquids or solids, they can be readily sealed,
and therefore a high pressure can be readily obtained.
Increasing the compression ratio may be disregarded in the case of a liquid
or solid, unlike the case of a gas, because liquids and solids are
non-compressible. Accordingly, the difficulties accompanying the provision
of a heat exchanger such as a reheater in a gas engine can be disregarded.
In addition, as the compression ratio can be disregarded, it is
unnecessary to provide an auxiliary power source for use during the
starting period of the engine.
The increase of the temperature of the high temperature side is one of the
fundamental conditions for increasing the thermal efficiency. Accordingly,
this should be taken into consideration in connection with the
aforementioned synthetic resin, materials of paraffin series or
substitutes thereof; that is, it is necessary to make a temperature region
where the volumetric change is a maximum, as high as possible. This
temperature region is often the softening point of a non-crystalline
material.
The thermal operating substance should have the following properties. It
should undergo a great volumetric change at high temperature (in this
case, the temperature in the operating range should be a middle
temperature between the temperature on the high temperature side and the
temperature on the low temperature side), and in addition it has a low
specific heat and a high heat conductivity.
With respect to the heat exchange, it is unnecessary to provide a heat
exchanger such as a reheater for the thermal operating substance; that is,
the high temperature side and the low temperature side can be maintained
at respective predetermined temperatures.
Referring now to FIG. 1 of the drawings, there is illustrated the operating
principle of the heat engine according to this invention. The heat engine
comprises essentially a thermal operating section T and a power output
section P. The thermal operating section T comprises an enclosure 10
containing therein thermal operating substance S, which is a
non-compressible material such as a liquid or a solid, as mentioned
hereinbefore, and may be polyethylene, for example. A piston 11 is
slidable in the direction of arrow X along the enclosure 10 and serves to
isolate or separate a high temperature zone H and a low temperature zone C
from each other. The power output section P comprises a cylinder 12 fixed
to the enclosure 10 and having an interior communicating with the interior
of the enclosure 10 and an output piston 13 slidable in the cylinder 12.
The high and low temperature zones H and C form the environment
surrounding the enclosure 10.
When the isolating piston 11 is moved downward, almost the entire enclosure
10 is brought into the high temperature zone H, and as a result the
thermal operating substance S is heated and expanded. As the internal
volume of the enclosure 10 is constant, a part, corresponding to the
increase in volume, of the substance S thus expanded is caused to move
into the cylinder 12, so that the piston 13 is pushed upward.
When the piston 11 is moved upward, almost the entire enclosure 10 is
brought into the low temperature zone C, as a result of which the thermal
operating substance S is cooled and contracted. Accordingly, the piston 13
loses the support by the upward pushing force, and is returned to its
initial position by gravity or by a restoring force afforded by restoring
means such as a spring (not shown). The piston 13 will be pushed upward
again by moving the isolating piston 11 downward.
FIG. 2 shows a first form of the heat engine according to this invention.
Again, the engine comprises a thermal operating section T and a power
output section P. The thermal operating section T includes a casing 15 in
the form of a cylinder in which an isolating piston 16 is slidable. The
piston 16 serves to divide the interior of the casing 15 into a high
temperature zone H and a low temperature zone C. The high temperature zone
H is filled with a hot fluid medium such as hot water or heated oil. The
hot medium is heated in and supplied from a heater 17 and supplied into
the high temperature zone H through an inlet 18, the hot medium being
discharged through an outlet 19 thereby to maintain a constant high
temperature in the high temperature zone. Likewise, a cool or cold fluid
medium such as water or oil at ambient temperature is introduced into the
low temperature zone C through an inlet 20 and discharged through an
outlet 21 thereby to maintain a constant low temperature in the zone C.
The casing 15 has therein a hollow header 23 fixedly secured to the top
wall of the casing. The header 23 supports a number of cylinder units 24
each of which comprises inner and outer cylinders 24a and 24b coaxially
and vertically disposed, as also shown in FIG. 3, so as to define an
annular space 24c therebetween. The cylinder units 24 are fixedly secured
at their upper parts to the header 23 with their annular spaces 24c
communicating with the interior of the header 23. The lower ends of the
annular spaces 24c are closed by plugs 25, so that the interiors of the
annular spaces 24c and the header 23 are in mutual communication. The
thermal operating substance S of the previously stated nature fills the
mutually communicating interiors of the header 23 and the annular spaces
24c. It will be noted that the header 23 and the cylinder units 24 form
the enclosure means for the thermal operating substance. The hollow
interiors of the inner cylinders 24a are in communication with the high
temperature zone H so that the hot fluid medium can enter them.
The piston 16 is generally in the form of a disc, as clearly illustrated in
FIG. 3, with a number of circular holes for sliding engagement with the
outer surfaces of the cylinder units 24 and with a number of cylindrical
sections 16a each forming a small piston which is slidable in the inner
cylinder 24a and disposed coaxially within the associated circular hole.
The small pistons 16a and the remaining part of the piston 16 have piston
rods 27 extending downward and fixed at their lower ends to a supporting
disc 28 which is in turn connected to a piston rod 29 of a piston 30
slidable in a hydraulic cylinder 31.
The power output section P comprises an output piston 32 slidable in a
cylinder 33 fixedly secured to the top wall of the casing 15. Connected
contiguously to and coaxially with the cylinder 33, there is provided a
hydraulic cylinder 34 in which a piston 35 is slidable. A piston rod 36
fixed coaxially to the output piston 32 extends upward slidably through
the hydraulic piston 35 and is slidably guided by a top wall 37 of the
hydraulic cylinder 34. The piston rod 36 has an enlarged abutting part 36a
in the form of a flange disposed above the piston 35. A shoulder 32a is
formed between the piston 32 and the rod 36.
The upper side of the piston 35 is communicatively connected to the lower
side of the aforementioned hydraulic piston 30 via a hydraulic conduit 40,
while the lower side of the piston 35 is communicatively connected to the
upper side of the hydraulic piston 30 via another hydraulic conduit 41. A
compression spring 43 is interposed between the wall 37 and the flange
36a.
The operation of the above described heat engine starts with the hydraulic
piston 30 and therefore the isolating piston 16 at their lowermost
positions. In this condition, the high temperature zone H prevails in the
casing 15, and the hot fluid medium is introduced into the high
temperature zone to heat the thermal operating substance S. Then, the
operating substance expands and the output piston 32 is forced to move
upward against the force of the spring 43.
When the output piston 32 has moved upward almost to its upper dead point,
the shoulder 32a thereof abuts against the lower surface of the hydraulic
piston 35 and causes the latter to move upward. As a result, the hydraulic
fluid on the upper side of the piston 35 is caused to flow through the
conduit 40 to the lower side of the hydraulic piston 30, so that the
piston 16 separating the high and low temperature zones H and C is moved
upward to expand the lower temperature zone C so that it prevails in the
interior of the casing, whereby the thermal operating substance S is
cooled and contracted. As a consequence, the output piston 32 is moved
downward by the force of the spring 43.
During the descending movement of the output piston 32, its abutting flange
36a abuts against the upper surface of the hydraulic piston 35 and causes
the same to move downward, so that the hydraulic fluid at the lower side
of the piston 35 is caused to flow toward the upper side of the hydraulic
piston 31, and the isolating piston 16 is therefore moved downward to
allow the high temperature zone H to expand so as to surround the cylinder
units 24. As a result, the thermal operating substance S is again
subjected to the high temperature fluid medium in the zone H and is
expanded to cause the output piston 32 to carry out its advancing stroke.
In the above described embodiment of the invention, the operating substance
S is enclosed in the enclosure means comprising the inner and outer
cylinders 24a and 24b, which cooperate to define the annular spaces 24c
therebetween. This arrangement is advantageous in that the operating
substance S in the annular spaces 24c is heated and cooled through both
the inner and outer cylinders. In order to promote the heat transfer
between the operating substance S and the high and low temperature fluid
medium in the high and low temperature zones, the inner and outer
cylinders 24a and 24b may be provided with a number of radially extending
fins 44 and 45 on the outer and inner surfaces thereof, respectively, as
illustrated in FIG. 4.
A modification of the embodiment of the invention shown in FIG. 2 is
illustrated in FIG. 5. In this modification, the expansion and contraction
of the thermal operating substances S is not transmitted to the output
piston 32 directly but transmitted through a pressure medium. More
specifically, a pressure medium chamber 50 is provided between the header
23 and the cylinder 33. The pressure medium chamber 50 contains a pressure
medium 51 such as water or oil. A diaphragm 52 is provided so that the
pressure medium 51 is not mixed with the thermal operating substance S. It
will be noted that in this modified form the output of the engine can be
taken out in any desired direction by the provision of the pressure medium
chamber.
In this modified form, as the thermal operating substances S is expanded,
the diaphragm 52 is moved upward by the same amount as the amount of
expansion. As a result, the medium 15 pushes the piston 32 upward. In this
connection, it is preferable from the point of view of thermal efficiency
that the heat of the thermal operating substance S be blocked by the
diaphragm 52 so as not to be transferred to the medium 51. When the
thermal operating substance is contracted, the pressure of the medium 51
is reduced with the return of the diaphragm 52, and the output piston 32
also returns to its initial position.
A second form of the heat engine according to the invention is shown in
FIG. 6, in which the pressure medium can be moved so that the thermal
operating substance reciprocates between the high temperature zone and the
low temperature zone.
The heat engine comprises a cylindrical housing 60 having fins 60a
therearound for promoting heat transfer to and from the cylindrical
housing 60. The housing 60 has a cylindrical inner wall 61, and a
plurality of vertically extending cylindrical hollow spaces 62 are formed
between the inner and outer walls of the housing. Within each of the
spaces 62, there are provided upper and lower sealing pistons 64 and 65
which are slidable relative to the space 62. The thermal operating
substance S fills the space between the upper and lower sealing pistons 64
and 65, whereby they are maintained spaced apart vertically from each
other.
The housing 60 is divided into upper and lower sections with a
heat-insulating material 69 interposed therebetween to prevent heat
transfer.
An upper header 67 is fixedly secured to the top of the housing 60 in a
manner such that the interior of the header and the spaces 62 in the
housing 60 communicate with each other. Similarly, a lower header 68 is
fixedly secured to the bottom of the housing 60 in a manner such that the
interior of the header and the spaces 12 in the housing are in mutual
communication.
A control cylinder 70 has a control piston 71 slidable therein, and the
cylinder spaces above and below the piston 71 are connected to the upper
and lower headers 67 and 68 via conduits 72 and 73, respectively. The same
hydraulic fluid mediums fill the headers, control cylinder and conduits.
Each of these mediums functions as a pressure medium for transmitting
force due to pressure increase caused by the expansion of the thermal
operating substance S to the output piston 32.
The output piston 32 is slidably supported in output cylinder 33 fixedly
supported on the upper header 67, which output cylinder 33 is connected to
hydraulic cylinder 34 slidably receiving therein piston 35, through which
piston rod 36 forming an integral continuation of the output piston 32
passes slidably. The piston rod 36 has an abutting flange 36a as well as
another abutting flange 32b at the upper and lower side of the hydraulic
piston 35, respectively. Compression spring 43 is interposed between top
wall 37 of the cylinder 34 and the flange 36a. A hydraulic cylinder 31A,
identical in function with the hydraulic cylinder 31 shown in FIG. 2,
receives slidably therein a piston 30A which is coupled to the
aforementioned piston 71 through a piston rod 29A. The chambers of the
cylinder 31A above and below the piston 30A are in communication with the
chambers of the cylinder 34 above and below the piston 35 via conduits 40
and 41, respectively.
The atmosphere surrounding the upper section of the housing 60 constitutes
the high temperature zone H, while the atmosphere surrounding the lower
section of the housing 60 constitutes the low temperature zone C. In order
to form the high temperature zone H, the outer wall of the upper section
of the housing 60 is directly heated by flames of combustor nozzles or
burners 80 or may be subjected to a combustion gas of high temperature.
Alternatively, only the upper section of the housing 16 may be encased by
a casing such as the casing 15 shown in FIG. 2, and a high temperature
fluid such as heated oil may be supplied into the casing to heat the
housing upper section. In contrast, the lower section of the housing 60
may be left as it is or may be cooled by water flowing therearound. In the
former case, the surrounding air forms the low temperature zone C and in
the latter case, the water constitues the same.
In the above stated embodiment of the invention, the spaces 62 and the
sealing pistons 64 and 65 are of circular cross section, but the spaces 62
may be replaced by a single annular space and annular sealing pistons may
be slidably fitted in the annular space.
In the condition shown in the figure, the output piston 32 has just
finished its advancing or upward stroke, and the thermal operating
substance S has just moved to its lowermost position. Since the substance
S is now being cooled by the low temperature zone C, it contracts and the
pressure of the fluid within the header 67 is decreased whereby the output
piston 32 is allowed to descend by the force of the spring 43. When the
output piston 32 has moved downward almost to its lowermost position, its
abutting flanges 36a abuts on the upper surface of the hydraulic piston 35
and causes the piston 35 to shift downward. As a result, the hydraulic
piston 30A is moved downward to cause the control piston 71 to shift
downward.
Then, the fluid medium in the lower chamber of the cylinder 70 is moved via
the conduit 73 toward the interior of the lower header 68, while the fluid
medium in the upper header 67 is moved via the conduit 72 toward the upper
chamber of the cylinder 70. As a result, the upper and lower sealing
pistons 64 and 65 as well as the thermal operating substance S are shifted
upward in the annular space 62 to the region surrounded by the high
temperature zone H, whereby the operating substance S is heated and
expanded to increase the pressure of the fluid mediums in the upper and
lower headers 67 and 68. This increase of the fluid medium pressure causes
the output piston 32 to move upward.
It will be understood that the increased pressures of the fluid mediums
above and below the piston 71 are of the same value and are in
equilibrium. However, in the process of expansion of the operating
substance S, the fluid medium in the upper header 67 is allowed to escape
into the output cylinder 33 while forcing the output piston 32 upward,
whereas the fluid medium in the lower header 68 has no space to escape
into, so that, actually, the operating substance S is further shifted
upward by some small distance or the piston 71 is slightly moved back
upward. Therefore, the amount of shift of the piston 71 at the beginning
should be determined in consideration of the above fact.
The distance between the upper and lower sealing pistons 64 and 65 is
preferably such that when one of them is in the region of one temperature
zone the other sealing piston is in the region of the other temperature
zone.
When the output piston 32 is forced upward and has almost reached to the
upper dead point, the abutting flange 32b of the piston 32 abuts against
and lifts the hydraulic piston 35, so that the hydraulic fluid above the
piston 35 flows into the lower chamber of the cylinder 31A to shift the
piston 30A, which is in the lowered position, upward. As a result, the
piston rod 29A causes the control piston 71 to move upward to its original
position, whereby the thermal operating substance S is shifted downward
back to the position shown in the figure. Accordingly, the operating
substance S is now subjected to influence of the low temperature zone C
and is cooled and contracted to allow the output piston 32 to return to
its original position by the returning force of the spring 43.
During the descending movement of the output piston 32, the abutting flange
36a abuts against the upper surface of the piston 35 and causes the same
to move downward as was already described hereinbefore. Consequently, the
operating substance S is again shifted upward to undergo the heating by
the high temperature zone H and the advancing stroke of the output piston
32 is carried out. It will be understood that the above stated operation
is carried out repetitively.
It is desirable that the sealing piston 64 have at least one adjusting plug
75 for enabling the venting of air in the space between the upper and
lower sealing pistons 64 and 65 as well as for enabling the adjustment of
the amount of the thermal operating substance S to be charged.
FIGS. 7 and 8 show a third form of the heat engine according to this
invention. This form is considered to be the most practical form.
This form of the heat engine also has a cylindrical housing 90 made up of
four housing sections 90a, 90b, 90c and 90d. The uppermost first section
90a is in the shape of a cap, while the second and third sections 90b and
90c have the same cross-sectional shape and are formed with annularly
arranged peripheral cylindrical holes 91 and a central cylindrical hole 92
as clearly shown in FIG. 8. The first section 90a and the second section
90b are bolted together with a heat insulating material 93 interposed
therebetween. The second and third sections 90b and 90c are also bolted
together. However, in this case, a relatively thick regenerative heat
exchanger 94 is interposed therebetween. The third and fourth sections 90c
and 90d are also bolted together with a heat insulating material 95
interposed therebetween.
Similarly as in the engine shown in FIG. 6, the second housing section 90b
is surrounded by the high temperature zone H, and the third housing
section 90c is surrounded by the low temperature zone C. These high and
low temperature zones can be provided in the same way as described in
connection with the engine shown in FIG. 6. The fourth or bottom housing
section 90d has a recessed space 97 through which the peripheral
cylindrical holes 91 and the central cylindrical hole 92 are in mutual
communication.
As in the second embodiment of the invention, each of the peripheral holes
91 slidably receives therein upper and lower sealing pistons 98 and 99
together with the thermal operating substance S charged therebetween.
Again, each upper sealing piston 98 may be provided with an adjusting plug
100.
In the interior space within the first housing section 90a, there is
provided a control cylinder 101 fixed to the upper surface of the second
housing section 90b, and a control piston 102 is slidably disposed in the
cylinder 101. The piston 102 has a vertical hole 103 through which a rod
104 with an abutting flange 104a extends loosely. The flange 104a is
applied with a packing 104b for sealing engagement with the lower surface
of the piston 102. The rod 104 is rigidly connected to an output piston 32
of larger diameter so that an abutting shoulder 32b is formed. The output
piston 32 is slidable in an output cylinder 33 fixedly secured to the top
of the first housing section 90a, and extends upward to terminate in the
uppermost portion 32c, which is slidably passed through a bush 105 secured
in a supporting frame 106, which is in turn fixedly supported on the first
housing section 90a. The output piston 32 has a spring mounting flange 107
on its portion extending upward, and a compression coil spring 109 is
interposed between the flange 107 and the frame 106 to urge the output
piston 32 downward.
Into the interior of the housing 90 is charged a hydraulic fluid medium,
such as oil, which serves as a pressure medium. In FIG. 7, the interior
space of the first housing section 90a and the recessed space 97 of the
fourth housing section 90d are shown as being connected to conduits 110
and 111, respectively. However, in this form now being described, these
conduits should be disregarded for purpose of clarity.
In the state of the heat engine shown in FIG. 7, the masses of the thermal
operating substance S together with the upper and lower sealing pistons 98
and 99 have just moved upward in the region of the high temperature zone H
and are being heated by the zone. As a consequence, the masses of the
operating substance S expand so that the pressure of the fluid medium in
the housing 90 is increased, whereby the output piston 32 is pushed upward
against the force of the spring 109 because the interior space of the
housing 90 is completely closed.
When the output piston 32 has almost reached its upper dead point, the
abutting flange 104a of the rod 104 abuts against the lower surface of the
piston 102 to cause the latter to move upward relative to the cylinder
101, and, as a result, the pressure medium above the piston 102 causes the
masses of the thermal operating substance S together with the sealing
pistons 98 and 99 to descend in the holes 91 into the region of the low
temperature zone C. Consequently, the masses of the operating substance S
are cooled and contracted and the output piston 32 is moved downward, by
the force of the spring 109, back to the original position. Near the end
of this downward movement, the shoulder 32b abuts against the upper
surface of the piston 102 to cause the piston to shift downward, whereby
the masses of the thermal operating substance S as well as the upper and
lower sealing pistons 98 and 99 are shifted upward in the holes 91 to the
positions shown in FIG. 7, and the expansion of the masses of the
operating substance S is carried out again to urge the output piston 32
upward in its advancing stroke.
In order to adjust the position of the center of the strokes of the output
piston 32, an adjusting plug 113 may be screwed in the wall of the
housing. The plug 113 serves to control the quantity and pressure of the
pressure medium. If desired, the plug 113 may be connected to a load
variation detector (not shown) or to a maximum and minimum stroke detector
(also not shown) to enable the control of the position of the center of
the strokes. A removable screw 114 in the adjusting plug 113 is for
venting air which may be remaining in the housing.
The regenerative heat exchanger 94 is provided for heat economy. When the
operating substance S is in the position shown in FIG. 7, it is heated by
the high temperature zone H and retains the heat therein. As the substance
S is then shifted downward toward the region of the low temperature zone
C, it gives off heat to the heat exchanger 94. When the substance S is
again shifted to the high temperature zone H, it receives and absorbs the
heat which has been accumulated in the heat exchanger.
As indicated by chain lines in FIG. 7, an identical engine may be installed
in parallel relation to the above stated engine with some operational
phase difference, for example 180.degree., therebetween. In this case, the
aforementioned conduits 110 and 111 may be provided to connect the
interior spaces of the first housing sections 90a of the two engines to
each other and to connect the recessed spaces 97 of the two engines to
each other, for pressure equilibrium between the two engines.
FIG. 9 shows how a rotary motion can be derived from the reciprocating
motion of the output shafts 32 of the two engines E1 and E2 installed in
parallel relationship. The two output shafts 32 are respectively coupled
to two crank mechanisms 120 of known type which transform the
reciprocating motion into rotation of a rotary shaft 121. This shaft 121
has a gear 121a fixed thereto, which is in mesh with a gear 122a of an
output rotary shaft 122.
It will be seen from FIG. 9, that there is a difference in operational
phase angle between the two engines E1 and E2. When the two engines are
combined in this manner, the restoring springs 43 and 109 shown in FIGS.
2, 6 and 7 can be dispensed with because the force to return the output
shaft 32 to its lower or inner dead point can be obtained from the
advancing stroke of the other engine. It will be understood that more than
two engines could be combined in the same manner.
In FIG. 10, there is shown a modification of the engine illustrated in FIG.
7. In this modification, the output piston 32 is connected to an
engagement flange 123 integrally formed with the control piston 102
through a spring 124, and the rod 104 (FIG. 7) is dispensed with. This
spring 124 is anchored at its upper and lower ends to the output piston 32
and the engagement flange 123 and operates both in tension and
compression. On the upward extension of the output shaft 32 there is
formed a cam 126, while cam followers 127 and 127A are provided at
positions at which the cam 126 will arrive when the output shaft 32 has
moved to its upper and low dead points, respectively. The cam followers
127 and 127A are coupled to pistons 128 and 128A slidably disposed in
cylinders 129 and 129A, respectively.
Arresting members 130 and 130A are provided in the control cylinder 101 to
engage the upper and lower surfaces of the flange 123 so as to prevent
upward and downward movements of the control piston 102, respectively. The
arresting members 130 and 130A are fixedly mounted on the free ends of
sliding bars 131 and 131A passing through the housing 90 to the outside
and rigidly coupled to pistons 132 and 132A slidably disposed in cylinders
133 and 133A, respectively. The pistons 132 and 132A are constantly urged
toward the housing by compression springs 134 and 134A in the cylinders
133 and 133A. Hydraulic fluid lines 135 and 136, and 135A and 136A connect
the cylinders 129 and 133, and 129A and 133A, as shown.
When the operating substance S is in the upper position shown in FIG. 7 and
is heated and expanded, the output piston 32 are forced upward. However,
since the arresting member 130 prevents the flange 123 and hence the
control piston 102 from moving upward, only the output shaft 32 is allowed
to move upward, the spring | | |
