[0001] The present invention relates to a machine for the transformation of thermal energy
into mechanical work or electrical energy through the evolution of a working fluid.
[0002] The high cost of fossil fuels and their limited availability has led to the production
of machines capable of producing mechanical work and/or electrical energy from recovered
heat or low temperature heat, but also heat produced by solar energy or other alternative
energy sources. However, large scale use of these machines is restricted due to their
dimensions and costs, which are often such that they limit the applications thereof.
[0003] US 2006/0053793 A1 relates to a heat regenerative engine that uses water as working fluid and as lubricant.
This engine comprises, although enclosed in a single container, various subgroups
of members separated from one another, each adapted to carry out a specific step of
the thermodynamic cycle that uses heat to produce mechanical work. Therefore, the
size and the production costs of this engine are quite substantial in relation to
the supplied power.
[0004] In the state of the art indicated above, the problem of providing a compact machine
with very limited costs for the transformation of thermal energy into mechanical work
or electrical energy that is versatile as regards the source of thermal energy used,
i.e. is able to use, besides heat produced by combustion, also recovery heat or low
temperature heat or heat produced through solar energy or other alternative energy
sources to fossil fuels, remains unresolved or resolved in an unsatisfactory manner.
[0005] Therefore, it would be desirable to provide a machine for the transformation of thermal
energy into mechanical work or electrical energy adapted to use any form of heat source,
whether of solar origin, produced by combustion or obtained as waste heat from processes
of any kind, which is relatively small in size and compact in shape, and which is
also suitable to be used for distributed energy generation.
[0006] Therefore, an aspect of the invention regards a machine for the transformation of
thermal energy into mechanical work or electrical energy characterized by comprising:
- i) a first and a second cylindrical block, coaxial and side by side, separated by
a cylindrical partition of insulating material, said cylindrical blocks and said insulating
partition being provided with axial cavities housing a rotary member provided with
a first and a second cam, each placed in correspondence of each of said cylindrical
blocks;
- ii) a series of cylindrical working chambers in each of said cylinder blocks, each
of said working chambers being open at the bottom towards said axial cavities of said
cylindrical blocks and being provided with a single-acting piston provided with a
contrast spring and acting on an idle roller in contact with said cams of said rotary
member, thereby defining a first series of working chambers in said first cylindrical
block , a second series of working chambers in said second cylindrical block, a first
series of pistons acting on a corresponding first series of rollers in contact with
said first cam, and a second series of pistons acting on a corresponding second series
of rollers in contact with said second cam;
- iii) a plurality of communication channels between said first and second series of
working chambers, each of said channels putting in communication a chamber of said
first cylindrical block with a corresponding chamber of said second cylindrical block
through said insulating partition, each of said chambers being also provided with
communication channels with an external reservoir for a fluid working in said chambers,
and a plurality of distribution valves of said fluid between said communication channels
and said working chambers;
- iv) said first cylindrical block being operatively exposed to a heat source adapted
to heat said working fluid in said first working chambers, while said second cylindrical
block is thermally isolated from said heat source and suitably cooled by a suitable
heat dissipation system to a lower temperature, so that in said first and second working
chambers said working fluid carries out thermodynamic cycles according to the laws
of motion defined by the profile of said cams, said profiles of the two cams being
defined, so as to produce, in said working chambers, following the movement of the
related working cylinders and of the presence of said communication channels between
the various cylinders, volume variations that determine the following thermodynamic
transformations of the working fluid according to a cycle comprising the following
steps:
- a. a rapid compression, approximately adiabatic, in the lower temperature cylinder;
- b. a transfer to the higher temperature cylinder and an approximately isothermal expansion;
- c. a second expansion step, approximately adiabatic;
- d. a transfer to the cold cylinder with consequent cooling and return to step a.,
conventionally assumed at the start of the cycle.
[0007] In the implementation of the invention described the difference in temperature between
said cylinder blocks at higher temperature and at lower temperature is such that the
thermodynamic equilibrium of the cycle described is positive, i.e. the torques transmitted
during the expansion steps of said working fluid to said cams and, from these, to
said movement (rotary) members, are higher than those transmitted in the opposite
direction during the compression steps;
[0008] According to a preferred characteristic of the invention, said cylindrical working
chambers are oriented radially in each of said cylindrical blocks according to longitudinal
axes incident on the longitudinal axis of said rotary member.
[0009] Another aspect of the invention regards the machine as defined above in the embodiment
dedicated to the transformation of mechanical energy associated with said rotary shaft
into electrical energy by providing a plurality of permanent magnets coupled to said
rotary member in a radially distal location thereto, and a stator housed in the axial
cavity of said cylindrical blocks between said permanent magnets and said rotary shaft,
said stator being provided with electrical windings on which there are induced electromotive
forces that support the production of electrical current exploitable directly or indirectly
by electric utilities external to the machine.
[0010] Therefore, the machine according to the present invention allows the transformation
of thermal energy deriving from any heat source into mechanical work and optionally,
due to the arrangement of the aforementioned members of which it is composed, its
transformation into electrical energy.
[0011] In a single very compact mechanical assembly, the machine performs thermodynamic
cycles for the transformation of heat into work in a single mechanical assembly, contrary
to what is known in the state of the art, in which the cycle consisting of compression,
heating, expansion and cooling is performed in different components of a complex system,
therefore with greater costs, size and weight.
[0012] As stated, this assembly can also comprise the electromechanical elements for direct
transformation of the mechanical work produced into electrical energy, also in this
case avoiding complex motion transfer systems and, ultimately, obtaining a device
that is more efficient, of smaller size, lighter in weight and less expensive than
those available in the state of the art.
[0013] The machine according to the present invention is applicable in any process for which
it is useful to obtain energy in mechanical or electrical form from a heat source,
in particular, due to the characteristics that will be illustrated in more detail
hereinafter in the description, is suitable to exploit limited temperature gradients
with acceptable thermodynamic outputs offering a useful tool for better exploitation
of all energy sources, whether from fuel, from solar radiation of from recovery of
heat dispersed by industrial processes. It is also suitable for small-scale use so
as to allow a production of energy distributed in the territory.
[0014] The machine substantially comprises two cylindrical blocks kept at different temperatures,
in which a working fluid, or evolving fluid, that evolves following the motion of
a plurality of pairs of pistons that act on two cams, one for each cylindrical block,
is input into variable volume working chambers. The chambers are arranged in the two
cylindrical blocks and in communication with each other according to suitable connections.
The profile of the cams is produced so that the motion of the pistons generates variations
of volume of the working chambers so as to carry out a predetermined thermodynamic
cycle described in detail hereinafter in the description.
[0015] The work generated on the active surface of the pistons is then transferred to the
cams and from these to a rotary member connected thereto and utilized mechanically,
i.e., utilized to generate a rotary magnetic field that in turn generates an electromotive
force in suitable stator windings.
[0016] In an embodiment dedicated to the production of electrical energy, the machine also
comprises the electromechanical elements for direct transformation of the mechanical
work produced into electrical energy, also in this case avoiding complex motion transfer
systems and, ultimately, obtaining a product that is more efficient, of smaller size,
lighter in weight and less expensive than those available in the state of the art.
[0017] Another aspect of the invention regards the use of the machine defined above to perform
thermodynamic cycles of compression, heating, expansion and cooling of a working fluid,
in which the thermal exchanges are carried out in the condition of variation of the
state of aggregation of said fluid from liquid to vapor and vice versa.
[0018] Moreover, according to the conditions of application, the profile of the cams can
be defined, without compromising the operation of the device described, so that the
fluid performs a complete thermodynamic cycle several times during one revolution,
in this way the rotation speed of the motion transfer members can be adapted to different
operating needs, as the rotation speed is approximately inversely proportional to
the number of cycles carried out during a rotation.
[0019] Some preferred embodiments of the machine according to the present invention will
now be described with reference to the accompanying drawings, provided by way of non
limiting example, wherein:
- Figs. 1 and 2 are partially sectional schematic perspective views of a first embodiment
of the machine according to the invention;
- Fig. 3 is an enlarged sectional schematic view of a detail of Fig. 1;
- Figs. 4A and 4B are two sectional schematic views according to a transverse plane
of the machine of Fig. 1;
- Fig. 5 is an enlarged sectional schematic view of a detail of Fig. 4;
- Fig. 6 is an enlarged sectional schematic view of a detail of the machine according
to the invention;
- Figs 7,7A and 8,8A are sectional views of details relating to the distribution valves
of the machine according to the invention;
- Fig. 9 is a partially sectional perspective view of a second embodiment of the machine
according to the invention;
- Fig. 10 is a schematic sectional view according to a transverse plane of the machine
of Fig. 9;
- Fig. 11 is an enlarged sectional schematic view of a detail of Fig. 10;
- Fig. 12 is an exploded view of the machine according to the invention;
- Fig. 13 indicates the lift profiles of the cams of the machine according to the present
invention;
- Fig. 14 represents a phase diagram of the cams of Fig. 13;
- Fig. 15 represents a phase diagram of the cold side of the machine according to the
present invention;
- Fig. 16 represents a phase diagram of the hot side of the machine according to the
present invention;
- Fig. 17A illustrates a longitudinal section in the direction of the rotation axis
of the shaft of a second embodiment of the machine according to the invention;
- Fig. 17B illustrates a cross section perpendicular to the rotation shaft of the machine
of Fig. 17A.
[0020] With reference to Figs. 1-3, the machine comprises a first cylindrical block 20 and
a second cylindrical block 22, arranged coaxially and side by side along an axis X-X,
but separated by a cylindrical partition of heat insulating material 21. The two cylindrical
blocks 20, 22 and the insulating partition interposed between them are fixed to one
another by means of tie rods, only schematically indicated.
[0021] The machine is operatively arranged so that the first cylindrical block 20 is exposed
to a heat source capable of increasing the temperature of a working fluid in this
block, as will be illustrated hereinafter in the description, while the second cylindrical
block 22 is at a lower temperature, so that the working fluid can perform a thermodynamic
cycle with production of work. The lower temperature condition of the cylindrical
block 22 is acquired both due to the presence of the insulating partition 21 and due
to the optional presence of a cooling system acting thereon. In the present description
the first cylindrical block 20 is also defined "hot block" while the cylindrical block
22 is also defined "cold block".
[0022] In order to reach significant thermodynamic outputs, it is important for the thermal
insulation to be very efficient. A particularly advantageous material as thermal insulation
for producing the partition 21 is a solid foam known with the name "Aerogel".
[0023] Both the cylindrical blocks 20, 22 and the insulating partition 21 are provided with
corresponding axial cavities according to the axis X-X, housing a rotary member comprising
a rotary shaft 24 mounted on bearings 26, as is known in the art (Fig. 3). The bearings
26 are part of a fixed support 28
[0024] A first cam 30 and a second cam 32, which in the embodiment illustrated in the figures
are made entirely in once piece, are fixed to the rotary shaft 24. Therefore, the
cams 30, 32 rotate integrally with the shaft 24. The cam 30 is placed in correspondence
of the cylindrical block 20 and the cam 32 is placed in correspondence of the cylindrical
block 22. The cams 30, 32 are staggered with respect to each other, as shown in Fig.
1.
[0025] Lubrication of the parts in reciprocal motion is obtained with a lubricating additive
in the evolving fluid as in the case of some two-stroke engines, for example used
for motorcycles. The state of the art provides numerous possibilities of choice of
these lubricants as a function of the nature of the evolving fluid and of the cycle
temperatures, and, in some cases, if these are very high and this is justified by
the increase in available power, the device illustrated could be provided with auxiliary
lubrication systems as known in the state of the art; the additional cost of this
choice would in this case be justified by the greater thermodynamic output and consequently
by an increase in available power.
[0026] With reference also to Figs. 4A, 4B and 5, it can be noted that Fig. 4A and 4B are
cross sections of a cylindrical block 20 or 22, which are identical, so that Fig.
4A is designated as a cross section of the cylindrical block 20. Fig. 5 is an enlarged
view of a detail of Fig. 4a. The term cross section is meant as a section according
to a plane orthogonal to the axis X-X passing through the centerline of the cylindrical
block 20 and coincident with the longitudinal axis of the rotary member 24.
[0027] Figs. 4A, 4B and 5 show that the cylindrical block 20 is provided with a series of
cylindrical working chambers 34 oriented radially. The longitudinal axes Y-Y of the
chambers 34 are all incident on the axis X-X of the rotary member 24 and are perpendicular
to this axis X-X.
[0028] Corresponding cylindrical working chambers 34' are produced in the cold cylindrical
block 22 (Figs. 1-3) so that each cylindrical working chamber 34 of the first cylindrical
block 20 is side by side with a corresponding cylindrical working chamber 34' of the
second cylindrical block 22. In the present description the working chambers 34, 34'
are at times referred to as "corresponding" or "side by side" or "adjacent", these
terms meaning that the two chambers 34, 34' are placed substantially at the same radial
distance from the axis X-X, but with the interposition of the insulating partition
21 between the two blocks 20, 22.
[0029] In the following description the components of the second cylindrical block 22 are
indicated using the same numbers used to indicate the components of the cylindrical
block 20, with the addition of an inverted comma <'> . Unless otherwise indicated,
the description of the members and of the components of the second cylindrical block
22 is the same as that of the first cylindrical block 20 and is therefore described
together with that of the first cylindrical block 20, with the addition of an inverted
comma <'>.
[0030] Each working chamber 34, 34' is open at the bottom towards the axial cavity of the
cylindrical block and mounted slidably therein is a single-acting piston 36, 36',
the rod 37, 37' of which extends into an upper cylindrical portion 35, 35' of the
chamber 34, 34'. This cylindrical portion 35, 35' is of smaller diameter with respect
to the diameter of the chamber 34, 34', so as to correspond substantially to the diameter
of the rod, 37, 37', with suitable clearance to allow the stroke of the rod and to
form the sliding guide thereof. Housed at the top of the upper cylindrical portion
35, 35' is a coil spring 38, 38' that opposes the piston stroke. In a preferred embodiment
the ratio between the surfaces of the walls of the chambers 34, 34' and the volume
of these chambers is very high, the diameter of the chambers 34 and 34' having an
aspect ratio with respect to the piston stroke so that during the heating and cooling steps the
volume contained in the chambers is small with respect to their surface. In this way,
due to their nature proportional to the surface through which they take place, the
thermal exchanges are large with respect to the mass contained in the volume, so that
the temperature of the fluid very rapidly approaches the temperature of the walls,
meaning that this takes place in an interval of time during which the rotation angle
of the cam varies by an extent that is less than the duration of each step. Fixed
to the lower end of each piston 36, 36' is a roller 40, 40', in contact with the cams
30, 32, respectively. Each roller 40, 40' is mounted idle on a pin 42, 42' whose longitudinal
axis is parallel to the axis X-X of the rotary shaft 24. The pin 42, 42' is fixed
to the piston through a fork 44, 44', as shown in Fig. 3. The spring 38, 38' maintains
the roller 40, 40' pressed constantly against the cam 30, 32, respectively.
[0031] With reference to Fig. 6, which is a cross sectional view of the cylindrical chambers
34, 34', in the cylindrical blocks 20, 22 and through the insulating partition 21
there is produced a communication channel 46 between each working chamber 34 of the
first cylindrical block 20 and the corresponding adjacent working chamber 34' of the
second cylindrical block 22. This channel 46 is preferably arranged according to a
tangent common to the working chambers 34, 34', as indicated in Fig.6, so as to generate
a rotary flow field that promotes thermal exchange with the walls.
[0032] Each working chamber 34, 34' is also in communication with an external reservoir,
destined to contain a fluid, through a central channel 48, 48' that extends axially
in each piston 36, 36' and along the related rod 37, 37', and through a pair of channels
49, 49'. These channels 48, 48', 49, 49' are controlled by distribution valves that
regulate their opening and closing as a function of the pressure conditions that occur
in the working chambers 34, 34' and in the fluid reservoir. With reference to Fig.
11, these valves consist of a filling valve 45 and a maximum pressure valve 90.
[0033] According to a preferred embodiment, these distribution valves 45 and 90 are produced
in the body of the piston 36, 36', as shown in Figs. 7, 7A and 8, 8A.
[0034] In this embodiment the channels 49, 49' are produced in the piston 36, 36' starting
from the surface thereof facing the chamber 34, 34' and leading into the axial channel
47, 47'. Therefore, they place the central channel 48, 48' in communication with the
working chamber 34, 34'. Considering by way of example the chamber 34, as shown in
Fig. 7, the channels 49 put the chamber 34 in communication with the central channel
48, which is in turn connected to an external reservoir, not illustrated, as indicated
by the arrow B in Figs. 7 and 8. As is shown in Fig. 5, a bored through connector
50 for mounting a duct that leads to the reservoir is fixed to the upper end of the
central channel 48, 48'.
[0035] The filling valve 45 is preferably installed in the first series of pistons 36 belonging
to the first working chambers 34 in the hot block, while the control valve 90 of the
maximum working pressure is preferably installed in the second series of pistons 36'
belonging to the second working chambers 34' in the cold block.
[0036] As will be better explained hereinafter, the filling valves 45 are preferably located
in the hot block so that the fluid introduced into the chambers 34 is already hot
and increases the total enthalpy in the working fluid, while the maximum pressure
valves are preferably arranged in the cold block, to reduce the enthalpy released
by the fluid of the chambers 34' towards the reservoir. The configuration in which
the position of the valves is inverted, as illustrated in the accompanying figures,
is not detrimental to the operation of the machine according to the present invention.
[0037] The filling valve 45 is represented in Figs. 7, 7A. It is installed in the piston
36, inside a channel 47 that forms a first portion of the lower extension of the axial
channel 48, with respect to which the lower extension 47 has a larger diameter so
as to define an abutment seat 51 for the upper portion 57 of a moving element 50 housed
slidably in the channel 47. A further lower extension 470 of the channel 47, of larger
diameter with respect thereto, houses the widest portion of the moving element 50
with radial clearance. The filling valve also comprises a spring 52 housed inside
a spacer 55 between the base of the moving element 50 and a lower closing cap 54.
The moving element 50 is formed with a lower portion 56 and an upper portion 57, and
is provided with an axial through hole 58. The lower portion 56 has a smaller diameter
to that of the channel 470, thereby defining a gap for passage of the fluid.
[0038] With reference to Figs. 7, 7A, the filling valve is consequently in communication
with the working chamber 34 through the two channels 49 and with the reservoir through
the channel 48. When the pressure that the fluid present in the working chamber 34
exerts on the moving element 50 is greater than the resultant force of the load of
the spring 52 and of the force exerted by the pressure of the reservoir, the moving
element 50 is thrust towards the spacer 55 and its lower portion 56 abuts against
it, thereby closing passage of the fluid towards the reservoir through the opening
existing between the spacer 55 and the lower portion 56 of the moving element 50.
In the opposite case, for example during the first operating steps, when the increase
of the volume of the working chambers 34 causes a reduction of the pressure therein,
the moving element 50 is moved away from the spacer 55 allowing passage of fluid from
the reservoir to the chamber 34 through the clearance between the moving element 50
and the channel 47, in particular between the lower portion 56 of the moving element
50 and the lower extension 470 of the channel 47.
[0039] The maximum pressure valve 90 is represented in Figs. 8, 8A. It is installed in the
piston 36', inside a channel 47' that forms the lower extension of the axial channel
48', with respect to which the lower extension 47' has a larger diameter so as to
define an abutment seat 51' for a moving element 50' housed slidably in the channel
47'. The moving element 50' is formed with a lower portion 56' and an axial through
hole 58'. The filling valve further comprises a spring 52' housed between the base
of the moving element 50' and a closing cap 54'.
[0040] The maximum pressure valve is also in communication with the working chamber 34'
through the two channels 49', which are closed when the spring 52' thrusts the moving
element 50' against the sealing seat 51', thus preventing passage of the fluid (Fig.
8). Instead, when the force exerted by the pressure in the chamber 34' overcomes the
force of the spring 52', the moving element is displaced from the sealing seat and
allows the outflow of fluid towards the communication channel 48' with the reservoir,
as indicated by the arrow B.
[0041] The pressure of the fluid in the reservoir must be more or less the same as the minimum
pressure provided in the cycle at the end of the expansion step or during cooling
Operation of the machine according to the invention with reference to the embodiment
described above is illustrated below.
[0042] As already stated, the two cylindrical blocks 20, 22 are maintained at different
temperatures. The cylindrical block 20 is the hot block, and is therefore maintained
at a higher temperature than the block 22, which is the cold block.
[0043] The hot block 20 is maintained at high temperature by any heat source. For example,
the incident thermal power is considered to be represented by a radiant power such
as concentrated solar power, represented by the arrows A of the Figs. 1, 2 and 3.
The cold block 22 is instead cooled by a flow of air generated by a fan 60 aligned
with the rotary shaft 24 (Figs. 1, 2 and 3). With reference to Fig. 3, the fan 60
produces a flow of cold air that strikes the cold block 22 according to the arrow
C, in a cooling chamber defined between the block 22 and a wall 62 of the outer casing
of the machine.
[0044] In other embodiments, cooling can be obtained through the passage of another cooling
fluid or by a thermal exchange through natural convection in air. In any case the
hot block 20 receives heat from an external source, is isolated from the cold block
22 through the insulating partition 21, and the cold block 22 is subjected to the
cooling action of a suitable heat dissipation system.
[0045] There is introduced into the cylindrical working chambers 34 of the hot block 20
and into those 34' of the cold block 22, a working fluid that evolves therein and
carries out a thermodynamic transformation. The volume of the working chambers 34,
34' is varied by the pistons 36, 36', whose stroke is defined by the cams 30, 32 that
rotate with the rotary shaft 24 about the axis X-X, and by the springs 38, 38' that
ensure following of the profile of the cam. With each chamber 34 of the hot block
20 there corresponds at least a chamber 34' of the cold block 22 to which it is connected
through the channel 46 through which the working fluid flows (Fig. 6). The stroke
of the pistons 36 obliges the fluid to pass between the hot chambers 34, from which
it receives heat, and the cold chambers 34', to which it transfers heat, according
to the arrow D of Fig. 6. Moreover, the motion of the pair of pistons 36, 36' causes
the volume of the working fluid to vary so that the thermodynamic cycle that the fluid
performs generates, based on classic thermodynamic theory, mechanical work that is
transferred from the pistons to the cams 30, 32, from which it is drawn through the
coaxial shaft 24 and transferred to the user.
[0046] The channel 46 can be produced so as to generate suitable turbulence in the input
motion into the chamber in order to improve the thermal exchange, for example positioning
it parallel to a tangent common to the two cylindrical chambers, so as to promote
the occurrence of a rotary flow of the fluid in the chamber downstream as indicated
by the arrows D of Fig. 6.
[0047] The working principle of the machine is based on the fact that the same volume of
fluid can be arranged in the hot chamber 34 or in the cold chamber 34', and therefore
exchange heat in one direction or in the other towards the walls, appropriately positioning
the two pistons of the adjacent chambers.
[0048] Moreover, to allow the thermodynamic cycle for the production of work to be performed
rapidly, the surface of the walls must be as large as possible with respect to the
volume of the chambers, and the thermal exchanges must preferably be carried out in
the condition of variation of the state of aggregation of the fluid from liquid to
vapor and vice versa. The first requirement is satisfied by the geometrical design
of the chambers and the second by the choice of working fluid as a function of the
temperatures of the sources. Therefore, it is possible to use organic fluids such
as methanol, ethanol or butanol up to temperatures of the hot source in the order
of 500 K, and water in the case of temperatures up to around 600 K. A class of working
fluids known as "HFO", acronym for "Hydro-Fluor-Olefins", which have noteworthy properties
for use in the machine according to the present invention, without negative or harmful
effects for the environment, in particular for the earth's ozone layer, have recently
become available in the art.
[0049] Transformation of the linear motion of the piston 36, 36' into rotary motion of the
rotary shaft 24 takes place due to the profile of the cams 30, 32, against which the
piston presses by means of the rollers 40, 40', as shown in Figs. 4A and 4B.
[0050] The cams are produced with lift profiles indicated qualitatively in Fig. 13, i.e.,
so that the displacement of the pistons is as described in Fig. 14 in correspondence
of the steps indicated in the same figure.
[0051] The cams 30, 32 are provided with a profile such as to cause the corresponding pistons
of the two cylindrical blocks to perform a coordinated motion adapted to generate
changes in the volume of the chambers 34 and 34' that subsequently result in a compression
of the fluid carried out through a reduction of the volume of the chambers, preferably
the cold chamber, followed by its displacement inside the cylinder at high temperature
such that it can be heated, through a further reduction of the volume of the cold
chamber and an increase of the volume of the hot chamber, such heating being further
followed by an expansion obtained through an increase of the total volume of the chambers,
preferably on the hot side, which is also followed by a further cooling, obtained
with a displacement of the fluid in the cold chamber due to an increase of the volume
of this latter and a reduction of the volume of the hot chamber, and finally a new
compression, carried out as defined above to start the cycle again. The machine is
also provided with a reservoir of the working fluid, not represented in the figures,
as not essential to the description of the invention, which is put in communication
with the chambers 34, 34' by the filling and control valves of the maximum working
pressure, described previously (arrows B of Figs. 3, 7, 8).
[0052] The operating steps of the machine according to the invention are described below,
where, for clarity of description, they have been clearly separated from one another,
while in their effective implementation they can be partially overlapped in order
to optimize the mechanical and thermodynamic output:
A. Compression, (continues from E):
The fluid is compressed rapidly to the minimum volume of the cycle and transferred
entirely to the hot chamber 34, therefore the piston 36' of the cold chamber is at
the top dead center, as near as possible to the upper end of the cold chamber 34'
as the machining tolerances will allow, while the piston 36 of the hot chamber 34
is taken to a height corresponding to the minimum volume of the cycle, very near to
the top dead center, in this step the torque generated on the cam is negative, and
therefore it is necessary to supply mechanical work to the system to carry out compression
(Figs. 15 and 16).
B. Heating:
With the piston 36' of the cold chamber 34' stopped at the top dead center, the piston
36 of the hot chamber 34 descends causing expansion of the fluid that, in this step
absorbs heat from the walls of the chamber. The law of motion of the piston and therefore
expansion of the fluid is such as to approximate as much as possible an isothermal
expansion so as to maximize the output, approximating the theoretical Carnot cycle.
In this step the torque generated on the cam is positive, and therefore useful work
is generated. (Figs. 15 and 16)
C. Expansion:
After reaching the final heating conditions, the piston 36' of the cold chamber 34',
and optionally the piston 36 of the hot chamber 34, is made to descend rapidly for
a length corresponding to the desired expansion. In this step further useful work
is generated (Fig. 3).
In Figs. 14, 15 and 16, to simplify the description and to highlight the subsequent
transfer described in step D, the case in which expansion is carried out only by the
cylinder 36 of the hot chamber 34 is illustrated but, as a function of the process
variables of each application, i.e., rotation speed, working fluid and size of the
machine and of the communication channel between the chambers 34 and 34', the law
of motion of the two pistons 36 and 36' that gives the maximum total output, total
meaning the product of the mechanical and the thermodynamic output, must be calculated
or defined experimentally.
D. Transfer and Cooling
The piston 36' of the cold chamber 34' is then taken towards the bottom dead center
while the piston 36 of the hot chamber 34 is transferred to the top dead center expelling
all of the fluid towards the cold chamber 34', where this transfers heat to the walls
of the chamber.
The piston 36' of the cold chamber 34' is then slowed and its motion is reversed so
as to perform an approximately isothermal cooling until reaching the condition in
which compression starts. In this step the torque generated on the cams 30 and 32
is negative and it is necessary to supply work to the shaft 24 for its rotation (Figs.
15 and 16).
E. Compression:
The piston 36' of the cold chamber 34' is thrust to the top dead center while that
of the hot chamber 34 descends until generating the volume indicated in step A. Also
in this step work must be supplied to the shaft to carry out the compression step.
The cycle starts again with step A (Figs. 15 and 16).
[0053] The chambers 34, 34' are put in communication with the reservoir of the working fluid
by two distribution valves. As stated above, the valve located in the chambers 34'
of the cold block 22 only opens when reaching the maximum design pressure, at the
end of the compression step or during heating of the fluid, allowing outflow from
the chambers 34' to the reservoir, thereby maintaining the maximum pressure of the
cycle below acceptable values for the mechanical strength of the machine members.
[0054] The valve located in the chambers 34 of the hot block opens when the pressure in
the chambers 34 drops below the pressure of the reservoir, allowing the outflow of
fluid from the reservoir into the chambers 34. In this way, the amount of fluid in
the chambers 34, 34' is regulated automatically as a function of the operating conditions.
[0055] The design of the cams 30, 32 and of their connection to the shaft 24 must take account
of the existence of positive and negative torque phases and of the need to have regular
rotation of the moving elements of the distribution valves. It is therefore provided
with suitable inertia so as to reduce the oscillations of the rotation speed of the
shaft in correspondence of the changes of torque, while to start the machine it must
be accelerated with an external means to the operating speed.
[0056] The profile of the cam is determined according to the known kinematic and dynamic
techniques so as to make the compression and expansion steps as rapid as the contact
stresses between roller and cam in the acceleration steps will allow and avoiding
loss of contact between them during the deceleration steps. On the contrary, the motion
of the piston during the heating and cooling steps is determined by the heat balance
of the working fluid according to the criterion of better approximating the isothermal
transformations in order to maximize the thermodynamic output of the cycle.
[0057] In the case in which the machine is used to produce mechanical work to be exploited
directly, as indicated in the drawing B, the cam will be provided with a drive 350
(Fig. 3), parallel to the rotation axis X-X.
[0058] In an embodiment dedicated to the production of electrical energy the machine therefore
also comprises the electromechanical elements for direct transformation of the mechanical
work produced into electrical energy, also in this case avoiding complex motion transfer
systems and, ultimately, providing a product that is more efficient, of smaller size,
lighter in weight and less expensive than those available in the state of the art.
[0059] With reference to Figs. 9-11, there is illustrated an embodiment of the machine according
to the invention dedicated to the production of electrical energy.
[0060] The description of the components of the machine is the same as the embodiment dedicated
to the production of mechanical work, and therefore they will not be described in
detail, apart from the following aspects.
[0061] Fixed integrally to the cams 30, 32 is a plurality of permanent magnets 70 while
a plurality of stator windings 72 is mounted integrally to an axis 240 that supports
the bearings 26 on which the cams 30 and 32 are mounted, the former being adapted
to generate a rotary magnetic field that induces in the latter an electromotive force
exploitable directly or indirectly by electric utilities external to the machine after
suitable transformations through a plurality of electrical or electronic circuits
derivable from the state of the art.
[0062] With reference to Figs. 17A and 17B, there is illustrated a second embodiment of
the machine according to the invention in which the cylindrical working chambers are
oriented longitudinally in each of said cylindrical blocks according to longitudinal
axes (Y) parallel to the longitudinal axis (X) of the rotary member.
[0063] In this embodiment the cylinders, the pistons and the corresponding working chambers
are arranged in a direction parallel to the rotation axis instead of concurrent with
respect thereto and their motion is determined by a front cam instead of by a radial
cam, as known in the state of the art. To simplify the description this arrangement
will be called "axial", while the version with concurrent axes on the rotation axis
will be called "radial"; moreover, to highlight the correspondence between the two
arrangements, in the description below the components of the axial version will be
indicated with the corresponding number of the radial version followed by the suffix
".
[0064] The thermodynamic working principle is identical to that of the radial version and
therefore will not be described again.
[0065] In the axial embodiment the two cylinder blocks 20"and 22" separated by the insulating
partition 21", are maintained at different temperature by fluids that circulate respectively
in the chambers 80 and 81, these fluids representing the heat sources at different
temperature that are the source of thermal energy whose transformation is the ultimate
aim of the machine described. Said cylinder blocks 20" and 22" house the working chambers
34" and the pistons 36", these latter provided with return springs 38" and rollers
40". These rollers are engaged by two front cams 30" and 32", towards which they are
thrust, in order not to lose contact by the springs 38". In this embodiment the chambers
34" inside which evolves the fluid involved by thermodynamic transformation aimed
at the production of work, extend between the hot block and the cold block with continuity
although it is possible to identify a portion 34A", which will be called hot chamber,
in contact with the hot block 20" and a portion 34B", which will be called cold chamber,
in contact with the cold block 22", the fluid being brought into contact with the
hot or cold portions of the walls according to the position of the pistons 36", facing
each other, and, therefore, to the steps of the cycle.
[0066] The cylinder blocks 20" and 22" house the bearings 26" on which the shaft 24" is
assembled, which can therefore rotate with respect to said cylinder blocks 20" and
22".
[0067] The front cams 30" and 32" are assembled on the shaft 24" rigidly and determine,
upon rotation thereof, the motion of the pistons 36" so that they produce in the working
chambers 34" the changes of volume and the displacements of the fluid according to
the diagram of the steps illustrated in Fig. 14.
[0068] The working chambers are put in communication with the reservoir of the working fluid
with the channels 48" through control valves known in the state of the art. In this
way, in correspondence of the maximum pressure of the cycle, i.e., at the end of compression
and at the start of heating, all excesses are discharged into the fluid reservoir
while, in correspondence of the minimum pressure of the same cycle, i.e., in correspondence
of the end of expansion and during cooling, if the pressure drops below an appropriate
limit, the fluid flows out of the reservoir and into the working chamber.
[0069] These communication openings can be closed by the piston during its motion. In fact,
if this is advantageous, in order to improve the output of the cycle the piston could
cover the communication hole with the chamber so as to shut off the communication
route with the reservoir.
[0070] In the case in which the machine is employed for the generation of mechanical work,
this can simply be drawn from the shaft 24" through devices known in the state of
the art such as cogwheels, belts or couplings for the direct transmission of motion.
Instead, in the case in which the machine is used for the production of electrical
energy, permanent magnets 70" or windings will be arranged on the shaft so as to generate
a rotary magnetic field, while the cylinder blocks 20" and 22" can house stator windings
72" in which an electromotive force, employable in electrical utilities external to
the machine of the present invention, will be generated through electromagnetic induction.
[0071] The present arrangement has advantages and disadvantages with respect to the radial
configuration: the advantages consist of simpler construction, elimination of the
communication channels 46 between the chambers, the possibility of obtaining higher
compression ratios minimizing the distance between pistons at the end of compression,
the possibility of closing the communication openings towards the reservoir and the
possibility of displacing the fluid entirely into the appropriate working chamber
according to the step of the cycle. On the other hand, the disadvantage consists of
not being able to place several elements side by side on the same axis, placing the
cylindrical bodies side by side, so as to permit a modular embodiment capable of covering
subsequent levels of performance with several identical components.
[0072] The embodiments described above of the machine according to the invention show that
it allows the transformation of thermal energy deriving from any heat source into
mechanical work and optionally, due to the arrangement of the aforesaid members of
the machine, the transformation of this latter into electrical energy.
[0073] It is therefore possible to carry out thermodynamic cycles for the transformation
of heat into work in a single very compact mechanical assembly, which is thus lighter
in weight and less expensive with respect to those of prior art systems, which are
more complex and consequently have greater costs, size and weight.
1. A machine for the transformation of thermal energy into mechanical work or electrical
energy
characterized by comprising:
i) a first (20, 20') and a second (22, 22') coaxial and cylindrical block side by
side, separated by a cylindrical partition (21) of insulating material, said cylindrical
blocks (20, 22') and said insulating partition (21) being provided with axial cavity
housing a rotary member (24) provided with a first (30) and a second (32) cam, each
placed in correspondence of each of said cylindrical blocks (20, 22) and having the
two cam profiles such as to generate a coordinated movement of the pistons housed
in said cylindrical blocks;
ii) a series of cylindrical working chambers (34, 34') in each of said cylinder blocks
(20, 22), each of said working chambers (34, 34') being open at the bottom towards
said axial cavity of said cylindrical blocks (20, 22) and being provided with a single-acting
piston (36, 36') provided with a contrast spring (38, 38') and acting on an idle roller
(40, 40') in contact with said cams (30, 32) of said rotary member (24), thereby defining
a first series of working chambers (34) in said first cylindrical block (20), a second
series of working chambers (34') in said second cylindrical block (22), a first series
of pistons (36) acting on a corresponding first series of rollers (40) in contact
with said first cam (30), and a second series of pistons (36') acting on a corresponding
second series of rollers (40') in contact with said second cam (32);
iii) a plurality of communication channels (46) between said first and second series
of working chambers (34, 34'), each of said channels (46) putting in communication
a chamber (34) of said first cylindrical block (20) with a corresponding chamber (34')
of said second cylindrical block (22) through said insulating partition (21), each
of said chambers (34, 34') being also provided with communication channels (48, 48')
with an external reservoir for a fluid working in said chambers, and a plurality of
distribution valves of said fluid between said communication channels and said working
chambers;
said first cylindrical block (20) being operatively exposed to a heat source (A) adapted
to heat said working fluid in said first working chambers (34), while said second
cylindrical block (22) is thermally isolated from said first cylindrical block (20)
and placed in contact with a lower temperature heat source whereby it is cooled, such
that in said first (34) and second (34') working chambers said working fluid carries
out thermodynamic cycles of compression and expansion as a result of the motion of
said pistons (36, 36') and the corresponding rotation of said cams (30, 32) and of
said rotary shaft (24).
2. A machine for the transformation of thermal energy into mechanical work or electrical
energy
characterized by comprising:
iv) a first a (20") and a second (22") coaxial and cylindrical block side by side,
separated by a cylindrical partition (21) of insulating material, said cylindrical
blocks (20", 22") and said insulating partition (21") being provided with axial cavity
housing a rotary member (24") provided with a first (30") and a second (32") cam,
each placed in correspondence of each of said cylindrical blocks (20", 22") and having
the two cam profiles such as to generate a coordinated movement of the pistons housed
in said cylindrical blocks;
v) a series of cylindrical working chambers (34 ") in said cylindrical blocks (20",
22"), each of said working chambers (34") being axially open towards the portion of
said cylindrical block (20", 22") facing said cams (30", 32") and being provided each
with a pair of single-acting pistons (36") provided with a contrast spring (38") and
acting on an idle roller (40") in contact with said cams (30", 32") of said rotary
shaft (24");
vi) said chamber (34") being further provided with communication channels (48") with
an external reservoir for a working fluid in said chamber, and a plurality of distribution
valves of said fluid between said communication channels and said working chambers;
said first cylindrical block (20") being operatively exposed to a heat source (A)
adapted to heat said working fluid in a first portion (34A") of said working chambers
(34") and being said second cylindrical block (22") thermally isolated from said first
cylindrical block (20") and placed in contact with a lower temperature heat source
whereby it is cooled, such that the working fluid in a second portion (34B") of said
working chambers (34") is cooled and carries out thermodynamic cycles of compression
and expansion as a result of the motion of said pairs of pistons (36 ") and the corresponding
rotation of said cams (30", 322) and of said rotating shaft (24").
3. Machine according to claim 1, characterized in that said cylindrical working chambers (34, 34') are radially oriented in each of said
cylindrical blocks (20, 22) along longitudinal axes (Y) incident on the longitudinal
axis (X) of said rotating member (24).
4. Machine according to claim 2, characterized in that said cylindrical working chambers (80, 81) are oriented in the longitudinal direction
in each of said cylindrical blocks (20", 22 ") according to longitudinal axes (Y)
parallel to the longitudinal axis (X) of said rotary member (24 ").
5. Machine according to claim 1 or 2, characterized in that said distribution valves comprise a filling valve and a maximum pressure valve.
6. Machine according to claim 1, characterized in that said distribution valves (45, 90) are located inside said pistons (36, 36 ') of said
first (34) and second (34') working chambers.
7. Machine according to claim 1 or 2, characterized in that the ratio between the heat exchange surface and the volume of working fluid in it
is such as the working fluid achieves in a short time a temperature very close to
that of the walls.
8. Machine according to claim 1, characterized in that said communication channel (46) between said chamber (34) of said first cylindrical
block (20) and said chamber (34') of said second cylindrical block (20) is arranged
parallel to a common tangent of said cylindrical chambers (34, 34'), thereby generating
a rotary motion of the fluid in said chamber (34').
9. Machine according to claim 1 or 2, characterized in that it said cams are provided with a profile such as to cause the corresponding pistons
of the two cylindrical blocks to perform a coordinated motion adapted to generate
changes in the volume of the cylindrical working chambers that subsequently result
in a compression of the fluid carried out through a reduction of the volume of the
chambers followed by its displacement inside the cylinder at high temperature such
that it can be heated, through a further reduction of the volume of the cold chamber
and an increase of the volume of the hot chamber, such heating being further followed
by an expansion obtained through an increase of the total volume of the chambers which
is also followed by a further cooling, obtained with a displacement of the fluid in
the cold chamber due to an increase of the volume of the latter and a reduction of
the volume of the hot chamber, and finally a new compression, carried out as defined
above to start the cycle again.
10. Machine according to claim 1or 2, for the transformation of thermal energy into electric
energy, characterized in that there are fixed to said rotary member (24, 24") a plurality of permanent magnets
(70, 70") in a radially distal location to said rotary member (24, 24"), said machine
further comprising a stator (72, 72") housed in the axial cavity of said cylindrical
blocks (20, 22, 20", 22") between said permanent magnets (70, 70") and said rotary
member (24, 24"), said stator (72, 72") being provided with electrical windings on
which there are induced electromotive forces that support the production of electrical
current exploitable directly or indirectly by electric utilities external to the machine.
11. Use of the machine according to one or more of the preceding claims to perform thermodynamic
cycles of compression (A), heating (B), expansion (C) and cooling (D) of a working
fluid, in which the thermal exchanges are carried out in the condition of variation
of the state of aggregation of said fluid from liquid to vapor and vice versa.
12. Use according to claim 11, wherein said fluid is a mixture of components selected
from the group consisting of methanol, ethanol, butanol, HFO and water.