"Compressed gas engine"

[0001] The present invention relates to a compressed gas engine, and an apparatus comprising such engine.

[0002] The growing level of environmental pollution, as indeed the increase in prices and the reduced availability of fossil fuel increasingly impose the identification and development of green technology.

[0003] In particular, in the automobile sector, industry efforts are directed at the use of batteries to power the locomotion of vehicles, or to designing hybrid functioning vehicles, that is to say functioning in an alternate manner with different fossil fuels (for example methane gas and petrol) or by fitting internal combustion engines together with electric motors.

[0004] However, such technical solutions, despite being an improvement from many points of view cannot be considered tout court eco-compatible as a result of the gaseous products generated by the combustion reaction which must in any case take place for the gaseous fuels, but above all because in the medium to long term the disposal of - the batteries used in the electric motors will pose a serious environmental problem.

[0005] The present invention thus falls within such context, setting but to provide an engine functioning with compressed gas, in particular compressed air or vapour (for example water vapour) , suitable therefore to prevent it from creating harmful combustion products, and the functioning of which does not entail global warming nor worsening of the greenhouse effect.

[0006] Such objective is achieved by an engine according to claim 1, and by means of an apparatus according to claim 15. The dependent claims describe advantageous embodiments.

[0007] The object of the present invention will now be described in detail with the help of the attached drawings, wherein:

[0008] - figure 1 shows a schematic diagram of the apparatus of the present invention, according to a possible embodiment;

[0009] - figure 2 shows a cross-sectional view of the engine usable in the apparatus in figure 1, according to one implementation of the invention;

[0010] - figure 3 shows a view from above of the engine in figure 2, in which the head has been removed;

[0011] - figure 4 is a schematic diagram of the contact surfaces between the engine body and the propulsion rotor at the bevelled surface of the former;

[0012] - figure 5 shows a variant of a rotation pin, usable as an alternative to the pin shown in figure 2; and [0013] - figure 6 shows a cross-section along the plane VI- VI of figure 5 of the rotation pin and of the radially innermost portion of the rotating drum.

[0014] With reference to the aforementioned drawings, reference numeral 2 globally denotes a compressed gas engine .

[0015] Such engine 2 comprises an engine body 10 and a propulsion rotor 12 which circumscribes, together with the engine body 10, two or more expansion chambers 14, 16, 18, 20 for the compressed gas. Preferably three or more (for example four or more) of the aforesaid chambers are provided. This way, the rotor 12 and the expansion chambers 14, 16, 18, 20 are susceptible to a rotation in relation to the engine body 10 around a primary rotation axis X under the expansion effect of the compressed gas. For example, the drawings show an engine 2 with four expansion chambers angularly equidistant, although other variants may provide for a greater or smaller number of such chambers (and of corresponding pistons) . Embodiment variants with a non-equidistant distribution in a circumferential direction (an irregular pitch) of the expansion chambers may also be hypothesised.

[0016] Consequently, the expansion of the gas acts on the engine body 10, and in particular on a head 44 thereof, and on the propulsion rotor 12 to promote its rotation. In turn, such rotor is configured to move other kinematisms (,not shown) mechanically suitable for connection to the latter by means of transmission means 74. Merely by way of example, the movement of the propulsion rotor 12 may be used to move a transmission shaft of a motor vehicle, engageable with said means 74.

[0017] Merely by way of example, a power axis Y of the engine 2 may be inclined in relation to the primary rotation axis X, for example at an angle of 140° to 165°, preferably approximately 150°-160°, in particular 155°.

[0018] Preferably, the engine body 10 comprises a substantially cylindrical wall 70 which extends around the primary rotation axis X. Said cylindrical wall 70 delimits an abutment surface 72 with the propulsion rotor 12, preferably bevel-shaped.

[0019] According to one variant, the engine body 10 further defines an inner chamber 76, wherein the propulsion rotor 12 is at least partially housed. According to said variant, the abutment surface 72 circumscribes the access aperture to the inner chamber 76.

[0020] According to one advantageous embodiment, the propulsion rotor 12 is axially constrained to the engine body 10 by means of a retention flange 102.

[0021] For example, in the variant- shown in figure 2, such flange is in abutment with the rotor · 12 so that the latter is free to rotate, and is retained to the engine body by one or more tie-rods 104, 104' which axially compact the engine. This way, the structure thus conceived is . suitable to resist considerable internal pressures.

[0022] The engine 2 further comprises at least one entrance aperture 22 of the compressed gas and at least one exit aperture 24 of the expanded gas, fluidically connected upstream and downstream of the expansion chambers 14, 16, 18, 20 in the transit direction T of the gas, schematically shown by an arrow in figures 1 and 3.

[0023] Preferably, a single entrance aperture 22 and a single exit aperture 24 are made in the engine body 10. For example, the entrance aperture is made at the head 44, while a further variant provides that the exit aperture 24 crosses the cylindrical wall 70.

[0024] A further embodiment (not shown) provides, conversely, that the entrance aperture is made in the cylindrical wall, while the exit aperture is made in the head, as happens for example in the Newcomen steam engine. In such case, the direction of transit of compressed gas would obviously be opposite to that shown in the figures, in that the gas would act from the lower part of the pistons, according to the picture shown in figure 2. [0025] According to one embodiment, the engine 2 comprises interception means 48 to regulate the flow of compressed gas to the expansion chambers. Preferably, the interception means 48 comprise at least one (solenoid) valve or at least one gate valve.

[0026] Advantageously, such means 48 can be positioned at the entrance aperture 22. According to this variant, the interception means are thus suitable to vary the through cross-section of the compressed gas through the entrance aperture.

[0027] According to a particularly advantageous embodiment, the head 10 of the engine body 44 delimits a proximal storage 46 of compressed gas communicating with the expansion chamber 14, 16, 18, 20; this way, the flow of compressed gas coming out of the proximal storage 46 is immediately made available to the expansion chambers, without the dead time which would be needed in the case of a storage or tank 8, 8' positioned more distally to the engine 2.

[0028] According to one variant the interception means 48 are at least partially housed in the proximal storage 46, for example as shown by the dotted line in figure 2, in particular in abutment with an end wall 100 which delimits the head 44 in the direction of the expansion chambers. [0029] According to a further variant, the interception means 48 are positioned downstream of the proximal storage 46, and can be commanded to control the flow of gas coming out therefrom.

[0030] Optionally, the engine 2 comprises heating means (for example an electric resistor) in thermal communication with the aforesaid storage 46 to increase the calorific value - thus the expansion - of the compressed gas upon its introduction into the expansion chambers 14, 16, 18, 20.

[0031] The propulsion rotor 12 comprises a plurality of pistons 26, 28, 30, 32 movable (preferably translatable) inside the expansion chambers 14, 16, 18, 20 to vary the volume thereof.

[0032] Consequently, each piston 26, 28, 30, 32 is movable in the respective expansion chamber 14, 16, 18, 20 between a position of minimum volume VI of the chamber 14, 16, 18, 20 wherein the pressure of the compressed gas is maximum, and a position of maximum volume V2 of the chamber wherein said pressure is minimum and wherein the gas is expanded.

[0033] In other words, the expansion of the compressed gas in the expansion chambers causes a distancing of the pistons (for example in relation to the head 44 ^' or in relation to the end wall 100 of the engine body) so that each of such chambers passes alternately from the minimum volume VI to the maximum volume V2. The movement of the pistons produces a rotation of the propulsion rotor 12.

[0034] The pistons 26, 28, 30, 32 are further rotatable around the primary rotation axis X along a rotor trajectory R, for example circular or ellipsoidal, which intercepts the axis X at an angle A other than 90°. For example, the representation in figure 1 shows an obtuse angle A while figure 2, substantially specular to the previous, identifies an acute angle A.

[0035] In fact, if there were no inclination of the aforesaid rotor trajectory R, the at least two expansion chambers would have the same volume in any angular position of the propulsion rotor and the pistons, so that the compressed gas would not find the necessary space to expand.

[0036] As a result, with reference for example to figure 2, the piston 26 is initially placed in the position of minimum volume VI of the respective expansion chamber 14. Given that in such circumstance the pressure of ^" the compressed gas entering the chamber through the entrance aperture 22 is maximum, the piston is distanced under the thrust of the pressure accomplishing the movement (or preferably translation) in the expansion chamber, and rotating along the rotor trajectory R, for example in a circular direction (as shown schematically by the arrow in figure 3) . After going through a rotation of approximately 180°, such piston 26 will occupy the opposite position (which in the figures is that engaged by the piston 30) wherein the volume V2 of the chamber is maximum and where, by virtue of the expansion of the gas having taken place, the pressure is minimal.

[0037] At that point, the at least two pistons will have inverted their positions, so that at the piston marked by reference numeral 30 a new cycle of expansion of the gas as described may take place. Obviously, for a greater number of pistons and chambers, the frequency of entrance and of expansion of the compressed gas will take place with a reduced rate for example, for an engine with four pistons such as that shown, every 90° of rotation.

[0038] According to an advantageous embodiment, each piston 26, 28, 30, 32 is connected and extends towards the expansion chambers 14, 16, 18, 20 from a bottom surface 50 of the propulsion rotor 12. Said connection is preferably made by a cuff 52, 54 which receives a rod 56, 58 of the piston 26, 28, 30, 32 with a swivelling movement around several axes M, Z.

[0039] As may be noted for example from the diagram in figure 2, by virtue of the presence of the cuff 52, 54 each piston is rotatable around a secondary rotation axis M (in the case in point substantially parallel to the primary rotation- axis X) and around a tertiary rotation axis Z, for example incident or orthogonal to the aforesaid secondary axis M.

[0040] According to the variant shown, the bottom surface 50 is destined for sliding contact with the abutment surface 72 of the cylindrical wall 70. To such purpose, the interposition of roller means 78', 78", for example one or more roller bearings, may be provided for.

[0041] Given that the roller means 78', 78" are rotatable along a circular trajectory, but the abutment surface 72 has an generally ellipsoidal/ovoidal inner perimeter (by virtue of the preferred bevel shape discussed) , the cylindrical wall 70 has a variable thickness of wall around the primary rotation axis X.

[0042] In particular with reference for example to the schematic diagram in figure 4, such wall has a minimum wall thickness at the greater semi-axis 108 of the ellipsis/ovoid, while it has a maximum thickness at the smaller semi-axis 110.

[0043] This way, the cylindrical wall 70 has a pair of opposite sickle-shaped portions 112, 112', preferably having their concavities facing towards the primary rotation axis X. For example, the centre of symmetry of such portions 112, 112' is positioned at the smaller semi-axis 110 of the ellipsis.

[0044] According to the variant shown, each cuff 52, 54 delimits an articulation basin 80 suitable for housing at least partially an end portion of the rod 56, 58, the latter for example of a generally spherical shape.

[0045] According to a preferred embodiment, the propulsion rotor 12 comprises a rotating drum 34, partially housed in the engine body 10, in particular partially housed in the inner chamber 76 which separates the expansion chambers 14, 16, 18, 20 and guides the movement of the pistons 26, 28, 30, 32.

[0046] The rotating drum 34 may for example be seen from above in figure 3 where the head 44 has been removed from the engine. According to the illustration, the drum has a plurality of drum lobes 82, 84, 86, 88 at the various chambers. Between each pair of said drum lobes a housing 90, 92, 94, 96 may be provided for the at ^' least partial housing of a magnetic element 68 (described below) .

[0047] In an advantageous embodiment, the rotating drum 34 delimits an access opening 36, 38, 40, 42 of the compressed gas for each expansion chamber 14, 16, 18, 20; the openings are distanced from each other so that, in any angular position of the drum 34, a single access opening is aligned with the entrance aperture 22 identified by the engine body 10. This way, the compressed gas is released into a single expansion chamber at a time, so as to avoid unwanted pressure drops inside the pneumatic circuit of the engine.

[0048] In order to ensure a seal and prevent leaks between the drum and the engine body (or the head) ceramic rubbing surfaces may be foreseen.

[0049] Advantageously, the propulsion rotor 12 and/or the rotating drum 34 are guided in rotation by a rotation pin 60 connected centrally to the engine body 10, and in particular engaged with the head 44. The rotation pin 60 which extends along the primary rotation axis may be fitted coaxially to the engine body 10 and/or to the rotating drum 34.

[0050] According to a preferred implementation of the invention, the pin 60 is traversed by at least one fluidic passage 62, 126, 64 to. place in communication the expansion chamber 14, 16, 18, 20 and the exit aperture 24 of the expanded gas.

[0051] In fact, as may be noted for example from figure 2 or from the view in figure 5, when the volume V2 of the expansion chamber 18 is maximum, the piston 30 is distanced from a venting aperture 98 of the expansion chamber 18, so as to place in communication said chamber with the space occupied by the rotation pin. The expanded gas is thus free to exit from the aforesaid chamber through the venting aperture 98, and to transit from- a first 62 to a second 64 pin aperture fluidically connected to each other by an axial duct 126. This way, the gas can lastly reach the exit aperture 24.

[0052] In other words, according to this embodiment, each expansion chamber 18 communicates externally by means of the venting aperture 98 of the expanded gas, and each piston 26, 28, 30, 32 is configured to act as an interception component of the expanded gas towards the exit aperture 24. Specifically, the stroke of the pistons makes it possible to free the venting aperture 98 when the propulsion rotor 12 is in a specific angular position, thereby permitting the fluidic connection.

[0053] Preferably, a check valve 128 may be provided for at the fluidic passage 62, 126, 64 to prevent the return of the expanded gas towards the expansion chamber which it has just left. For example, such valve may be at least partially housed inside the pin 60, and specifically inside the axial duct 126.

[0054] Preferably, the rotation pin 60 is axially divided into a first portion 122 integral with the engine body 10 (for example joined in rotation) and in a second portion 124, rotatable in relation to the ^* first portion 122 and delimiting at least a part of the fluidic passage 62, 126, 64. [0055] Consequently, according to the previous variants, the rotation pin 60 or the second portion 124 preferably houses at least partially the check valve 128 to prevent the aforesaid return to the expansion chamber.

[0056] For example, with reference to the variant shown in figure 6, the rotation pin 60 has a spider cross-section so as to delimit a plurality of passages 126, and specifically to delimit a fluidic passage 126 for each expansion chamber.

[0057] In addition, optionally, one or more pistons may have a slot or a fall 106, facing towards the venting aperture 98, to anticipate the exit of the expanded gas.

[0058] According to a further variant, the engine body comprises a plurality of coil windings 66 suitable for interacting with at least one magnetic element 68 joined in rotation to the propulsion rotor 12 to generate an electric current. For example, four magnetic elements are provided for, each housed in a respective housing 90, 92, 94, 96 of the drum.

[0059] According to one embodiment, the aforesaid electric current may be used to power the heating means of the proximal storage 46.

[0060] The present invention also relates to an apparatus 1 comprising a compressed gas engine 2 according to any of the previous embodiments, electric-mechanical means of re-compression 4, 6 of the expanded gas and at least one collection tank 8, 8'.

[0061] Preferably, the apparatus 1 comprises a pair of collection tanks 8, 8 ' , for example arranged in parallel for alternate or concurrent use.

[0062] For example, by acting on one or more first valves 114, 116 positioned upstream of the collection tanks 8, 8 ¹ it is possible to regulate the entrance of re- compressed gas into only one of the two tanks, or a perform simultaneous filling.

[0063] In the same way, a further embodiment provides that, by operating one or more second valves 118, 120 positioned downstream, the emptying of such tanks 8, 8' may also be regulated at will.

[0064] The electric-mechanical re-compression means are connected downstream to the exit aperture 24 (again with reference to the direction of transit T of the gas in the circuit) , and are preferably also powered by the electric current generated by the interaction of the coil windings 66 with the magnetic element 68. The term "also" being taken to mean that, given the inevitable dispersion of energy, such current must necessarily be integrated by means of a supplementary external source.

[0065] In addition, the collection tank 8, 8' is suitable to feed the compressed gas to the engine 2, and is advantageously configured to receive compressed gas at least from the electric-mechanical re-compression means 4, 6.

[0066] For example, such means 4, 6 may comprise an engine 6 operating a mechanical compressor 4. Preferably, the engine and compressor are positioned coaxially to the rotation axis of the shaft of said engine 6.

[0067] Preferably, the re-compression means 4, 6 comprise an engine such as that illustrated according to any of the previous variants; however such engine will need to be modified in such as way as to cause a re-compression of the expanded gas entering therein, by means of a mechanical action of the pistons on the gas generated through a consumption of electricity, thereby obtaining the compressed gas.

[0068] Although such configurations do not represent a perfect heat/energy cycle, the present apparatus is nonetheless highly integrated to delay the moment in which refuelling of compressed gas in the collection tank 8, 8' is necessary, and to reduce the quantity of supplementary electricity for powering the re-compression means .

[0069] Innovatively, the engine and method according to the present invention are suitable to completely eliminate the use of fossil fuels for the locomotion of vehicles or other means, and to prevent them from generating harmful products of combustion.

[0070] Advantageously, the apparatus described is highly integrated, in a perspective of optimising energy and consumption.

[0071] Advantageously, the engine and method according to the present invention are suitable to immediately make available the power required in specific functioning circumstances, thereby avoiding the dead times of gas transport.

[0072] Advantageously, the engine and method according to the present invention present an innovative swivelling system of the pistons which permits a freedom of movement with a reduced rate of wear.

[0073] A person skilled in the art may make variations to the embodiments of the engine and apparatus described above so as to satisfy specific requirements, replacing elements with others functionally equivalent.

[0074] Such variants are also contained within the scope of protection defined by the following claims.

[0075] In addition, each of the characteristics described as belonging to a possible embodiment may be realised independently of the other embodiments described.