DESCRIPTION OF THE INVENTION The invention relates to an operating/driving machine for transmitting energy to, or receiving energy from, fluids in general. In particular, the machine is able to transmit motion to a fluid, thus operating as an operating machine, or receive motion from a fluid, operating in this case as a driving machine. Many different types of fluid machines are known in the prior art, both operating and driving machines.

One example of a machine of known type are the operating machines used in marine propulsion systems.

Marine propulsion systems comprise an engine, which can be an internal combustion engine (typically a diesel engine), or an electric motor.

The engine drives a rotating shaft onto which a propeller is mounted. The propeller is provided with a hub to which a plurality of blades are fitted.

Both fixed pitch propellers are known, in which the blades are fixed to the hub without possibility of modifying the orientation thereof, and variable pitch propellers. In variable pitch propellers, the blades are orientable because they can be rotated around the longitudinal axis thereof.

The propellers in marine propulsion systems have some critical aspects, which are due to the conditions in which the propeller has to operate, which can also generate significant drawbacks.

Generally, the propellers operate near the surface separating two fluids (air and water), one of which (water) can be subject to wave motion. This can also alter the motion of the fluid on the propeller, affecting propeller performance. Further, the propeller has to be positioned in such a manner as to be sufficiently immersed to prevent a significant thrust produced by the propeller being discharged in the air instead of the water, which would reduce the useful propulsion thrust.

Also, it must be remembered that the pressure difference of the water, which increases with the increase in depth, means that the propeller blades, during a rotation, operate in zones with different pressures. This causes uneven thrusts of the propeller on the fluid, which depend on the hydraulic resistance that the blades encounter.

One significant drawback of these machines is caused by cavitation, a phenomenon to which the blades are subject. Cavitation occurs when gas (air) bubbles form in the liquid (water), typically in the zones in which there is a vacuum. These bubbles move rapidly to the zones in which the pressure is higher, so that, during this movement, they hit the surface of the blades, which get damaged. On the surface of the blades numerous holes then form that compromise the structural integrity of the blades and thus make it necessary to replace the propeller.

Further, the bubbles that form create a sort of air cushion on the surface of the blades, reducing propeller performance. It is thus clear that in order to avoid the problems set out above, cavitation has to be avoided.

In order to overcome these problems that are due to cavitation, positioning the propeller at a greater depth or rotating the propeller at lower rotation speeds is known, such that the fluid interacting with the propeller reaches lower maximum pressures, at which cavitation does not occur.

Alternatively, propellers are also known that are provided with very extensive blades, such that the pressure that the fluid exerts thereupon is less owing to the fact that the fluid distributes thrust force over a greater surface.

Nevertheless, it will be appreciated that these solutions for avoiding cavitation are not suitable for all types of watercraft and marine applications.

In fact, it is clear that a propeller like the one disclosed above, i.e. which rotates at low rotation speed, having very large blades, and which in use operates at significant depths, is not suitable for some types of watercraft, in particular for fast watercraft of small size, nor for those with great tonnage with speeds above about 20-25 knots.

More in general, fluid machines are machines that do not have great efficiency because in the transformation of mechanical energy into kinetic energy, or vice versa, much energy is dissipated.

Another drawback of these machines is that the efficiency thereof, already rather low, is significantly affected by the motion of the fluid, in particular in the impact zone between the fluid and the members of the machine arranged for interacting therewith. For example, the cavitation or a turbulent motion of the fluid cause a further reduction in the efficiency of the machine.

One object of the invention is to improve fluid machines of known type.

Another object is to make available a fluid machine that is able to operate effectively both as an operating machine and as a driving machine.

A further object is to make available a versatile machine that is able to interact with a fluid in different contexts and applications. Still another object is to provide a machine that is intended to be incorporated into a watercraft, in particular into the propulsion and steerage system thereof.

A still further object is to provide a machine intended to be incorporated into a mixing device for mixing the fluid in a homogeneous manner.

According to the invention, a machine according to claim 1 is provided. The invention can be better understood and implemented with reference to the attached drawings, which illustrate an embodiment thereof by way of non-limiting example, in which:

Figure 1 is a schematic section view of a machine according to the invention; Figure 2 is an enlarged and schematic section view of a portion of the machine of Figure 1 ;

Figure 3 is a schematic diagram that illustrates an operating condition of the machine in Figure 1.

With reference to Figures 1 and 2, a machine is shown for transmitting energy to, or receiving energy from, fluids in general, which has been indicated overall by 1.

The machine 1 comprises a containing structure 2 that receives an impeller 3 on which a plurality of blades 4 is rotatably mounted that are suitable for interacting with the fluid to transmit motion to, or receive motion from, the fluid. In the embodiment illustrated, the plurality of blades 4 comprises four blades 4a, 4b, 4c, 4d, which are visible in Figure 3. It is understood that in other embodiments a different number of blades can be provided.

The machine 1 comprises a guide shaft 10 to which the impeller 3 is connected. The guide shaft 10 extends along a main axis X. As the guide shaft 10 and the impeller 3 are coaxial with the main axis X, the rotation of the impeller 3 causes the consequent rotation of the guide shaft around the same axis.

Each blade 4a, 4b, 4c and 4d of the plurality of blades 4 rotates around its own rotation axis that is parallel to the main axis X. In the figures, where only the rotation axes of the blades 4a and 4c are clearly visible, such axes have been indicated respectively by Xa and Xc (Figure 1). Each blade 4a, 4b, 4c and 4d can rotate both clockwise, and anticlockwise around its own rotation axis. The blades 4 are rotatably mounted on the impeller 3 near a peripheral edge 3 a of the impeller 3 and are angularly equidistant from one another so as to adopt a symmetrical arrangement with respect to the main axis X. In the illustrated embodiment, the blades 4 are mounted on the impeller 3 spaced angularly apart from one another by an angle of 90°, as more clearly visible in Figure 3.

Each blade 4a, 4b, 4c and 4d can be symmetrical with respect to its rotation axis. In the illustrated embodiment, the blades 4 have a narrow and elongated shape.

It is understood that this shape of the blades is only one of the possible shapes that the blades can have. Depending on the mode of use of the machine 1 (see the different operating embodiments disclosed below) the blades 4 can have optimised dimensions and shapes according to the application.

The machine 1 further comprises fluid suction means 5 that sucks fluid into the impeller 3 along the main axis X.

The fluid suction means 5 is configured for promoting recirculation of the fluid inside the impeller 3 so as to increase the pressure of the fluid inside the impeller.

The fluid suction means 5 extends (in a longitudinal direction) coaxially with the main axis X, which is a central axis of symmetry of the impeller 3. Accordingly, the fluid suction means 5 is substantially equidistant in a radial direction from each blade 4a, 4b, 4c and 4d.

The fluid suction means 5 can comprise a worm screw or a propeller or a conveyor.

Owing to the fluid suction means 5, it is possible to deliver fluid inside the impeller 3, and thus increase the pressure inside the impeller 3, and, at the same time promote expulsion of the fluid. In other words, the fluid suction means 5 favours the circulation of the fluid inside the impeller 3, increasing the pressure so as to avoid the formation of vacuum zones where cavitation could be generated. Further, the fluid suction means 5 enables the drift effect that is caused by the rotation of the impeller 3 to be compensated. As the fluid suction means 5 is coaxial with the main axis X, it is also coaxial with the guide shaft 10 and with the impeller 3.

The fluid suction means 5 is fixed to the impeller 3 so as to rotate integrally therewith.

In one alternative embodiment that is not shown, the fluid suction means 5 can be rotatably connected to the impeller 3, such as to be able to rotate with respect to the latter. In this case, the impeller 3 and the fluid suction means 5 can rotate in different directions, for example one anticlockwise and the others clockwise, as schematised in the diagram of Figure 3. For this to be possible, it is opportune for the fluid suction means 5 and the impeller 3 to have different driving systems. In this embodiment, the driving system for driving the fluid suction means 5 can be integrated with the driving means of the blades 4, or can be a distinct driving system. The machine 1 comprises adjusting means 6 arranged for adjusting the position of the blades 4. In other words, the adjusting means 6 is arranged for modifying the orientation of each blade 4a, 4b, 4c and 4d around the respective rotation axis by a desired angle. The adjusting means 6 thus enables the machine 1 to act as a steering means (rudder) of a watercraft with which the machine 1 is associated. The adjusting means 6 comprises a plurality of motion transmitting elements, of known type, which are configured in such a manner as to rotate each blade 4a, 4b, 4c and 4d by a rotation of a certain angle around its own rotation axis.

The adjusting means 6 can be configured according to various versions, each comprising different motion transmitting elements. In the different embodiments the adjusting means 6 can comprise, by way of non-limiting example, known mechanical elements such as levers, gears, chains, belts, etc...

It is understood that the adjusting means 6 illustrated in the figures, which will be disclosed below, are merely an example of one possible embodiment that is able to rotate the blades 4 in a controlled manner.

The adjusting means comprises a first motion transmitting element 7 that acts as a control element and is intended to be connected to a source of energy that rotates the control element. The first transmitting element 7 can be configured as a shaft or as a belt or a chain. The first element is driven when an operator acts on a manoeuvring member functionally connected thereto. For example, if the machine 1 is associated with a watercraft, the first motion transmitting element 7 is rotated when the helmsman acts on the rudder to modify the course of the watercraft. A control system (that is not shown) is thus provided that is associated with the adjusting means 6 to connect functionally the rotation of the blades 4 to the position of the manoeuvring member (rudder).

The adjusting means 6 comprises a plurality of further elements 8, 9 to which the motion is transmitted by the first motion transmitting element 7, for example owing to a plurality of wheels or gears.

The further elements can comprise a shaft 8 and a belt or chain, or another element 9, for example a toothed belt. The shaft 8, rotating, drives the belt 9, which rotates a hollow shaft 14 that can rotate freely around the guide shaft 10. In other words, the hollow shaft 14 can rotate with respect to the guide shaft 10.

The belt or chain or another element 9 can be driven by the rotation of a wheel fitted to the shaft 8 and rotates the hollow shaft 14, with which it engages. The adjusting means 6 further comprises a pinion 19 mounted on the hollow shaft 14.

The machine 1 further comprises motion transmitting means 11 arranged for rotating the blades 4. The motion transmitting means 11 comprises toothed means 12, for example configured as one or more toothed wheels, connected to the impeller 3 and arranged for engaging, in use, with the pinion 19.

The motion transmitting means 11 further comprises a further element 13, for example configured as a belt or chain, or something else that is driven by the toothed means 12. The further element 13 is connected to the blades 4, such that, when the further element 13 is moved it is able to rotate each blade 4a, 4b, 4c and 4d around the respective rotation axes.

The motion transmitting means 11 can be configured as a single system that enables rotation to be transmitted to all the blades 4, or, alternatively, can comprise different kinematic chains, each of which can rotate a different blade 4a, 4b, 4c, 4d.

An expert person will understand that the motion transmitting means 11 can be configured according to different configurations, which are all technically equivalent, according to the choices made during the design step. For example, the motion transmitting means 11 can also comprise two driving systems, each of which transmits motion to a pair of blades.

The machine 1 further comprises driving means 15 for driving the impeller intended for rotating the impeller 3 and comprising a power shaft 16 that is connectable to a source of energy, such as, for example, an internal combustion engine.

To the power shaft 16 a bevel gear 17 is fitted that engages with a gear 18 to which the impeller 3 is connected stiffly. The gear 18 can, for example, be coaxial with the main axis X. In use, a rotation of the power shaft 16 thus causes a corresponding rotation of the impeller 3.

Different operating embodiments of the machine 1 according to the invention are disclosed below. EMBODIMENT 1

In a first embodiment, the machine 1 is used as an operating machine that is able to transfer kinetic energy (motion) to a fluid from incoming mechanical energy received by the power shaft 16.

In this embodiment, the machine 1 can be comprised in propulsion and steering means of a watercraft. In particular, the machine 1 can be connected to the hull 20 of the watercraft by connecting means 21, which are for example configured as a collar.

The machine 1 can give the fluid the thrust necessary for obtaining the displacement of the hull, owing to the principle of action and reaction.

The machine 1 further enables a laminar and non-swirling flow to be generated.

Owing to the possibility of orienting the blades 4 through the adjusting means 6, the machine 1 enables the flow of fluid to be directed in the desired direction. In fact, by modifying the arrangement of the blades 4, it is possible to orient the flow by any angle with respect to the longitudinal axis of the hull. Consequently, the machine 1 can act as a steering means for steering the watercraft, which can be devoid of the traditional rudder.

The machine 1 is generally arranged in the stern zone of the watercraft, where the propulsion propellers and the rudder are typically positioned.

It should nevertheless be noted that the machine 1 can also be located in other zones of the watercraft, depending on the type of watercraft and on the service requested.

With reference to Figure 3, a schematic diagram is shown of an operating condition of the machine 1.

The machine 1 has an initial position in which the blades 4 are oriented according to an arrangement that is such as to give the fluid a thrust indicated by the arrow F4, thus obtaining the reaction that determines the advancement direction of the hull, indicated by the arrow Fl .

The arrow Fl is arranged along the longitudinal axis of the watercraft in such a manner that when the blades 4 are in this arrangement the watercraft proceeds in its advancement direction. This initial position of the machine thus defines a position that can be called the "zero point".

The impeller 3, driven by the driving means 15, is rotating anticlockwise, as indicated by the arrow F2. The rotation of the impeller 3 involves the rotation of the toothed means 12, which engages with the pinion 19, which on the other hand remains stationary. The toothed means 12 thus rotates the plurality of blades 4a, 4b, 4c and 4d, each around its own rotation axis. The thrust on the fluid generated by the combined rotation of the impeller 3 and of the blades 4 is thus directed as indicated by the arrow F4.

It is understood that the machine 1 can generate a thrust on the fluid directed in an opposite direction, in particular by reversing the rotation of the power shaft 16. In this case, the combined rotation of the impeller 3 and of the blades 4 generates a thrust on the fluid that will give the hull a thrust oriented according to the arrow F4. In this operating condition, the machine 1 is giving the fluid a thrust indicated by the arrow Fl and thus the watercraft is moving backwards in the direction indicated by the arrow F4, i.e. in a direction opposite the previously mentioned advancement (Fl) direction.

Unlike the embodiment illustrated in Figures 1 and 2 disclosed previously, in the diagram in Figure 3 the fluid suction means 5 is driven by dedicated driving means and is rotating anticlockwise, as indicated by the arrow F3.

In the "zero point" position, the blades 4 are angularly staggered in relation to one another. In the illustrated embodiment, in which four blades 4a, 4b, 4c, 4d are provided, they are staggered in relation to one another by an angle of 45°. The machine 1 is configured in such a manner that whilst the impeller 3 performs a rotation of 90°, each blade 4a, 4b, 4c, 4d rotates around its own rotation axis by an angle of 45°. In this manner, whilst the impeller 3 rotates by 360°, each blade 4a, 4b, 4c, 4d has rotated by 180° around its own rotation axis.

When the helmsman desires to change the course of the watercraft, the helmsman acts on a manoeuvring member, positioning the manoeuvring member in such a manner as to follow the desired course.

The displacement of the manoeuvring member (rudder) activates the adjusting means 6. In particular, the first motion transmitting element 7 (through the shaft 8 and the belt 9) rotates the hollow shaft 14 by an angle that is proportional to the displacement of the manoeuvring member. The rotation of the hollow shaft 14 causes the rotation of the pinion 19, which, by engaging with the toothed means 12, through the latter causes the blades 4 to rotate by a certain angle.

In this manner, the blades 4 adopt a new configuration, owing to which the force that the machine 1 exerts on the fluid is no longer oriented along the longitudinal axis of the watercraft (as shown in Figure 3), but is instead oriented in such a manner as to form any angle with the longitudinal axis. It is understood that the force Fl can thus be oriented according to any angle along the complete round angle. Owing to the possibility of orienting simply and rapidly the thrust on the fluid, which makes it possible to eliminate the rudder, the machine 1 is extremely versatile.

In particular, the machine 1 is very suitable for being included in propulsion and steering means of watercraft that require frequent manoeuvres, in limited spaces and with strong currents. The machine 1 thus gives the watercraft great manoeuvrability. For example, the machine 1 can be advantageously comprised in propulsion and steering means of a ferry or a steamer, or large ships manoeuvring in ports, on river barges, or on cable-laying ships or on survey ships. In other embodiments, the machine 1 can be advantageously applied in tugs, which have to push a ship both from the bow and the side, or in ships intended to give support to offshore operations or become systems of propulsion and positioning of an offshore oil platform, which has to be positioned with extreme precision on the extraction site.

Another advantage of the great manoeuvrability offered by the machine 1 is that of increasing safety for persons and operators involved in the manoeuvring operations. A further advantage of the machine 1, which generates a laminar and thus substantially horizontal flow, is that of being able to be used even on low seabeds, respecting marine flora and fauna.

Yet another advantage of the machine 1, which is particularly efficient at low speeds, is that of reducing consumption, which enables savings to be made on the cost of fuel and further enables polluting emissions into the environment to be reduced.

EMBODIMENT 2 In another embodiment, the machine 1 is used as a driving machine that is able to generate mechanical energy from the kinetic energy of a fluid.

The machine 1 is positioned in such a manner as to be immersed into a fluid, for example water. The fluid flow, can, for example, be substantially orthogonal to the main axis X. It is understood that the flow of fluid can hit the machine 1 according to any direction. It is clear to the expert person that the efficiency of the machine 1 depends, amongst other things, also on the angle of tilt at which the flow of fluid hits the machine 1. When the flow of fluid meets the blades, the fluid exerts such a pressure on the blades as to rotate the impeller 3.

The impeller 3 rotates the gear 18, which is connected to the impeller 3 and transmits the rotation to the bevel gear 17. Consequently, as the latter is fitted to the shaft 16, also the shaft rotates.

In this embodiment, the machine 1 thus comprises a shaft 16 intended for being rotated by the impeller 3, which is in turn rotated by the fluid. The shaft 16 is in this case a driven shaft that can be connected to a generator, and to which mechanical energy is supplied that is obtained by converting the kinetic energy of the operating fluid. It is understood that in this embodiment, unlike the preceding embodiment, the structure of the machine 1 can be different from the embodiment disclosed and illustrated in the attached figures according to the different modes of use of the machine. For example, the blades 4 can have a geometry (shapes and dimensions) that is different from what is illustrated in the attached figures, assuming, for example, a disc shape.

EMBODIMENT 3

In still another embodiment, the machine 1 is comprised in a mixing device. The mixing device is arranged for transmitting motion to a fluid and thus acts as an operating machine.

The mixing device comprising the machine 1, owing to the latter, enables a fluid to be mixed homogeneously.

For example, the mixing device is suitable for mixing paints, resins or medicines in fluid state. In general, the mixing device can be used for mixing very dense or viscous fluids and/or materials with a high degree of instability. The mixing device can be advantageously used in particular when a fluid, in order to preserve the chemical and physical features thereof, has to be mixed slowly, for a long time and at a substantially constant speed.