Field of the invention

[0001] The present invention generally relates to the technical field of pneumatic or oil-hydraulic devices, and it particularly relates to an improved fluid dynamic device for transmitting power from a drive shaft of a rotating machine to a driven shaft of a mechanical load.

Background art

[0002] The use of rotating machines having a drive shaft rotatable around a corresponding rotation axis and adapted to dispense a drive torque with predetermined value to promote the motion of a mechanical load or provide a transmission to a kinematic mechanism has been long known.

[0003] In many practical applications there is required the adjustment of the rotation speed of the drive shaft and/or of the torque dispensed by the machine and this can be particularly complicated, especially when the machines are required to meet specific dimensional limits.

[0004] With the aim of at least partly overcome these problems, combined with the rotating machines there are often used motion transmission devices, such as for example gear reducers or the like, having an input connected to the drive shaft and an output operatively connected with the mechanical load to be moved.

[0005] Such reducer devices have a predetermined reduction ratio to provide an output drive torque increased with respect to the input torque.

[0006] Nevertheless, even such solutions are not exempt from drawbacks, such as for example their high cost, a limited multiplication of the torque, the increase of the overall dimensions of the machine-gear reducer assembly and the still limited performance.

[0007] A particularly negative drawback of such solutions lies in the fact that the output rotation speed at the reducer devices is always lower than the rotation speed of the drive shaft of the rotating machine.

[0008] As a matter of fact, as a result, in order to promote the rotation of the load at a pre-established nominal rotation speed there arises the need to use a rotating machine having a rotation speed of the drive shaft substantially equal to the product of the nominal speed by the reduction ratio.

[0009] This requires particularly strict design limitations as to the sizing the rotary components and choosing the rotating machine to be used, and this significantly reduces the flexibility of the assembly.

[0010] Furthermore, a further drawback lies in the fact that the systems comprising reducer devices associated with the rotating machines are particularly complex and they have particularly high management costs.

Technical problem

[0011] In the light of the prior art, the technical problem addressed by the present invention is to allow the efficient transmission of power from a rotating machine to a mechanical load with limited complexity of the system.

Summary of the invention

[0012] An object of the present invention is to overcome the abovementioned drawbacks, by providing a fluid dynamic device for transmitting power which is highly efficient and relatively cost-effective.

[0013] A particular object of the present invention is to provide a fluid dynamic device of the type described above which has low costs and overall dimensions.

[0014] Another object of the present invention is to provide a fluid dynamic device of the type described above which promotes an efficient transmission of power.

[0015] A further object of the present invention is to provide a fluid dynamic device of the type described above which can be easily used with any type of rotating machine.

[0016] Another object of the present invention is to provide a fluid dynamic device of the type described above which allows to reduce the design limitations of the rotating machine to which it is connected.

[0017] These and other objects that will be more apparent hereinafter are achieved by a fluid dynamic transmission device for transmitting power from a drive shaft of a rotating machine to a driven shaft associated with a mechanical load according to claim 1 , which device comprises a stationary box-like casing defining an inner chamber filled with a fluid, a drive shaft rotatable around a primary axis and a driven shaft coaxial to the drive shaft, a first rotor and a second rotor housed in the chamber and respectively coupled to the drive shaft and to the driven shaft.

[0018] The first and the second rotor are axially offset to define between them a laminar gap with substantially constant thickness and the first and/or with the second rotor is/are associated with at least one propeller or similar device coupled to the respective shaft.

[0019] Advantageously, the first and the second rotor have respective substantially annular inner and outer peripheral surfaces joined by a respective plurality of substantially radial partitions and a respective transversal closing wall substantially shaped as a circular crown, and the peripheral surfaces, the plurality of partitions and the closing walls being adapted to define respective first and second radial cavities and respective central cavities, the latter being placed in communication with the laminar gap and with the inner chamber. Furthermore, the at least one propeller is positioned in one or both central cavities and it is configured to generate a differential pressure in the fluid between the central cavities and the inner chamber to promote the circulation of the fluid through the laminar gap and the driving in rotation of the second rotor and the driven shaft.

[0020] Advantageous embodiments of the invention are attained according to the dependent claims.

Brief description of the drawings

[0021] Further features and advantages of the invention will be more apparent in the light of the detailed description of a preferred but nonexclusive embodiment of a fluid dynamic device for transmitting power according to the invention, shown by way of non-limiting example with reference to the following drawing sheets, wherein:

FIG. 1 is a cross-sectional lateral view of an embodiment of the fluid dynamic device according to the invention;

FIGS. 2 and 3 are top cross-sectional views of the fluid dynamic device of Fig. 1 along a first cross-sectional plane ll-ll and a second cross-sectional plane Ill-Ill.

Detailed description of a preferred embodiment

[0022] With reference to the figures mentioned above, there is shown a fluid dynamic device, globally indicated with the reference numeral 1, for transmitting power from a drive shaft 2 of a rotating drive machine M to a driven shaft 3 associated with a mechanical load W.

[0023] In particular, the machine M may preferably be an electric motor of the per se known type having predetermined torque and rotation speed.

[0024] In the most essential embodiment, the fluid dynamic device 1 comprises a box-like casing 4 that is stationary with respect to the drive shaft 2 and to the driven shaft 3 and defines an inner chamber 5 filled with a fluid F.

[0025] Preferably, the inner chamber 5 of the box-like casing 4 has a substantially cylindrical lateral wall 6.

[0026] As better shown in FIG. 1, the casing 4 is hermetically closed to seal the fluid F in the inner chamber 5. The fluid F may comprise a liquid, preferably water, or a pressurised gas.

[0027] The casing 4 comprises an upper wall 7 and a bottom wall 8. The upper wall 7 may be movable with respect to the side wall 6 so as to act as a lid for closing the chamber 5.

[0028] In a per se known manner, the upper wall 7 may be coupled to the side wall 6 using appropriate connection means 9.

[0029] The fluid dynamic device 1 comprises a drive shaft 2 rotatable around a substantially longitudinal primary axis X, a driven shaft 3 coaxial with respect to the drive shaft 2 and a transmission shaft 3’ connected to the driven shaft 3 and directly connected to the mechanical load W.

[0030] The transmission shaft 3’ may be coaxial with the driven shaft 3, as shown in a first embodiment, shown in FIG. 1, or radially offset with respect to the driven shaft 3 in a second embodiment, not shown in the figures.

[0031] The drive shaft 2 crosses a first hole 10 formed in the bottom wall 8 and it has a first end positioned outside the chamber 5 and coupled to the rotating machine M and a second end located inside the chamber 5.

[0032] Furthermore, the driven shaft 3 crosses a second hole 11 formed in the upper wall 7 of the casing 4 and it has a first end positioned outside the chamber 5 and operatively coupled to the mechanical load W and a second end located inside the chamber 5.

[0033] Advantageously, the drive shaft 2 and the driven shaft 3 or the transmission shaft 3’ are rotatably supported at the first 10, at the second hole 11 using respective bearings 12 and sealings.

[0034] A first substantially cylindrical rotor 13 coupled to the drive shaft 2 and a second substantially cylindrical rotor 14 coupled to the driven shaft 3 are housed in the chamber 5.

[0035] Suitably, as shown in the figures, the first 13 and the second rotor 14 may have substantially equal diameters and thicknesses. Alternatively, the diameters and the thicknesses of the two rotors 13, 14 may also be different.

[0036] The first 13 and the second rotor 14 are axially offset to define between them a laminar gap 17 with substantially constant thickness.

[0037] As shown in the figures, the first 13 and/or the second rotor 14 is/are associated with at least one propeller 28, or similar device, coupled to the respective shaft 2, 3.

[0038] According to a peculiar aspect of the invention, the first 13 and the second rotor 14 have respective substantially annular inner 18, 19 and outer peripheral surfaces 18’, 19’, and such peripheral surfaces 18, 19; 18’, 19’ are joined by a respective plurality of substantially radial partitions 20, 20’ and by a respective transversal closing wall 15, 16 substantially shaped as a circular crown and opposite to the laminar gap 17, as better shown in FIG. 2.

[0039] Furthermore, the peripheral surfaces 18, 19; 18’, 19’, the plurality of partitions 20, 20’ and the closing walls 15, 16 are adapted to define respective first 21 and second radial cavities 2T and respective central cavities 24, 25, all placed in communication with the laminar gap 17 and with the inner chamber 5.

[0040] Therefore, the at least one propeller 28 is positioned in one or both the central cavities 24; 25 and it is configured to generate a differential pressure in the fluid F between the central cavities 24, 25 and the inner chamber 5, to promote the circulation of the fluid F through the laminar gap 17 and the driving in rotation of the second rotor 14 and of the shaft 3.

[0041] In the embodiment shown in FIGS. 1-2, the propeller 28 is positioned between the cavities 24, 25 and its blades 28’ touch the laminar gap 17. However, the propeller 28 may be present also, or only, in the central cavity 25, or in the central cavity 24, with similar, or better, driving results of the second rotor 14.

[0042] In particular, the central cavity 24, 25 of the first 13 and second rotor 14 may be obtained in the entire thickness thereof.

[0043] According to a particular aspect of the invention, the transversal closing wall 16 of the second rotor 14 comprises a plurality of blades 22 parallel to the partitions 20 and configured to form respective radial channels 22’ adapted to promote the circulation of the fluid F towards the central cavities 24, 25 and therefore towards the propeller 28.

[0044] Furthermore, in correspondence of the radial channels 22’ and/or at the transversal closing wall 16 of the second rotor 14, the side wall 6 is provided with a shaped profile 23 adapted to define a substantially toroidal annular cavity 26 configured to promote the circulation of the fluid F towards the radial channels 22’ and therefore towards the central cavity 24, 25.

[0045] Preferably, the shaped profile 23 at the substantially toroidal annular cavity 26 has an annular member 27 configured to facilitate the conveyance of the fluid F towards the radial channels 22’ and therefore towards the central cavity 24, 25.

[0046] Obviously, the annular member 27 may be supported inside the annular cavity 26 using suitable supports 27’, as better shown in FIG. 3.

[0047] In order to further facilitate the conveyance of the fluid F towards the propeller 28, the central cavity 25, 24 is flared and has a larger diameter in proximity of the transversal closing wall 16, 15 of the rotor 14, 13 and a smaller diameter at the propeller 28.

[0048] In the light of the foregoing, it appears that the device 1 is configured to displace the fluid F towards the central cavity 24, 25 in the most efficient manner possible thereby avoiding turbulences and consequently increasing the fluid dynamic efficiency thereof.

[0049] To this end, the blades 22 and the partitions 20, 20’ are angularly aligned and angularly offset with respect to each other by a predetermined angle.

[0050] Preferably, each rotor 13, 14 comprises eight radial partitions 20, 20’ angularly offset with respect to each other by 45°. However, a different number of partitions 20, 20’ may be provided depending on the needs of the device without departing from the scope of protection of the present invention.

[0051] Furthermore, the partitions 20, 20’ may have a configuration inclined, twisted, extended in the radial and longitudinal direction or they may be distributed asymmetrically with respect to the rotors, without departing from the scope of protection of the present invention.

[0052] The device 1, further comprises first transmission means 29, positioned inside the box-like casing 4, connected to the driven shaft 3 and to the first rotor 13 and/or to the second rotor 14 for transmitting the rotary motion from the first 13 and/or second rotor 14 to the propeller 28 and vice versa.

[0053] As better shown in the figures, the second rotor 14 comprises a first support wall 16’ for supporting the first transmission means 29 parallel to the transversal closing wall 16 of the second rotor 14 and connected to the latter using the plurality of blades 22.

[0054] Similarly, the first rotor 13 is coupled to the drive shaft 2 through a second support wall 17’ keyed to the drive shaft 2, spaced apart from and parallel to the transversal closing wall 15 of the first rotor 13. Furthermore, the second support wall 17’ is connected to the transversal closing wall 15 through at least three parallel columns 17”.

[0055] Such configuration allows the fluid F to freely flow from the central cavity 24, 25, ascend along the side wall 6 touching the outer peripheral surfaces 18’, 19’ of the rotors 13, 14 to be subsequently channelled into the respective radial channels 22’.

[0056] Operatively, the rotation of the drive shaft 2 and of the first rotor 13 causes, in the latter, the flow of the fluid F from the radial channels 21 to the radial channels 2T through the laminar gap 17, generating a free vortex which promotes the rotation of the second rotor 14.

[0057] Inside the second rotor 14, during rotation thereof, the flow of the fluid F travels across a contrary path, that is from the radial channels 2T to the radial channels 21 through the laminar gap 17, while keeping it in rotation.

[0058] Furthermore, the rotation of the second rotor 14 promotes, through the first transmission means 29, the rotation of the driven shaft 3 (therefore of the propeller 28) as well as of the transmission shaft 3’ directly connected to the load W.

[0059] Suitably, there are provided second transmission means 30 suitable to connect the driven shaft 3 to the transmission shaft 3’ so as to transfer the rotary motion of the second rotor 14 to the mechanical load W.

[0060] In the embodiment shown in FIG. 1, in which the transmission shaft 3’ is axial to the driven shaft 3, the second transmission means 30 comprise a mechanical joint. [0061] In a second embodiment, not shown in the figures and in which the transmission shaft 3’ is radially offset with respect to the driven shaft 3, the second transmission means 30 may comprise a mechanical kinematic mechanism operatively coupled to the first transmission means 29.

[0062] In particular, the first transmission means 29, as well as the mechanical kinematic mechanism, are selected from the group of gearwheels and/or ring gears, transmission belts, magnetic transmissions.

[0063] By way of example, as shown in FIG 1, the first transmission means 29 comprise a ring gear 33 integral with the first support wall 16’ which interacts with a first gearwheel 34 integral with an idler shaft 35 supported by the upper wall 7 of the box-like casing 4.

[0064] Furthermore, on the driven shaft 3 there is keyed a second gearwheel 36 meshing with the first gearwheel 34 for transmitting the rotary motion from the second rotor 14 to the driven shaft 3 and finally to the propeller 28.

[0065] In the second embodiment, not shown in the figures and wherein the transmission shaft 3’ is radially offset with respect to the driven shaft 3, the mechanical kinematic mechanism may comprise a third gearwheel integral with the transmission shaft 3’ and interacting with the ring gear 33 for transmitting the rotary motion from the second rotor 14 to the shaft 3’.

[0066] In both embodiments, the transmission shaft 3’ may be directly connected to the mechanical load W through an electromagnetic and/or mechanical clutch 38 and a flywheel 39, or similar device, adapted to transmit the rotary motion of the transmission shaft 3’ to the mechanical load W.

[0067] In the light of the foregoing, the fluid dynamic device according to the invention achieves the established objects, allowing to adjust the rotation speed and/or the torque dispensed by the drive shaft of a rotating machine in a particularly simple manner.

[0068] Although the fluid dynamic device has been described with particular reference to the attached figures, the reference numerals used in the description and in the claims are meant for improving the intelligibility of the invention and do not limit the claimed scope of protection in any manner whatsoever. Industrial applicability

[0069] The present invention can be applied at industrial level because it can be produced in an industrial scale by industries belonging to the field of manufacturing adjustment fluid dynamic devices and it can be used in various fields, for example trade, industrial and private.