Field of The Invention

[0001] The present invention generally finds application in the field pf pneumatic or oil-hydraulic devices and particularly relates to a fluid-dynamic device for transferring power from a drive shaft of a rotating machine to a driven shaft (3) of a mechanical load.

Background art

[0002] It has long been known to use rotating machines having a drive shaft rotating about a corresponding axis of rotation and adapted to deliver a torque of predetermined value to promote the movement of a mechanical load or transmit a drive to a mechanism.

[0003] Nevertheless, many practical applications require control of the rotation speed of the drive shaft and/or the torque delivered by the machine, which may be quite difficult, especially with machines that must comply with close dimensional restrictions.

[0004] At least some of the above problems have been solved using transmission devices, such as reduction gear or the like, having an input connected to the drive shaft and an output operably connected with the mechanical load to be moved.

[0005] Such reduction gear devices have a predetermined reduction ratio to output a torque that is higher than the torque at the input.

[0006] Nevertheless, these solutions still have drawbacks, such as a high cost, limited torque multiplication, increased overall layout of the machine- reduction gear assembly, and limited performance.

[0007] Furthermore, a serious handicap of these solutions is that the output rotation speed of these reduction gear devices is still lower than the rotation speed of the drive shaft of the rotating machine.

[0008] Thus, in order that the load is rotated at a predetermined rated rotation speed it is necessary to use a rotating machine whose drive shaft has a rotation speed that is substantially equal to the product of the rated speed by the reduction ratio.

[0009] This imposes highly stringent design restrictions on the dimensions of the moving parts and the selection of the rotating machine to be used, which involves a considerably lower versatility of the assembly.

[0010] A further drawback is that the systems that comprise reduction gear devices associated with the rotating machines are highly complex and have very high management costs.

Technical Problem

[0011] In the light of the prior art, the technical problem addressed by the present invention consists in affording efficient power transmission from a rotating machine to a mechanical load, while limiting the complexity of the system.

Disclosure of the invention

[0012] The object of the present invention is to obviate the above drawbacks, by providing a fluid-dynamic power transmission device that is highly efficient and relatively cost-effective.

[0013] A particular object of the present invention is to provide a fluid- dynamic device as described hereinbefore that has a low cost and a small size.

[0014] Another object of the present invention is to provide a fluid-dynamic device as described hereinbefore that promotes efficient power transmission.

[0015] A further object of the present invention is to provide a fluid-dynamic device as described hereinbefore that is very simple.

[0016] Another object of the present invention is to provide a fluid-dynamic device as described hereinbefore, that can reduce the design restrictions of the rotating machine with which it is connected.

[0017] A further object of the present invention is to provide a fluid-dynamic device as described hereinbefore that can be easily used with any type of rotating machine.

[0018] These and other objects, as more clearly explained below, are fulfilled by a fluid-dynamic device for transferring power from a drive shaft of a rotating machine to a driven shaft of a mechanical load as defined in claim 1 , and comprising a stationary box-like housing which defines an inner chamber with side walls, filled with a liquid, a drive shaft rotating about a main axis which extends through a first hole of the box-like housing, a driven shaft coaxial with the drive shaft and extending through a second hole of the box-like housing, a substantially cylindrical first rotor accommodated in the chamber and coupled to the drive shaft and a substantially cylindrical second rotor accommodated in the chamber and coupled to the driven shaft.

[0019] The first and second rotors are axially offset and have front surfaces in facing relationship to define a gap having a constant thickness therebetween. Furthermore, the first and second rotors have substantially cylindrical peripheral surfaces with substantially radial blades at uniform distances from the side walls of the housing to define a substantially annular space, such that the rotation of the first rotor, driven by the drive shaft will cause the liquid to circulate in the chamber and through the gap and the space, and the second rotor and the driven shaft to be driven into rotation.

[0020] Advantageous embodiments of the invention are obtained in accordance with the dependent claims.

Brief Description of The Drawings

[0021] Further features and advantages of the invention will be more apparent upon reading of the detailed description of a preferred, non-exclusive embodiment of a fluid-dynamic power transmission device of the invention, which is described as a non-limiting example with the help of the annexed drawings, in which:

FIG. 1 is a schematic view of a mechanical system comprising the fluid- dynamic device of the invention;

FIG. 2 is a broken-away side view of the fluid-dynamic device of Fig. 1 ; FIG. 3 is a broken-away top view of the fluid-dynamic device of Fig. 1 .

Detailed description of a preferred exemplary embodiment

[0022] The above figures show a fluid-dynamic device, generally designated by numeral 1 , for transferring power from a drive shaft 2 of a rotating machine M to a driven shaft 3 of a mechanical load W.

[0023] Particularly, the rotating machine M may preferably be a known electric motor having predetermined torque and rotational speed v characteristics.

[0024] It its basic embodiment, the fluid-dynamic device 1 comprises a box- like housing 4, which is stationary relative to the drive shaft 2 and the driven shaft 3 and defines an inner chamber 5, filled with liquid L and having a pair of side walls 6, 7.

[0025] Furthermore, the housing 4 comprises a top wall 8 and a bottom wall 9. The top wall 8 may be removable relative to the side walls 6, 7 yo act as a closing cover for the chamber 5.

[0026] The housing 4 may be stably mounted to a support frame, not shown, by means of appropriate connection means.

[0027] The housing 4 is hermetically sealed to hold the liquid L within the inner chamber 5. The liquid L may be pressurized in the chamber 5 and is preferably water.

[0028] The fluid-dynamic device 1 comprises a drive shaft 2 that rotates about a substantially longitudinally main axis X and a driven shaft 3 coaxial with the drive shaft 2.

[0029] The drive shaft 2 and the driven shaft 3 extend through first 10 and second 1 1 holes formed in the bottom wall 9 and the top wall 8 respectively of the housing 4 and have a first end 2', 3' located outside the chamber 5 and coupled to the rotating machine M or the mechanical load W and a second end 2", 3" located within the chamber 5.

[0030] Advantageously, the drive shaft 2 and the driven shaft 3 are rotatably supported at the first 10 and second 1 1 holes, via respective bearings 12 and hydraulic seals.

[0031] The device 1 comprises a substantially cylindrical first rotor 13 accommodated in the chamber 5 and coupled to the drive shaft 2 and a substantially cylindrical second rotor 14, which is also accommodated in the chamber 5 and is coupled to the driven shaft 3.

[0032] In the embodiment of the figures, the first rotor 13 is located below the second rotor 14. Nevertheless, the positions of the two rotors 13, 14 may be also reversed, without departure from the scope of the present invention.

[0033] Conveniently, as shown in the figures, the first 13 and second 14 rotors may have substantially different diameters d and thicknesses t. Alternatively, the diameters d and thicknesses t of the two rotors 13, 14 may be also equal.

[0034] In a peculiar aspect of the invention, the first 13 and second 14 rotors are axially offset and have front surfaces 15, 16 in facing relationship to define a gap 17 having a constant thickness therebetween.

[0035] In addition, the first 13 and second 14 rotors have substantially cylindrical peripheral surface 18, 19 with substantially radial blades 20, spaced apart from the side walls 6, 7 of the housing 4 to define a substantially annular space 21 .

[0036] In this configuration, the rotation of the first rotor 13 driven by the drive shaft 2 causes the liquid L to circulate in the chamber 5, through the gap 17 and the space 21 and the second rotor 14 and the driven shaft 3 to be driven into rotation.

[0037] As best shown in FIG. 3, each rotor 13, 14 comprises four radial blades 20, which are angularly offset through 90°. Nevertheless, a different number of radial blades 20 may be also envisaged as needed, without departure from the scope of the present invention.

[0038] Furthermore, the blades 20 may have an inclined, warped or elongated configuration, in the radial or longitudinal direction or may be asymmetrically distributed with respect to the rotors, without departure from the scope of the present invention.

[0039] In the illustrated embodiment, the first rotor 13 is keyed to the drive shaft 2 at the second end 2" by means of respective tongues 22 or similar members, whereas the second rotor 14 is coupled to the driven shaft 3 at the second end 3", by means of a plurality of angularly offset spokes 23.

[0040] In an alternative embodiment, not shown, both rotors 13, 14 are keyed to the drive shaft 2 or the driven shaft 3 by means of respective pluralities of tongues 22.

[0041] As best shown in FIG. 2, the first 13 and second 14 rotors comprise respective central cavities 24, 25 in mutually facing relationship and in fluid communication with the gap 17 and the inner chamber 5.

[0042] Namely, the central cavity 25 of the second rotor 14 may be formed throughout the thickness t thereof and may have a first opening 25' facing the gap 17 and a second opening 25' formed on the face 26 opposite to the gap 17.

[0043] In this configuration, the spokes 23 for keying the second rotor 14 to the driven shaft 3 are respectively connected to the outer wall 27 of the driven shaft 3 and to the circular edge 28 of the second opening 25", as shown in FIG. 3.

[0044] Preferably, the first 13 and second 14 rotors may comprise respective radial channels 29, 30, which are adapted to connect the central cavities 24, 25 with their respective peripheral surface 18, 19, particularly with the above described space 21 .

[0045] These channels 29, 30 can guide the liquid L between each central cavity 24, 25 and the space 21 to generate a free vortex in the chamber 5.

[0046] In operation, the rotation of the drive shaft 2 and of the first rotor 13 causes the liquid L to flow in the latter from the central cavity 24 to the space 21 . This flow generates the free vortex in the inner chamber 5, promoting the rotation of the second rotor 14.

[0047] In the second rotor 14, during its rotation, the flow of the liquid L follows an inverse path, i.e. from the space 21 to the central cavity 25, which helps it to keep on rotating after the action of the first rotor 13.

[0048] In the illustrated embodiment, each of the first 13 and second 14 rotors comprise four radial channels 29, 30, which are angularly offset from the corresponding radial blade at a predetermined angle, e.g. approximately 45° as shown in the figures.

[0049] Nevertheless, as stated concerning the blades 20, a different number of radial blades 30 may be also envisaged as needed, without departure from the scope of the present invention.

[0050] Namely, the blades 20 may be substantially vertical and have a height that is slightly smaller than the thickness t of the first 13 and second 14 rotors. In addition, they may be mounted to the portions of the peripheral surface 18, 19 that do not have the openings of the radial channels 29, 30.

[0051] As best shown in FIGS. 2 and 3, a plurality of front blades 31 are provided on the opposite face 26 of the second rotor 14 with respect to the gap 17, to increase the rotating effect of the free vortex.

[0052] The front blades 31 are angularly aligned with the radial vanes 20 and are mounted to the second rotor 14 only when the latter is keyed to the driven shaft 3 by means of the spokes 23.

[0053] Nevertheless, the front blades 31 may be also angularly offset with respect to the radial blades 20, without departure from the scope of the present invention.

[0054] It will be appreciated from the foregoing that the fluid-dynamic device of the invention fulfills the intended objects, by affording a very simple control of the rotation speed and/or the torque delivered by the drive shaft of a rotating machine.

[0055] The fluid-dynamic device of the invention is susceptible to a number of changes and variants, within the inventive concept disclosed in the appended claims.

[0056] All the details thereof may be replaced by other technically equivalent parts, and the materials may vary depending on different needs, without departure from the scope of the invention.

[0057] While the fluid-dynamic device has been described with particular reference to the accompanying figures, the numerals referred to in the disclosure and claims are only used for the sake of a better intelligibility of the invention and shall not be intended to limit the claimed scope in any manner.

Industrial Applicability

[0058] The present invention may find application in industry, because it can be produced on an industrial scale in factories for production of fluid-dynamic control devices and may be used for various applications, e.g. for commercial, industrial and private purposes.