Gyroscope for Anti-roll stabilizer and gyroscopic effect Anti-roll stabilizer

Abstract

A gyroscope (1) for an anti-roll stabilizer for a seacraft is described, comprising: a flywheel (3), mounted on a shaft (4) having a first end (41) and a second end (42) which is opposite to said first end (41) wherein the ends of the shaft (4) are supported by pairs of angular contact ball bearings arranged in tandem, with an overall "O" configuration, and an adjustable preload member (7) to axially push the outer rings (832, 842) of the angular contact ball bearings (83, 84) and thereby to preload all the bearings of the gyroscope (81, 82, 83, 84).

Description

[0001] GYROSCOPE FOR ANTI-ROLL STABILIZER AND GYROSCOPIC EFFECT ANTI-ROLL

[0002] STABILIZER

[0003] DESCRIPTION

[0004] Related applications

[0005] This application claims the priority of the Italian patent application 102023000027381, filed on December 20, 2023, and the Italian patent application 102023000027387, filed on December 20, 2023, the content of which is fully incorporated herein.

[0006] Technical Field

[0007] A gyroscope for an anti-roll stabilizer for a seacraft is described herein below.

[0008] A gyroscopic effect anti-roll stabilizer, of the two-degrees-of-freedom type, which comprises such gyroscope is also described.

[0009] Background art

[0010] Anti -roll stabilizers are devices used for reducing the rolling of seacrafts .

[0011] Gyroscopic effect anti-roll stabilizers are devices installed inside the hulls of the seacrafts, typically near the keel of the seacraft.

[0012] Gyroscopic effect anti-roll stabilizers exploit the physical principle of the gyroscope, whereby a rotating mass opposes an external force which attempts to deviate the initial rotational axis thereof.

[0013] The gyroscope of an anti-roll stabilizer comprises a flywheel mounted on a shaft, actuated by an electric motor, which is supported by rolling bearings (usually ball bearings).

[0014] Extremely briefly, the gyroscope rotating about an axis and being able to oscillate with respect to a second axis, creates an action of contrast to the oscillations whereto the seacraft is subjected and, in particular, to rolling.

[0015] WO2019224322 discloses a gyroscope for an anti-roll stabilizer for a seacraft, comprising a housing and a flywheel, placed inside the housing, attached to a shaft mounted between a first group of bearings and a second group of bearings.

[0016] An electric motor, of the type having an internal rotor and an external stator, is provided to rotate the shaft and thereby the flywheel.

[0017] The motor is positioned externally to the two groups of bearings.

[0018] W02022234080 discloses a gyroscope for an anti-roll stabilizer of a seacraft, comprising a housing and a flywheel, connected to a shaft, placed inside the housing and mounted between a first group of bearings and a second group of bearings.

[0019] An electric motor, of the type having an external rotor and an internal stator, which is positioned in an intermediate positioned between the two groups of bearings, is provided to rotate the flywheel.

[0020] The currently known gyroscopic effect anti -roll stabilizers have some drawbacks. For example, they are subject to frequent periodic operations for maintenance and replacement of the worn components, such as the rolling bearings.

[0021] Summary

[0022] A gyroscope for an anti-roll stabilizer for seacrafts, which is able to at least partially overcome the problems of the prior art and in particular at least one part the above mentioned problems, is described.

[0023] In particular a gyroscope for an anti-roll stabilizer for seacrafts, which allows the wear of the rolling bearings and thereby the frequency of bearing replacement operations to be reduced is described.

[0024] These objectives are achieved by means of an anti-roll stabilizer according to the description and the drawings.

[0025] Further advantages can be achieved by means of a gyroscopic effect anti-roll stabilizer according to the content of the present application.

[0026] Brief description of the drawings

[0027] A possible embodiment of a gyroscope for an anti-roll stabilizer for seacrafts is described herein below with reference to the accompanying sheets of drawings in which:

[0028] Figure 1 is a schematic perspective view of a gyroscopic effect anti -roll stabilizer;

[0029] Figure 2 is a sectional view of a gyroscope ;

[0030] Figure 3 is an enlarged view of a portion of the gyroscope in Figure 2 with respect to a first section plane;

[0031] Figure 4 is an enlarged view of the same portion of the gyroscope as in Figure 3 with respect to a second section plane;

[0032] Figure 5 is an enlarged longitudinal sectional view of another portion of the gyroscope in Figure 2;

[0033] Figure 6 is a hydraulic diagram relating to the preload of the gyroscope bearings;

[0034] Figure 7 is the same view as in Figure 2 and highlights the “O” configuration of the thrust axes of the bearings;

[0035] Figure 8 is an exploded view relating to the flywheel and the shaft of the gyroscope flywheel;

[0036] Figure 9 is a longitudinal sectional view of a flywheel and shaft assembly for a gyroscope according to an embodiment alternative to the one in Figure 8;

[0037] Figure 10 is an enlarged longitudinal sectional view of a portion of a gyroscope according to an embodiment alternative to the one which is shown in Figure 5; and

[0038] Figure 11 is an enlarged view of another portion of a gyroscope according to an embodiment alternative to the one in Figure 4.

[0039] Detailed description

[0040] With reference to the numbering adopted in the accompanying sheets of drawings, reference number 10 indicates, as a whole, a gyroscopic effect anti -roll stabilizer for a seacraft.

[0041] As shown in Figure 1, the anti -roll stabilizer 10 comprises a frame 11 and a gyroscope 1. The gyroscope 1 comprises a dismountable container 2, better described below.

[0042] In the example shown in Figure 2, the dismountable container 2 has a substantially and / or essentially spherical shape and is made of metal, for example an aluminium alloy .

[0043] The dismountable container 2 defines a chamber 20, for example having an approximately spherical shape, which houses a flywheel 3.

[0044] In the shown example the chamber 20, defined inside the dismountable container 2, has an approximately spherical shape .

[0045] The dismountable container 2 of the gyroscope 1 is mounted on a suspension 102, integral with the frame 11, and is adapted to oscillate about a first rotational axis Y (also known as the precession axis) parallel to the pitch axis of the hull which houses the anti -roll stabilizer 10.

[0046] A damper 103 is provided to dampen the oscillations of the container 2 of the gyroscope 1 about the first rotational axis Y.

[0047] In particular, the damper 103 can be a hydraulic damper with an adjustable damping coefficient (for example depending on the angular velocity of oscillation coy of the container 2 about the axis Y and / or other parameters such as the angular position of the container 2 with respect to the frame 11 and the angular position of the stabiliser 10 with respect to the roll axis of the hull in which the stabiliser 10 is located).

[0048] For example, the damper 103 may comprise four hydraulic pistons, two on each side.

[0049] The damper 103 may comprise one or more proportional valves (not shown) to adjust the oil flow into and out of the hydraulic pistons.

[0050] In the shown embodiment, the dismountable container 2 is an airtight container.

[0051] The gyroscope 1 may comprise a vacuum sensor, not shown, which is located in the container 2, so as to detect the pressure inside the container 2; furthermore, a vacuum pump (not shown) may be provided which is activated if the internal pressure of the container 2 exceeds a predetermined value.

[0052] In the shown example, the flywheel 3 is mounted on a shaft 4 and is adapted to rotate about a second axis X, orthogonal to the first axis Y.

[0053] In one alternative embodiment, the flywheel 3 and the shaft 4 form a single body (figure 9).

[0054] In the absence of the pitching movement, the second axis X, or rotational axis of the gyroscope flywheel, corresponds to the yaw axis of the hull of the seacraft.

[0055] The anti-roll stabilizer 10 and the gyroscope 1 are also subjected to oscillation with respect to a third axis Z, which is also orthogonal to the first axis Y, parallel to the pitch axis.

[0056] The shaft 4 of the flywheel 3 comprises a first end 41 and a second end 42, which is opposite to the first end 41.

[0057] An electric motor 9 is provided to rotate the shaft 4 of the flywheel 3.

[0058] In the example shown in figure 2, the motor 9 is a radial flux motor, more precisely it is a motor with an internal rotor 91 and an external stator 92.

[0059] In the shown example, the rotor 91 is connected, by means of a coupling 93, to the first end 41 of the shaft 4. Therefore, when the rotor 91 is rotated, it transmits motion to the shaft 4 and the flywheel 3.

[0060] A first bearing support member 5 is provided to support the first end 41 of the rotating shaft 4, and a second bearing support member 6 is provided to support the second end 42 of the rotating shaft 4.

[0061] The first and the second support member 5, 6 allow the shaft 4, and thereby the flywheel 3, to relatively rotate with respect to the container 2.

[0062] In the example shown in Figure 8, the flywheel 3 is a circular crown flywheel and has a central hole 31 to allow a central part of the shaft 4 to be inserted.

[0063] In the exemplary embodiment, the central part of the shaft 4 has a flanged portion 40 designed to abut a seat 30, made in the flywheel 3.

[0064] Fastening elements are also provided to connect the shaft 4 to the flywheel 3.

[0065] In particular, a plurality of screws is provided to tighten the flanged portion 40 of the shaft 4 to the seat 30 of the flywheel 3.

[0066] Again, a suitable conical flange 35 is provided on the side opposite to the seat 30 of the flywheel 3, which is coupled, by interference, to a portion 32, with reduced thickness, of the flywheel 3.

[0067] In the example shown in Figure 5, the first support member 5 (better described below) comprises a plurality of first rolling bearings 81, 82.

[0068] In the example shown in Figure 4, the second support member 6 (better described below) comprises a plurality of second rolling bearings 83, 84.

[0069] The first bearings 81, 82 have outer rings 811, 821 which are integral with the container 2 and therefore act as stationary rings and inner rings 812, 822 which are integral with the first end 41 of the shaft 4 and therefore act as rotating rings.

[0070] Similarly, the second bearings 83, 84 have outer rings 831, 841 which are integral with the container 2 and therefore act as stationary rings and inner rings 832, 842 which are integral with the second end 42 of the shaft 4 and therefore act as rotating rings.

[0071] In the shown embodiment, the first rolling bearings 81, 82 comprise a pair of angular contact ball bearings 81, 82 arranged in tandem, that is to say with parallel load action lines, and the second bearings 83, 83 are angular contact ball bearings and are also arranged in tandem.

[0072] In the shown example, the first and the second angular contact rolling bearings 81, 82; 83, 84 have the same contact angle.

[0073] More specifically, the first bearings 81, 82 are arranged in such a way that the axial thrust load is directed towards the first end 41 of the shaft 4 while the second bearings 83, 84 are arranged in such a way that the axial thrust load is directed towards the second end 42 of the shaft 4.

[0074] In the shown example, spacers 861, 862; 863, 864 are interposed between the paired rings of the bearings 81, 82 and 83, 84.

[0075] In other words the first bearings 81, 82 and the second bearings 83, 84 are arranged in such a way that their thrust directions form an “O” configuration, that is to say with load lines diverging outwards (see Figure 7). The tandem arrangement of the two pairs of bearings 81, 82; 83, 84 allows for a preload system to be provided for the first bearings 81, 82 and the second bearings 83, 84.

[0076] In the shown embodiment, a preload member 7 is provided (better described below) to axially preload the (stationary) outer rings 831, 841 of the angular contact ball bearings 83, 84 on the corresponding inner rings 832 and 842 of the second support 6.

[0077] The preload member 7 generates a force F having the same direction as the axis X and directed towards the end 42 of the shaft 4.

[0078] The preload action exerted by the preload member 7 is also transmitted to the bearings 81, 82 of the first support 5 through the shaft 4.

[0079] In particular, the preload action generated by the preload member 7 allows the bearings to be able to better absorb the axial and radial thrusts which are generated due to the oscillatory movement of the container 2 about the first axis Y (which oscillatory movement, due to the gyroscopic effect, is caused by the rolling of the seacraft when at sea).

[0080] In the shown embodiment, the preload member 7 is able to generate a variable load, during the operation of the gyroscope 1 depending on the operating conditions of the gyroscope 1.

[0081] In particular, the load generated by the preload member 7 can vary depending on the angular velocity coy (known as precession angular velocity) with which the flywheel 2 oscillates about the first axis Y (which oscillation is caused by the rolling movement of the seacraft on which the gyroscope is placed).

[0082] As better described below, the adjustment of the preload exerted on the bearings 81, 82, 83, 84 can also vary depending on one or more additional operating parameters such as the rotational speed of the gyroscope flywheel, the roll angle of the seacraft on which the gyroscope is placed and the angular roll velocity of the seacraft).

[0083] In the example shown in Figure 4, the preload member 7 comprises a piston 71 (for example a body with a generic annular shape such as a bush) which is able to slide along the axis X.

[0084] The piston 71 is therefore able to push against the outer rings 831, 841 of the angular contact ball bearings 83, 84 so as to subject the second bearings 83, 84 to the axial preload and, through the shaft 4, also the first bearings 81, 82.

[0085] In the shown example, the piston 71 is substantially a hollow rotational solid, to accommodate the second rolling bearings 83, 84 and the internal element 62 of the second support member 6.

[0086] As better explained below, a first force Fl, generated by at least one elastic element 72, which guarantees a minimum preload value, acts on the piston 71.

[0087] The at least one elastic element 72 allows, among other things, a "constant" preload to be guaranteed, even in the presence of the temperature variations that tend to thermally expand the elements involved.

[0088] In particular, the at least one elastic element 72 allows a constant preload, compensating for the effect of the thermal expansions of the shaft 4 to be guaranteed. In the shown example, the first force Fl is generated by a plurality of helical springs 72, 72, ... , 72, circumferentially distributed about the axis X, which work under compression and provide the minimum desired preload value.

[0089] In the shown example, the piston 71 can be subjected, if required or deemed convenient, to a second force F2, synergic to the first force Fl, which is obtained by means of a hydraulic thrust.

[0090] The hydraulic thrust that generates the second force F2 can be adjusted according to the working conditions of the gyroscope 1 .

[0091] For example, the value of the hydraulic thrust can be adjusted according to the angular velocity coy with which the flywheel 2 oscillates about the first axis Y, the angular velocity cox with which the flywheel rotates about the second axis X, the angular velocity coz with respect to the third axis Z and the inclination of the gyroscope 1 with respect to the third axis Z.

[0092] In this way, it is possible to adjust the preload applied to the bearings 81, 82; 83, 84 according to certain operating conditions and, in general, the radial and axial loads that they must withstand during the operation of the gyroscope 1 and thereby of the anti-roll stabilizer 10.

[0093] In other words, thanks to this feature, it is possible to adapt the axial preload generated by the preload member 7 to the stresses to which the bearings 81, 82; 83, 84 are subjected, which stresses in turn depend on the sea conditions.

[0094] It is therefore possible to work with a low axial preload, so as to reduce the friction to which the bearings are subjected, for example during the start-up phase of the gyroscope (a phase that can last even more than one hour) or when the sea is calm, thus increasing the operating life of the rolling bearings 81, 82; 83, 84.

[0095] It is also possible to work with a high axial preload, to allow the bearings to resist the radial and axial thrusts generated by the mass of the flywheel during the oscillation of the container 2 when the sea conditions require it.

[0096] In fact, it is not necessary to apply the full preload in every operating condition, because the preload can be kept lower, if allowed by the sea conditions.

[0097] In this way, the operating life of the bearings is increased, preventing them to be always subjected to a maximum preload condition.

[0098] A high preload, in fact, means greater resistance to the axial and radial load but also greater mechanical wear and a shorter life of the bearings.

[0099] In other words, in the gyroscope described the preload of the bearings is adjustable, depending on the operating conditions of the gyroscope and, in particular, depending on the oscillation speed of the gyroscope about the first axis Y (that is to say the precession speed of the gyroscope flywheel following the roll to which the hull where the anti-roll stabilizer is housed is subjected).

[0100] This allows to compensate for the axial and radial loads to which the gyroscope bearings are subjected depending on the oscillations to which the seacraft is subjected. In the shown example, the piston 71 is a single-acting piston that can be controlled by introducing a pressurized fluid, for example a hydraulic oil, into a chamber 73 delimited by a portion of the surface of the first element 61 of the second support member 6 and a portion of the surface of the piston 71.

[0101] The chamber 73 is connected to an opening 77, which is located on the outside of the container 2, through ducts 771 made in the first element, or flanged element, 61 of the second support member 6.

[0102] The opening 77 is hydraulically connected through an external pipe 75 with a hydraulic actuator 74 which is able to introduce a pressurized fluid, for example a hydraulic oil, into the chamber 73.

[0103] The hydraulic actuator 74 can be, for example, an external hydraulic piston pump, driven by a gearmotor unit 76, (the electric motor 761 and the planetary gearbox 762), which in turn is controlled by a regulator 78, for example an electronic regulator.

[0104] The hydraulic oil pressure is detected by a special sensor 79 which is positioned downstream of the hydraulic pump.

[0105] The hydraulic actuator 74 is able to regulate the intensity of the piston thrust on the rings of the outer rings 832, 842 of the angular contact ball bearings 83, 84 of the second support 6, thereby varying the axial preload of all the bearings of the gyroscope 1.

[0106] In the shown example, the electronic regulator 78 is interfaced to a first sensor 781 from which a first and a second signals SI, S2 are obtained, representing the angular position of the container 2 with respect to the first axis Y and the angular velocity coy with which the container 2 oscillates about the first axis Y (derivative in time of the precession angle), respectively.

[0107] The electronic regulator 78 is also interfaced to a second sensor 782 from which a third signal S3 arrives, representing the angular velocity cox of the flywheel 2 about the second axis X (constant rotation speed at steady state).

[0108] In a possible embodiment, the electronic regulator 78 is also interfaced to a third sensor 783, for example a Mems integrated within the regulator, which provides a fourth signal S4 and a fifth signal S5 representing the angular position of the stabilizer 10 with respect to a third axis Z - which is orthogonal to the first and second axes Y, X (roll angle) - and the angular velocity coz with which the stabilizer 10 oscillates with respect to the third axis Z (time derivative of the roll angle), respectively.

[0109] In the embodiment shown in figure 6, the regulator 78 thus provides an output signal, to control the motor 761, depending on the information indicated above and the operating state of the gyroscope (acceleration phase or constant speed operation phase).

[0110] The hydraulic actuator 74 can be kept deactivated until the angular velocity cox of the flywheel 3 reaches the steady state and the angular velocity coy of oscillation of the container 2 does not exceed a preset value.

[0111] In fact, it has been verified that this method of managing the preload of the rolling bearings allows their operating life to be significantly extended.

[0112] In further embodiments, not shown, the hydraulic actuator 74 can generate a fair amount of pressure values, or continuously vary the pressure, depending on the operating conditions of the gyroscope 1. In a further embodiment, the regulator 78 can comprise a feedback control to compensate for pressure variations due to the temperature variations in the pressurized liquid pumped into the chamber 73.

[0113] In the shown embodiment, the dismountable container 2 comprises a first annular element 21 and a second annular element 22.

[0114] The first and second annular elements 21, 22 are connected to each other by means of reversible fastening members, for example threads.

[0115] In the example shown in Figure 7, the dismountable container 2 also comprises a first cover 23 (which covers the motor 9 and the first support member 5) and a second cover 24, opposite to the first cover 23 (which covers the second support member 6).

[0116] In the shown embodiment, the first support member 5 comprises a first element, or external element 51, which is integral with the first annular element 21 of the container 2, and thereby stationary.

[0117] In the shown example, the first element, or external element, 51 of the first support member 5 comprises a recess 510 extending coaxially to the axis X, designed to contain the first bearings 81, 82.

[0118] The outer rings 811, 821 of the first bearings 81, 82 are integral with the first element 51 of the first support member 5.

[0119] The inner rings 812, 822 of the first bearings 81, 82 are made integral with the first end 41 of the shaft 4.

[0120] In a possible embodiment, the inner rings 812, 822 of the first bearings 81, 82 are mounted directly on the first end 41 of the shaft 4 (Figure 10).

[0121] The first end 41 of the shaft 4 has a shoulder which ensures that the inner rings 812, 822 of the bearings 81, 82 and the first end 41 of the shaft 4 are correctly positioned in relation to each other.

[0122] In other embodiments, the first support member 5 may also comprise a second element, or internal element 52, which is integral with the first end 41 of the shaft 4 and thereby rotating with it (figure 5).

[0123] In this case, the inner rings 812, 822 of the first bearings 81, 82 are made integral with the second element 52 of the first support member 5.

[0124] In the example shown in Figure 5, the second element 52 of the first support member 5 comprises a bush 52 on which the inner rings 812, 822 of the rolling bearings 81, 82 are mounted.

[0125] The bush 52 is in turn inserted into the first end 41 of the shaft 4.

[0126] Also in the embodiment shown in Figure 5, the first end 41 of the shaft 4 has a shoulder which ensures that the bush 52 and the first end 41 of the shaft 4 are positioned in relation to each other, and thereby that the first pair of bearings 81, 82 are correctly positioned.

[0127] Similarly, the second support member 6 comprises a first element, or external element 61, which is integral with the second annular element 22 of the container 2, and thereby stationary.

[0128] In the shown example, the first element 61 of the second support member 6 comprises a recess 610 extending coaxially to the axis X, which is adapted to contain the second bearings 83, 84 and the piston 71.

[0129] The second bearings 83, 84 comprise outer rings 831, 841 which are made integral with the first element 61 of the second support member 6. The inner rings 832, 842 of the second bearings 83, 84 are made integral with the second end 42 of the shaft 4.

[0130] In a possible embodiment, the inner rings 832, 842 of the bearings 83, 84 are directly mounted on the second end 42 of the shaft 4 (Figure 11).

[0131] The second end 42 of the shaft 4 has a shoulder which ensures that the inner rings 832, 842 of the bearings 83, 84 and the second end 42 of the shaft 4 are correctly positioned in relation to each other.

[0132] In other embodiments the second support member 6 may also comprise a second element, or internal element 62, which is integral with the second end 42 of the shaft 4 and thereby rotating with it (Figure 4).

[0133] In this case, the inner rings 832, 842 of the second bearings 83, 84 can be made integral with the second element 62 of the first support member 5.

[0134] In the example shown in Figure 4, the second element 62 of the second support member 6 comprises a bush 62 on which the inner rings 832, 842 of the rolling bearings 83, 84 are mounted.

[0135] The bush 62 is in turn mounted on the second end 42 of the shaft 4.

[0136] Also in the embodiment shown in Figure 4, the second end 42 of the shaft 4 has a shoulder which ensures that the bush 62 and the second end 42 of the shaft 4 are correctly positioned in relation to each other and therefore that the second pair of bearings 83, 84 are correctly positioned.

[0137] The bushes 52, 62 and the inner rings 812, 822; 832, 842 of the first and second bearings 81, 82; 83, 84 are made integral with the ends 41, 42 of the shaft 4, respectively, by means of locking brackets 53, 63 (screwed to the opposite ends 41, 42 of the shaft 4) which press axially (along the axis X).

[0138] In this way, the bushes 52, 62 and the inner rings 812, 822, 832, 842 rotate together with the shaft 4.

[0139] In the shown example, a sleeve 512, for example a steel sleeve, is inserted in the internal surface of the recess 510 of the external element 51 of the first support member 5.

[0140] Therefore, in the shown example, the outer rings 811, 821 of the first bearings 81, 82 are coupled to the sleeve 512 which, in turn, is coupled inside the recess 510 of the external element 51 of the first support member 5.

[0141] This allows a sufficiently hard and resistant support surface to be created for supporting the bearings; in fact, the element 51 is made of aluminium (to contain the overall weight).

[0142] In the shown example, a sleeve 612, for example a steel sleeve, is inserted in the internal surface of the recess 610 of the external element 61 of the second support member 6.

[0143] Furthermore, the piston 71 has a seat 710 which is designed to receive the outer rings 831, 832 of the second bearings 83, 84.

[0144] Therefore, the external surface of the piston 71 is adapted to slide on the surface of the sleeve 612.

[0145] As already mentioned, the outer rings 811, 821 of the first bearings 81, 82 act as stationary rings while the inner rings 812, 822 act as rotating rings.

[0146] Similarly, the outer rings 831, 841 of the second bearings 83, 84 act as stationary rings while the inner rings 832, 842 act as rotating rings. In the shown example, the first element 51 of the first support member 5 comprises a flanged portion 511, which is interposed between the first annular element 21 and the first cover 23 and is fastened, by means of reversible fastening members, to the first annular element 21 of the container 2.

[0147] Similarly, the first element 61 of the second support member 6 comprises a flanged portion 611, which is interposed between the second annular element 22 and the second cover 24 and is fastened to the second annular element 22 of the container 2 by means of reversible fastening members.

[0148] In the shown example, the flanged portion 511 of the first element 51 and the flanged portion 611 of the first element 61 help to forming the container 2 of the gyroscope 1.

[0149] This construction solution represents an undoubted advantage in terms of ease of construction and maintenance of the gyroscope.

[0150] In fact, the entire container 2 must not necessarily be removed to access it and pull out one of the support members 5, 6 and replace the bearings housed therein; whereas it is sufficient to remove the screws which hold the flanged part 511 fastened to the annular element 21 or the flanged part 611 to the annular element 22 and slide the entire support member upwards.

[0151] A further advantage of this solution is that it is not necessary to provide internal refrigerant fluid supply ducts that enter the container and reach the group of bearings for cooling the group of bearings or for arranging the thermal sensors that monitor its temperature.

[0152] The refrigerant fluid can be supplied through holes made directly in the flanged part 511, 611 of the external element 51, 61 of the support member 5, 6.

[0153] This allows avoiding the presence of pipes (which pass through the wall of the container 2) and additional gaskets (for example O-rings) or other known solutions to ensure the vacuum sealing.

[0154] The annular elements 21, 22, the covers 23 and 24 and the flanged portions 511, 611 are coupled together by means of gaskets (for example O-rings), so as to allow an airtight coupling.

[0155] Typically at start-up the preload device 7 will be adjusted to a minimum value (the one generated by the springs) until the operating speed of the flywheel 3 is reached.

[0156] Once the operating speed of the flywheel 3 is reached, the preload device is adjusted depending on the angle (inclination) of the container 2 with respect to the first axis Y and / or depending on the angular speed of oscillation coy of the container 2 with respect to the first axis Y and / or depending on the angular speed cox with which the flywheel 3 rotates about the second axis X and / or depending on the angular speed coz with respect to the third axis Z and / or of the angle (inclination) of the stabilizer 10 with respect to the third axis Z. Schedule of Reference Numerals

[0157]

Claims

CLAIMS1. A gyroscopic effect anti -roll stabilizer (10) for a seacraft, comprising a) a dismountable container (2), al) mounted on a suspension (102) and adapted to oscillate about a first axis (Y); b) a flywheel (3) with a shaft (4), placed inside said container (2), bl) said flywheel (3) with said shaft (4) being adapted to rotate about a second axis (X), orthogonal to said first axis (Y), b2) said shaft (4) of said flywheel (3) having a first end (41) and a second end (42) which is opposite to said first end (41); c) a first support member (5) with first rolling bearings (81, 82), placed inside said container (2), to support said first end (41) of said shaft (4), said first rolling bearings (81, 82) having stationary outer rings (811, 821) and rotating inner rings (812, 822), said first bearings being angular contact ball bearings (81, 82) arranged in tandem and with a thrust load directed towards said first end (41) of said shaft (4); d) a second support member (6) with second rolling bearings (83, 84), placed inside said container (2), to support said second end (42) of said shaft (4), said second bearings having stationary outer rings (831, 841) and rotating inner rings (832, 842), said second rolling bearings (83, 84) being angular contact ball bearings (83, 84) arranged in tandem and with a thrust load directed towards said second end (42) of said shaft (4); e) an electric motor (9), which is adapted to transmit a torque to said flywheel (3); f) a damper (103), to dampen the oscillations of said container (2) about said first axis (Y); g) a preload member (7) to axially preload said angular contact ball bearings (81, 82; 83, 84); characterized in that the axial preload generated by said preload member (7) is adjustable.

2. The stabilizer according to claim 1, wherein said preload member (7) can be adjusted depending on at least one operating condition of said stabilizer (1).

3. The stabilizer according to claim 2, wherein said at least one operating condition comprises the angle with respect to said first axis (Y) and / or the angular velocity of oscillation (coy) of said container (2) with respect to the first axis (Y) and / or the angular velocity (cox) with which the flywheel rotates about the second axis (X) and / or the angle of said stabilizer with respect to the third axis (Z) and / or the angular velocity (coz) of said stabilizer with respect to the third axis (Z).

4. The stabilizer (10) according to one of the preceding claims, wherein said first support member (5) comprises a first element (51) which is removably connected to said container (2),first bearings (81, 82) comprising outer rings (811, 821) which are integral with said first element (51) of said first support member (5), and wherein said second support member (6) comprises a first element (61), which is removably connected to said container (2), said second rolling bearings (83, 84) comprising outer rings (831, 841) which are integral with said first element (61) of said second support member (6).

5. The stabilizer (10) according to claim 4, wherein said first support member (5) comprises a second element (52), which is coaxial to said first element (51), removably mounted on said first end (41) of said shaft (4) and integral with said first end (41) of said shaft (4), and wherein said first bearings (81, 82) have inner rings (812, 822) which are integral with said second element (52) of said first support member (5), and wherein said second support element (6) comprises a second element (62), which is coaxial to said first element (61), removably mounted on said second end (42) of said shaft (4) and integral with said second end (42) of said shaft (4), and wherein said second bearings (83, 84) comprise inner rings (832, 842) which are integral with said second element (62) of said second support (6).

6. The stabilizer (10) according to one of the preceding claims, wherein said preload member (7) comprises a piston (71) adapted to push against the outer rings (832, 842) of said second bearings (83, 84) so as to subject said first and second bearings (81, 82; 83, 84) to the axial preload.

7. The stabilizer (10) according to claim 6, wherein said piston (71) is subjected to a first force (Fl) generated by at least an elastic element (72), and wherein said piston (71) can be subjected to a second force (F2), synergic to the first force (Fl), obtained by means of a hydraulic thrust.

8. The stabilizer (10) according to claim 7, wherein said hydraulic thrust is generated by a hydraulic actuator (74) controlled by a regulator (78), said regulator (78) receiving a first and a second signal (SI, S2) representing the angular position with respect to said first axis (Y) and the angular velocity (coy) with which said container (2) oscillates about the first axis (Y), respectively, said regulator (78) further receiving a third signal (S3) representing the angular position (cox) with which the flywheel (2) rotates about the second axis (X).

9. The stabilizer (10) according to claim 7 or 8, wherein said regulator (78) receives a fourth signal (S4) representing the angular position of said stabilizer (10) with respect to said third axis (Z) and a fifth signal (S5) representing the angular velocity (coz) with which said stabilizer (10) oscillates with respect to a third axis (Z) .

10. A method of starting and operating a gyroscopic stabilizer (10) of the type comprising an oscillating container (2) containing a flywheel (3) supported by first angular contact ball bearings (81, 82) arranged in tandem and second angular contact ball bearings (83, 84) arranged in tandem and wherein the first bearings (81, 82) and the second bearings (83, 84) are arranged in such a way that their thrust directions form an “O” configuration, the method providing for maintaining the preload force applied on the ball bearings (81, 82; 83, 84) at a minimum value until thesteady-state speed of the flywheel (3) has been reached, and thereafter adjusting the preload force depending in the angle with respect to said first axis (Y) and / or the angular velocity of oscillation (coy) of said container (2) with respect to said first axis (Y) and / or the angular velocity (cox ) with which the flywheel (3) rotates about the second axis (X) and / or the angle with respect to the third axis (Z) and / or the angular velocity (coz) with respect to the third axis (Z).

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