Gyrostabilizer assembly

Abstract

The present invention relates to a gyro stabilizer assembly (1) for a marine vessel, comprising: a casing (2) defining a chamber (3) for supporting an at least partial vacuum; a flywheel (4) mounted within the chamber (3) for rotating about an axis of rotation (Z) under the partial vacuum; a flywheel shaft (5) on which the flywheel (4) is supported and mounted in the casing for rotation of the flywheel about the axis of rotation (Z), the flywheel shaft being rotatably supported by a first rotary bearing (6) at one end region of the shaft (5) and a second rotary bearing (7) at an opposite end region of the shaft (5); a lubrication system (8) configured to circulate lubricant (O) from a lubricant tank (9) to the rotary bearings (6, 7). The tank (9) is provided within or on the casing (2) to collect lubricant from the rotary bearings (6, 7) under the action of gravity, and the first and second rotary bearings (6, 7) are provided in the casing (2) for operation under the partial vacuum. The invention also relates to a vehicle, in particular a marine vessel, comprising the gyro stabilizer assembly (1).

Description

TECHNICAL FIELD

[0001] The present invention relates to a gyro stabiliser assembly, and in particular to a lubrication system for bearings in a gyro stabiliser assembly.

[0002] The gyro stabiliser assembly of the present invention is generally designed for use in a marine vessel, and it will be convenient to describe the invention in that exemplary context. However, it will be appreciated that the gyro stabiliser assembly of the present invention is not limited to this particular embodiment and can be designed for use in many other applications, such as other fixed and floating structures, other vehicles and / or camera mounts. BACKGROUND

[0003] The following discussion of the background to the application is not to be taken as an admission that any of the background is prior art or that any of the background is widely known or forms part of the common general knowledge of the art in Australia or in any other country.

[0004] The structure and operation of marine gyro stabiliser assemblies is generally well understood, and these devices are increasingly being adopted in commercial and recreational vessels. A gyro stabiliser assembly generally comprises a rotating flywheel mounted in a gimbal frame that allows two of the three possible rotational degrees of freedom, and the frame is rigidly mounted within the vessel. The particular way in which the flywheel rotational motion is constrained allows the angular momentum of the rotating flywheel to combine with the precessional oscillation of the flywheel to produce a large time-varying torque to directly oppose the dynamic rolling motion of the vessel caused by wind and / or waves. In the absence of any intervention, the rolling motion of the vessel combines with the flywheel angular momentum to produce an oscillating precessional motion. This then combines with the angular momentum to produce a stabilising torque that directly opposes the unwanted rotational motion of the vessel (such as wave-induced rolling motion). By arranging the gimbal in a particular way, the rolling stabilisation device is formed using naturally occurring gyrodynamic physics that functions without further intervention. An example of a marine gyro stabiliser assembly is described in the applicant’s co-pending Australian patent application AU 2017216483 Al, the contents of which are incorporated herein in their entirety by direct reference.

[0005] Due to the high speed of the outer rim of the flywheel in a gyro stabiliser, the gimballed frame often includes a chamber enclosing the flywheel which is evacuated to enable the flywheel to rotate in a vacuum. This reduces the aerodynamic drag on the flywheel, reducing the power required to maintain the flywheel speed (rpm). It can also reduce the heat generated by the air drag on the rotating flywheel rim, improving efficiency. The rotating bearings used to locate and retain the flywheel about the axis of rotation are subject to high loads and high rotational speeds, which also generate heat and noise. The rotating bearings and the rotating motor are usually located within the vacuum chamber to avoid sealing issues associated with the vacuum chamber, where the rotating shaft exits the vacuum chamber. However, locating the rotating bearings within the vacuum chamber can make it difficult to lubricate these bearings as well as cool the bearings. Cooling the interior of the flywheel shaft and rotating bearings can be particularly difficult because they are rotating and are not easily cooled by contact with a cooling jacket.

[0006] Co-pending Australian patent application AU 2017216483 Al describes an apparatus having an oil lubrication system for lubricating and cooling the bearings, by which the flow of oil to the bearings can be selected to provide lubrication and exchange of heat generated by the bearings into the oil. The oil lubrication system is desirable for its ability to reduce noise, extend bearing life and carry heat away from the interior of the bearings. In this system, oil is drawn from an oil sump by one or more scavenge pumps, arranged similarly to the "dry sump" pump arrangement on racing cars. To allow the scavenge pumps to operate, this arrangement separates the upper and lower bearing cavities from the vacuum cavity, which encloses the flywheel by a rotating shaft seal on the flywheel shaft. One seal is located below the upper bearing cavity and the other seal is located above the lower bearing cavity, the upper and lower bearing cavities being joined together by a drain tube between them. With this arrangement, the flywheel can be rotated at a sufficiently low pressure in a partial vacuum or near vacuum, significantly reducing or eliminating air drag, while the bearing housings, which are manifolded so they operate at the same pressure, are able to operate at a sufficiently high pressure for the scavenge pumps to effectively pump oil to the rotating bearings.

[0007] However, the apparatus described in AU 2017216483 Al has the disadvantage that it requires a dual vacuum pressure management system for the vacuum cavity and the bearing cavities, and the rotating shaft seal components are subject to rotational drag from high contact surface speeds, which can lead to wear and associated maintenance and / or replacement costs later, as well as higher power requirements to maintain the required flywheel speed (rpm).

[0008] It would therefore be desirable to provide a new gyro stabilizer device which substantially overcomes or ameliorates one or more of the above-mentioned disadvantages. In this regard, it would be desirable to provide a new gyro stabilizer device which employs an oil lubrication system to lubricate and cool the bearings and which is less complex. SUMMARY

[0009] According to a broad aspect, therefore, the present invention provides a gyro stabilizer assembly comprising:

[0010] a housing defining a chamber for supporting a working pressure;

[0011] a flywheel mounted within the chamber for rotation about an axis of rotation under the working pressure;

[0012] a flywheel shaft, the flywheel being supported by and mounted in the housing by first and second rotary bearings located at opposite end regions of the shaft to enable rotation of the flywheel about the axis of rotation; and

[0013] a lubrication system for the first and second rotary bearings configured to supply or circulate lubricant from an oil tank to the bearings. The lubricant oil tank is arranged within or on the housing to collect lubricant from the first and second rotary bearings under the action of gravity. The first and second rotary bearings are arranged in the housing under the working pressure, or for use / operation under the working pressure (e.g. if the working pressure is only applied in use).

[0014] In this way, the present invention is able to provide a relatively simple device or construction of a gyro stabilizer assembly in which rotary bearing seals are not required to separate or isolate the rotary bearings from the working pressure of the flywheel chamber. This has the benefit that it eliminates the need for a dual vacuum pressure management system and simplifies the device by reducing the number of components and potential points of failure, thereby making the gyro stabilizer assembly more reliable and robust. In particular, the device eliminates the need for rotary shaft seals which are susceptible to wear, thereby saving time and cost in terms of maintenance and / or replacement of the seals. Since shaft seals typically create significant rotational drag, the new device also reduces the power required to maintain flywheel speed (rpm) and eliminates flywheel speed limitations imposed by the ability of shaft seals to cope with high contact surface speeds.

[0015] In preferred embodiments, the first and second rotary bearings are configured and arranged within the housing such that lubricant supplied, circulated or delivered to the first and second bearings drains from each respective bearing to return to the oil tank under the action of gravity. In this regard, it will be appreciated that the lubricant is liquid at operating pressure and temperature. The lubricant typically comprises oil, e.g. synthetic oil.

[0016] It will be appreciated that the term "rotary bearing" used throughout this document is understood to mean a bearing designed to mount or support a flywheel shaft for rotation, preferably free rotation, about an axis of rotation. The term "rotary bearing" will thus be understood as a rotary bearing and will include a range of rotary bearing designs, including hydrodynamic bearings and rolling element bearings.

[0017] In preferred embodiments, the first and second rotary bearings are configured as rolling element bearings; for example having an inner race for rolling elements rigidly attached to the flywheel shaft for rotation with the shaft, and an outer race rigidly fixed relative to the housing. In alternative embodiments, the first and second rotary bearings can be configured as sliding bearings; for example sliding hydrodynamic bearings.

[0018] In preferred embodiments, the working pressure is at least partial vacuum, such that the chamber in which the flywheel is mounted forms a vacuum chamber. It is preferred that the chamber containing the flywheel and bearings be placed under at least partial vacuum (for example less than 0.5 bar, preferably less than 0.25 bar) as this reduces the aerodynamic drag on the flywheel, thereby reducing the power required to maintain the flywheel speed (rpm) while reducing the heat generated by the air drag on the rotating flywheel. In this way, the entire vacuum chamber in the gyro stabilizer assembly forms a single chamber operating at one vacuum pressure. The vacuum pressure should be low enough to significantly reduce or eliminate any air drag and the heat generated thereby. Testing and experience has shown that the working pressure should preferably be less than or equal to about 0.2 bar.

[0019] In preferred embodiments, the lubrication system comprises a lubricant circuit through which lubricant is circulated from the oil tank to the bearings and back to the oil tank. In this connection, the lubrication system comprises at least one pump for circulating lubricant from the oil tank to the first and second rotating bearings. The at least one pump is preferably in the form of a positive displacement pump and the pump is desirably arranged so that the lubricant in the oil tank provides a positive pressure head at the inlet of the pump. To this end, the pump can be arranged to be immersed in the lubricant within the oil tank. Alternatively, the pump can be arranged in or on the housing with the pump inlet in fluid communication with the oil tank at a level lower than the level of the lubricant held in the oil tank. This arrangement can significantly simplify the lubrication system known from co-pending application AU 2017216483 Al. That is, rather than using a sump or collection tank for de-aeration of the lubricant (e.g. oil) and using a separate oil tank for the de-aerated oil from the sump, and a return pump for returning oil from the sump to the oil tank and a supply pump for delivering oil from the reservoir to the rotating bearings, the present arrangement can eliminate the need for a separate tank for de-gassing of the oil prior to the supply pump inlet and can therefore also eliminate the need for a separate return pump. That is, de-aeration of the oil can desirably occur in the oil tank which also forms the sump or collection tank for the oil. That is, the oil tank can serve as a contaminant settling tank, a de-aeration tank and a cooling tank for the oil.

[0020] In preferred embodiments, the lubrication system comprises a lubricant delivery outlet, particularly a lubricant injection outlet, for targeted delivery or injection of lubricant at each of the first and second bearings. The lubrication system can thus comprise an “oil injection” system. The oil flow is desirably selected to provide lubrication and to allow heat exchange generated at the bearings into the oil. The oil injection through the injection outlet ensures that the oil can be aimed at the rolling or sliding elements in the rotating bearings at sufficient speed and pressure to mix with the boundary layer oil to provide effective lubrication and cooling effect. The pump for delivering lubricant (i.e. oil) from the oil tank to the first and second rotating bearings is thus designed to be able to initiate and deliver the necessary back pressure to drive the oil through the oil delivery outlet at the required speed. By careful selection of the pump to provide the required pressure and flow, the arrangement and size of the pump can meet the required conditions for the oil to circulate through one or more filters and / or one or more heat exchangers in the oil circuit before passing through the oil delivery outlet.

[0021] Thus, in preferred embodiments, the lubrication system can form a cooling system for the rotating bearings. In particular, the engine oil can act as a coolant to take away heat from the first and second bearings. To this end, the oil circuit preferably comprises one or more heat exchangers for removing heat from the engine oil before it is delivered to the first and second rotating bearings. In this regard, the walls of the housing can form a heat exchanger for the engine oil, optionally by means of a cooling medium arranged in the walls of the housing, e.g. a water jacket, and / or optionally by means of fin elements formed in the walls, as the engine oil returns under the influence of gravity to the oil tank and / or is circulated from the reservoir to the rotating bearings. These heat amounts can then be discharged as heated cooling water, e.g. to the outside of the vessel. It is beneficial to degas the lubricant (engine oil) at the point of delivery to the bearings, as it ensures that the role of the delivery outlet is to provide a directed jet with sufficient velocity to punch into the boundary layer to provide the necessary mixing and improve heat transfer through the heat exchanger. It is also generally required to filter the engine oil before re-injection.

[0022] For the gyro assembly of the present invention, both the horizontal and vertical directions of the flywheel shaft are considered, and the lubricant (e.g. engine oil) is delivered to the respective rotating bearings and then recycled for re-application.

[0023] In preferred embodiments, the flywheel shaft is mounted in a substantially vertical direction within the housing for rotation about a substantially vertical rotation axis. Thus, the first and second bearings form an upper and lower rotating bearing, respectively. The vertical flywheel shaft direction is preferred as this allows the housing to be arranged as a pendulum with a near vertical natural stable point. This means that no additional mechanism is required to ensure that the precession angle of the gyro assembly remains in the middle of the “center” of the travel. The engine oil returning from the upper and lower bearings is thus directed to a common oil tank or sump in a lower region or bottom of the housing located below the vacuum chamber. The engine oil in the oil tank can be scavenged and then circulated by at least one pump located in or near the oil tank.

[0024] In preferred embodiments, the lubrication system comprises two or more outlet ports from the oil tank, located at different positions and in fluid communication with the pump inlet, for ensuring that the lubricant is circulated to the rotating bearings irrespective of the working position of the gyro. That is, the oil tank outlet ports can be positioned to ensure that the lubricating oil is always effectively pumped or circulated despite the engine oil moving within the oil tank as the gyro assembly swings or moves (e.g. as a pendulum) during operation. For example, the housing can swing or rotate + / - 70 degrees during operation, which can cause the engine oil in the oil tank to move away from a single outlet port. By providing two or more outlet ports at different positions (e.g. on different sides of the oil tank) and in communication with the inlet of the pump, this can ensure that at least one outlet port of the oil tank is flooded at any time so that the engine oil can be effectively circulated.

[0025] In preferred embodiments, the gyroscope assembly includes a member, such as a disc-shaped member, that is securely or rigidly attached to the flywheel shaft to rotate with it and is disposed below the upper rotational bearing for capturing oil that flows down from the upper rotational bearing under the force of gravity. Thus, this member is designed to distribute the oil radially outward onto the inner wall of the housing that encloses the flywheel cavity so as to return to the oil tank under the force of gravity. In this regard, the high rotational speed of the disc component that rotates with the flywheel shaft serves to accelerate the oil radially outward onto the inner wall of the housing by centrifugal effect, where the oil can flow downward to the oil tank under the force of gravity. Alternatively or additionally, the flywheel can include one or more channels formed therethrough, for example, near the shaft, that define a flow path for collecting and directing the oil that flows downward from the upper rotational bearing to the oil tank under the force of gravity. The channels are desirably identical and arranged symmetrically about the rotational axis, given the need for rotational stability of the flywheel. However, such channels can be impractical in some cases due to the high stresses in the flywheel. In the absence of a disc member and / or any channels through the flywheel, the lubricating oil from the upper rotational bearing can flow directly downward onto the flywheel and radially outward over the outer rim of the flywheel to the housing wall, and then to the oil tank located at the bottom of the housing.

[0026] In preferred embodiments, the gyroscope assembly includes a rotational motor for driving the flywheel in rotation about the rotational axis. In one embodiment, the rotational motor is mounted within the chamber. In an alternative embodiment, the rotational motor is mounted outside the chamber and connected to the flywheel shaft by a magnetic sealed coupling or shaft connection. If the shaft needs to be connected to a rotational motor mounted outside the chamber, this will again require a rotational shaft seal. However, an advantage here is that the shaft connecting the rotational motor to the flywheel shaft only needs to transmit a relatively small torque, and therefore can be relatively small in diameter. This in turn limits the speed of the seal contact surface (reduced circumference at a given rpm results in lower speed), which greatly expands the possible rpm before the sealing capacity becomes limited, and reduces the rotational resistance of the seal. By contrast, in the current arrangement, the rotational shaft seal is provided on the flywheel shaft, which must withstand the full gyroscope torque that is completely reversed at every rpm cycle. Thus, the shaft is much larger in diameter and circumference, resulting in higher contact surface speed, higher wear, and technical challenges to extend the seal life.

[0027] According to another aspect, the present application provides a gyro stabilizer assembly for a marine vessel, comprising: a housing defining a chamber for supporting an at least partial vacuum; a flywheel mounted within the chamber for rotation about an axis of rotation under the partial vacuum; a flywheel shaft supporting and mounting the flywheel in the housing for rotation of the flywheel about the axis of rotation, the flywheel shaft being rotatably supported by a first rotary bearing located in a region of one end of the shaft and a second rotary bearing located in a region of an opposite end of the shaft; a lubrication system configured to supply lubricant from a lubricant tank to the rotary bearings. The tank is arranged within or on the housing to collect lubricant from the bearings under the action of gravity. The first and second rotary bearings are arranged in the housing under the partial vacuum or are used / operate under the partial vacuum (e.g. if the vacuum is applied only in use).

[0028] Since, as mentioned above, the structure and operation of a marine gyro stabilizer is generally well understood, the present description does not aim to provide a detailed description of all components of a gyro stabilizer assembly, such as the flywheel, the flywheel shaft, the gimbal bearings, etc. Rather, the present description directs the reader skilled in the art to other publications to describe or explain those components.

[0029] According to another aspect, the present application provides a marine vessel, such as a boat, comprising or incorporating a gyro stabilizer assembly of the present application according to any of the above embodiments.

[0030] It will be appreciated that the term "gyro stabilizer assembly" used throughout this document is understood to refer to a gyro stabilizer device or unit that can be incorporated or mounted in a vehicle such as a marine vessel, or in some other equipment that is to be subjected to unwanted rotational motion, such as rolling motion caused by waves, to counteract and / or reduce such unwanted motion. BRIEF DESCRIPTION OF DRAWINGS

[0031] For a more complete understanding of the present application, and the advantages thereof, exemplary embodiments of the application will be described in detail with reference to the following figures, wherein like reference numerals refer to like parts, and in which:

[0032] Figure 1 is a schematic cross-sectional side view of a gyro stabilizer assembly according to a preferred embodiment of the present application.

[0033] Figure 2 is a schematic cross-sectional side view of a gyro stabilizer assembly according to another preferred embodiment of the present application.

[0034] Figure 3 is a schematic cross-sectional side view of a gyro stabilizer assembly according to a further preferred embodiment of the present application.

[0035] Figure 4 is a schematic cross-sectional side view of a gyro stabilizer assembly according to yet another preferred embodiment of the present application. And

[0036] Figure 5 is a schematic cross-sectional side view of a gyro stabilizer assembly according to yet another preferred embodiment of the present application.

[0037] The accompanying drawings are included to provide a further understanding of the present application and are incorporated in and constitute a part of this specification. The drawings illustrate particular embodiments of the present application and, together with the description, serve to explain the principles of the present application. Other embodiments and many of the attendant advantages of the present application will be readily appreciated as they become better understood by reference to the following detailed description, when considered in connection with the accompanying drawings.

[0038] It should be understood that common and / or well-understood elements that can be useful or necessary in commercially feasible embodiments have not necessarily been depicted to promote a more abstract view of the embodiments. The elements of the drawings are not necessarily shown to scale relative to each other. It should also be understood that certain acts and / or steps within methods of embodiments can be described or depicted in a particular, order, but the skilled artisan will understand that unless otherwise specified, the particular, order of certain acts and / or steps can not be required. DETAILED DESCRIPTION

[0039] Referring to the drawings of Figure 1 , a gyro stabilizer assembly 1 according to a preferred embodiment is shown. The gyro stabilizer assembly 1 has an outer housing 2 defining a vacuum chamber 3 for supporting a partial vacuum V (e.g., less than or equal to about 0.2 bar) as a working pressure, and a flywheel 4 integral with or fixed to a flywheel shaft 5 that is mounted within the vacuum chamber 3 for rotation about a generally vertical spin or rotational axis Z at the working pressure. The flywheel shaft 5 on which the flywheel 4 is fixed and supported is mounted within the housing 2 via upper and lower rotational bearings 6, 7 (also referred to as "spin bearings") located at opposite end regions of the shaft 5 for rotation of the flywheel 4 about the rotational axis Z. In this embodiment, the upper and lower bearings 6, 7 are in the form of rolling element bearings in which rolling elements (e.g., steel balls) are held and moved between an inner race fixed firmly to the shaft 5 and an outer race fixed firmly to the housing 2. The vertical orientation of the flywheel shaft 5 and rotational axis Z allows the housing 2 to be disposed or mounted as a pendulum about a pivot axis X with a natural stable point that is close to vertical. As a result, no mechanism is required to ensure that the precession angle of the gyro assembly 1 remains centered at the center of travel. The gyro assembly 1 includes an electric drive motor or rotary motor (not shown) for driving the flywheel 4 to rotate about the rotational axis Z, and the rotary motor is mounted within or on the housing 2.

[0040] The gyro stabilizer assembly 1 further comprises a lubrication system 8 (based on engine oil) for the upper and lower rotary bearings 6, 7, which is configured to circulate oil O from an oil tank 9 to each of the bearings 6, 7. The lubrication system 8 thus provides an oil circuit 10 through which the oil O is circulated from the oil tank 9 to the respective rotary bearing 6, 7 and back to the oil tank 9. The oil circuit 10 can comprise lines or conduits located inside and / or outside the housing 2 through which the oil O is transported or supplied from the oil tank 9 to each of the bearings 6, 7. The upper and lower rotary bearings 6, 7 are constructed and arranged within the housing 2 such that the engine oil circulating or transported to the rotary bearings 6, 7 from each respective bearing 6, 7 drains under the action of gravity back to the oil tank 9. In this connection, the lubrication system 8 comprises at least one pump 11 for circulating or transporting oil from the oil tank 9 to the upper and lower bearings 6, 7. The at least one pump 11 is a positive displacement pump, such as a gear pump, and is arranged such that the oil O in the oil tank 9 provides a positive pressure head at an inlet 12 of the pump. To this end, the pump is arranged within or on the housing 2 with the pump inlet 12 spaced below the liquid level L of the engine oil held in the oil tank 9 at a location in fluid communication with the oil tank 9. The vertical direction Z of the rotary shaft means that the oil O returning from the upper and lower bearings 6, 7 is directed to a common oil tank 9 (or sump). The oil tank 9 is located in a base 13 of the housing 2 below the vacuum chamber 3 to collect engine oil from the upper and lower rotary bearings 6, 7 under the action of gravity via a return line or conduit 14, the rotary bearings 6, 7 within the housing 2 being at working pressure V. In this way, the vacuum chamber 3 is a single chamber operating at one pressure V. This not only reduces the aerodynamic drag on the flywheel 4, but also reduces the power required to maintain the flywheel speed (rpm) and the heat generated by air resistance on the rotating flywheel 4, but also results in a simpler arrangement of the gyro stabilizer assembly 1 in which rotary shaft seals for isolating the upper and lower rotary bearings 6, 7 from the working pressure V of the flywheel chamber 3 are no longer required.

[0041] With further reference to Figure 1 It can be seen that the flywheel 4 has a channel 15 formed adjacent the shaft 5, which forms a flow path for collecting and directing the flow of engine oil under the action of gravity from the upper rotary bearing 6 downwards back to the oil tank 9. Without such a channel 15 through the flywheel 4, the lubricating oil from the upper rotary bearing 6 would flow directly downwards onto the flywheel 4 and then radially outwards under centrifugal action across the outer periphery of the flywheel and then to the oil tank 9 in the base 13 of the housing 2.

[0042] The oil lubrication system 8 comprises oil injection outlets 16 at each of the upper and lower rotating bearings 6, 7 for targeted delivery or injection of oil by at least one pump 11. The oil flow is chosen to provide both lubrication and heat exchange into the oil generated at the bearings 6, 7. Thus, the oil lubrication system 8 also forms a cooling system for the rotating bearings 6, 7, wherein the oil acts as a coolant to take away heat from the bearings. In particular, the oil injection via the injection outlets 16 ensures that the oil is aimed at the rolling elements in the bearings 6, 7 with sufficient speed and pressure so that the oil mixes with the boundary layer oil to achieve effective lubrication as well as a cooling effect. To this end, the oil circuit 10 typically comprises one or more heat exchangers for removing heat from the oil O before it is delivered to the upper and lower bearings 6, 7. In this regard, the walls 17 of the housing 2 enclosing the chamber 3, against which the oil will be "injected" by the centrifugal action of the flywheel 4 onto the inner surface of its walls 17, can form or act as a heat exchanger for the oil O, optionally by means of a cooling medium provided in the walls 17 (e.g. in the manner of a cooling jacket) and / or by means of fin elements (not shown) formed in the walls 17, as the oil returns to the oil tank 9 under the action of gravity. The oil circuit 10 typically also comprises one or more filters (not shown) for filtering the oil before reinjection at the injection outlets 16.

[0043] Referring to Figure 2 , there is shown a gyro stabiliser assembly 1 according to a further preferred embodiment. This embodiment has most of the same features as the gyro stabiliser assembly 1 shown in Figure 1 . However, in this embodiment, there is no passage 15 provided through the flywheel 4, thus ensuring greater rotational stability of the flywheel 4. Instead, a disc member 18 is rigidly attached to the flywheel shaft 5 for rotation therewith above the flywheel 4 but below the upper rotating bearing 6, to capture oil flowing down from the upper bearing 6 under the action of gravity. In this way, the disc member 18 works to distribute oil radially outwards ("fling") onto the inner walls 17 of the housing 2 enclosing the flywheel chamber 3, so as to return to the oil tank 9 under the action of gravity. In this regard, the high rotational speed of the disc member 18 rotating with the flywheel shaft 5 serves to accelerate the oil radially outwards to the inside of the walls 17 of the housing 2 by centrifugal force, whereupon the oil can then flow down under the action of gravity and into the oil tank 9.

[0044] Referring to Figure 3 , there is shown a gyro stabiliser assembly 1 according to a further preferred embodiment. This embodiment has most of the same features as the gyro stabiliser assembly 1 shown in Figure 2 , but without the disc member 18 for distributing oil radially outwards onto the walls 17 enclosing the flywheel chamber 3. Instead, in this case, the flywheel 4 itself works to "throw" the oil O onto the walls 17. As with Figure 2Another difference in the embodiment is that, instead of rolling element bearings, the upper and lower rotary bearings 6, 7 are provided as sliding hydrodynamic bearings. These bearings are structurally simpler than rolling bearings and are generally less expensive and more durable. Oil flows through lines or conduits in oil passage 10 to... Figure 1 and Figure 2 The same method is used to deliver the material to these upper and lower sliding hydrodynamic rotary bearings 6 and 7.

[0045] Refer to the attached diagram. Figure 4 This illustrates a gyro stabilizer assembly 1 according to yet another preferred embodiment. This embodiment is similar to... Figure 3 The difference in the illustrated embodiment is that the flywheel 4 has a substantially uniform cross-section (i.e., no reduced thickness near the flywheel shaft 5). This configuration is used to give the flywheel 4 a greater mass for a given diameter, which, while less efficient, increases angular momentum. This would be useful if the gyro-stabilizer assembly 1 is size-constrained (i.e., diameter-constrained), for example, when it is to be integrated into an outboard engine. This configuration also prevents oil from accumulating on the upper side of the flywheel when the gyro-stabilizer assembly 1 is not operating (i.e., stopped).

[0046] Finally, now refer to the attached diagram. Figure 5 This illustrates a gyro stabilizer assembly 1 according to yet another preferred embodiment. This embodiment is similar to... Figure 2 The difference in the illustrated embodiment is that the flywheel shaft 5 lacks the disc member 18, but the flywheel shaft 5 is hollow or has a central channel 19 for receiving lubricating oil O from the oil passage 10 to provide cooling for the inner bearing rings of each of the upper and lower rotary bearings 6, 7. In this respect, as referenced Figure 1 In this embodiment, the upper and lower rotary bearings 6 and 7 are rolling element bearings (e.g., steel balls) with rolling elements, held and movable between an inner ring firmly fixed to the shaft 5 and an outer ring firmly fixed to the housing 2. Engine oil circulates through the central channel 19 of the flywheel shaft 5, for example, through the spray outlet 16, thus serving to cool the inner bearing race firmly fixed to the shaft 5.

[0047] While specific embodiments of the application have been described and illustrated, it will be understood by those skilled in the art that a variety of alternatives and / or equivalents exist. It should be understood that the example embodiments are only examples and are not intended to limit the scope, applicability, or configuration of the application in any way. Rather, the foregoing summary and detailed description will provide those skilled in the art with a convenient road map for implementing an example embodiment, it being understood that various changes can be made in the function and arrangement of elements described in the example embodiments without departing from the scope of appended claims and their legal equivalents. In general, this application is intended to cover any modifications or variations of the specific embodiments discussed herein.

[0048] It will also be understood that the terms "comprise", "comprising", "include", "including", "contain", "containing", "have", "having", and any variations thereof, throughout this document, are intended to be construed in an inclusive (i.e., non-exclusive) manner, such that processes, methods, devices, apparatuses, or systems described herein are not limited to those features, integers, parts, elements, or steps recited, but can include other features, integers, parts, elements, or steps as appropriate to the particular embodiment being described. In addition, the terms "a" and "an" as used herein are intended to be construed to cover one or more, unless otherwise indicated. Furthermore, the terms "first", "second", "third", etc. are used merely as labels, and are not intended to impose numerical requirements or establish a hierarchy. Moreover, positional terms such as "lower" and "upper" as used in the above description are to be understood in the context of the embodiments described in the figures, and are not to be interpreted as limiting the application to the literal interpretation of the terms, but as understood by those skilled in the art in the appropriate context.

[0049] Reference Signs

[0050] 1 gyro stabilizer assembly

[0051] 2 housing

[0052] 3 vacuum chamber

[0053] 4 flywheel

[0054] 5 flywheel shaft

[0055] 6 upper bearing

[0056] 7 lower bearing

[0057] 8 lubrication system

[0058] 9 oil tank

[0059] 10 oil passage

[0060] 11 pump

[0061] 12 pump inlet

[0062] 13 housing base

[0063] 14 return pipe or conduit

[0064] 15 channel

[0065] 16 jet outlet

[0066] 17 housing wall

[0067] 18 disc member

[0068] 19 channel mid-axis

[0069] Z axis of rotation or spin axis

[0070] V partial vacuum

[0071] X pivot axis

[0072] O oil

[0073] L oil tank level

Claims

1. A gyro stabilizer assembly comprising: a housing defining a chamber for supporting a working pressure of less than 0.5 bar; a flywheel mounted within the chamber for rotation about an axis of rotation at the working pressure; a flywheel shaft supporting the flywheel and mounted in the housing for rotation of the flywheel about the axis of rotation by first and second rotary bearings located at opposite end regions of the flywheel shaft, each of the first and second rotary bearings comprising rolling or sliding elements; and a lubrication system for the first and second rotary bearings configured to supply lubricant from an oil tank to the first and second rotary bearings, wherein in use the oil tank at the working pressure is arranged within or on the housing to collect the lubricant from the first and second rotary bearings under the action of gravity, and the first and second rotary bearings are arranged within the housing at the working pressure; and wherein the lubrication system comprises a jet outlet aligned with each of the first and second rotary bearings so as to deliver the lubricant directly to the rolling or sliding elements of each of the first and second rotary bearings. the lubrication system comprises at least one pump for circulating the lubricant to the first and second rotary bearings, wherein the at least one pump is arranged such that lubricant in the oil tank provides a pressure head at an inlet of the pump.

2. The gyro stabilizer assembly of claim 1, wherein, the pump is arranged in the oil tank immersed in the lubricant, or wherein the pump is arranged within or on the housing and the inlet of the pump is in fluid communication with the oil tank at a location spaced below a level of the lubricant in the oil tank.

3. The gyro stabilizer assembly of claim 2, wherein, the pump is a variable volume vacuum pump.

4. The gyro stabilizer assembly of claim 2 or 3, wherein, the first and second rotary bearings are configured and arranged within the housing such that lubricant circulated to the first and second rotary bearings drains from each respective rotary bearing under the action of gravity to return to the oil tank.

5. The gyro stabilizer assembly of any one of claims 1 to 3, wherein, the flywheel shaft is mounted within the housing in a substantially vertical orientation for rotation about a substantially vertical axis of rotation, wherein the first and second rotary bearings comprise upper and lower rotary bearings respectively.

6. The gyro stabilizer assembly of any one of claims 1-3, wherein, 7. The gyro stabilizer assembly of claim 6, further comprising a member rigidly attached to the flywheel shaft for rotation therewith and arranged below the upper rotary bearing for capturing lubricant draining from the upper rotary bearing and dispensing the lubricant radially outwardly onto an inner wall of a housing enclosing the chamber for return to the oil tank under the action of gravity. a wall of the housing forms a heat exchanger for the lubricant as it returns to the oil tank under the action of gravity.

8. The gyro stabilizer assembly of any one of claims 1-3, wherein, 8. The gyro stabilizer assembly of claim 7, wherein the member comprises a plurality of radially extending vanes.

9. The gyro stabilizer assembly according to any one of claims 1 to 3, comprising a rotary motor for driving the flywheel in rotation about the rotation axis, wherein the rotary motor is mounted inside the chamber.

10. The gyro stabilizer assembly according to any one of claims 1 to 3, comprising a rotary motor for driving the flywheel in rotation about the rotation axis, wherein the rotary motor is mounted outside the chamber and connected to the flywheel shaft by a magnetic seal coupling or shaft connection.

11. The gyro stabilizer assembly of any one of claims 1 to 3, wherein, The working pressure is a partial vacuum, so that the chamber in which the flywheel is mounted forms a vacuum chamber.

12. The gyro stabilizer assembly of any one of claims 1-3, wherein, The lubricant is liquid at the working pressure and temperature and comprises synthetic machine oil.

13. The gyro stabilizer assembly of claim 7, wherein, The member is a disc member.

14. The gyro stabilizer assembly of claim 8, wherein, The wall of the housing forms the heat exchanger by means of a cooling medium in the wall and / or by means of fin elements formed in the wall.

15. A gyro stabilizer assembly for a marine vessel, comprising: a housing defining a chamber for supporting an at least partial vacuum; a flywheel mounted inside the chamber for rotation about a rotation axis under the partial vacuum; a flywheel shaft on which the flywheel is supported and mounted for rotation about the rotation axis, the flywheel shaft being rotatably supported by a first rotary bearing located in a region of one end of the flywheel shaft and a second rotary bearing located in a region of an opposite end of the flywheel shaft, each of the first and second rotary bearings comprising rolling or sliding elements; a lubrication system configured to supply lubricant from a lubricant tank to the first and second rotary bearings, wherein the lubricant tank, in use, is arranged inside or on the housing to collect the lubricant from the first and second rotary bearings under the action of gravity, wherein the first and second rotary bearings are arranged inside the housing to operate under the partial vacuum; wherein the lubrication system comprises a jet outlet aligned with the rolling or sliding elements of each of the first and second rotary bearings so as to deliver the lubricant directly and specifically to the rolling or sliding elements of the first and second rotary bearings.

16. A marine vessel comprising a gyro stabilizer assembly according to any one of claims 1 to 15.

17. The marine vessel according to claim 16, wherein the marine vessel is a boat or a motor yacht.

Images