Patent Grant
11780542
The present disclosure relates generally to boat roll stabilizers for reducing the sideways rolling motion of a boat and, more particularly, to controlled moment gyroscopes for reducing the roll of a boat based on the gyroscopic effect.
The sideways rolling motion of a boat can create safety problems for passengers and crew on boats, as well as cause discomfort to passengers not accustomed to the rolling motion of the boat. A number of technologies currently exist to reduce the sideways rolling motion of a boat. One technology currently in use is gyroscopic boat stabilization for roll suppression, which is based on the gyroscopic effect. A control moment gyroscope (CMG) is mounted in the boat and generates a torque that can be used to counteract the rolling motion of the boat. The CMG includes a flywheel that spins at a high speed. A controller senses the attitude of the boat and uses the energy stored in the flywheel to “correct” the attitude of the boat by applying a torque to the hull counteracting the rolling motion of the boat.
Although, CMGs are gaining in popularity, particularly for smaller fishing boats and yachts, such devices are somewhat complicated to assemble correctly. For example, CMGs that utilize some forms of bearing cooling for the bearings supporting the flywheel that include having a low vapor pressure fluid disposed in or around end portions of the flywheel shaft, such as in cavities formed in the end portions of the flywheel shaft. Filling these cavities with the low vapor pressure fluid, and sealing that fluid in the cavities as appropriate, may be challenging both during initial assembly, and during any rework/repair operations.
Thus, there is a need for approaches to configuring control moment gyroscopes to allow for efficient assembly and/or repair, particularly in relation to filling and/or inspecting the cavities and/or sealing arrangements for bearing cooling systems.
The present disclosure relates to a gyroscopic roll stabilizer for a boat, and related methods. In an aspect, the gyroscopic roll stabilizer includes a flywheel assembly rotatably mounted inside an enclosure for rotation about a flywheel axis. The flywheel assembly includes a flywheel and flywheel shaft; the flywheel shaft has a longitudinal through passage that connects first and second open-ended cavities at opposing ends of the flywheel shaft. This longitudinal passage may be used for inspection of one of the cavities and/or an associated seal, from the direction of the other cavity.
In one or more aspects, the gyroscopic roll stabilizer includes an enclosure, a flywheel assembly, and a motor. The enclosure is mounted to a gimbal for rotation about a gimbal axis and configured to maintain a below-ambient pressure. The flywheel assembly is rotatably mounted inside the enclosure for rotation about a flywheel axis. The flywheel assembly includes a flywheel and flywheel shaft. The flywheel shaft has a first end and an opposite second end; a first open-ended cavity formed in the first end and facing away from the second end; and a second open-ended cavity formed in the second end and facing away from the first end. The motor is operative to rotate the flywheel assembly. The flywheel shaft has a longitudinal passage connecting the first cavity and the second cavity. A liquid heat transfer medium is optionally disposed in the first cavity, the second cavity, and the longitudinal passage. In some aspects, the gyroscopic roll stabilizer is such that:
Other aspects of the disclosure relates to methods of assembling or maintaining a gyroscopic roll stabilizer for a boat. The gyroscopic roll stabilizer includes an enclosure and a flywheel assembly supported in the enclosure for rotation about a flywheel axis. The flywheel assembly includes a flywheel shaft and a flywheel. The method includes accessing a first open-ended cavity in a first end of the flywheel shaft; and inspecting a second open-ended cavity in a second end of the flywheel shaft and/or a seal associated with the second cavity via a longitudinal passage in the flywheel shaft that extends between the first cavity and the second cavity; wherein the longitudinal passage is accessed via the first cavity for the inspecting. The inspecting may comprise executing a pressure test and/or using an inspection tool inserted into the longitudinal passage. The method optionally includes thereafter filling the second cavity with a liquid heat transfer medium via the longitudinal passage. The first cavity may be above the second cavity during the inspecting, or the positions/roles may be reversed. In some aspects, the method is such that:
In other aspects, the disclosure relates to a method of assembling a gyroscopic roll stabilizer for a boat. The gyroscopic roll stabilizer includes an enclosure and a flywheel assembly supported in the enclosure for rotation about a flywheel axis. The flywheel assembly includes a flywheel shaft and a flywheel. The method includes installing a second seal associated with a second open-ended cavity in a second end of the flywheel shaft; accessing a first open-ended cavity in an opposing first end of the flywheel shaft; inspecting, with the second seal installed, the second open-ended cavity and/or the second seal via a longitudinal passage in the flywheel shaft that extends between the second cavity and the first cavity; filling the second cavity with a liquid heat transfer medium via the longitudinal passage by adding the liquid heat transfer medium to the longitudinal passage and/or the first cavity; after the filling, closing the enclosure; wherein the longitudinal passage is accessed via the first cavity for the inspecting. The first cavity may be above the second cavity during the inspecting, or the positions/roles may be reversed. In some aspects, the method is such that:
The features, functions and advantages that have been discussed above, and/or are discussed below, can be achieved independently in various aspects or may be combined in yet other aspects, further details of which can be seen with reference to the following description and the drawings.
Referring now to the drawings,
Referring now to
The gimbal 20 comprises a support frame 22 that is configured to be securely mounted in the boat 5. Preferably, the gimbal 20 is mounted along a longitudinal axis L of the boat 5 with the gimbal axis G extending transverse to the longitudinal axis L. Conventionally, the gimbal 20 is mounted in the hull of the boat 5, but could be mounted at any location. The support frame 22 of the gimbal 20 comprises a base 24 and two spaced-apart supports 26. A bearing 28 is mounted on each support 26 for rotatably mounting the enclosure 30 to the supports 26. For this purpose, the enclosure 30 includes two gimbal shafts 32 projecting from diametrically opposed sides of the enclosure 30. The gimbal shafts 32 are rotatably journaled in the gimbal bearings 28 to allow the enclosure 30 and flywheel assembly 40 to rotate or precess about the gimbal axis G in the fore and aft directions.
The basic elements of enclosure 30 are the same in the various embodiments described herein but vary in some details depending on the design of the bearing cooling system 100. The enclosure 30 is generally spherical in form and comprises two main housing sections 34 and two cover plates 36. The two main housing sections 34 join along a plane that typically bisects the spherical enclosure 30. The cover plates 36 join the main housing sections 34 along respective planes closer to the “poles” of the spherical enclosure 30. All joints in the enclosure 30 are sealed to maintain a below-ambient pressure within the enclosure 30 to reduce aerodynamic drag on the flywheel assembly 40. Typical below-ambient pressures should be in the range of 1-40 torr (133-5333 Pa, 0.02-0.77 psi). Although the construction of the enclosure 30 is generally the same in the embodiments herein described, the details of the housing sections 34 and cover plates 36 vary as described more fully below depending on the design of the bearing cooling system used.
Referring to
The flywheel assembly 40 is supported by upper and lower bearing assemblies inside the enclosure 30. Each bearing assembly comprises a bearing 50 mounted within a bearing block 58. Each bearing 50 comprises an inner race 52 that is affixed to and rotates with the flywheel shaft 44, an outer race 54 that is mounted inside the bearing block 58, and one or more ball bearings 56 disposed between the inner and outer races 52, 54. The bearing blocks 58 are secured to the interior of the enclosure 30. The outer race 54 is mounted to bearing block 58, and bearing block 58 is mounted to the enclosure 30, so that the outer race 54 is rotationally fixed relative to the enclosure 30. The mounting of the bearing block 58 to the enclosure 30 may be via any suitable means, such as by suitable lip(s) in the bearing block 58 and one or more bearing cap plates 59a held by screws. Likewise, the affixing of the inner race 52 to the flywheel shaft 44 may be by any suitable means, such as press fitting, and/or suitable lip(s) in the flywheel shaft 44 and one or more bearing cap plates 59b held by screws. The bearing block 58 may be generally round in cross-section (perpendicular to flywheel axis F), but this is not required and any suitable shape may be employed, including faceted shapes. Seals (not shown) are disposed on the top and bottom of the bearings 50 to contain lubricant in the bearings 50.
The motor 60 rotates the flywheel assembly 40 at a high rate of speed (e.g., 9000 rpm). The motor 60 typically includes a rotor 62 that mounted to the flywheel shaft 44 and a stator 64 that this secured to the enclosure 30 by any suitable mounting system. Although the motor 60 is advantageously mounted inside the enclosure 30, it is also possible to mount the motor 60 on the exterior of the enclosure 30. In one embodiment, the motor 60 operates on 230 Volt single phase AC power (or could be three-phase AC power, or AC or DC battery power, such as from a lithium ion battery pack).
The torque control system 70, shown in
When the flywheel assembly 40 rotates at high speed, the bearings 50 and motor 60 will generate a substantial amount of heat, particularly when the flywheel assembly 40 is precessing, which could lead to bearing and/or motor failure. Cooling the bearings is challenging, particularly when the interior of the enclosure 30 is a significantly below ambient pressure environment. Bearing cooling system 100 allows cooling of bearings 50 and other heat generating components contained within the enclosure without direct contact of the recirculated oil or liquid coolant with the bearings 50, which may result in high frictional losses. In general, heat is transferred by solid and/or liquid conduction to a heat sink that is cooled by oil, glycol, or other liquid coolant flowing along the cooling circuit 100.
Note that the flywheel shaft 44 has a first end and an opposite second end. For ease of reference, these may be referred to as the north end 47N and the south end 47S, it being understood that such labels are merely for convenience, and the orientations may be reversed as desired. The north end 47N of the flywheel shaft 44 includes an open-ended cavity 46N, which faces away from the flywheel 42. Likewise, the south end 47S of the flywheel shaft 44 includes an open-ended cavity 46S, which faces away from the flywheel 42. These cavities 46N,46S are involved with cooling the bearings 50, and may generically be referred to as cavity 46. Note that the cavities 46 are open-end in that they are open-ended with respect to the rest of the flywheel shaft 44, even if the cavities 46 are closed off by other components, such as seal 125 and/or cover plates 36. In the discussion below, cooling of bearings 50 associated with the north end 47N will be discussed; it being understood that cooling of bearings 50 associated with the south end 47S is advantageously performed similarly, and discussion of the cooling of the bearings 50 associated with the south end 47S is generally omitted for clarity.
Bearing cooling circuit 100 is configured to transfer heat away from the inner race 52 of the bearing 50 by recirculating cooling fluid 90. See
As shown in
In some aspects, the heat transfer shaft assembly 130 is a simple unified shaft that includes an internal chamber for the cooling fluid to be circulated through. In other aspects, the heat transfer shaft assembly 130 includes a shaft 131, a sleeve 136, and fluid channel 120. The shaft 131 extends from the enclosure 30 and into cavity 46. The shaft 131 advantageously has outer groove(s) 132 and an inner passage 134. Groove(s) 132 may be oriented perpendicular to the flywheel axis F, or may advantageously spiral around the flywheel axis F, such as by being helical or other spiral shape. Alternatively, groove(s) 132 may wind around the shaft 131 in any suitable fashion, such as in a sinusoidal shape, or a zig-zag shape, whether regular or irregular. Advantageously, the fluid pathway 210 peripherally surrounds the flywheel axis F, such as by circumnavigating the shaft 131. The sleeve 136 is disposed about the shaft 131 in spaced relation to the “floor” of the groove(s) 132 and in spaced relation to an inner wall on flywheel shaft 44 defining the cavity 46. A fluid channel 120 is jointly defined by the sleeve 136 and the groove(s) 132, with the fluid channel 120 having the cooling fluid therein. A closed fluid pathway 210 for recirculating cooling fluid 90 extends through fluid channel 120. Note that in alternative embodiments, the groove(s) 132 are alternatively and/or additionally formed on the sleeve 136. Thus, it should be considered that the fluid channel 120 is jointly formed by the shaft 131 and sleeve 136, regardless of whether the groove(s) 132 are in the shaft 131, or the sleeve 136, or both.
Cooling fluid 90 flows through the bearing cooling circuit 100, including the fluid channel 120. When shaft 131 with inner passage 134 is present, the inner passage 134 may be downstream relative to the fluid channel 120 along the fluid pathway 210, so that cooling fluid 90 flows through the fluid channel 120, and then out of the heat transfer shaft assembly 130 via the inner passage 134. In other aspects, the flow is reversed so that cooling fluid 90 flows through the inner passage 134, and then out of the heat transfer shaft assembly 130 via the fluid channel 120.
As shown schematically in
For the
As can be appreciated, keeping liquid heat transfer medium 122 in cavity 46 allows proper cooling of bearing 50. As such, seals, such as seal 125 in
An exemplary process (300) of assembling or maintaining the gyroscopic roll stabilizer 10 is shown in
The exemplary process (300) discussion above has been in the context of the south cavity 46S and/or the seal associated with the south cavity 46S being inspected via the longitudinal passage 45. Such an approach may be particularly useful when assembling the gyroscopic roll stabilizer 10, starting with assembly of the southern portions. With the enclosure 30 inverted, such that the south cavity 46S is disposed above the north cavity 46N, the southern heat transfer shaft assembly 130 may be inserted into the south cavity 46S, the associated seal 125 installed, and the south cover plate 36 installed. At this point, the south cavity 46S does not have heat transfer medium 122 therein. The enclosure 30 is then “righted” so that the north cavity 46N and the north end 47N of the flywheel shaft 44 is disposed above the south cavity 46S and the south end 47S of the flywheel shaft 44. The process of inspecting (330) the south cavity 46S and/or seal 125, and filling (350), is then carried out. The north cavity 46N is then fully filled with heat transfer medium 122 as appropriate, and the north seal 125 installed. The north cover plate 36 is then installed. The CMG 10 is then optionally tested, such as by spinning (380) the flywheel, as appropriate.
The presence of the longitudinal passage 45 connecting the cavities 46 provides benefits which may be present all together, or separately, depending on the particular embodiment of the gyroscopic roll stabilizer. First, the longitudinal passage 45 allows the south cavity 46S and/or seal 125 to be inspected both after the southern portion is closed up with the seal 125 in place, and from the opposing (north) end 47N of the enclosure 30. Second, the longitudinal passage 45 allows heat transfer medium 122 to be added to south cavity 46S both after the southern portion is closed up with the seal 125 in place, and from the opposing (north) end 47N of the enclosure. The heat transfer medium 122 flows down into the south cavity 46S along the longitudinal passage 45, and any displaced air/gas can escape through the longitudinal passage 45. Thus, gravity can assist in filling the south cavity 46S with the enclosure 30 inverted. The ability to inspect and/or fill one cavity 46 from the opposing end 47 may be particularly beneficial during assembly, or during maintenance (servicing), when access to one end 47 or the other of the enclosure 30 may be restricted. A further benefit is that fluid pressure of the heat transfer medium 122 may be equalized between the north cavity 46N and the south cavity 46S, because the two cavities 46 are in fluid communication via the longitudinal passage 45, which may be beneficial for some situations.
It should be understood that the roles and positions of the north and south cavities 46 (and north and south ends 47) may be reversed, as is desired.
The discussion above has been in the context that the approach to cooling the bearings 50 includes a bearing cooling circuit 100 having a heat transfer shaft assembly 130. However, additional and/or alternative approaches to cooling the bearings 50 may be employed. For example, the outer race 54 may be cooled via a suitable fluid channel 220 in bearing block 58, which may be formed in part by one or more grooves 222 on the bearing block 58, and which may optionally for an additions portion of bearing cooling circuit 100. And, other known approaches to cooling the bearings 50 may be employed, such as those disclosed in U.S. Patent Application Publication 2009/0367137, the disclosure of which is incorporated herein by reference in its entirety.
The longitudinal passage 45 may, in some embodiments, be the only passage through the flywheel shaft 44 that connects the cavities 46. However, in some embodiments, there may be multiple longitudinal passages 45 that connect the cavities 46. If there are multiple passages 45, care should be taken in locating them so that the flywheel assembly 40 is properly balanced, such by locating the various passages symmetrically about the flywheel axis F.
The present disclosure may, of course, be carried out in other ways than those specifically set forth herein without departing from essential characteristics of the disclosure. The present embodiments are to be considered in all respects as illustrative and not restrictive, and all changes coming within the meaning and equivalency range of the appended claims are intended to be embraced therein.
This application claims benefit of U.S. Provisional Application No. 63/085,324, which was filed Sep. 30, 2020, the disclosure of which is incorporated herein by reference in its entirety.
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