Key information

Title
Method for vibration damping of and vibration damper assembly for semi-submerged or submerged elongated structure
Application number
20170585
Case type
National
Status
11.06.2019 Patent meddelt (B1)
Filed
07.04.2017
Effective date
07.04.2017
Publicly available
08.10.2018
Next annual fee due
30.04.2027
Applicant
MOMENTUM TECHNOLOGIES AS (NO)
Owner
MOMENTUM TECHNOLOGIES AS (NO)
Inventor
Even Lund (NO) et al.
Agent
ACAPO ONSAGERS AS (NO)
Granted
11.06.2019
Patent number
343819
Expiry date
07.04.2037

Abstract and drawing

Disclaimer: This text has been machine-scanned and may contain errors – please refer to "Publications" for legally binding content.
Method for vibration damping of and vibration damper assembly (100) for semi-submerged or submerged elongated structure (200), based on separating hydrodynamic added mass (madd) from the semi-submerged or submerged elongated structure (200) by means of a vibration damper assembly (100) exhibiting spring and/or damper properties and use the hydrodynamic added mass (madd) as a reaction mass in the vibration damper assembly (100).

Publications

B1A1
Checking availability of the latest published version...

Documents

 Expand Download files (33)
Date
 Date Doc. No. Process Case number In/Out Journal description To/from
 10.03.2023 02-01 Endring av søker/innehaver 2023/03224 UT GH Forespørsel CURO AS
 01.03.2023 01-01 Endring av søker/innehaver 2023/03224 INN Generell henvendelse CURO AS
 14.06.2019 13-01 Saksbehandling 20170585 UT PT Registreringsbrev Nasjonal Patent (15) (PT20170585)
03.06.2019 02-01 Endring av søker/innehaver 2019/06806 UT GH Forespørsel CURO AS
 24.05.2019 01-01 Endring av søker/innehaver 2019/06806 INN Generell henvendelse CURO AS
 03.05.2019 12-01 Saksbehandling 20170585 UT Intention to grant CURO AS
 15.03.2019 11-07 Saksbehandling 20170585 INN Patenttegninger CURO AS
 15.03.2019 11-06 Saksbehandling 20170585 INN Patenttegninger med sporing CURO AS
 15.03.2019 11-05 Saksbehandling 20170585 INN Beskrivelse med sporing CURO AS
 15.03.2019 11-04 Saksbehandling 20170585 INN Beskrivelse CURO AS
 15.03.2019 11-03 Saksbehandling 20170585 INN Hovedbrev CURO AS
 15.03.2019 11-02 Saksbehandling 20170585 INN Krav CURO AS
 15.03.2019 11-01 Saksbehandling 20170585 INN Korrespondanse (Hovedbrev inn) CURO AS
 08.03.2019 10-01 Saksbehandling 20170585 UT PT Varsel om betaling av første årsavgift (3317) (PT20170585)
30.01.2019 09-01 Saksbehandling 20170585 UT Realitet patent CURO AS
 10.11.2018 08-02 Saksbehandling 20170585 UT PT_report 10:47:23
10.11.2018 08-01 Saksbehandling 20170585 UT Realitet patent CURO AS
 26.04.2018 07-01 Saksbehandling 20170585 INN Korrespondanse (Hovedbrev inn) CURO AS
 24.01.2018 06-05 Saksbehandling 20170585 INN Beskrivelse ren Curo AS
 24.01.2018 06-04 Saksbehandling 20170585 INN Beskrivelse merket Curo AS
 24.01.2018 06-03 Saksbehandling 20170585 INN patenttegninger Curo AS
 24.01.2018 06-02 Saksbehandling 20170585 INN Hovedbrev Curo AS
 24.01.2018 06-01 Saksbehandling 20170585 INN Korrespondanse (Hovedbrev inn) Curo AS
 05.11.2017 05-02 Saksbehandling 20170585 UT PT report 01:04:51
05.11.2017 05-01 Saksbehandling 20170585 UT Realitet patent Curo AS
 16.05.2017 04-03 Saksbehandling 20170585 INN Fullmakt Curo AS
 16.05.2017 04-02 Saksbehandling 20170585 INN Overdragelsesdokument Curo AS
 16.05.2017 04-01 Saksbehandling 20170585 INN Korrespondanse (Hovedbrev inn) Curo AS
 20.04.2017 03-01 Saksbehandling 20170585 UT Formalia 1 Curo AS
 20.04.2017 02-01 Saksbehandling 20170585 UT Infobrev til oppfinner Curo AS
 07.04.2017 01-03 Saksbehandling 20170585 INN Beskrivelse Curo AS
 07.04.2017 01-02 Saksbehandling 20170585 INN U3821-figures Curo AS
 07.04.2017 01-01 Saksbehandling 20170585 INN Søknadsskjema Patent Curo AS

Description, claims and drawings

Disclaimer: This text has been machine-scanned and may contain errors – please refer to "Publications" for legally binding content. Description
Method for vibration damping of and vibration damper assembly for semi-submerged or submerged elongated structureThe present invention is related to a method for vibration damping of semi-submerged or submerged elongated structure, according to the preamble of claim 1.The present invention is also related to a vibration damper assembly for semi-submerged or submerged elongated structure, according to the preamble of claim 11.The present invention is especially related to a method for vibration damping of and vibration damper assembly for semi-submerged or submerged elongated structure utilizing hydrodynamic mass, that all semi-submerged or submerged elongated structures are experiencing, to reduce vibration and thus reduce the chances of fatigue failure thereof.BackgroundMany marine structures, both submerged and semi-submerged, are experiencing problems with dynamic motion, shock and vibration causing fatigue. The oil and gas industry is extending the life of old reservoirs, increasing the flow velocity in old pipelines that are beyond their original expiry date. This is increasing the chances of leaks of hydrocarbons to happen, creating great production losses, large environmental spills, repair costs and the risk of losing lives.Vibration and fatigue are not only related to the oil and gas industry, and it is likely that other renewable energy structures, such as wind power or tidal power, ships and fish farms, to name a few, are experiencing many of the same problems.Marine structures can be subjected to many types of dynamic forces: semi-submerged structures can have wind, wave and current loads. Submerged pipelines can also experience internal forces transferred through the structure from machinery or created from fluids flowing through the pipes or acoustics in the pipe.Common for many of the marine structures is that it is difficult to inspect and maintain systems under water. Marine structures thus need to be robust and usually require a lifetime beyond 20 years. Within this time frame the structure must withstand vibration caused by all the dynamic forces it is subjected to. There are a great number of different techniques available for controlling vibration. They can be sorted in active systems or passive systems.Active systems use energy to reduce vibration and are usually having an electronic vibration controller that use feedforward and/or feedback to control an actuator that is counteracting the motion. Passive damping systems are utilizing friction, viscous losses or magnetic or other types of losses to dissipate energy without using external power.It is not known that active systems have been used under water in the past, and passive vibration systems are also rarely used for subsea systems.Examples of such systems are viscous dampers and reaction mass dampers which can act in one or more axes. The viscous damper is the fundamental building block in mechanical lumped element models and has two connection points where usually the vibrating structure is connected to one end and a foundation to the other end. A dash pot or shock absorber for a car is behaving like a viscous damper.Reaction mass dampers use the inertia of a secondary mass to counteract the motion of the vibrating structure. Both passive and active systems exist. The passive systems are known as tuned mass dampers, harmonic absorbers, tuned absorbers or Lanchester dampers. The reaction mass for a passive system is connected to the vibrating structure trough spring and damper elements to create a reaction force. A combination of dissipation and transferal of mechanical energy is used to reduce the vibration in the main system.From SU 1725003 A1 it is known a device for damping oscillations of a pipeline. The solution is based on a physical parallelepiped-shaped mass element arranged to the surface of the pipeline. For submerged applications the prior art solutions suffer from that they do not work for low frequencies.The solutions of prior art further suffer from that they are only capable of damping vibrations within a relatively narrow frequency range.Prior art solutions further suffer from that they require arrangement to a foundation, at one side thereof.A disadvantage with prior art is further that, if more than one damping system is used, they will interact/counteract the function of each other. A further disadvantage with the prior art solutions is that they introduce large gravitational loads to the elongated structure.Prior art solutions further suffer from that they either work in vertical or horizontal direction under water, and is arranged for damping either transient or harmonic forces.A further disadvantage with prior art is that they comprise many mechanical parts exposed to wear.Another disadvantage with prior art reaction mass dampers is that they are arranged for reducing the mechanical response, but are not arranged for handling external forces, i.e. forces from the environment.ObjectThe main object of the present invention is to provide a method for vibration damping of and vibration damper assembly for semi-submerged or submerged elongated structures partly or entirely solving the drawbacks of prior art.An object of the present invention is to provide a method for vibration damping of and vibration damper assembly for semi-submerged or submerged elongated structure utilizing hydrodynamic mass to reduce vibration in the semi-submerged or submerged elongated structure.It is further an object of the present invention to provide a method for vibration damping of and vibration damper assembly for semi-submerged or submerged elongated structure capable of separating the hydrodynamic added mass from the semi-submerged or submerged elongated structure by means of at least one spring element and/or damper element.An object of the present invention is to provide a method for vibration damping of and vibration damper assembly for semi-submerged or submerged elongated structure realized as a tuned mass damper or tuned absorber, or as a Lanchester damper.It is an object of the present invention to provide a method for vibration damping of and vibration damper assembly for semi-submerged or submerged elongated structure capable of vibration reduction over a wide range of frequencies. An object of the present invention is to provide a method for vibration damping of and vibration damper assembly for semi-submerged or submerged elongated structure also working for low frequencies.A further object of the present invention is to provide a method for vibration damping of and vibration damper assembly for semi-submerged or submerged elongated structure which require no foundation.It is an object of the present invention to provide a method for vibration damping of and vibration damper assembly for semi-submerged or submerged elongated structure which do not interact/counteract the function of other damping systems used in connection with the semisubmerged or submerged elongated structure the vibration damper assembly according to the present invention is arranged to.A further object of the present invention is to provide a method for vibration damping of and vibration damper assembly for semi-submerged or submerged elongated structure having great vibration reduction abilities due to large mass ratios subsea.An object of the present invention is to provide a method for vibration damping of and vibration damper assembly for semi-submerged or submerged elongated structure that does not introduce large gravitational loads to the semi-submerged or submerged elongated structure.It is further an object of the present invention to provide a method for vibration damping of and vibration damper assembly for semi-submerged or submerged elongated structure working both in vertical and horizontal direction under water.It is an object of the present invention to provide a method for vibration damping of and vibration damper assembly for semi-submerged or submerged elongated structure that can be implemented with few mechanical elements providing a robust design.An object of the present invention is to provide a method for vibration damping of and vibration damper assembly for semi-submerged or submerged elongated structure working for both transient and harmonic forces.It is further an object of the present invention to provide a method for vibration damping of and vibration damper assembly for semi-submerged or submerged elongated structure capable of mitigating both external forces and mechanical response. An object of the present invention is to provide a method for vibration damping of and vibration damper assembly for semi-submerged or submerged elongated structure that can be implemented as an active or passive vibration damper assembly.A further object of the present invention is to provide a vibration damper assembly which in addition to the above objects also can provide buoyancy for a semi-submerged or submerged elongated structure.It is an object of the present invention to provide a method for damping of and vibration damper assembly for semi-submerged or submerged elongated structure that is scalable.Further objects of the present invention will appear from the following example description, claims and attached drawings.The inventionA method for vibration damping of a semi-submerged or submerged elongated structure according to the present invention is disclosed in claim 1. Preferable features of the method are disclosed in the dependent claims.A vibration damper assembly for a semi-submerged or submerged elongated structure according to the present invention is disclosed in claim 11. Preferable features of the vibration damper assembly are disclosed in the dependent claims.It is difficult to understand the complex motion of a vibrating elongated structure just by observing it by the eye, as shown in Figure 1 which is a principle drawing of a vibrating elongated structure and frequency response (time domain in air) thereof. It is though well known that this motion can be described as a superposition of multiple single frequency motions known as eigenmodes/natural modes, as indicated in Figure 2 showing eigenmodes for the vibrating elongated structure in Figure 1. When a force with a single frequency, is corresponding to the eigenfrequency/natural frequency of the eigenmode, you get resonance, a large amplification of the vibration at positions where the eigenmodes have large motion, known as antinodes. The vibration for this particular eigenmode will be lower for all other forcing frequencies than the vibration at the eigenfrequency, as e.g. as illustrated in Figure 3 for the vibrating elongated structure in Fig. 1 and 2. The observed vibration for a given elongated structure will be the sum of motion from all eigenmodes. The frequency spectrum for a point along the elongated structure will further be given by the sum of the spectra for each eigenmode.It is further known, that when observing a point along the vibrating elongated structure, the motion of each of the eigenmodes can be mathematically described as a lumped mass system given by an equivalent mass meq, a spring k and damper c, as illustrated in Figure 4 which is a principle drawing of a lumped mass system. The equivalent lumped parameters can be extracted from the continuous system through measurement or simulation.The vibratory response for this simple one-degree-of freedom system, when the mass is subjected to a harmonic vertical force, is given by:where x is the vibration amplitude, F is the harmonic force amplitude, k is the stiffness coefficient, meq is the mass, c is the damping coefficient, ω is the rotational frequency and j is the imaginary unit for a complex number.The amplitude of the vibration is given by:The vibratory response for this system will in theory go to infinity if the damping coefficient is zero and the forcing frequency is where ω is the angular frequency [rad/s] and / is the frequency [Hz]. This is known as resonance. It is also worth noting that the system rarely will experience resonance if the stiffness coefficient is zero given that the c/meq ratio is sufficiently low, such as a system consisting of only a mass and a damper.When the same continuous vibrating elongated structure is submerged in a liquid, such as water, it is known that the structural dynamics will change due to the interaction with the liquid. This field of dynamics is known as hydrodynamics.The continuous system can be broken down to a similar set of mode shapes and the full response can be described as a superposition of the modes, similar to that of the elongated structure in air (Figure 2). The response at a point along the elongated structure can also be broken down to a superposition of the responses for each eigenmode as lumped mass representations with given frequency spectra. The main difference to air being that the hydrodynamic effects will change the parameters of the models. For a low viscous liquid, such as water, the additional damping coefficient will be negligible compared to in air. The additional mass will, on the other hand, be quite large for an elongated structure submerged in water. This additional mass is known as added mass, or hydrodynamic added mass and can be thought of as an additional mass layer surrounding the elongated structure when it is vibrating in water, as illustrated in Figure 5 which is a principle drawing of a pipe dynamic model.The lumped mass representation for a point along the elongated structure can be represented as the original representation with a mass added, connected directly to the formerly described equivalent mass, as illustrated in Figure 6 which is a principle drawing of a submerged lumped mass system.The hydrodynamic added mass effect of liquid is troublesome for elongated structures susceptible of vibration. The vibratory response will be higher and it will be more difficult to suppress the vibration through mitigating techniques. The former can be seen in the expression for the point response for each eigenmode: where meq is the equivalent structural mass and madd is the hydrodynamic mass. The denominator will shrink as the madd is being increased, thus increasing the vibration amplitude x.According to the present invention it is provided a method and vibration damper assembly which utilize the hydrodynamic added mass as a reaction mass in a vibration damper assembly exhibiting spring and/or damper properties.The method and vibration damper assembly according to the present invention is based on separating the hydrodynamic added mass from the semi-submerged or submerged elongated structure by means of at least one spring element and/or damper element. In this way it is possible to use the hydrodynamic added mass as a reaction mass in a vibration damper assembly, as illustrated in Figure 7 which is a principle drawing of the main principle of a vibration damper assembly according to the present invention. This change converts the hydrodynamic added mass from being a problem to benefiting from its use, hence it enables well known damping technologies to be implemented and customized for usage underwater. Accordingly, the method and vibration damper assembly according to the present invention are arranged to separate the hydrodynamic added mass from the semi-submerged or submerged elongated structure by means of at least one spring element, at least one damping element or a combination of these arranged in damper volume partly or entirely enclosing the elongated structure, wherein the damper volume is provided by an outer cover.A vibration damper assembly comprising a spring element, with or without damper element, for separating the hydrodynamic added mass, can be recognized as a tuned mass damper (TMD) or tuned absorber, as illustrated in Figure 8 which is a principle drawing of an embodiment of a vibration damper assembly according to the present invention. If the vibration damper assembly only comprises at least one damping element it is recognized as a Lanchester damper, as illustrated in Figure 9 which is a principle drawing of an embodiment of a vibration damper assembly according to the present invention. Tuned mass dampers, in particular, have been used in many applications from tall buildings, bridges, power lines, cars and planes, to reduce resonant vibration.The vibration damper assembly according to the embodiments described above do not require any foundation, compared to a viscous damper or a dash pot type of damper that requires the two ends of the damper to be attached to a moving and rigid part respectively. Further, the vibration damper assembly according to the present invention, as described above, will provide significant vibration reduction over a wide range of frequencies compared to the undamped response, if the consisting parameters (madd, c and k) are correctly tuned/set up according to the vibrating elongated structure in question.The main advantage of a method and vibration damper assembly according to the present invention in the form of a tuned mass damper is that the vibration reduction for a given mass ratio, μ=madd/meq, will be larger than for a method and vibration damper assembly according to the present invention in the form of a Lanchester damper, especially for low mass ratios. The mass ratio for the present invention will in almost any circumstance be above 1, which is very large compared to most other structures and applications where reaction mass dampers (TMDs or Lanchester) have been used. The performance of the method and vibration damper assembly according to the present invention in the form of a Lanchester damper will converge towards the performance of a TMD with high mass ratios, meaning that both designs will work well.The main advantage of the method and vibration damper assembly in the form of a Lanchester damper is that the vibration damper assembly can be set up without eigenfrequencies, which will accommodate the detrimental interaction effects that multiple TMDs can have on a vibrating elongated structure and that will affect the function of other dampers as well. This means that engineering of a vibration damper assembly according to the present invention with the use of Lanchester dampers will be easier than with TMD, as the function will be nearly guaranteed as long as the vibration damper assembly is arranged to a part of the elongated structure that is vibrating. This also means that a fewer number of vibration damper assemblies are necessary in order to reduce vibrations down to acceptable levels.Accordingly, the present invention provides a method and vibration damper assembly utilizing the hydrodynamic mass in a reaction mass damper. The method and vibration damper assembly according to the present invention have many advantages that other conventional dampers do not have.By the present invention it is provided a method and vibration damper assembly providing a solution working for low frequencies. This will be favourable as the most subsea application problems are related to low frequencies and lack of foundation for attaching a viscous damper at two ends.An advantage of the method and vibration damper assembly according to the present invention is capable of damping vibrations for a wide frequency range.It is further a considerable advantage of the method and vibration damper assembly according to the present invention that no foundation is required.A further advantage with the present invention over prior art is that it is not interacting/counteracting the function of other damping systems used in connection with the elongated structure the vibration damper assembly according to the present invention is arranged to.It is further an advantage that the method and vibration damper assembly according to the present invention have great vibration reduction abilities due to large mass ratios subsea.An advantage over prior art is that the present invention does not introduce large gravitational loads to the semi-submerged or submerged elongated structure.It is further a considerable advantage with the method and vibration damper assembly according to the present invention are working both in vertical and horizontal direction under water. A further advantage with the present invention is that the method and vibration damper assembly according to the present invention can be implemented with few mechanical elements providing a robust design.It is further an advantage that the method and the vibration damper assembly according to the present invention work for both transient and harmonic forces.A considerable advantage with the method and vibration damper assembly according to the present invention is further the capability to mitigate both external forces and mechanical response.A further advantage of the method and vibration damper assembly according to the present invention are that the vibration damper assembly can be implemented both as an active or passive vibration damper assembly. For underwater/submerged application it will often be preferred to use a passive vibration damper assembly due to the harsh environment and no need for external powering.A considerable advantage with the present invention is that is not only related to radial movement, but will also work axially, in rotation about the longitudinal axis (torsion) of the semisubmerged or submerged elongated structure and tilting around the longitudinal axis of the semisubmerged or submerged elongated structure. Accordingly the present invention provides a method and vibration damper assembly with six degrees of freedom.An advantage of the vibration damper assembly according to the present invention is further that it can be divided in segments enabling it to be retrofitted to existing semi-submerged or submerged elongated structures.Another advantage with the present invention is that it introduces low amount of static drag, which is a known problem for semi-submerged and submerged elongated structures.It is further a considerable advantage with the present invention that it is capable of absorbing harmonic and transient stress (vibrations and slugs).Another advantage with the present invention is that it will further work on both linear and nonlinear elongated structures. An advantage of the present invention is further that it provides a scalable solution enabling it to be easily adapted to anything from small/short elongated structures to very large/long elongated structures.It is further an advantage with the present invention that it can be used for replacing other mechanism used on semi-submerged or submerged elongated structures for Vortex Induced Vibration (VIV), as helical strakes and fairings.An advantage with the present invention is that it can be implemented adjustable if desired or requested.It is further an advantage with the present invention that it provides a plain and cost effective solution for implementation to a semi-submerged or submerged elongated structure.Further preferable features and advantageous details of the present invention will appear from the following example description, claims and attached drawings.ExampleThe present invention will below be described in further detail with references to the attached drawings, where:Fig.1 is a principle drawing of a vibrating elongated structure and frequency response thereof, Fig.2 is a principle drawing showing the eigenmodes/natural modes of the vibrating elongated structure in Figure 1,Fig.3 is principle drawing of frequency response at given position in Figure 2,Fig.4 is a principle drawing of a lumped mass system,Fig.5 is a principle drawing of a pipe dynamic model,Fig.6 is a principle drawing of a submerged lumped mass system,Fig.7 is a principle drawing of the main principle of a vibration damper assembly according to the present invention, Fig.8 is a principle drawing of vibration damper assembly according to an embodiment of the present invention recognized as a tuned mass damper,Fig.9 is a principle drawing of a vibration damper assembly according to an embodiment of the present invention recognized as a Lanchester damper,Fig.10a-b are principle drawings of examples of outer cover for the vibration damper assembly according to the present invention,Fig.11a-b are principle drawings of a further embodiment of the vibration damper assembly according to the present invention,Fig.12-15 are principle drawings of further embodiments of the vibration damper assembly according to the present invention, respectively,Fig.16a-b are principle drawings of a further embodiment of the vibration damper assembly according to the present invention comprising several vibration damper assemblies arranged to each other in longitudinal direction of an elongated structure,Fig.17 is a principle drawing of a vibration damper assembly divided in segments, andFig.18 is a principle drawing of a further embodiment of the vibration damper assembly according to the present invention.A vibration damper assembly 100 according to the present invention can be realized through many different types of designs, which will be described below.Reaction mass, madd can be realized with an outer cover 110 arranged to partly or entirely enclose an elongated structure 200. An elongated structure 200 according to the present invention will typically be pipelines for subsea use in the oil and gas industry, such as SCRs, risers (export, drilling, production), jumpers, flexloops, export and transport pipelines and tubing are some examples. Other examples of elongated structures 200 are protruding valves. Yet other examples of elongated structures 200 can be support structures or structural members (e.g. beams or rods) of a semi-submerged or submerged offshore installation. These are only a few examples of elongated structures 200 which the present invention is applicable for. The further example description will mainly be related to an elongated mainly tubular structure 200, such as a pipe, pipeline, tube or tubing, cable or cable assembly, wire, chain, etc.The outer cover 110 exhibits an outer circumference being larger than the elongated structure 200 and is arranged to surround the elongated structure 200 in a circumferential direction thereof. The outer cover 110 will further exhibit a length in longitudinal direction of the elongated structure 200 to provide a damper volume 111 between outer surface of the elongated structure 200 and inner circumference of the outer cover 110.The outer cover 110 will thus provide an enclosure around a part/section of the elongated structure 200, but can in some embodiments enclose mainly the entire elongated structure 200. The further description will mainly be related to an outer cover 110 enclosing a part/section of the elongated structure 200.The outer cover 110 can further be provided with seals 112 at ends thereof, sealing against the elongated structure 200 and providing a sealed damper volume 111 that is separated from the water surrounding the elongated structure 200. The seals 112 can e.g. be rubber bellows, sleeves, gaskets, seals or similar, but can also be more sophisticated/advanced mechanical solutions, which will be apparent for a skilled person.The hydrodynamic added mass or added inertia is accordingly created in all six degrees of freedom for the outer cover 110 (reaction mass). Three translational degrees axial 2 x lateral, three rotational torsional 2 x rocking.Reference is now made to Figures 10a-b showing examples of outer cover 110 for the vibration damper assembly 100 according to the present invention. The design of the outer cover 110 can be everything from a simple cylindrical cover, to more advanced designs involving fins 113, grids 114, spacers 115 or other designs arranged to, in addition to being an outer cover, provide secondary effects to the vibration damper assembly 100, namely reduction of vortex shedding and vibration due to external forcing, such as Vortex Induced Vibrations (VIV).It is important that the geometry/design of the outer cover 110 being used has the minimum static drag coefficient possible, but the maximum dynamic drag coefficient. High static forces are created when the static drag coefficient is high, which is a common problem for submerged elongated structures 200 with strong water current passing by. Accordingly, by means of the shown designs of the outer cover 110 according to the present invention, the static drag is kept at a minimum. High hydrodynamic masses are created when the dynamic drag coefficient is high, as required by the damper mass and preferred to reach high performance. Calculations made by the applicant show that four small fins 113 extending mainly orthogonally out from the outer cover 110 around the circumference will create a hydrodynamic mass that is approximately 1.4 times the hydrodynamic mass for a cylinder with the same outer diameter.It should be mentioned that the shown alternatives of the outer cover 110 are only example embodiments and that the outer cover 110 can vary from this, e.g. by that the fins 113 have different shape and size and the number of fins 113 can be both higher and lower than in the shown embodiments.Further, according to the present invention, the damper volume 111 can be filled with a material with lower density than the ambient liquid (water in the example), thus giving buoyancy to elongated structure 200 requiring neutral or positive buoyancy. According to the present invention also existing buoyancy elements (not shown) of an elongated structure 200 can be used as the outer cover 110 of the vibration damper assembly 100 according to the present invention or that the vibration damper assembly 100 according to the present invention is used in combination with buoyancy elements (not shown) of the elongated structure 200.Buoyancy can according to the present invention be achieved by that the damper volume 111 is filled with air, or that the outer cover 110 is provided with spacers 115 having buoyancy, buoyancy in annular spacers 130 (as shown in Figure 16a) or in a separate inner layer or spacer 132 (as shown in Fig.16b) or buoyancy in outer cover 110.Reference is now made to Figures 11a-b which are principle drawings of a further embodiment of the vibration damper assembly 100 according to the present invention. The damping coefficient c can be realized through a viscous fluid layer 116 in the damper volume 111 between the outer cover 110 and the elongated structure 200. Different types of fluids such as pitch (i.e. bitumen), silicone fluid or other types of viscoelastic polymers can be used in the viscous liquid layer 116 given that the viscosity is sufficiently high to produce the necessary damping. The thickness of the viscous fluid layer 116 should accommodate the necessary full range motion of the vibration damper assembly 100.Reference is now made to Figure 12 which is a principle drawing of a further embodiment of the vibration damper assembly 100 according to the present invention providing an alternative solution for realization of the damping coefficient c to the embodiment of Figures 11a-b. In the embodiment of the vibration damper assembly 100 in Figure 12 the damping coefficient c is achieved by means of a magnet or magnet assembly 117 and plates 118 with high electrical conductivity. According to the shown embodiment two plates 118 are arranged extending mainly perpendicularly from the outer circumference of the elongated structure 200 and towards the inner circumference of the outer cover 110, and spaced apart in the longitudinal direction of the elongated structure 200, i.e. in the damper volume 111, but not in contact with the outer cover 110. According to the shown embodiment the magnet or magnet assembly 117 is arranged extending mainly perpendicularly from the inner circumference of the outer cover 110 and towards the outer circumference of the elongated structure 200, i.e. in the damper volume 111, arranged such that the magnet or magnet assembly 117 is extending between the plates 118. Accordingly, by using magnet or magnet assembly 117 and plates 118 with high electrical conductivity, an eddy current damping element can be provided. The plates 118 can alternatively be arranged to the outer cover 110 and the magnet or magnet assembly 117 to the elongated structure 200. Further, a number of such eddy current damping elements can be arranged spaced apart in the longitudinal direction of the elongated structure 200, within the damper volume 111. The magnet or magnet assembly 117 can e.g. comprise strong rare earth magnets and the plates 118 can e.g. be copper or aluminium plates. When the magnet or magnet assembly 117 are moving close to the plates 118 an alternating electric current will be produced in the plates 118. The alternating electric current will create an alternating magnetic field that will oppose the movement of the magnet or magnet assembly 117, reducing the velocity of the magnet or magnet assembly 117 and thus introduce damping.Reference is now made to Figure 13 which is principle drawing of a further embodiment of a vibration damper assembly 100 according to the present invention. The stiffness coefficient k can according to the present invention be realized for a horizontally vibrating elongated structure 200 by arranging the outer cover 110 to the elongated structure 200 by means of fastening means 119, such as wires, chains, etc., wherein the fastening means 119 are arranged to the elongated structure 200 at one end and to the inner circumference of the outer cover 110 at the other end, wherein the fastening points in the elongated structure 200 and outer cover 110 for the fastening means 119 are displaced in the longitudinal direction of the outer cover 110, for in this way to provide a pendulum. By changing the length of the fastening means 119, i.e. the pendulum, the frequency of the vibration damper assembly 100 can be tuned.Reference is now made to Figure 14 which is a principle drawing of a further embodiment of the vibration damper assembly 100 according to the present invention. In this embodiment, the seals 112 separating the outer cover 110 from the elongated structure 200 can in addition act as a spring element for the vibration damper assembly 100. Providing the seals 112 with springfunctionality can according to the present invention be achieved by that the seals 112 are formed by elastic materials like elastomers/rubber capable of providing a bellows/gasket/sleeve/seal that provides the necessary stiffness.Reference is now made to Figure 15 showing a principle drawing of a further embodiment of the vibration damper assembly 100 according to the present invention, which is an alternative embodiment to the embodiment of Figure 14. In this embodiment the vibration damper assembly 100 is provided with one or more mechanical springs or spring assemblies 120 extending between the outer circumference of the elongated structure 200 and the inner circumference of the outer cover 110, arranged in the viscous layer 116 in the damper volume 111.Reference is now made to Figure 16a showing a further embodiment of the vibration damper assembly 100 according to the present invention, where several separate vibration damper assemblies 100 are arranged to each other in longitudinal direction of an elongated structure 200. According to the present invention several vibration damper assemblies 100 can be arranged to each other by means of annular spacers 130 which keep the vibration damper assemblies 100 in place to the elongated structure 200. The annular spacers 130 are preferably provided with sliding surfaces 131 for the outer covers 110 of the vibration damper assemblies 100. The sliding surfaces 131 of the annular spacers 130 can have low or high friction. At high friction the viscous layer 116 can be replaced with an incompressible fluid, such as water. Accordingly, the sliding surfaces 131 can be used for providing the damper assembly 100 with a desired damping coefficient c. The annular spacers 130 will further act as a buoyancy element for the elongated structure 200.Reference is now made to Figure 16b which is a principle drawing of a modified embodiment of the embodiment shown in Figure 16a. In the embodiment shown in Figure 16b there is arranged an inner layer or longitudinal spacer 132 between the viscous layer 116 and the elongated structure 200. This will enable the assembly of several vibration damper assemblies 100 to form a damper unit which is simple to retrofit to a semi-submerged or submerged elongated structure 200. The inner layer or longitudinal spacer 132 can further act as a buoyancy element similar to the annular spacers 130 and outer cover 110.The viscous layer 116 in Figures 16a-b can be replaced with a friction surface, eddy current damping and/or spring as described above.Further, the vibration damper assemblies 100 arranged to each other can be arranged to cover different vibration frequency ranges. Reference is now made to Figure 17 which is a principle drawing of a further embodiment of the vibration damper assembly 100 according to the present invention. The vibration damper assembly 100 according to the present invention can further be arranged for retrofitting to existing elongated structures 200 by that it is divided in segments 100a arranged for mutual connection by being provided with a snap-on or a clamp-on mechanism 140 that can be handled by divers or a ROV. This will also enable segments 100a of the vibration damper assembly 100 to be arranged in circumferential direction of the elongated structure 200 for use with large elongated structures 200.The length of the vibration damper assembly 100 according to the present invention can be varied from very short, below the diameter for the elongated structure 200, up to very long lengths. The vibration damper assembly 100 according to the present invention should allow for the vibrating elongated structure 200 to move freely without getting in contact with the outer cover 110. The mass ratio will not be affected by the length as the ratio is given by the cross section geometry of the outer cover 110 in comparison to the mass per length properties of the vibrating elongated structure 200.The vibration damper assembly 100 according to the present invention will not add hydrodynamic or gravity loads to the elongated structure 200 due to the separation of the hydrodynamic mass from the vibrating elongated structure 200 and the use of ambient water instead of a metal mass, that is usually used in a conventional TMD.The vibration damper assembly 100 according to the present invention will maintain near neutral buoyancy of the outer cover 110 creating the effect of the hydrodynamic reaction mass. This will prevent the outer cover 110 from being in contact with the vibrating elongated structure 100 at all times and thus allowing the vibration damper assembly 100 according to the present invention to be oriented in both the vertical and horizontal direction.The outer cover 110 for the vibration damper assembly 100 according to the present invention does not require to be made in any particular material, but plastic or composite is most likely due to its near neutral buoyancy and ease of production and cost. The material of the outer cover 110 can be rigid or flexible and have additional damping added. Reference is now made to Figure 18 which is a principle drawing of a further embodiment of the damper assembly 100 according to the present invention arranged for introducing stiffness and/or damping in series to the above described spring elements 112, 119, 120 and/or damping elements 116, 117-118. This can according to the present invention be achieved by that the outer cover 110 is of a rigid or flexible material.The above described embodiments of the vibration damper assembly 100 according to the present invention can be combined to form other modified embodiments within the scope of the attached claims.The vibration damper assembly 100 according to the present invention can be used for all types of semi-submerged or submerged elongated structures 200 that can have problems with vibration underwater. The size of the elongated structure is not limiting the design, neither are the amplitudes of the vibration or the operational frequency.The vibration damper assembly 100 is especially suitable for semi-submerged or submerged elongated mainly tubular structures 200, such as elongated pipes in the form of drilling risers, where operation can be stopped during certain periods of the year due to high underwater currents. The addition of the described vibration damper assembly 100 on parts of or the full length of the riser can both reduce VIV forcing with an outer anti-VIV geometry and resonant vibration from external and internal forces (flow induced vibration (FIV), wave loads etc.) with the tuned mass damper effect of the vibration damper assembly 100.Another pipe example which the vibration damper assembly 100 according to the present invention is suitable for is flexloops. Flexloops are flexible pipelines connecting the wellhead to a manifold and will have to be flexible to enable connection and to accommodate tolerances due to well growth, thermal expansion, position inaccuracy, etc. Flexloops are known to have FIV problems due to high forcing from well flow that can be mitigated with the vibration damper assembly 100 according to the present invention.Other elongated subsea piping can be subjected to both FIV, VIV and flow induced pulsation (FLIP). Vibration from all forcing, as mentioned above, can be mitigated with the vibration damper assembly 100 according to the present invention.Other applications which the vibration damper assembly 100 according to the present invention is suitable for are structural members for submerged or semi-submerged elongated structures 200, such as support elongated structures for offshore platforms or wind turbines, where the minimum amount of material is desired, but where structural integrity due to both dynamic and static loads are vital. The addition of the vibration damper assembly 100 according to the present invention will reduce dynamic loads from waves, winds, currents etc., similar to the reduction of vibration of pipelines as earlier described.Other elongated structures that will benefit from the use of the present invention are umbilicals, fresh water supply, sea cables and mooring lines (cables, wires).ModificationsThe hydrodynamic added mass can according to a modification of the present invention be activated by means of the vibration damper assembly being provided with an actuator for being used as an active vibration damper assembly. This can according to the present invention be achieved by that the vibration damper assembly is arranged to a surface or side of the elongated structure instead of enclosing it entirely as described above. Alternatively this can be achieved by designing the outer cover such that it has different hydrodynamic mass in different directions and thus achieve different damping properties to meet different eigenfrequencies the elongated structure must have. In a further alternative this is achieved by using friction disks for adding damping.
Claims
Claims1. Method for vibration damping of a semi-submerged or submerged elongated structure (200), characterized by separating hydrodynamic added mass (madd) from the semi-submerged or submerged elongated structure (200) by means of a vibration damper assembly (100) exhibiting spring and/or damper properties and use the hydrodynamic added mass (madd) as a reaction mass in the vibration damper assembly (100).2. Method according to claim 1, characterized by separating the hydrodynamic added mass (madd) by means of arranging an outer cover (110) enclosing partly or entirely the elongated structure (200) and providing a damper volume (111) between the outer cover (110) and elongated structure (200).3. Method according to claims 1-2, characterized by providing a damping coefficient for the vibration damper assembly (100) by sealing the damper volume (111) and arranging a viscous fluid (116) in the damper volume (111).4. Method according to claims 1-2, characterized by providing a damping coefficient for the vibration damper assembly (100) by arranging a magnet or magnet assembly (117) and plates (118) at each side of the magnet or magnet assembly (117) in the damper volume (111), arranged to the outer cover (110) and elongated structure (200), respectively, or vice versa, providing an alternating magnetic field.5. Method according to claims 1-2, characterized by providing a damping coefficient for the vibration damper assembly (100) by arranging annular spacers (130) with sliding surfaces (131) with high friction sealing the damper volume (111) and arranging an incompressible fluid in the damper volume (111), or arranging annular spacers (130) with sliding surfaces (131) with low friction at each end of the outer cover (110) and arranging a magnet or magnet assembly (117) and plates (118) at each side of the magnet or magnet assembly (117) in the damper volume (111), arranged to the outer cover (110) and elongated structure (200), respectively, or vice versa, providing an alternating magnetic field.6. Method according to claims 1-2, characterized by providing a stiffness coefficient for the vibration damper assembly (100) by arranging fastening means (119) extending between an inner circumference of the outer cover (110) and outer circumference of the elongated structure (200).7. Method according to claims 1-2, characterized by providing stiffness coefficient for the vibration damper assembly (100) by using elastic seals (112) at ends of the outer cover (110).8. Method according to claims 1-2, characterized by providing stiffness coefficient for the vibration damper assembly (100) by arranging one or more springs or spring assemblies (120) in the damper volume (111) extending between outer surface of the elongated structure (200) and inner surface of the outer cover (110).9. Method according to any one of the claims 2-8, characterized by introducing stiffness and/or damping in series with the at least one spring element (112, 119, 120) and/or damping element (116, 117-118) by using an outer cover (110) of a rigid or flexible material.10. Method according to any one of the preceding claims, characterized by arranging several vibration damper assemblies (100) to each other in longitudinal direction of the elongated structure (200) separated by annular spacers (130) with sliding surfaces (131) with high or low friction to provide a damper coefficient.11. Vibration damper assembly (100) for a semi-submerged or submerged elongated structure (200), characterized in that the vibration damper assembly (100) comprises at least one spring element (112, 119, 120) and/or damper element (116, 117-118) arranged for separating hydrodynamic added mass (madd) from the semi-submerged or submerged elongated structure (200) and utilizing the separated hydrodynamic added mass (madd) as reaction mass in the vibration damper assembly (100).12. Vibration damper assembly (100) according to claim 11, characterized in that the vibration damper assembly (100) comprises an outer cover (110) arranged to partly or entirely enclose the elongated structure (200) and form a damper volume (111) between the outer cover (110) and the elongated structure (200).13. Vibration damper assembly (100) according to claim 12, characterized in that the outer cover (110) at ends thereof is provided with seals (112) sealing against the elongated structure (200).14. Vibration damper assembly (100) according to claims 11-13, characterized in that the at least one damper element (116) is formed by a viscous liquid layer (116) arranged in the damper volume (111).15. Vibration damper assembly (100) according to claims 11-13, characterized in that the at least one damper element is formed by at least one magnet or magnet assembly (117) and plates (118) arranged at each side of the at least one magnet or magnet assembly (117) in the damper volume (111), arranged to the outer cover (110) and elongated structure (200), respectively, or vice versa.16. Vibration damper assembly (100) according to claim 12, characterized in that to each side of the outer cover (110) is arranged annular spacers (130) with sliding surfaces (131) with high friction and that an incompressible fluid is arranged in the damper volume (111), or that to each side of the outer cover (110) is arranged annular spacers (130) with sliding surfaces (131) with low friction and a magnet or magnet assembly (117) and plates (118) at each side of the magnet or magnet assembly (117) arranged in the damper volume (111), arranged to the outer cover (110) and elongated structure (200), respectively, or vice versa, providing an alternating magnetic field.17. Vibration damper assembly (100) according to claim 16, characterized by that it further comprises an inner layer or longitudinal spacers (132) arranged between the viscous layer (116) and the elongated structure (200).18. Vibration damper assembly (100) according to claim 12, characterized in that the vibration damper assembly (100) further comprises fastening means (119) extending between inner circumference of the outer cover (110) and outer circumference of the elongated structure (200).19. Vibration damper assembly (100) according to claim 13, characterized in that the seals (112) are formed by an elastic material.20. Vibration damper assembly (100) according to claim 12, characterized in that the vibration damper assembly (100) further comprises one or more springs or spring assemblies (120) arranged in the damper volume (111), extending between outer circumference of the elongated structure (200) and inner circumference of the outer cover (110).21. Vibration damper assembly (100) according to any one of the claims 11-20, characterized in that several vibration damper assemblies (100) are arranged to each other in longitudinal direction of the elongated structure (200) separated by annular spacers (130) provided with sliding surfaces (131) with high or low friction.22. Vibration damper assembly (100) according to claim 12, characterized in that outer cover (110) at outer surface thereof is formed by or provided with fins (113), grids (114), spacers (115) or a combination thereof.23. Vibration damper assembly (100) according to any one of the claims 12-22, characterized in that the outer cover (110) is formed by a rigid or flexible material introducing stiffness and/or damping in series with the at least one spring element (112, 119, 120) and/or damping element (116, 117-118).24. Vibration damper assembly (100) according to any one of the claims 11-23, characterized in that the vibration damper assembly (100) is divided in segments (100a) provided with means (140) for mutual connection.Patentkrav1. Fremgangsmåte for vibrasjonsdemping av en delvis eller helt nedsenket langstrakt struktur (200), karakterisert ved å skille hydrodynamisk tilleggsmasse (madd) fra den delvis eller helt nedsenkede langstrakte strukturen (200) ved hjelp av en vibrasjonsdempersammenstilling (100) hvilken oppviser fjærende og/eller dempende egenskaper og bruke den hydrodynamiske tilleggsmassen (madd) som reaksjonsmasse i vibrasjonsdempersammenstillingen (100).2. Fremgangsmåte i samsvar med krav 1, karakterisert ved å skille den hydrodynamiske tilleggsmassen (madd) ved hjelp av å innrette en ytre mantel (110) hvilket omgir helt eller delvis den langstrakte strukturen (200) og tilveiebringe et dempervolum (111) mellom den ytre mantelen (110) og den langstrakte strukturen (200).3. Fremgangsmåte i samsvar med krav 1-2, karakterisert ved å tilveiebringe en dempningskoeffisient for vibrasjonsdempersammenstillingen (100) ved å forsegle dempervolumet (110) og innrette et viskøst fluid (116) i dempervolumet (111).4. Fremgangsmåte i samsvar med krav 1-2, karakterisert ved å tilveiebringe en dempningskoeffisient for vibrasjonsdempersammenstillingen (100) ved å innrette en magnet eller magnetsammenstilling (117) og plater (118) ved hver side av magneten eller magnetsammenstillingen (117) i dempervolumet (111), innrettet til den ytre mantelen (110) og henholdsvis den langstrakte strukturen (200), eller motsatt, hvilket tilveiebringer et alternerende magnetisk felt.5. Fremgangsmåte i samsvar med krav 1-2, karakterisert ved å tilveiebringe en dempningskoeffisient for vibrasjonsdempersammenstillingen (100) ved å innrette ringformede avstandsstykker (130) med glidende overflater (131) med høy friksjon hvilke forsegler dempervolumet (111) og innrette et inkompressibelt fluid i dempervolumet (111), eller innrettet ringformede avstandsstykker (130) med glidende overflater (131) med lav friksjon ved hver ende av den ytre mantelen (110) og innrette en magnet eller magnetsammenstilling (117) og plater (118) ved hver side av magneten eller magnetsammenstillingen (117) i dempervolumet (111), innrettet til den ytre mantelen (110) og henholdsvis den langstrakte strukturen (200), eller motsatt, hvilket tilveiebringer et alternerende magnetisk felt.6. Fremgangsmåte i samsvar med krav 1-2, karakterisert ved å tilveiebringe en stivhetskoeffisient for vibrasjonsdempersammenstillingen (100) ved å innrette festemidler (119) hvilke strekker seg mellom en indre omkrets av den ytre mantelen (110) og ytre omkrets av den langstrakte strukturen (200).7. Fremgangsmåte i samsvar med krav 1-2, karakterisert ved å tilveiebringe en stivhetskoeffisient for vibrasjonsdempersammenstillingen (100) ved bruk av elastiske tetninger (112) ved ender av den ytre mantelen (110).8. Fremgangsmåte i samsvar med krav 1-2, karakterisert ved å tilveiebringe en stivhetskoeffisient for vibrasjonsdempersammenstillingen (100) ved å innrette en eller flere fjærer eller fjærsammenstillinger (120) i dempervolumet (111) hvilke strekker seg mellom ytre overflate av den langstrakte strukturen (200) og indre overflate av den ytre mantelen (110).9. Fremgangsmåte i samsvar med ett av kravene 2-8, karakterisert ved å introdusere stivhet og/eller dempning i serie med den minst ene fjærelementet (112, 119, 120) og/eller dempningselementet (116, 117-118) ved bruk av en ytre mantel (110) av fast eller fleksibelt materiale.10. Fremgangsmåte i samsvar med ett av de foregående krav, karakterisert ved å innrette flere vibrasjonsdempersammenstillinger (100) til hverandre i lengderetning av den langstrakte strukturen (200) adskilt av ringformede avstandsstykker (130) med glidende overflater (131) med høy eller lav friksjon for å tilveiebringe en dempningskoeffisient.11. Vibrasjonsdempersammenstilling (100) for en delvis eller helt nedsenket langstrakt struktur (200), karakterisert ved at vibrasjonsdempersammenstillingen (100) omfatter minst et fjærelement (112, 119, 120) og/eller dempningselement (116, 117-118) innrettet for å skille hydrodynamisk tilleggsmasse (madd) fra den delvis eller helt nedsenkede langstrakte strukturen (200) og benytte den adskilte hydrodynamiske tilleggsmassen (madd) som reaksjonsmasse i vibrasjonsdempersammenstillingen (100).12. Vibrasjonsdempersammenstilling (100) i samsvar med krav 11, karakterisert ved at vibrasjonsdempersammenstillingen (100) omfatter en ytre mantel (110) innrettet for å helt eller delvis omgi den langstrakte strukturen (200) og danne et dempervolum (111) mellom den ytre mantelen (110) og den langstrakte strukturen (200).13. Vibrasjonsdempersammenstilling (100) i samsvar med krav 12, karakterisert ved at den ytre mantelen (110) ved ender derav er forsynt med tetninger (112) hvilke tetter mot den langstrakte strukturen (200).14. Vibrasjonsdempersammenstilling (100) i samsvar med krav 11-13, karakterisert ved at det minst ene dempningselementet (116) er dannet av et viskøst væskelag (116) innrettet i dempervolumet (111).15. Vibrasjonsdempersammenstilling (100) i samsvar med krav 11-13, karakterisert ved at det minst ene dempningselementet er dannet av minst en magnet eller magnetsammenstilling (117) og plater (118) innrettet ved hver side av den minst ene magneten eller magnetsammenstillingen (117) i dempervolumet (111), innrettet til den ytre mantelen (110) og henholdsvis den langstrakte strukturen (200), eller motsatt.16. Vibrasjonsdempersammenstilling (100) i samsvar med krav 12, karakterisert ved at til hver side av den ytre mantelen (110) er innrettet ringformede avstandsstykker (130) med glidende overflater (131) med høy friksjon og at et inkompressibelt fluid er innrettet i dempervolumet (111), eller at til hver side av den ytre mantelen (110) er innrettet ringformede avstandsstykker (130) med glidende overflater (131) med lav friksjon og en magnet eller magnetsammenstilling (117) og plater (118) ved hver side av magneten eller magnetsammenstillingen (117) innrettet i dempervolumet (111), innrettet til den ytre mantelen (110) og henholdsvis den langstrakte strukturen (200), eller motsatt, hvilket tilveiebringer et alternerende magnetisk felt.17. Vibrasjonsdempersammenstilling (100) i samsvar med krav 16, karakterisert ved at den videre omfatter et indre lag eller langsgående avstandsstykker (132) innrettet mellom det viskøse laget (116) og den langstrakte strukturen (200).18. Vibrasjonsdempersammenstilling (100) i samsvar med krav 12, karakterisert ved at vibrasjonsdempersammenstillingen (100) videre omfatter festemidler (119) hvilke strekker seg mellom indre omkrets av den ytre mantelen (110) og ytre omkrets av den langstrakte strukturen (200).19. Vibrasjonsdempersammenstilling (100) i samsvar med krav 13, karakterisert ved at tetningene (112) er dannet av et elastisk materiale.20. Vibrasjonsdempersammenstilling (100) i samsvar med krav 12, karakterisert ved at vibrasjonsdempersammenstillingen (100) omfatter en eller flere fjærer eller fjærsammenstillinger (120) innrettet i dempervolumet (111), hvilke strekker seg mellom ytre omkrets av den langstrakte strukturen (200) og indre omkrets av den ytre mantelen (110).21. Vibrasjonsdempersammenstilling (100) i samsvar med ett av kravene 11-20, karakterisert ved at flere vibrasjonsdempersammenstillinger (100) er innrettet til hverandre i lengderetning av den langstrakte strukturen (200) adskilt av ringformede avstandsstykker (130) forsynt med glidende overflater (131) med høy eller lav friksjon.22. Vibrasjonsdempersammenstilling (100) i samsvar med krav 12, karakterisert ved at den ytre mantelen (110) ved ytre overflate derav er dannet ved eller forsynt med finner (113), gitter (114), avstandsstykker (115) eller en kombinasjon av dette.23. Vibrasjonsdempersammenstilling (100) i samsvar med ett av kravene 12-22, karakterisert ved at den ytre mantelen (110) er dannet av et fast eller fleksibelt material hvilket introduserer stivhet og/eller dempning i serie med det minst ene fjærelementet (112, 119, 120) og/eller dempningselementet (116, 117-118).24. Vibrasjonsdempersammenstilling (100) i samsvar med ett av kravene 11-23, karakterisert ved at vibrasjonsdempersammenstillingen (100) er oppdelt i segmenter (100a) forsynt med midler (140) for innbyrdes sammenkobling.
Drawings

Priority

No priority

Patent classes

IPC classesF16F 7/10B63B 22/18CPC classesF16F 7/10B63B 22/18

Citations

SU 1725003 A1 (A1)US 20120103739 A1 (A1)US 6397988 B1 (B1)WO 2015017792 A1 (A1)US 20100215440 A1 (A1)WO 2010141843 A2 (A2)

Applicants, owners and inventors

Owners
MOMENTUM TECHNOLOGIES AS
Ranheimsvegen 9 7044 TRONDHEIM NO (TRONDHEIM Municipality, Trøndelag county)Org. number: 817201822Inventors
Even Lund
Rykkjasvegen 108 7510 SKATVAL NO (STJØRDAL Municipality, Trøndelag county)
Lina Ödlund
Smiskaret 3 7563 MALVIK NO (MALVIK Municipality, Trøndelag county)
Tomas Lundqvist
Viktor Baumanns vei 40 C 7020 TRONDHEIM NO (TRONDHEIM Municipality, Trøndelag county)
Håvard Bjørkøy Johnsen
Eventyrvegen 53 7056 RANHEIM NO (TRONDHEIM Municipality, Trøndelag county)

Agent

ACAPO ONSAGERS AS
ACAPO ONSAGERS AS

Org. number: 932214636

Name and address are automatically synchronized with the Brønnøysund Register Centre.

Open in The Brønnøysund Register Centre
Edvard Griegs vei 1 5059 BERGEN NO (BERGEN Municipality, Vestland county)
Org. number: 932214636
Reference: P20170585NO

Status history

Payment history

Oppositions and appeals

No oppositions or appeals

Administrative limitation

No administrative limitation

Liens and licences

No liens or licenses registered

Gazette entries

No Gazette entries foundOnly events from 2024.03.04 and onwards are shown.