Integrity assessment of corroded oil and gas pipelines using machine learning: A systematic review

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In this article, a new and general three-dimensional (3-D) analytical frame for evaluating the performance characteristics of the permanent magnet (PM) eddy-current coupling is presented using a magnetic vector potential formulation. Based on the 3-D Cartesian coordinate system, the actual coupling geometry is equated to a linear structure by applying the mean radius (for cylindrical conductor and PM rotors) and the equivalent cuboid (for PMs of various shapes) assumptions. The torque contribution from the overhangs of conductor back iron and the effects of PM and air gap thicknesses are all taken into considered. A verification process is implemented and it is shown that, in any case, the proposed 3-D analytical model can yield the results very close to those obtained by both the 3-D finite-element analysis and experimental measurement.

A Generic 3-D Analytical Model of Permanent Magnet Eddy-Current Couplings Using a Magnetic Vector Potential Formulation

Eddy-current couplings are becoming popular devices for speed and torque control. Efficiency of these couplings depends on the excitation level; therefore, the routes and density of induced currents affect it significantly. This paper focuses on the design of a squirrel cage-type coupling disk, which forces eddy currents to flow perpendicular to both magnetic field lines and the axis of rotation. Lorentz force and transmitted torque are consequently optimized. The investigation is performed both numerically and experimentally, with results being presented for variable air gaps and speeds. A comparison between plain and slotted disk conductors, tested under identical set-ups, demonstrates the effect of the proposed design on torque throughput and efficiency. In addition to this, the influence of number and size of slots and the effect of filling slots with iron are studied by parametric finite-element modeling verified by experiments.

Eddy Current Coupling with Slotted Conductor Disc

In this article, a new and general three-dimensional (3-D) analytical frame for evaluating the performance characteristics of the permanent magnet (PM) eddy-current coupling is presented using a magnetic vector potential formulation. Based on the 3-D Cartesian coordinate system, the actual coupling geometry is equated to a linear structure by applying the mean radius (for cylindrical conductor and PM rotors) and the equivalent cuboid (for PMs of various shapes) assumptions. The torque contribution from the overhangs of conductor back iron and the effects of PM and air gap thicknesses are all taken into considered. A verification process is implemented and it is shown that, in any case, the proposed 3-D analytical model can yield the results very close to those obtained by both the 3-D finite-element analysis and experimental measurement. 

In this article, a new magnetic equivalent circuit (MEC) model was presented to predict torque characteristics and reaction flux in slotted-type eddy-current couplings (SECs). The magnetomotive force and reaction field caused by eddy current in the conductor were innovatively introduced into the model; particularly, the modulations of the magnetic field and eddy current by iron teeth in conductor disk were taken into account by dividing magnetic flux paths in air gap into several branches. The expressions of magnetic flux and torque were obtained by combining Kirchhoff’s law and Ampere’s loop law. The torque was calculated using the method proposed and was compared with those obtained by the 3-D finite element method (FEM) and experiment, respectively. The results indicated that the method proposed is accurate and effective under conditions of low slip speeds and short air gap lengths.

Torque Characteristics Analysis of Slotted-Type Eddy-Current Couplings Using a New Magnetic Equivalent Circuit Model

The invention relates to the technical field of transmission in mechanical engineering, and relates to a magnet rotating cylindrical adjustable speed magnetic coupler, which consists of an outer rotorand an inner rotor, wherein a conductor rotor is on the outer rotor; a permanent magnet rotor is on the inner rotor; a rotating permanent magnet speed adjusting device is installed on the permanent magnet rotor; and an axial speed adjusting device is installed on the conductor rotor. A rotating unipolar permanent magnet transmit power to the speed adjusting shaft through meshing of a bevel gear,the speed adjusting shaft and the rotating permanent magnet assembly are installed together, and thus, the rotating permanent magnet assembly rotates for a certain angle; and the axial speed adjustingdevice is a moving square bearing base, a sleeve is driven through a bidirectional thrust ball bearing, the sleeve and a conductor rotor yoke are connected by screws, and thus, the conductor rotor ismoved. In the case of speed adjustment, the average right facing area and the air gap distance between partial permanent magnets such as the rotating permanent magnet assembly and a copper conductorcan be changed through axially moving the conductor rotor and the rotating unipolar permanent magnet or simultaneously axially moving the conductor rotor and the rotating unipolar permanent magnet, and speed adjustment is thus realized.

Magnet rotating cylindrical adjustable speed magnetic coupler

The invention relates to the field of mechanical transmission, and is a monopole magnet rotating speed adjustable cage type magnetic coupling. In the invention, the copper disc uses a cage type copperdisc, all the fan-shaped grooves generate fan-shaped ring current around, the generated eddy current loss is small and the transmission efficiency is high, the fan-shaped grooves of the cage type copper disc and the small bumps on the surface of the yoke are in interference fit, and the small bumps of the yoke modulate the magnetic field, thereby further increasing the electromagnetic torque of the coupler. The coupler provides three speed adjustment methods that the first is to adjust the air gap between the copper disc and the permanent magnet disc through an axial moving device, the secondis to change the rotation angle of the rotating permanent magnet by fixing the air gap to further adjust the head-on area between a conductor disc and the permanent magnet disc, and the third is to use the composite speed adjustment of the air gap between the two disks in axial movement and the rotating permanent magnet, so that the coupler can meet different degrees of speed adjustment requirements.

Monopole magnet rotating speed adjustable cage type magnetic coupling

The invention relates to the technical field of transmission in mechanical engineering, and particularly to a speed-adjustable magnetic coupler of a guiding rail sliding block type. The coupler is formed by a conductor round-platform-shape disc assembly and a permanent-magnet cone-shape disc assembly. A speed adjustment device is mounted on the permanent-magnet cone-shape disc assembly. A driven disc is mounted at an inner surface of a driven base body disc by conductor rings to form a conductor round-platform-shape disc assembly. Driving discs are respectively fixed on outer surfaces of ball-type straight-line guiding rail sliding blocks by permanent magnets in a manner of alternate arrangement of N and S poles to form the permanent-magnet cone-shape disc assembly. Silk poles are driven through motors to rotate, sleeve barrels and straight-line bearings are enabled to move in an axial direction of a driving shaft, sliding rods and compression springs fixed on the sleeve barrels push the sliding blocks, the ball-type straight-line guiding rail sliding blocks are enabled to slide along straight-line guiding rails, then direct facing areas between the permanent magnets and the conductor rings are enabled to change simultaneously in circumferential directions and guiding rail sliding directions, and thus highly efficient speed adjustment is realized.

Speed-adjustable magnetic coupler of guiding rail sliding block type

The invention relates to the technical field of transmission in mechanical engineering, and specifically relates to a disc-type magnetic gear applying a magnetism gathering type magnetism adjusting device. The magnetic gear is composed of a driving disc assembly, a driven disc assembly and a magnetism gathering type magnetism adjusting device assembly, and is characterized in that a magnetism adjusting block of the magnetism gathering type magnetism adjusting device is of a structure with the side edge 1/2 period sine and the section similar to an isosceles trapezoid, and the reliability of the magnetic gear is enhanced in combination with a mechanical structure installed in a matched mode. Different connection modes can be selected according to different base materials of the magnetism adjusting block. In order to prevent end magnetic flux leakage, a transverse soft magnetic material is additionally arranged, the magnetism adjusting device achieves the magnetism adjusting and gathering effects at the same time, the magnetism adjusting performance is improved, and the magnetism gathering capacity is improved. The permanent magnets of the driving disc and the driven disc adopt an arrangement mode with high magnetic energy density such as a 90-degree Halbach arrangement mode or a close arrangement mode. The torque density of the magnetic gear is enhanced by designing the structure of the magnetism adjusting device and the arrangement of the permanent magnets, so that the magnetic gear is widely applied to a high-torque working environment.

Tai Jiangxi

Papers

Torque Characteristics Analysis of Slotted-Type Eddy-Current Couplings Using a New Magnetic Equivalent Circuit Model

Magnet rotating cylindrical adjustable speed magnetic coupler

Monopole magnet rotating speed adjustable cage type magnetic coupling

Speed-adjustable magnetic coupler of guiding rail sliding block type

Disc-type magnetic gear applying magnetism gathering type magnetism adjusting device