RU2553793C2 - Direct drive hoist with constant magnets - Google Patents

Abstract

FIELD: transport.

SUBSTANCE: set of inventions relates to direct drive hoist and to drilling rig. The direct drive hoist contains electric motor with constant magnets, shaft passing from the mentioned motor so that the motor directly rotates the shaft, and drum connected to the shaft at a distance from the motor so that shaft rotation causes corresponding drum rotation, herewith, the mentioned motor contains housing, stator located in the housing and rotor interacting with the stator, herewith, the rotor is connected to or interconnected with the shaft, herewith, the rotor has drive plate connected to it. And the shaft is directly attached to drive plate. Drilling rig includes rig, pulley supported by the rig, wire rope passing through the pulley and having an end passing downwards from the pulley, casing block connected with wire rope end, drum located adjacent to lower part of the rig where the wire rope passes around the drum, shaft attached to the drum and passing outwards from it, and electric motor with constant magnets which motor accepts the shaft inside itself and is intended to impart rotational force to the shaft to rotate drum in order to wind or unwind wire rope where the mentioned motor contains housing, stator located in the mentioned housing and rotor interacting with the stator where the shaft is attached to or interconnected with the shaft, herewith, the stator has multiple windings mutually spaced on the inner surface of the stator, herewith, the rotor is ring-shaped element and has multiple constant magnets mutually spaced along rotor peripheral, herewith, the rotor has drive plate attached to it, herewith, the shaft is directly attached to the drive plate.

EFFECT: decrease in weight and energy consumption, increase in energy efficiency and specific power.

15 cl, 7 dwg

Description

FIELD OF TECHNOLOGY

The present invention relates to oilfield equipment. More specifically, the present invention relates to a winch used in the extraction and production of oil and gas. More specifically, the present invention relates to a winch having a permanent magnet motor.

BACKGROUND

A winch is a common element of oilfield equipment that is used in the extraction and production of oil and gas. A winch is usually installed near the rig. The overall function of a winch is to raise and lower the drill pipe and casing from and into the wellbore. A winch may be called a lifting device or reel. There are many different sizes of winches that are used for winches in the drilling and mining industries. The dimensions of the winches are reflected in the rated loads for such winches. These winches share similar operating modes and similar equipment.

Winches are used to raise and lower loads, such as a drill pipe, when inserting into and removing a drill pipe from an open well. Pipe removal may require the extraction of more than 30,000 feet of pipe in order to change drill bits or tools during drilling operations. During normal oil drilling operations, a drill pipe often rises and falls many times.

During mining operations, similar equipment is used when lifting coal, overburden, sand and gravel, phosphates and other minerals. There are just a few common jobs that use winches. In mining operations, the tub is often lowered to load the tub with the rock. After loading the tub, the winches are used to raise the loaded tub to a level where the tub is unloaded in a place above the ground.

Figure 1 shows a traditional oil rig 10, which uses the well-known winch 26. The winch 26 is installed on the drilling site 12 inside the oil rig 11. The winch 26 has a wire cable 24 extending around the pulley 25 in order to raise from and lower into the drill pipe 14 and wellbore 16. Pulley 25 is also called crown block. The borehole 16 is formed in the ground 15. The drill pipe 14 may be a drill string, which is a plurality of drill pipes extending inside the bore 16 of the well in the earth 15. A separate drill pipe 14 is connected to the drill string by a threaded joint 17. The drill string sections may have stabilizing portions that include stabilizing elements 18 that spiral along the outer surface of the pipe 14 in order to engage the wall of the wellbore 16 so as to center the pipes 14 in it.

The winch 26 poisons and selects the wire rope 24 through the pulley 25, which is mounted on the oil rig 11, in order to raise and lower the drilling unit 19, which holds the drill pipe 14. The cable 24 is attached to the movable block 23. The movable block 23 is suspended and moves up and down with a cable 24, which is etched and selected by the winch 26. The mobile unit 23 is connected to the drilling unit 19. The drilling unit 19 has a swivel 22 at its upper end, in which the drilling fluid is introduced into the drill pipe 14 and by which the drilling unit 19 is suspended from block 23. The drilling unit 19, the pipe manipulator 21 and the corresponding connecting elements are moved vertically along the axis 20. The vertical movement is guided by two vertical guide rails or tracks 27 that are rigidly attached to the tower 11. The drilling unit 19 is attached to the slide 28. The slide 28 rollers that are engaged with the rails 27. The rails 27 guide the slide 28 for vertical movement up and down along the rail 27, parallel to the vertical axis 20. The drill pipe 14 is inserted into and removed from the barrel 16 wells through the mouth of 13 wells.

Winch 26 usually has a hollow drum, a shaft that connects the drum to the electric motor, a drive located between the electric motor and the drum, and a brake system to slow down the rotation of the drum. The winch 26 is installed on the platform 12 of the oil rig 10. The longitudinal axis of the drum and shaft is parallel to the drilling site 12. The conventional electric motors used on the winch 26 are AC electric motors, DC electric motors and diesel internal combustion engines. Power is usually transmitted from the electric motor to the shaft by a chain drive mechanism or a gear drive mechanism. The brake system can use many technologies to brake the drum. The braking system may use disc brakes, belt brakes, water-cooled brakes or electric brakes. As the cable 24 is selected by the winch 26, the cable 24 is wound on the drum of the winch 26. Winding the cable 24 on the winch 26 is similar to winding the thread on a spool.

Using a drive causes many problems, often associated with conventional winches. The drive is expensive, increases the weight of the winch and requires periodic repair. Maintenance of the drive can be expensive especially in the event of a complete drive failure. Power is also lost when using the drive due to frictional forces that cannot be eliminated when using the drives. Conventional winches 26 also consume large amounts of energy to change the direction of rotation of the winch 26. Thus, there is a need for a simple winch design that is lighter, easier to maintain, consumes less energy and more energy efficient.

Various patents related to winches have been granted in the past. For example, US Patent No. 6182945 dated February 6, 2001 discloses a fully redundant winch with two complete and completely independent systems for controlling and powering the drum and shaft of the winch drum. Each system has at least one power source, a mechanical drive, and a coupler coupled to the power source and the drum drive and shaft. Each system has a braking system, such as disc brakes, belt brakes, electric brakes or water-cooled brakes. In the event that any component of one system fails, a fully duplicating winch has the ability to lift the drill pipe from the wellbore in order to eliminate the risk of a "jamming" of the drill pipe.

US patent No. 4226311 of October 7, 1980 discloses a disc braking device configured to be installed in conjunction with a winch for drilling a wellbore. The device automatically recognizes any case of reverse torque in the drill pipe and quickly activates the brake to prevent any reverse torque from being transmitted to its clamping device on the rotary table of the installation.

US patent No. 3653636 of April 4, 1972 discloses a reversible hydraulic motor and a system of high / low pressure hydraulic manifolds that are used to balance the weight of a drill string or other drilling equipment suspended from a cable wound on a winch located on a floating base. The weight sensor monitors the output torque and direction of the output drive of the hydraulic motor. As the floating base moves down, the high pressure hydraulic fluid from the accumulator moves through the hydraulic motor to the low pressure hydraulic fluid manifold to provide increased winch torque as the winch wraps a wire rope. When the floating base is moved up, the hydraulic motor reverses in order to move the low pressure fluid from the low pressure manifold to the high pressure accumulator. This reduces torque and changes the direction of the winch as the winch poisons the cable.

U.S. Patent Application Publication No. 2008/0116432 of May 22, 2008 discloses a coil that includes an electric motor having a fixed stator and a cylindrical rotor that rotates around the stator. The drum is attached to the rotor and supports the cable, which is wound or reeled up by a reel. The coil may be a winch for a derrick. The electric motor may be a permanent magnet electric motor. The supporting mechanism is located between the stator of the electric motor and the rotor of the electric motor.

US patent No. 3211803 discloses an electric drive powered by a generator for a winch that has a winch, electric motors, a drive connection between electric motors and a winch, a generator, an electrical connection of a generator and electric motors for supplying electric power to electric motors, a motor and a connection between the engine and a generator for supplying power to the generator. Electric motors have a total power consumption that substantially exceeds the engine power output, resulting in a torque available for driving the winch that is substantially greater than would be available from electric motors having a total power consumption equal to the engine power output.

U.S. Patent No. 4,438,904 of March 27, 1984 discloses a winch that has a drilling platform supporting the winch, a cable drum shaft rotatably supporting the cable drum between two vertical support members, an input shaft, a drive mechanism for rotating the input shaft, a chain sprocket and a chain sprocket an actuator with a switching clutch for rotating the drum shaft and the cable drum at any of a variety of speeds in response to the rotation of the input shaft, and a controller located outside one of the supporting elements. The drum shaft has an extension beyond one of the supporting elements. One external brake is attached to the drum shaft extension.

US patent No. 6029951 of February 29, 2000 discloses a system and method for using a winch, in which the winch has a rotatable drum on which the cable is wound. A winch and cable are used to facilitate the movement of cargo suspended from the cable. The winch control system controls and controls the winch. The brake device is attached to a rotatable drum to limit rotation of the rotatable drum. An electric motor is attached to a rotatable drum for driving a rotatable drum. The winch control system provides a signal that is the calculated value of the torque of the electric motor, resulting in a preliminary torque in the electric motor in response to the signal. The rotation control of the rotatably rotated drum is transmitted from the brake device to the electric motor when the pre-torque value of the electric motor is substantially equal to the calculated torque value.

US patent No. 4046355 of September 6, 1977 discloses a control device for use with an assembled winch, which has a part suspended from the cable and pulling it. One end of the cable is wound on a drum. The rotation of the cable is regulated by a mechanical brake. The control device has a cable tension sensor, which generates a tension signal proportional to the cable tension. The pulse generator generates a pulse control signal. The brake control unit provides a tension signal to the mechanical brake in response to a control signal.

U.S. Patent Application No. 60/726077, filed October 13, 2005 by the present inventor, discloses a winch for drilling and mining operations. The winch has a wire rope drum that is driven by at least one AC motor. A drive shaft connects the brake to the wire rope drum. The engine is powered by a power source. The winch has a flywheel system that accumulates energy when braking the rotation of the drum of the winch wire rope. The energy stored in the flywheel is used to start another rotation of the wire rope drum.

An object of the present invention is to provide a direct drive winch.

Another objective of the present invention is to provide a winch that does not require a gear mechanism.

Another objective of the present invention is to provide a winch that has a very high power density.

Another objective of the present invention is to provide a winch that has a relatively low weight.

Another objective of the present invention is the creation of a winch, which can be easily transported on traditional road networks.

Another objective of the present invention is to provide a winch that has the least assembly requirements in an oil field.

Another objective of the present invention is to provide a winch that is easily interchangeable in an oil field.

Another objective of the present invention is the creation of a winch, which has reduced inertial effects.

Another objective of the present invention is the creation of a winch, which reduces maintenance and repair costs.

These and other objects and advantages of the present invention will become apparent from the accompanying description and the appended claims.

SUMMARY OF THE INVENTION

The present invention provides a permanent magnet direct drive winch comprising a permanent magnet motor, a bearing seat coupled to an electric motor, a shaft coupled to the electric motor and passing through the bearing housing, and a drum connected to an end of the shaft opposite to the electric motor. The brake system is located on the side of the drum, opposite the electric motor.

The permanent magnet electric motor comprises a housing, a stator located inside the housing, and a rotor interacting with the stator and located in the stator inside the housing. The rotor is made to be connected to the shaft, so that the rotational movement imparted by the electric motor is directly communicated to the shaft and, accordingly, to the winch.

The housing contains an inner chamber surrounded by a wall. The stator is adjacent to the wall of the housing. The stator has many windings passing around it. The windings are located at a distance from each other on the inner surface of the stator. The windings extend radially inward from the housing wall. Suitable air channels are made in the housing to improve the cooling effect of air exchange with the stator.

The rotor is located inside the stator. The rotor is an annular element. Permanent magnets are located at a distance from each other on the periphery of the rotor. Permanent magnets interact with the windings to ensure repulsion of parallel conductors with opposed currents of the permanent magnet motor. The drive disc is attached to the rotor. The drive disk has an inner hole formed to engage the shaft slot. The rotor drive disc receives the shaft. Essentially, when the rotational forces are communicated to the rotor, the rotational forces are directly communicated to the shaft and the winch. Essentially, the present invention provides direct shaft rotation without the need for switching mechanisms or drive systems.

The present invention is also a derrick. This drill rig includes a rig, a pulley supported by the rig, a wire rope passing through the pulley and having an end extending downward from it, a tack unit paired with a wire rope, a drum located adjacent to the bottom of the derrick and having a wire rope extending around the drum, a shaft attached to the drum and extending outward from it, and a permanent magnet motor receiving the shaft. The electric motor is designed to communicate rotational forces to the shaft for rotating the drum and winding or reeling the wire rope.

The permanent magnet electric motor comprises a housing, a stator located in the housing, and a rotor interacting with the stator. The rotor is attached to or interconnected with the shaft. The stator includes many windings located at a distance from each other on the inner surface of the stator. The rotor is an annular element having many magnets located at a distance from each other along the periphery of the rotor. The rotor has a drive disk attached to it. The shaft is directly attached to the drive disk. The bearing housing is connected to a permanent magnet motor. The shaft passes through and is pivotally supported by the bearing housing. The braking means takes the shaft. This braking means is used to apply force to the shaft to create resistance to the rotational movement of the shaft.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 shows a side view of a drilling rig using a known winch.

Figure 2 shows a side view of a preferred embodiment of a permanent magnet direct drive winch of the present invention.

Figure 3 shows a perspective view of a preferred embodiment of a direct permanent magnet drive of the present invention.

4 shows a cross-sectional view of a permanent magnet electric motor of the present invention.

5 shows a top view of a drive disk associated with a permanent magnet motor of the present invention.

6 shows a perspective view of a rotor of a permanent magnet motor of the present invention.

7 shows a perspective view of a stator of a permanent magnet electric motor of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

2 is a side view of a preferred embodiment of the permanent magnet direct drive winch 100 of the present invention. The winch 100 has a permanent magnet electric motor 40. The shaft 41 is connected to the motor 40. The bearing socket 45 is adjacent to the electric motor 40 and the shaft 41. The shaft 41 passes through the bearing socket 45 and into the interior of the electric motor 40. The drum 43 is attached to the end 47 of the shaft 41, opposite the electric motor 40. Wire cable 24 wound around the drum 43. The drum 43 is located in the frame 53. The frame 53 supports the shaft 41 in order to hold the drum 43 and the motor 40 above the floor surface, for example, the drilling platform 12. The brake system 49 is located on the side of the drum 43, prot vopolozhnoy motor 40. Figure 2 brake 49 has a brake disc 51, positioned adjacent the drum 43. The brake system 49 in Figure 2 is water-cooled. A power source 48 is connected to an electric motor 40 for supplying power thereto.

The electric motor 40 rotates the shaft 41, which rotates the drum 43. The rotation of the drum 43 causes etching or selection of the wire rope 24 depending on the direction of rotation of the drum 43. When the wire rope 24 is selected, the wire rope 24 is wound on the outer surface of the drum 43. The longitudinal axis of the drum 43 is aligned with the longitudinal axis of the shaft 41. The longitudinal axis of the drum 43 and the shaft 41, in General, parallel to the drilling site 12.

3 is a perspective view of a permanent magnet direct drive winch 100 of the present invention. The permanent magnet motor 40 has a housing 42. The rotor and stator are located inside the housing 42, as described in more detail below. The housing 42 has a generally cylindrical shape. The housing 42 has an inlet 55 and an outlet 57. To cool the rotor and stator of the electric motor 40, air passes into the inlet 55, circulates in the interior of the housing 42 and is discharged through the outlet 57. The housing 50 is attached to the upper surface 44 of the housing 42. Disk 51 the brake system 49 is adjacent to the drum 43 inside the frame 53. The drum 43 has a coil shape for efficient storage of long cables.

The drum 43 has a wire rope wound around it. The rotation of the drum 43 is used to wind and reel this wire rope. A wire cable extends from the drum 43 in the manner previously described with respect to FIG. 1. Essentially, the rotation of the drum 43 caused by the electric motor 40 can cause the wire rope to be wound and wound to raise or lower the tackle block.

Figure 4 shows a cross-sectional view of the housing 42 of the permanent magnet motor 40. The housing 42 defines an inner chamber 60. The shaft 41 extends outside the inner space 60 of the housing 42 of the motor 40. The stator 62 is attached to the wall of the housing 42. The stator 62 extends along the annular inner surface of the housing 42. The rotor 64 is located in the immediate vicinity of the stator 62. The rotor 64 has many permanent magnets formed around its circumference (described in more detail below). The stator 62 has wire coils located on the inner surface of the stator 62. The interaction of the stator coils 62 and the permanent magnets of the rotor 64 provides the torque of the electric motor 40. The drive disk 66 is attached to the upper part of the rotor 64. The shaft 41 is engaged with the drive disk 66 so that the rotational energy communicated to the driving disk 66 by the rotor 64 was communicated to the shaft 41. The shaft 41 extends outward from the inner chamber 60 of the housing 42. The end of the frame 53 can be seen located between the bearing housing 45 and the motor 40. Thus, the shaft 41 passes It is driven through an electric motor 40, a frame 53 and a bearing seat 45.

Permanent magnet motors rotate due to the torque that is caused by the interaction of two magnetic fields. These magnetic fields are created by permanent magnets mounted on a rotating rotor and by a magnetic field that is induced by the fixed stator windings. Torque is greatest when the magnetic vector of the rotor is 90 ° with the magnetic vector of the stator. In this position, it causes the rotor poles to rotate in the direction of the stator field. In a DC brushless motor powered by a trapezoidal signal, an electric current sequentially alternating in two of the three coils creates a stator field. The remaining third coil controls the back emf (electromotive force) of the two active coils. Reverse EMF occurs when the permanent magnet motor rotates. Each winding creates a voltage that counteracts the mains voltage of the windings. The reverse EMF depends on the rotor speed, the magnetic field that the rotor magnets create, and the number of turns in the stator windings. The reverse EMF of the electric motor provides feedback of the position of the rotor relative to the stator windings. Permanent magnet motors with sensors provide similar positive feedback. With sinusoidal switching, which uses a permanent magnet permanent magnet motor, the drive control loop simultaneously feeds three coils.

Permanent magnet motors have been commercially available since the 1990s. However, permanent magnet motors are not widely used due to the high cost associated with expensive permanent magnets on the rotor. Additionally, their sophisticated control algorithms require specialized engineering expertise, as well as additional costs for the embedded processor. Permanent magnet motors are more efficient than AC induction motors. However, due to the recent rise in copper prices, current-wound asynchronous motors have risen in price, and permanent-magnet motors have become relatively cheaper. Additionally, recent advances in technology have improved the output power of permanent magnet motors, with the result that such motors have a specific power exceeding that of existing asynchronous motors. Essentially, the permanent magnet motor 40, as shown in FIG. 4, provides superior power output for direct drive of the shaft 41 and drum 43 of the winch 100.

Figure 5 shows a top view of the drive disk 66 of the permanent magnet motor 40 of the winch 100 of the present invention. The drive disk 66 has a circular shape with an outer circumference 90. The bolt holes 92 are formed adjacent to the outer circle 90. The bolt holes 92 allow bolting the drive disk 66 to the top of the rotor. A spline hole 94 is formed in the center of the drive disk 66 to accommodate the shaft splines 41. Air circulation openings 96 are formed on the inner surface of the drive disk 66. The openings 96 facilitate the circulation of air within the permanent magnet motor 40.

Figure 6 shows a separate perspective view of the rotor 64 of the permanent magnet motor 40 of the winch 100 of the present invention. The drive disk 66 can be mounted directly on the upper part of the rotor 64. Permanent magnet packages are attached to the outer surface of the rotor 64 from each other. Separators 106 are used to isolate one package of permanent magnets from an adjacent package. The spacers 106 may be separate elements or they may simply be a contoured surface on the outer circumference of the rotor 64. The rotor 64 has an opening 110 of the rotor bearing formed in its center.

7 shows a separate perspective view of the stator 62 of the permanent magnet motor 40 of the winch 100 of the present invention. The stator 62 has an outer casing 120, which serves to separate the coils 122 from the inner wall of the housing 42. The coils 122 extend radially inward from it. The inner surface 124 of the coils 122 forms a circular hole in which the rotor 64 is placed. As a result, the permanent magnet packages 104 are in close proximity to the coils 122 so that the electric motor 40 can function properly. Suitable electronic equipment is connected to the electric motor 40 to facilitate the proper operation of the electric motor 40.

The permanent magnet direct drive winch 100 is directly connected to the shaft 41, with no gearing devices or other drive mechanisms that are coupled in these areas. Thus, the winch 100 provides increased power density for proper rotation of the drill string in a relatively lightweight configuration. The weight associated with the drive systems is effectively eliminated by the present invention. Moreover, the complexity of installing such drive systems so that the power of an induction motor can be transferred to the drive system is eliminated in the present invention. As a result, the permanent magnet direct drive winch of the present invention can serve to properly rotate the lowest weight drill string. In contrast to modern electric motors associated with drilling operations, which can weigh more than 100,000 pounds, the permanent magnet electric motor of the present invention will weigh only approximately 60,000 pounds. Essentially, it can be easily transported on roads by a conventional truck. Unlike the prior art, the electric motor 40 does not require its own assembly or assembly with a drive system in the field. Essentially, the present invention eliminates the specialized need for personnel for the installation that would otherwise be required for these systems that require drives between the electric motor and the winch. The reduction in weight of the permanent magnet electric motor of the present invention eliminates some inertial effects that would otherwise adversely affect the functioning of traditional asynchronous electric motors. The electric motor 40 of the present invention can be interchangeable as desired for use with a top drive of a direct drive derrick or a drill pump of a derrick. Since no drive systems are required, the supply of such permanent magnet motors can be provided for drilling operations to be used either in conjunction with a winch or for other purposes. If any electric motor fails, then any other electric motor can be used instead without any downtime on the rig.

The foregoing description of the invention is illustrative and explanatory. Various changes in the details of the illustrated construction can be made without departing from the essence of the invention. The present invention is limited only by the following claims.

Claims (15)

1. A direct drive winch comprising a permanent magnet electric motor, a shaft extending from said electric motor, so that the electric motor directly rotates the shaft, and a drum connected to the shaft at a distance from the electric motor, so that the rotation of the shaft causes a corresponding rotation of the drum, wherein said electric motor comprises a housing, a stator located in the housing, and a rotor cooperating with the stator, the rotor being attached to or interconnected with the shaft, the rotor having a drive disk, attached ny to him, and the shaft is directly connected to the drive disk. 2. The direct drive winch according to claim 1, in which the housing has an inner chamber surrounded by a wall, the stator is adjacent to said wall, and the rotor is located inside the stator. 3. The direct drive winch according to claim 2, wherein the stator has a plurality of windings spaced apart from each other on the inner surface of the stator, the rotor being an annular element having a plurality of permanent magnets mounted spaced apart from one another along the periphery of the rotor. 4. The direct drive winch according to claim 3, wherein the plurality of windings extend radially inward to the rotor and act on said plurality of permanent magnets to provide rotation of the rotor. 5. The direct drive winch according to claim 1, in which the drive disk has an opening formed in its center and slots extending inwardly into the hole, the shaft having a spline end engaged with the splines of the drive disk. 6. The direct drive winch according to claim 1, further comprising a bearing housing connected to said electric motor, the shaft extending through and pivotally supported by the bearing housing. 7. The direct drive winch according to claim 6, wherein the bearing seat is installed between said electric motor and a drum. 8. The direct drive winch according to claim 1, further comprising braking means receiving the shaft and intended to apply force to the shaft to provide resistance to its rotational movement. 9. The direct drive winch according to claim 8, in which the braking means is located adjacent to the end of the drum opposite to the aforementioned electric motor. 10. A direct drive winch according to claim 1, further comprising a power source electrically connected to said electric motor for supplying electric energy thereto. 11. The direct drive winch according to claim 1, further comprising a wire rope extending around a drum configured to rotate to wind and rewind the wire rope. 12. The direct drive winch according to claim 11, further comprising a tower, a pulley located on the tower, the wire rope passing through the pulley, and a tackle block attached to the wire rope and extending downward from the pulley. 13. A rig containing a rig, a pulley supported by a rig, a wire rope passing through the pulley and having an end extending downward from the pulley, a tack block associated with the end of the wire rope, a drum located adjacent to the bottom of the derrick, the wire rope passing around the drum, a shaft attached to the drum and extending outward from it, and a permanent magnet motor that receives the shaft and is intended to impart a rotational force to the shaft to rotate the drum for winding or winding I have a wire rope, wherein said electric motor comprises a housing, a stator located in said housing, and a rotor cooperating with the stator, the shaft being connected to or interconnected with the shaft, the stator having many windings spaced apart from each other on the inner surface of the stator moreover, the rotor is an annular element and has many permanent magnets located at a distance from each other on the periphery of the rotor, and the rotor has a drive disk attached to it, and the shaft is not only attached to the master drive. 14. The derrick of claim 13, further comprising a bearing seat coupled to said electric motor, the shaft extending through and pivotally supported by the bearing seat. 15. The oil rig of claim 13, further comprising braking means receiving the shaft and for applying a force to the shaft to provide resistance to its rotational movement.

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