MX2008004414A - Top drive drilling system and other applications using a low speed direct drive ac motor - Google Patents

Abstract

A low speed alternating current motor having motor shaft speeds of about (300) is provided, and such motor has application in numerous industries and devices, such as, for example, in top drive drilling systems. Because of the low shaft speed, mechanical speed reduction equipment may not be necessary. In addition, the motor shaft may be hollow to facilitate the flow of fluid, such as, for example, drilling mud.

Description

PERFORATION SYSTEM OF UPPER TRANSMISSION AND OTHER APPLICATIONS USING A CA ENGINE DIRECT LOW SPEED DRIVING Field of the Invention The present disclosure generally relates to a low speed AC motor, and more particularly, to an AC motor, of variable frequency, low speed, for use in direct driving applications, such as overhead ducts. Background of the Invention The industry has used CA motors as primary mobilizers for many years. The typical AC motor is designed to operate at speeds from 3,000 to 3,600 rpm or more. Many applications and industrial processes using AC motors must reduce the speed of the motor, usually by mechanical gear, before the power supplied by the motor can be used. In the oil field, for example, conventional upper transmission drilling systems can use a variable frequency AC motor as the main mover. The AC motor is responsible, among other things, for supplying a necessary portion to rotate the drill string and the drill bit during drilling operations. The rotation speed of the auger and, consequently, the transmission upper is relatively slow, usually between 100 and 300 rpm and more usually around 150 rpm. The conventional variable frequency AC motors used in top driving applications have motor speeds of typically ten times the speed of the augers or 1000 to 3000 rpm. Therefore, it is conventional for a higher transmission system to include speed reduction equipment, such as a gearbox, to reduce the rotation speed of the AC motor at a more usable speed. The speed reduction equipment, such as the speed box mentioned above, is added to the cost of the system, increases the service requirements, and increases the number of parts that can fail, and increases the weight of the system. The present patent application describes a novel upper transmission drilling system using a variable frequency, low speed AC motor that does not require additional speed reduction equipment to achieve a rotation speed within the range of 100 to 300 rpm and Consequently, it is particularly suitable for direct driving applications. BRIEF DESCRIPTION OF THE INVENTION An upper transmission drilling system using a low speed AC motor is provided, wherein the systems comprise a motor structure, an assembly stator fixed to the motor structure comprising a plurality of stator laminates compressed in a stator core; a rotor assembly comprising a hollow tube star having a plurality of ribs located on the outer surface and oriented so that the length of the ribs matches the length of the tube and a core comprising a plurality of compressed rotor laminates fixed to the external radial surface of the ribs of the star; a hollow motor arrow to which the rotor assembly is coupled; and first and second bearing assemblies mounted between the motor structure and the motor shaft, so that the motor core can rotate relative to the rotor assembly; and a motor transmission to generate a signal modulated by bandwidth that rotates the motor shaft at speeds lower than approximately 500 rpm, thus preventing the speed reduction equipment from achieving a speed of the motor arrow in the range from about 100 to about 300 rpm. BRIEF DESCRIPTION OF THE DRAWINGS The brief description above, detailed description of the preferred embodiments, and other aspects of the description that will be better understood when read together with the drawings accompanying it, in which: Figure 1, a system transmission drilling direct superior according to the present invention. Figure 2 illustrates an embodiment of an AC motor that can be used in the upper transmission system illustrated in Figure 1. Figure 3 illustrates a stator lamination of an engine CA according to the present invention. Figure 4 illustrates a stator assembly of an AC motor according to the present invention. Figure 5 illustrates an end view of a stator assembly of an AC motor according to the present invention. Figure 6 illustrates an end view of a stator assembly within a stator assembly in an AC motor according to the present invention. Figure 7 illustrates a cross-sectional view of an AC motor according to the present invention. Figure 8 illustrates a rotor lamination that can be used in an AC motor according to the present invention. Figure 9 illustrates a rotor star that can be used in an AC motor according to the present invention.

Figure 10 illustrates a cross section of a rotor assembly gasket of an AC motor according to the present invention. Figure 11 illustrates an end view of the AC motor illustrated in Figure 2.

Although the present invention described herein is susceptible to various modifications and alternative forms, only some specific embodiments have been shown by way of example in the drawings, and are described in detail below. The figures and detailed descriptions of these specific embodiments are not intended to limit the meaning or scope of the inventive concepts of the appended claims in any way. Rather, the detailed figures and descriptions described are provided to illustrate the inventive concepts to one skilled in the art, as required by Document 35 USC § 112. Detailed Description of the Invention In general terms, the Applicants have created a new upper transmission drilling system using a variable speed, low speed AC motor that does not require mechanical speed reduction equipment. The AC engine described herein which has the ability to operate at speeds from 0 rpm to approximately 300 rpm, can be controlled by a conventional pulse width modulated variable speed (PWM) transmission, such as Oilfield-Electric-Marine's commercially available at V 3000 Active Energy Management Drive. The AC motors used in the present invention may have application in upper transmission drilling systems, as described herein, and in systems of extraction operations used in oil and gas exploration industries, transmission systems of large mining vehicles, excavation equipment and many other applications where high-level, low-speed torsional power is required. For the purposes of the present application, a detailed description of a new and unique upper transmission drilling system will be presented. It should be understood that the present invention is not limited to being used only in upper transmission systems, only by the modality described herein. An engine according to the present invention can be constructed having approximately 1500 horsepower and operating at speeds between about 0 and about 300 rpm at 600 volts. The motor can be designed with 8 poles, wired in a Delta mode, with a 10Hz inverter supply frequency to achieve a base rpm of 150. This design results in a good electromagnetic design balance and allows a practical number to be available of slots in space. In addition, the motor shaft may be hollow to allow the drill ground to pass through without the need for a separate pipe system to bypass the motor. The motor bearings can be designed, and in the preferred embodiment they are designed to only support rotor and braking assemblies and not the weight of the drill string. He Engine cooling can be supplied by circulating air or water. In addition, the motor can be braked mechanically, dynamically braked by dissipating power in the PWM transmission, braking through an energy recovery system, such as a steering wheel, or a combination. Figure 1 depicts an upper transmission drilling system 10 according to the present invention, incorporating a low speed direct drive AC motor 12. Also shown in Figure 1 is a conventional variable frequency transmission 13 having the capacity of supplying a PWM transmission signal to the Motor 12 and a dynamic braking motor 12. Alternatively, an energy recovery braking system 15 is also shown. The motor 12 comprises a rotor assembly 14, a stator assembly 16, an external motor enclosure 18, a cooling system 20, rpm encoders 22 and a mechanical braking system 24. FIG. 2 illustrates a perspective view of a preferred embodiment of an AC motor suitable for use with the present invention. The stator assembly 16 is observed to be placed inside the motor enclosure 18. The hollow motor arrow 26 is seen at the upper end of the motor 12 together with the cooling ports 28 and 30. In FIG. 2, the multiples of expulsion of cooling air 156, which are located opposite between yes in the exposed stator assembly 16. Turning now to a more detailed description of the stator assembly 16, the assembly may comprise laminates 40 (see FIG. 3) preferably made of a sheet of electric stainless steel, pre-covered with a thickness of 0.5 mm rated at 400 watts / sqm at 50Hz., Such as a low level silicone carbon sheet (Losil) 470-50-A5, with LS coating). Reference can be made to British Specification BS 6404: Section 8.4. To minimize cost, the stator can be designed using simple or continuous ring laminations. The alternative, which can be implemented in the present invention, is to create the stator laminates of a number of segments (not shown). This alternative, although it is viable, is not the preferred modality, because it increases the number of parts and incorporates complexity and, consequently, as a result a higher cost of the engine. Applicants have discovered that, normally, the laminate material 40 is commercially available in widths of up to 1240 mm. Laminates 40 having a diameter greater than 1240 mm can be cut from these sheets resulting in a modified circular laminate 40 four short level areas 42. The preferred design is a truly circular laminate, although the modified laminate 40 shown in Figure 3 , It is acceptable. When the laminate Modified 40 of Figure 3 is used, an effective diameter of approximately 1260 can be used in electrical design calculations. Of course, a more accurate effective diameter can be determined empirically by comparing the magnetic properties of the laminate 40 with unmodified circular laminates of various diameters, or analytically by calculating an effective diameter based on the area or other properties, such as flow density, loss by level areas. The smaller diameter of 1240 has an impact of the flux density in the stator core, consequently in the magnetization current, both of which may be, and have been taken into account in the design. In practice, applicants have discovered that the level areas 42 have little impact, since most of the laminate 40 has a larger diameter. The increased diameter of laminate 40 also has benefits that increase the area available for cooling. Each laminate 40 further comprises a plurality of teeth 44 and grooves 46. In the embodiment being described, the stator laminate 40 has 144 grooves. As shown in Figure 4, the stator laminates 40 are preferably assembled in a plurality of stator packages 48, each package comprising a plurality of individual laminates 40. In the present disclosed embodiment, each stator package 48 comprises approximately 132 laminates 40, making the packaging of stator 48 somewhat thick 66mm. Each stator pack 48 may be separated from its adjacent pack 48, to allow air or cooling fluid to circulate. The stator packages 48 can be separated by a plurality of radially oriented spacers 50. In the preferred embodiment, the spacers 50 are metal strips that are approximately 10 mm wide by 3 mm thick. The spacers can be fixed to the surface of the exposed adjacent laminates 40, preferably by welding. In the preferred embodiment, the strips form channels for the cooling system. The stator assembly 16 illustrated in Figure 4 has 18 stator gaskets 48. Turning now to Figure 5, the stator gaskets 48 can be held together between two compression plates 60, one at each end of the stator assembly 16. In the embodiment of Figure 5, the stator assembly 16 is connected together through one or more links or bars 62. A transfer plate 64 having a substantially laminated profile 40 is placed between the first stator gasket 48 and the compression plate 60 and between the last stator pack 48 and the other compression plate 60. The transfer plate 64 assists in transferring compression to the entire assembly 16, for example, to each laminate tooth 44, to maintain the pressure of the desired center. In the preferred embodiment illustrated in Figure 5, the compression plates 60 and the transfer plates 64 are separate structures. The alternative designs may include a compression / transfer plate combination that substantially coincides with the laminate profile 40 to effectively transfer compression to the entire assembly 16. The one or more bars 62 may be fixed to the laminates 40 and / or stator gaskets 48, and in the preferred embodiment, the bars 62 are released to alternate the stator gaskets 48. In a preferred embodiment, the stator assembly 16 is compressed to approximately 100 psi, with a hydraulic press, for example, and the core bars 62 are fixed to the stator packages 48 while the assembly is compressed. The spacers 50 and / or bars 62 can be modified, such as by a small cut, when intercepting or adjacent to each other to ensure that a closed activity is not created, which can interfere with the flow of the cooler. In the preferred embodiment, the stator coils are wrapped windings, completely formed with a copper strip with a thickness of 2.9 mm and a width of 8.2 mm. The stator coils are insulated, preferably using an insulation system comprising Kapton and mica insulation on the individual strips followed by a mica and glass layer or a total stator packing 48. The insulation system used in the copper strip (for example, coil) is suitable for voltages of at least up to 1500 volts. The insulation used in the stator assembly 16 provides additional dielectric protection and mechanical strength. The coils can be inserted into the laminated grooves 46 in a conventional manner, such as with a groove liner. The bovine can be fixed in their place and in the preferred mode they are kept in place in glass nails. The stator winding assembly can be vacuum pressure, impregnated with an electrical resin, such as a conventional resin H, epoxy or polyester. The protuberances of the winding of. stator 70, as shown in figures 4 and 6, can and are preferably reinforced against a short circuit. The stator is preferably, but not necessarily, wound in a Delta mode with eight parallel circuits. In a preferred embodiment, the parallel circuits were connected at the ends of the winding protuberances over twelve copper bus rings, effectively dividing the stator assembly 16 into six sections, each section having two phases. The cables can be connected directly to the bus ring, such as by fins, and the cables can be configured so that the motor can be operated at a supply voltage of 600V or 1200V, as desired. See Figure 4. The stator assembly may include temperature sensing apparatus and in the preferred embodiment, includes six thermistors and six RTDs, one for each stator section. The temperature sensors can be used to provide feedback to the AC motor drive, such as a variable frequency transmission. The stator assembly 16 is positioned within the outer enclosure 18 as illustrated in FIG. 2. In the preferred embodiment, the stator assembly is pressed into the motor enclosure 18 through a slight interference fit. Usually an interference fit is sufficient to locate the stator relative to the structure and in the preferred embodiment, the interference fit is between the outer diameter of the compression plates 60 and the outer enclosure 18. The stator assembly 16 also it can be clamped or otherwise adhered to the outer enclosure 18. In the preferred embodiment, an appropriate number of spiral pins are used, having a load holding capacity of 500% of the entire load torsion. The method of installing the preferred stator assembly 16 comprises placing the outer enclosure 18 in a vertical orientation so that the stator assembly 16 can be lowered into the enclosure, heating the external enclosure 18 sufficiently to overcome the interference fit. of the non-heated or cooled stator assembly, oriented the stator assembly 16 towards the outer enclosure 18 and descending the stator assembly 16 in the outer enclosure 18. As shown in FIG. 7, the outer enclosure 18 has one or more stator stops 32, such as a shoulder pad, to positively locate the stator assembly within the enclosure. Additional fixings, such as welds or fasteners, can be used to axially constrain and / or rotationally move the stator assembly 16 relative to the outer enclosure 18. The spiral pins of the preferred embodiment are added by drilling guide holes 34, in the outer enclosure 18 and in one or more stator compression plates 60. Turning now to the rotor, as illustrated in FIG. 8, the rotor assembly 14 can be made of the same material or a similar one of which The stator assembly 16 is manufactured. In the preferred embodiment, the rotor laminates 80 are pre-coated laminates with a thickness of 0.5mm similar, or identical to the material used for the stator laminates 40. As will be described in more detail more further, each laminate of the rotor 80 can have one or more orientation apparatuses, such as a key slot 81, to orient the laminates relative to the rotor assembly 14. The rotor laminate 80 has a plurality of rotor slots of a conventional AC motor design. For the preferred embodiment described herein, each rotor laminate has 160 rotor slots 83. Similar to the stator assembly 16, the rotor assembly 14 is comprised of a plurality of rotor packages 82, each package comprising a plurality of individual laminates 80. See Figure 9. In the currently described embodiment, each rotor package 82 comprises approximately 132 laminates 80, making each rotor package 82 somewhat coarse 66mm. As in the stator assembly 16, each rotor package 82 can be separated from its adjacent gasket 82 for heat transfer purposes. In the preferred embodiment, the rotor assembly 14 utilizes metal strip spacers 50 that are approximately 10 mm thick between the adjacent rotor packages 3 mm. The spacers can be fixed to the surface of exposed adjacent laminates 80, preferably, by welding. In the preferred embodiment, these strips form channels 84 for the cooling system. The assembly of the rotor packages 82 can also be completed at each end with a transfer plate 86 and a compression plate 88 to maintain the pressure on the individual rotor teeth within each rotor package 82. As with the stator, the Compression plate and transfer plate can be combined. In the preferred embodiment, the compression plate 88 is released so that it can be flattened slightly when pressure is applied, ensuring that the pressure is applied at the center of the laminate. The assembly of the rotor packages 82, is assembled in a rotor star 90, whose preferred embodiment is shown in FIGS. 9 and 10. The preferred rotor star 90 comprises a central hollow tube 92 with a plurality of ribs or legs extending radially 94. FIG. 9 shows the rotor star 90 with six radially extending star legs 94 approximately spaced apart from the circumference of the tube 92. The longitudinal axis of the legs 94 aligns with the longitudinal axis of the tube 92. The legs 94 may be in a shaped panel. given or in recesses in tube 92 and be welded to ensure geometric accuracy, when the star is manufactured. The star 90 is designed so that one leg 94 can react 500% of all the load torque of the motor without appreciable plastic deformation. One end of one or more legs 94, has an shoulder pad 96 against which the rotor packages 82 are located. The star 90 has a central disk 93 that separates the star into two cooling circuits. As shown in Figure 10, stiffening ribs on the legs can be used to reduce vibration due to intermittent cutting during machining of the star 90. Preferably, each laminate 80, and consequently each rotor package 82 has a slight interference fit with the external surface 98 of the legs 94. Additional fixation of the rotor packages 82 for the star 90 can be supplied through various means, such as a key slot 81 shown in FIG. 8. The assembly of the rotor packages 82 is compressed below approximately 100 psi against the shoulder of the star 96 and the assembly is secured and placed on the legs of the star 94. The conductors , preferably copper rods, are placed in the rotor grooves 78 and subsequently secured in place. The conventional Barlock system that uses pegs is suitable for this task. The rotor star 90 is preferably adjusted in a contracted manner to the motor shaft 100 (See Figures 6 and 7). Within the diameter sections 102 and 104 at each end of the star tube 92 the interference fit is provided (Figure 10), with the section between them being a space setting with the arrow of the motor 100. This adjustment arrangement of interference, allows dimensional accuracy to be maintained during the machining of the surface of the internal diameter of the tube 92. Otherwise, the radius of action of the tool of the machine can be very long and can lead to difficulties in maintaining the tolerances of dimension. The interference fit is designed to transmit a minimum of 230% total load torque, which is calculated at a minimum setting. An allocation has been made for the temperature of the drilling ground which passes through the hollow motor arrow 100. Any difference in temperature between the arrow 100 and the star 90 will increase the interference pressure between arrow 100 and star 90. It is assumed that a difference in temperature of 60 ° C may be possible, because the maximum temperature of the earth is approximately 100 ° C. The interference fit between the setting 100 and the star 90 may be designated, and in the preferred embodiment it has been designated, to provide a compromise between the transmission and tension of the torsion. Also, in the preferred embodiment, the shrinkage adjustment is increased with an axial key 106 in a section 102 or 104 only (FIG. 7). Figure 11 shows a piercing end view of a preferred engine 12, of an upper transmission drilling system 10. The motor end plate 160 is provided with one or more attachment points 162, such as pads, for adhere in a mechanical braking system (24 in Figure 1). In the preferred embodiment, a disk brake rotor 142 is adhered to the motor shaft 100 and one or more, and preferably four gauges are mounted on the end plate 160. The edge of the disk 142 can function as a recorder of the speed encoders 22 for variable frequency transmission 13. Also seen in Figure 11, internal strips 170 on the arrow of motor 100. In the preferred embodiment, two groups of strips 170 are separated by a slot or other adapted structure to accept a seal (not shown), such as an O-ring elastomeric The strips 170 allow the arrow or transmission tube 172 to move relative to the motor shaft 100 and the seal prevents communication of fluid (such as drilling earth) out of the motor shaft 100 / tube assembly. transmission 172. Referring to Figure 7, the rotor assembly 14 and the motor shaft 100 are shown positioned in the motor enclosure 18. The upper rotor bearing 110 is a spherical roller bearing, such as an SKF model QJ 1068 M. For horizontal motor applications, such as extraction operations, you can use the SKF model 23068 CC / W33 M. These bearings have a design life in excess of 100,000 hours based on a rotation speed of 150 rpm and with propulsion solely from the motor rotor. These bearings are lubricated with grease and a grease nipple can be placed near one end of the engine 12 to push grease between the two rows of rollers. The excess fat can be expelled in a grease release chamber 112, which can be emptied, as needed. In a preferred embodiment, the bearing 110 is held in place by a nut of the arrow 114, together with a locking clip collar 116. Under the nut 114 is a launcher to prevent rainwater from being collected in the upper part of the bearing seal. A seal between the bearing and the engine is not used in the preferred embodiment. The support of Upper bearing 120 is fitted with insulation to prevent conduction of potential damage currents through the bearing. The fasteners that hold the bracket are fitted with washers and insulation sleeves to prevent bridging the insulation. The bearing support also sits on a raised platform to reduce the possibility of bridging the insulation with water held there.

The rotor bearing of the lower part 130 can be a cylindrical roller bearing, such as SKF model NU 1072M, which is suitable for vertical or horizontal motors 12. This bearing has a life in excess of 100,000 hours as well. The grease adjustment for this bearing is similar to that of the upper bearing 110. The lower bearing 130 has an onboard seal 132 to protect the bearing from any water ingress caused by accumulation within the engine. The lower bearing can be adjusted with a simple clamp 136 to secure the bearing in place, and prevent damage by vibration in the transmission. The bra 136 simply pushes the bearing into its space. The fastener 136 must be removed before the operation of the motor 12. The effect of the temperature of the ground of the bore in the bearings 110, 130, must be taken into account. The effect of the earth passing through the arrow of the motor 100 must increase the temperature of the race of the inner bearing and thus possibly reduce the space in the bearing.

Although it is tempting to increase the bearing space for this effect, it is possible that the bearing spaces are too large when the bearing is cold, (i.e., not heated by the drilling earth) and the bearing can be damaged. In the preferred embodiment, and due to the relatively slow rotation speed of the motor shaft 100, standard bearing spaces are used. The engine 12 can be cooled in a variety of ways, although in the preferred upper transmission mode described in the present invention, the engine 12 is cooled by forced air circulation. The cooling or ambient air is introduced from the upper or non-transmission end of the motor 12 through the cooling ports 28 and 30. In the preferred embodiment, centrifugal fans are mounted separately with power of 15 hp 150 at the top of the engine 12, to supply the cooling air. Each fan can operate at approximately 3,000 cfm. If a fan fails, this setting allows the motor to continue operating, possibly with lower performance. Each cooling port 28 and 30 has a deflector 150 that effectively divides the air stream into two components, one component for the upper half of the engine 12 and the other component for the lower half of the engine 12. Based on the analysis heat transfer, the deflection can be provided in each fan to provide the amount of air that is divided through deflectors 150. Air passes over the windings of the end of the stator and into the magpie-shaped star sections 159 from each end. The air is then expelled through radial channels between the rotor packages 82 and into the adjacent radial channels in the stator assembly 16. By allowing the air to enter the upper and lower parts of the engine 12 from two points, it is improved the distribution of the cooling air in the engine 12. The air is expelled from the engine on both sides through ejection manifolds 156 (figure 7) under and outside the engine 12 to reduce the risk of re-circulation of air. The ejection manifolds are designed to prevent the entry of rainwater into the engine 12. The engine 12 as described in the present invention can be implemented in a variety of devices such as upper transmission drilling systems, drilling operations, pumps, excavation equipment, mining vehicles and many other applications in which low speed power is required (for example, 0 to 300 rpm). The present invention eliminates the need for costly and intensive maintenance speed reduction equipment. The previous description of the preferred modality and others do not intend to limit or restrict the scope or ability to apply the concepts of the present invention conceived by the Applicants. In the exchange for the description of a preferred embodiment of the present invention, the Applicants desire the higher scope for the appended claims allowed by the patent laws.

Claims (6)

1. CLAIMS 1. A top drive drilling system using a low speed AC motor, comprising: a motor structure, a stator assembly fixed to the motor structure and comprising a plurality of stator laminates comprised in a core of stator; a star comprising a hollow tube having a plurality of ribs located on the outer surface of the tube and oriented so that the length of the ribs matches the length of the arrow; a rotor core comprising a plurality of compressed rotor laminates affixed to the external radial surface of the star ribs; a hollow motor arrow to which the star is coupled; first and second bearing assemblies mounted between the motor structure and the motor shaft, so that the rotor core can rotate relative to the stator assembly; and an engine transmission to generate a variable frequency PWM signal to operate the AC motor at speeds of approximately 0 to 300 rpm, thus avoiding speed reduction equipment.
2. 2. The upper transmission system as described in claim 1, characterized in that the engine CA further comprises three delta phase windings that create 8 poles, and the motor transmission supplies a base frequency of 10 Hz.
3. The upper transmission system as described in claim 1, characterized in that the first and second bearings , support only the weight of the rotor assembly and braking assembly.
4. 4. The upper transmission system as described in claim 1, characterized in that the stator assembly is fastened with pins to the motor structure to support 500% of total load torque.
5. 5. The upper transmission system as described in claim 1, characterized in that the star of the rotor is inside a panel that has the form of a die to accept the ribs, and the ribs are welded with moldings to the arrow, so that any rib can support up to 500% of total load torque. The upper transmission system as described in claim 1, characterized in that the first bearing is a spherical bearing and is electrically isolated from the rotor and the motor structure, and wherein the second bearing is a cylindrical bearing and it is electrically isolated from the rotor and the motor structure.