Electro mechanical power actuator

Abstract

An actuator is for use in petroleum exploitation and is configured for displacing a rod for engaging a well barrier device. The actuator has a housing for at least a portion of the rod; at least two roller screws rotatably arranged in the housing; rotational means connected to the roller screws via one gear systems for each roller screw for simultaneous rotation of the roller screws; and a roller nut engaging each roller screw. The roller screws and roller nuts are configured such that rotation of the roller screws result in displacement of the roller nuts relative to the roller screws. Each roller nut is coupled with one actuation element via spherical bearings, and each actuation element is configured for mechanical coupling to an end portion of the rod for displacing the rod in operational use.

Claims

1. An actuator for use in petroleum exploitation, the actuator being configured for engaging a well barrier device, wherein the actuator comprises: a housing; a rod having a rounded end surface, wherein at least a portion of the rod is arranged in the housing; at least two actuator assemblies, wherein each actuator assembly comprises: a roller screw rotatably arranged in the housing; a rotational means connected to the roller screw by means of a gear system; a roller nut engaging the roller screw, the roller screw and the roller nut configured such that rotation of the roller screw results in displacement of the roller nut relative to the roller screw in an axial direction; and an actuation element coupled to the roller nut via a spherical bearing; wherein each of the gear systems is configured to enable simultaneous rotation of each of the roller screws of the at least two actuator assemblies; and wherein each of the actuation elements is mechanically coupled to an end portion of the rod such that the rounded end surface contacts a complementary contact face on each of the actuation elements for displacing the rod in the axial direction in operational use.

2. The actuator according to claim 1, wherein exactly two roller screws are rotatably arranged in the housing.

3. The actuator according to claim 2, further comprising a common gear for connecting each of the gear systems together.

4. The actuator according to claim 2, wherein the rotational means comprises an electric motor.

5. The actuator according to claim 1, further comprising a common gear for connecting each of the gear systems together.

6. The actuator according to claim 5, wherein each of the roller screws are configured to be rotated by rotation of the common gear.

7. The actuator according to claim 6, wherein the rotational means comprises an electric motor.

8. The actuator according to claim 5, wherein the rotational means comprises an electric motor.

9. The actuator according to claim 1, wherein the rotational means comprises an electric motor.

10. The actuator according to claim 9, further comprising a control system for controlling each of the electric motors.

11. The actuator according to claim 1, further comprising a brake system.

12. The actuator according to claim 1, wherein the rounded end surface of the rod directly contacts the complementary contact face on each of the actuation elements.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the following is described examples of preferred embodiments illustrated in the accompanying drawings, wherein:

(2) FIG. 1 shows a perspective view of the actuator according to one embodiment of the invention;

(3) FIG. 2 shows a cross-section through the actuator in FIG. 1;

(4) FIG. 3 shows, in a larger scale than FIG. 1, a sideview of the actuator without the end coyer;

(5) FIG. 4a shows a detailed view of the braking system in a larger scale than FIG. 2, the brake system being engaged, and

(6) FIG. 4b shows a detailed view of the braking system in the same scale as FIG. 4a, the brake system being disengaged.

DETAILED DESCRIPTION OF THE DRAWINGS

(7) The figures are depicted in a simplified manner, and details that are not relevant to illustrate what is new with the invention may have been excluded from the figures. The different elements in the figures may necessarily not be shown in the correct scale in relation to each other. Equal reference numbers refer to equal or similar elements. In what follows, the reference numeral 1 indicates an actuator according to one embodiment of the invention. The actuator 1 comprises a housing 2 with an end plate 24 and an end cover 23. Two motor housings 3a, 3b each comprising an electric motor 30a, 30b are connected to the end plate 24. The end cover 23 comprises an opening for an intervention adapter 231 for manual operation of the actuator 1, or override of the motors, for example by an ROV tool (not shown).

(8) FIG. 2 shows a cross-section through the actuator 1. Two roller screws 5a, 5b are supported in the housing 2 by a thrust bearing 51a, 51b in either end of the screws 5a, 5b. The thrust bearings 51a, 51b enable rotation of the screws 5a, 5b around its longitudinal axis 500a, 500b. Each screw 5a, 5b is arranged with a roller-nut 52a, 52b. The roller-nuts 52a, 52b comprises threaded rollers (not shown) in engagement with the threads (not shown) on the screws 5a, 5b. The threaded rollers enable the rotation of the screw 5a, 5b to be translated into an axial movement of the roller nut 52a, 52b along the screw 5a, 5b. Direction of axial movement of the roller-nuts 52a, 52b depends on the direction of rotation of the screw 5a, 5b.

(9) The roller nuts 52a, 52b are connected to actuation elements 53a, 53b by means of thrust bearings 54a, 54b. The thrust bearings 54a, 54b are spherical and concentrically arranged on the roller nuts 52a, 52b and actuation elements 53a, 53b. The thrust bearings 54a, 54b enable rotation of the roller nuts 52a, 52b without transferring the rotational movement to the actuation elements 53a, 53b. The actuation elements 53a, 53b envelop an end portion of the roller nuts 52a, 52b.

(10) A rod 4 protrudes the housing 2 through an opening 6. The opening 6 is sealing around the rod 4. The rod 4 is connected to the two actuation elements 53a, 53b by means of a bracket 401. The actuation elements 53a, 53b form a common contact face 400 for the rod 4. The contact face 400 is spherical and complementary to a first end portion 40 of the rod 4. A second end portion 41 of the rod 4 is connectable to e.g. a device (not shown) arranged in a machined block with cavities for well barrier devices (not shown).

(11) Each of the two electric motors 30a, 30b in the motor housings 3a, 3b comprise a stator, the stator comprising two sets of independent windings and a rotor. The stator is supplied with electric current via wires (not shown). Each of the motors are connected to a gear system 7a, 7b. Each gear system 7a, 7b comprises a first gear 71a, 71b coupled to the motor. The first gear 71a, 71b drives a second gear 72a, 72b and a third gear 73a 73b. The third gear 73a, 73b being connected to a planetary gear 74a, 74b. The planetary gear 74a, 74b is connected to the screw 5a, 5b.

(12) FIG. 3 shows a sideview of the actuator 1 without the end cover 23. The gear systems 7a, 7b are arranged in a void 8 between the end plate 24 and the end cover 23. In use, the void 8 is filled with a fluid (not shown) for lubricating the gears. The gear systems 7a, 7b are connected by a common gear 75 arranged between the third gears 73a, 73b. The common gear 75 enables rotation of both screws 5a, 5b by operating only one motor. The common gear 75 is also coupled to the intervention adapter 231. If the motors fail, the actuator 1 can be operated via the intervention adaptor 231 by connecting a rotational tool (not shown) thereto.

(13) FIGS. 4a and 4b shows a detailed view of the brake system 9, wherein FIG. 4a shows the brake system 9 when it is engaged, and FIG. 4b shows the brake system 9 when it is disengaged. The common gear 75 comprises a boss 91, wherein the boss 91 has a toothed end portion 910. A restraining device 911 comprises a toothed end portion 912 complementary to the toothed end portion 910 on the boss 91. An end portion of the restraining device 911 is coupled with a spring 913 opposite of the toothed end portion 912. The restraining device 911 comprises grooves 915 coupled to complementary grooves (not shown) in the end plate 24 to prevent the restraining device 911 from rotating. The restraining device 911 is displaceable along a centre axis 900 of the common gear 75. A spring force from the spring 913 is acting on the restraining device 911 and can displace it towards the boss 91. The toothed portions 910, 912 will mate and the restraining device 911 will restrain the common gear 75 from rotating. An electromagnet (not shown) is configured to, in use, counteract and overcome the spring force acting on the restraining device 911. When the common gear 75 is driven by the motors, the electromagnet is engaged and disconnects the restraining device 911 from the boss 91, such that the common gear 75 is free to rotate. If power to the actuator 1 is lost or shut off, the electromagnet is disengaged, and the spring 913 will displace the restraining device 911, and thus engage the brake system 9. In one embodiment, friction between the restraining device 911 and the boss 91 can contribute to braking the common gear 75.

(14) The teeth on the toothed end portions 910, 912 have chamfered corners 914. When the brake is engaged, i.e. the toothed end portions are mated, the chamfered corners 914 enables the boss 91 to ratchet with respect to the restraining device 911 if the rotational force acting on the common gear 75 exceeds a certain value (not defined). Ratcheting means that the teeth on the boss 91 can jump from one groove between teeth on the restraining device 911 to the next groove. Should the electromagnet unintentionally fail and the brake system 9 be engaged, the motors are strong enough to ratchet the boss 91, thus rotate the common gear 75.

(15) Connecting a complementary rotational tool (not shown) to the intervention adaptor 231 will also disengage the brake system 9. When the tool is connected to the intervention adaptor 231, the restraining device 911 will be pushed back and the toothed end portions 910, 912 be unmated.

(16) It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. Use of the verb “comprise” and its conjugations does not exclude the presence of elements or steps other than those stated in a claim. The article “a” or “an” preceding an element does not exclude the presence of a plurality of such elements.

(17) The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.