WO 2022/114961 PCT/N02021/050241

ACTUATOR DEVICE

This invention concerns an electromechanical force actuator device. More specifically it concerns a device that controls coordination of at least two parallel actuation devices that each comprise an electric motor, a gear system, a rolling screw and a rolling nut that are coupled to a common actuation element for an actuator spindle.

The term "force actuator" is used to emphasise that an actuator according to the invention is especially suitable for use where large actuation forces are needed. The area of appli cation is typically cutting and barrier functions in blow-out preventers (BOP) for drilling and well completion uses, as well as corresponding functions for lighter well intervention equipment. The force actuator can be adapted to subsea use.

NO344201 describes an electromechanical actuator solution with two cooperating, parallel rolling screws, rotatably arranged in an actuator housing. Each rolling screw is rotated by an electric motor via a gear system, and drives respective rolling nut that is coupled to a separate actuation element via spherical bearings. The construction allows some impreci- sion in the parallel drive of the rolling screws in that the actuation elements are coupled to the rolling nuts via spherical bearings, and each actuation element partially abuts a rounded end surface on an actuator spindle and displaces it in operative use.

The purpose of the invention is to remedy or reduce at least one of the disadvantages of prior art, or at least provide a useful alternative to prior art. The purpose is fulfilled by the features specified in the description below and the subse quent patent claims.

An electrically driven actuator solution is provided with at least two cooperating, parallel rolling screws rotatably arranged in an actuator housing. Each rolling screw is rotated by an electric motor via a gear system, and drives respective rolling nut that is coupled to a NIPO

WO 2022/114961 ² PCT/N02021/050241 common actuation element, where an actuator spindle is anchored. The motors are so- called stepper motors or synchronous motors, known from use in precise control of tool machines. With precise, electronic coordination of the rolling screws the construction can be made simpler, more compact and more robust compared to prior art, where the me- chanical construction is arranged to absorb some imprecision in the coordination of the rolling screws. Even load distribution can be achieved through precise control of torque and position of the rolling nuts and with a robust design of the common actuation element. When the actuator spindle is solidly anchored in the actuation element, the fastening does not limit the force with which the actuator spindle can be pulled back. Provided that thrust bearings for the actuator's rolling screws are appropriately dimensioned, the actuator can be operated at full force in both directions. An advantage of an electrically driven actuator solution compared to hydraulic operation, is full control and monitoring of force and posi tion of the effective stroke of the actuator and thereby the well barrier components. Fur ther, dampening end stops will give less load on the packers in the well barrier element. The invention is defined by the independent patent claim. The dependent claims define advantageous embodiments of the invention.

The invention concerns more specifically an actuator that comprises an actuator housing; at least two parallel rolling screws that each are rotatably bearingly supported in the actuator housing and are coupled via rotation means to an electric motor and are in engagement with a roller nut, wherein rotation of the rolling screws generates axial dis placement of the rolling nuts along the rolling screws; an actuator element is in engagement with the rolling nuts, and an actuator spindle is anchored in the actuator element; characterised in that a sensor head is arranged on the actuator element near each roller nut; and a contactless, linear position sensor is fastened in the actuator housing adjacent to each of the sensor heads and is arranged to communicate information about the position of the respective sensor head to a control system. The electric motor may be a stepper motor. Alternatively, the electric motor can be a syn chronous motor provided with a motor driver and at least one encoder. An effect of this is that the properties of the electric motor provide further possibilities for controlling the posi tion of each rolling nut. NIPO

WO 2022/114961 ³ PCT/N02021/050241

A transmission means may be arranged to be connectable to the rotation means and cou- plable to an external rotation means. An effect of this is that an external device, for exam ple an underwater vehicle, can operate the actuator if the power supply to the electric mo tors fails. In the following, an example is described of a preferred embodiment, illustrated in the at tached figure 1 that shows a partial axial section through the actuator. Details for rotation means, brake system and fastening of these are not shown.

All position indicators refer to the position shown on the figure.

An expert on the subject will understand that the figure is only a principle drawing. The relative ratio between individual elements may also be distorted.

In figure 1, the reference number 1 indicates a force actuator according to the invention. The force actuator 1 is configured to displace an actuator spindle 2 into a well barrier de vice (not shown) and comprises at least two parallel rolling screws 3A, 3B that are rotata bly arranged in an actuator housing 4 with thrust bearings 5A, 5B, 6A, 6B on the ends, and rotation means 7A, 7B coupled to the rolling screws 3A, 3B.

The rotation means 7A, 7B consist of a gear system (not shown) that is connected to re spective electric stepper motors or synchronous motors 8A, 8B via motor gears 9A, 9B for simultaneous rotation of the rolling screws 3A, 3B. Each of the motors 8A, 8B are provid ed with a motor driver 10A, 10B that from DC or AC supply voltage feeds current pulses to motor windings in a stepper motor, alternatively synchronises the rotation of a motor shaft to a synchronous motor with the frequency of the supply voltage, and an encoder 11 A,

11 B that provides feedback signals by tracking the speed and/or position of the motor shaft.

A control system 17 is coupled to the motor drivers 10A, 10B and the encoders 11 A, 11 B, and controls revolution, position and torque for the motors 8A, 8B and ensures precise, parallel coordination of the actuator devices. In addition to motor data, the control system 17 typically monitors other condition data such as possible water ingress, vibration, tem perature, and secondary measuring of the stroke displacement of the actuator 1.

A rolling nut 12A, 12B engages in each of the rolling screws 3A, 3B. Rotation of the rolling screws 3A, 3B leads to axial displacement of the rolling nuts 12A.12B along the rolling screws 3A, 3B. The rolling nuts 12A, 12B are enclosed by a common actuation element 13 and the actuator spindle 2 is anchored in a centred manner in the actuator element 13. NIPO

WO 2022/114961 ⁴ PCT/N02021/050241

An axial displacement of the rolling nuts 12A, 12B thereby results in a corresponding axial displacement of the actuation element 13.

Contactless, linear position sensors 14A, 14B are arranged on opposite sides inside the actuator housing 4 and register the stroke displacement of the actuator 1 by continuously measuring the position of respective sensor heads 15A, 15B that are mounted on oppo site sides of the actuation element 13, respectively. The signals are transferred to the con trol system 17 and act as a secondary position control of the actuation element 13 for comparison with information provided by the primary motor control provided by the previ ously mentioned encoders 11 A, 11 B. The actuator 1 is preferably provided with a brake system (not shown) to hold the actuator 1 locked when the motors 8A, 8B are not in operation.

By guiding a transmission means, shown as a gear 16 on the figure, to engagement with the rotation means 7A, 7B, the rolling screws 3A, 3B are brought to rotation by means of an external rotation means 18A, for example a moment tool on a subsea remotely operat- ed vehicle (ROV) 18, possibly after the not shown brake system is released. Operation of the actuator 1 with the external rotation means 18A can be necessary if for example the power supply to the motors 8A, 8B is interrupted.

Necessary seals are not described, but are known to a skilled person.

It should be noted that all embodiments mentioned above illustrate the invention, but do not delimit it, and experts on the subject will be able to design many alternative embodi ments without deviating from the scope of the attached claims. In the claims, the refer ence numbers in parenthesis shall not be considered delimiting.

The use of the verb “to comprise” and its different forms does not exclude the presence of elements or steps not mentioned in the claims. The indefinite articles “a” or “an” before an element do not exclude the presence of more such elements.