DESCRIPTION

Field of the invention

[0001]The present invention relates to a multi-turn actuator for valves, generally used in industrial plants, such as chemical or petroleum plants, for managing the flow of a fluid in a pipeline. Valves are generally of different types, according to requirements; in the plant engineering sector, for example, ball, butterfly, damper or gate valves and other types are widely used.

Prior art

[0002]All the valves have in common the presence of a gate which may switch from a completely closed position, in which it obstructs the pipeline and prevents the passage of fluid, to a completely open position, in which the passage of fluid through the maximum useful section is allowed. Between the two limit positions, there are numerous intermediate positions of partial opening. Generally, with reference to the useful passage section, the completely closed position corresponds to 0% of the useful section and the completely open position to 100% of the useful section. Depending on the type of valve or kinematics between actuator and valve, the transition of the actuator from the fully closed position to the fully open position corresponds to a predetermined number of turns of the actuator shaft.

[0003]An actuator of the type that is the object of the present invention is mechanically connected to the valve to control the opening and closing thereof by means of electrical controls, given remotely from the place of installation of the valve or locally, and is capable of managing the rotation of the shaft over several turns.

[0004]One of the most felt needs in the sector is the possibility of setting the duration of the opening or closing maneuver, for example the duration of the actuator position change between the completely closed position and the completely open position, since the response of the plant to a predetermined plant requirement may depend on this maneuver time.

[0005]At the moment, solutions of rotary actuators are known which, once the size of the electric motor and therefore the maximum torque which may be supplied have been defined, guarantee the transition from the completely closed position to the completely open position in a predetermined time interval. An example is described in the brochure "Experience in motion - The next generation in smart multiturn actuation", published by Flowserve Corporation. However, if the plant requirements vary, it is necessary to replace the actuator.

Object of the invention [0006]It is the object of this invention to make a multiturn actuator which meets the aforesaid requirements and overcomes the drawbacks of the prior art.

[0007]This object is achieved by a multi-turn actuator according to claim 1. The dependent claims describe additional advantageous embodiments.

Brief description of the drawings

[0008]The features and advantages of the multi-turn actuator according to this invention will become apparent from the following description, given by way of nonlimiting example according to the figures in the accompanying drawings, wherein:

- Figure 1 shows an assembly consisting of a valve and an actuator according to an embodiment of the present invention;

- Figure 2 depicts the actuator of Figure 1;

- Figure 3a illustrates a front view of the actuator of Figure 2;

- Figure 3b shows a top plan view of the actuator of Figure 2;

- Figure 4 is a sectional view of the actuator of Figure 2, according to the sectional plane IV-IV of Figure 3a;

- Figure 5 is a sectional view of the actuator of Figure 2, according to the sectional plane V-V of Figure 3a;

- Figure 6 is a sectional view of the actuator of Figure 2, according to the sectional plane VI-VI of Figure 3b;

Figure 7 depicts a local control interface of the actuator of Figure 2;

- Figure 8 depicts a diagram of a power unit and a control unit of the actuator of Figure 2;

- Figure 9 illustrates an example trend of the torque delivered by the actuator as a function of time or angular position;

- Figure 10 illustrates the trend of the torque and power delivered by the actuator, as a function of the rotation speed.

Description of a preferred embodiment

[0009]With reference to the figures of the accompanying tables, reference numeral 1 indicates as a whole an assembly consisting of a valve 2 applicable to a pipeline for the transit of a fluid and a multi-turn actuator 4 mechanically connected to the valve 2 to control it to open and close.

[0010]Preferably, the actuator 4 comprises a casing 6 which delimits an internal space sealed with respect to the external environment.

[0011]The casing 6 consists of a central body 7, for example made in a single piece, in metal material, preferably in aluminum, in the shape of a T, which extends along a longitudinal axis X and along a transversal axis Y orthogonal to the longitudinal axis.

[0012]The actuator 4 also comprises a first cover 8 and a second cover 10, applied to close the ends of the central body 7 along the longitudinal axis X, and a third cover 12, applied to close the end of the central body 7 along the transversal axis Y. Preferably, each cover 8, 10, 12 is made in a single piece, in a metal material, for example in aluminum.

[0013]Preferably, moreover, the actuator 4 comprises a handwheel 14 applied externally to the central body 7, manually rotatable about a main axis Z, orthogonal to an imaginary plane which contains the longitudinal axis X and the transversal axis Y. The handwheel 14 may be used for manually operating the actuator.

[0014]Furthermore, preferably, the actuator 4 comprises a release lever 16, applied externally to the central body 7, which may be operated manually to switch from the automatic operation of the actuator 4 to manual operation. [0015]The actuator 4 also comprises an electric motor 20 housed in the internal compartment of the casing 6, preferably inside the first cover 8 of said casing 6. The motor 20 has a rotating drive shaft 22, with a motor axis K preferably arranged parallel to the longitudinal axis X. [0016]The motor 20 is a brushless motor of the alternating current type,having a rotor 24, integral with the motor shaft 22, with permanent magnets, surrounded by a stator 26 provided with windings.

[0017]Advantageously, the alternating current brushless motor (called "BLAC motor") used guarantees better control, greater efficiency, lower noise and more stable behavior in temperature compared to direct current brushless motors (called "BLDC motors") usually used in the multi-turn actuators of the prior art.

[0018]In particular, advantageously, for the BLAC motor used, the current absorbed at start-up is linked exclusively to the torque delivered, not to slip or other phenomena observed at the start of rotation.

[0019]Furthermore, the control implemented for the BLAC motor used is of the FOC (field oriented control) type, which, even when starting a maneuver, recognizes the relative angular position between the stator and the rotor through an algorithm based on the magnetic saturation of the stator windings.

[0020]Furthermore, for the BLAC motor used, the measurement of the rotation speed of the rotor is also performed by means of a suitable algorithm, as a variation over time of the relative angular position between the stator and the rotor.

[0021]Advantageously, therefore, the motor 20 has no position sensors for detecting the relative angular position between rotor and stator and for detecting the speed of the rotor, and thus avoids running into the typical criticalities of electronic components at high temperatures; at the same time, the production of the actuator and the calibration and testing of the motor are simplified.

[0022]Advantageously, moreover, the BLAC motor used is capable of delivering the maximum torque at low rotation speeds. This allows the amplitude of the idle rotation of the motor shaft to be reduced and, consequently, the delay in reversing the direction of rotation to be reduced.

[0023]The actuator 4 also comprises a kinematic mechanism 28 adapted to transform the rotation of the motor shaft 22 about the motor axis K into a rotation of a main shaft 30 of the actuator about the main axis Z, orthogonal to the motor axis K. For example, said kinematic mechanism 28 comprises a worm screw 32 integral in rotation with the motor shaft 22 and preferably coaxial with it, and a toothed wheel 34, which meshes with the worm screw 32 and is integral in rotation with the main shaft 30 either directly or through a coupling device 31 controlled by an inserter fork connected to the release lever 16.

[0024]The main shaft 30 extends along the main axis Z between a first end 33 proximal to the handwheel 14 and a second end 35, opposite to the first, adapted to be mechanically connected to the valve 2, for example to a stem thereof integral with the gate, directly or indirectly through a gripping element 36 integral in rotation with the main shaft 30 and connectable to the valve 2.

[0025]The actuator 4 also comprises a transducer device 40 adapted to detect the angular position of the main shaft 30. For example, said transducer device 40 cooperates with a toothed shaft 42, having a transducer axis W, for example orthogonal to the main axis Z, which meshes permanently with a toothed wheel 44 integral in rotation with the main shaft 30 or obtained as a portion of said shaft. The transducer device 40 is further connected to a fixed flange 46, engaged with the toothed shaft 42.

[0026]Preferably, the transducer device 40 consists of a multi-turn absolute encoder, which is for example magnetic, provided with a system for energy recovery by the Wiegand effect. For example, the encoder has 24-bit resolution (12-bit single-turn and 12-bit multi-turn).

[0027]The actuator 4 further comprises a power unit (UP) 100 housed in the casing 7, preferably integral with the second cover 10 which closes the central body 6, and a control unit (UC) 200 housed in the casing 7, preferably fixed to the bottom of the second cover 10.

[0028]The power unit 100 comprises a rectifier 102 connected to the electric mains and adapted to transform an alternating current into a direct current; the rectifier

102 is operatively connected to the control unit 200 to power it electrically with direct current.

[0029]The power unit 100 further comprises an inverter 104 adapted to transform a direct current into an alternating current with variable frequency; the inverter 104 is operatively connected to the rectifier 102 to be powered with direct current and to the electric motor 20 to power it with alternating current at variable frequency, according to the torque to be supplied.

[0030]The control unit 200 comprises electronic processing means 202, for example comprising one or more microprocessors, configured or programmed to receive input data or signals, process them on the basis of software and transmit output data or signals. The processing means 202 are operatively connected to the power unit 100, and in particular to the inverter 104, to manage the operation thereof, and to the transducer device 40 to receive position signals Sp relating to the angular position of the main shaft 30.

[0031]Preferably, the control unit 200 further comprises a local control interface 204, accessible to a user from the bottom of the second cover 10, preferably comprising a numeric and graphic display 204a, a selector 204b for selecting operation in local or remote control mode or switch-off of the actuator (preferably provided with two Hall effect sensors for local or remote control mode), and buttons 204c for controlling the actuator to open or close or for immediate stop (each preferably provided with a Hall effect sensor). Preferably, the selector 204b is engageable with a padlock or the like, to allow the selection of an operating mode only to a user provided with a key.

[0032]Since the actuator 4, once mounted on the valve, may assume any orientation in space (with the exception of upside-down assembly), the second cover 10 may be mounted on the central body 6 in different angular positions, so that the local control interface 204 visible from the bottom of said second cover 10 may assume the most comfortable orientation for easy reading and use by the user.

[0033]Preferably, the control unit 200 further comprises a remote-control interface 206 for receiving controls remotely, for example via wireless or wired communication. [0034]Preferably, the control unit 200 comprises a backup system 208 for powering some circuits of the control unit 200, for example in energy saving mode or in emergency conditions.

[0035]Preferably, moreover, the backup system 208 is operatively connected to the transducer device 40 and to the local control interface 204, and in particular to the display 204a thereof. This allows the angular position information of the main shaft 30 of the actuator 4 to be available even when the actuator is not powered by the electric mains (LOW POWER operating mode). For this purpose, the transducer device 40 is provided with Hall effect sensors 210 operatively connected to the control unit 200.

[0036]When the actuator 4 is powered by the mains (POWER ON operating mode) , regardless of whether the manual operation is disabled or enabled, the transducer device 40 is powered electrically and provides a position signal Sp as a function of the angular position of the main shaft 30; the position signal Sp is processed by the control unit 200 and is represented on the display 204a of the local control interface 204.

[0037]When the actuator 4 is not powered by the electric mains (LOW POWER operating mode), regardless of whether the manual operation is disabled or enabled, the transducer device 40 is not normally powered electrically. When the main shaft 30 undergoes a rotation, due to a manual operation via the handwheel or an electric operation via an auxiliary power supply, the Hall effect sensors 210 send a wake-up signal Sw to the control unit 200, which, through the powering of the batteries 208, powers the transducer device 40 and detects a new position signal Sp; the new position signal Sp is processed by the control unit 200 and is represented on the display 204a of the local control interface 204, powered by the battery 208. [0038]A predetermined actuator is designed in such a way as to be able to deliver a rated torque C _n ; preferably, actuators according to the invention are available which are capable of delivering a rated torque C _n equal to 32 or 63 Nm, 125, 250 or 500 and 1000 Nm. This parameter defines the "size" of a predetermined actuator.

[0039]Before starting its normal operation, the actuator is configured by supplying the processing means 202 with the rated torque C _n and the time T _cycle in which to open or close the valve, for example the time Tioo in which to reach the fully open position (100%) starting from the completely closed position (0% at time To).

[0040]The processing means 202 are configured or programmed to make the actuator deliver, when the operation is started, for example starting from the fully closed (Figure 9) or fully open condition, a peak torque C _P k greater than the rated torque C _n , for example equal to 1.6 times the rated torque (in general, C _P k = n -C _n , where n is between 1.05 and 2), for a very limited period of time (T _P k) , sufficient to eliminate the holding effect exerted by the gaskets and by the static friction when the operation is started. The peak torque C _P k, i.e. the value n, and the holding time T _P k of the peak torque are settable by the user, for example via software.

[0041]Furthermore, the processing means 202 are configured or programmed to set a speed setpoint W* of the main shaft to reach the desired limit position (α%) of the main shaft 30 in a desired time (T), for example the fully open position (α% = 100%) in the desired time Tioo.

[0042]Preferably, moreover, the processing means 202 are configured or programmed to make the actuator deliver, at the start of the maneuver, a further peak torque, for example equal to the peak torque C _P k or to the rated torque C _n , in order to force the completely closed position, overcoming the deformation of the gaskets and the settling of the components.

[0043]Given the rated torque C _n which may be delivered by the actuator and the maximum rotation speed W _n of the main shaft 30 at the rated torque C _n , the rated power of the actuator is defined P _n = C _n • W _n .

[0044]The processing means 202 are configured or programmed to make the power unit 100 deliver such a motor supply current that (Figure 10):

- if the rotation speed W of the main shaft is lower than a predetermined reference speed W', for example the maximum rotation speed W _n , the torque C is constant; if the rotation speed W of the main shaft is greater than the reference speed W', for example the maximum rotation speed W _n , the power P = C -W is constant.

[0045]Advantageously, this allows a small number of sizes (for example only four) to be available to satisfy numerous requirements for maximum rotation speed (from 6 to 120 rpm) or maximum torque from 32 to 1000 Nm.

[0046]The functionality of the multi-turn actuator and the configurations or programming settable by the operator are always in compliance with the reference standard, such as UNI EN ISO 22153: 2021 and any subsequent amendments.

[0047]Furthermore, according to a preferred embodiment, the actuator 4 comprises a thermal protector 212 adapted to detect the temperature of the electric motor 20 and operatively connected to the control unit 200 which processes a temperature signal St generated by said temperature sensor 212 and signals an alarm condition for the actuator.

[0048]Furthermore, according to a preferred embodiment, the actuator 4 comprises a humidity sensor 214 adapted to detect the humidity inside the actuator casing and operatively connected to the control unit 200 which processes a humidity signal S _u generated by said humidity sensor 214 and signals an alarm condition for the actuator. [0049]Furthermore, according to a preferred embodiment, the actuator 4 comprises an accelerometer 216 adapted to detect an acceleration of the actuator casing and operatively connected to the control unit 200 which processes an acceleration signal S _a generated by said accelerometer 216 and signals an alarm condition for the actuator, due for example to an earthquake or a knock against the actuator. [0050]Innovatively, the actuator according to the present invention meets the needs of the sector and overcomes the drawbacks mentioned with reference to the prior art, since it allows the execution time of an opening or closing maneuver to be adjusted according to the needs.

[0051]It is understood that a person skilled in the art, in order to meet contingent needs, may make modifications to the actuator described above, all of which are contained within the scope of protection as defined by the following claims.