Electromechanical actuator

Abstract

The invention relates to a device formed by a spindle (11) connected to a nut (13) and one or more servomotors (40), such that the transmitted torque will be the sum of the individual torques of the servomotors, comprising a set of two or more rods (2) arranged around the spindle. The main shaft is supported in two bearing housings which limit axial movement in two directions, including an anti-reversal system enabling only rotation of the drive shaft (35), all of which are within the inner sleeve (14). An outer sleeve (12) moves along the outside of the inner sleeve below a stationary metal structure (18) for securing to the machine, keeping all the particle inlet units closed. Four elements (43 and 44) fixed by screws make it possible to place the spindle in a "parking position", facilitating replacement of worn units such as the spindle itself, bearings, etc.

Description

Technical Field

[0001] The present invention relates to a frame for a high performance electromechanical actuator which withstands forces exceeding 600 KN and has a stroke greater than 1500 mm.

[0002] Its industrial applications are primarily, though not exclusively, in the recycling sector and in the field of hay balers, both horizontal and double compression balers.

[0003] The object of the present invention is to provide an electromechanical actuator designed to withstand the high loads, movements and harsh working environments required for industrial applications, without producing components that are too large or expensive, with greater rigidity than other existing mechanisms, thus greater capacity, reducing the available cross section of the rod and simplifying the system, all achieved with a structure that prolongs the life of the device and minimizes its maintenance, better protected / isolated from dirt. Background Art

[0004] In the practical application field of the actuator designed for heavy loads of the present invention, there are many known inventions related to electromechanical actuators or mechanisms associated therewith.

[0005] The latest prior art is patent US4500805 for an electromechanical actuator for heavy loads, and although both this patent and the device of the present invention share certain structural features, they present a number of limitations and problems.

[0006] In this sense, the device described in patent US Pat. No. 4,500,805 consists of a set of four rods arranged circumferentially and joined at both ends by means of fastening screws, which limit the movements and the maximum loads borne due to the increase in the flexion length.

[0007] The device has two bearing housings located in the front and rear parts, consisting of angular ball bearings arranged in a straight line and connected back to back. This design severely limits the life of the components and the loads they can withstand.

[0008] Another problem with this device is that it involves four circumferentially arranged rods with a single locking element having four axial openings to allow the rods to pass through. This arrangement is problematic primarily in dirty environments where dust and particles can enter through the openings, causing problems with the spindle or shortening the life of the bearings.

[0009] At the same time, irreversible systems for electromechanical actuators are known, such as the system described in German patent DE3444946A1, which consists of an irreversible system actuated by a helical spring connected to two pads whose ends are provided with slots so that they engage with little play in a key located on the shaft on the side of the spindle.

[0010] Although the system achieves satisfactory design functions, the construction of the helical spring itself means that the system needs to be reduced in size and the complexity of the mounting structure needs to be reduced.

[0011] Description of the invention

[0012] The electromechanical actuator of the present invention fully and satisfactorily solves the above-mentioned problems in each of the above-mentioned aspects.

[0013] The solution is intended to replace the entire hydraulic technology of continuous and double box, double compression balers etc. both in the recycling sector and in the agricultural sector, without excluding other areas requiring similar performance.

[0014] More specifically, the present invention significantly improves the specifications of electromechanical actuators to above the thresholds of 600KN and 1500mm stroke, creating new applications in industry, shortening design time and engineering time, and enjoying the advantages of mechatronics such as energy saving and rapid return on investment.

[0015] To this end, the device of the present invention is composed of a main shaft, a planetary roller nut, an irreversible system, one or more servomotors directly coupled to the main shaft or coupled to the main shaft through a mechanical transmission device or various mechanical elements, so that the input torque of the main shaft is the sum of the torques provided by each servomotor individually, and the assembly is enclosed in a cylindrical tube or an inner sleeve.

[0016] The front section of the planetary roller nut is connected to the thrust connector in the direction of the load thrust, which may be a cylindrical connector and may have two or more cylindrical tubes arranged around the main axis, wherein the threaded inner wall receives two or more threaded end rods and the other end thereof is screwed into a load distribution pad, which is connected to the cover of the outer sleeve by a flange, and the diameter of the outer sleeve is larger than the above-mentioned inner sleeve, so that the outer sleeve slides forward and backward as the nut moves, covering all entry paths of foreign materials. Finally, the anchoring device for anchoring the block to be moved is attached to the cover of the outer sleeve by any conventional means; the anchoring device for anchoring can take different forms, depending on the anchoring requirements of the block to be moved.

[0017] The tubular structure is fastened to the inner sleeve by means of a flange, the tubular structure comprising fastening means for fastening to different parts of the machine having the shape required for the machine.

[0018] Returning to the nut, it is housed in a cylindrical closed housing whose internal geometry is complementary to the external geometry of the nut so as to prevent the nut from rotating inside the closed housing. As for the closed housing, it has a flange in its central outer area so as to attach it to the thrust connection by means of this flange, forming a circular guide in the middle. Finally, the assembly formed by the above elements is closed by means of a closing cover which is fixed or attached to the closed housing by screws by any conventional means, so that no relative movement between the elements forming the assembly is possible.

[0019] Two bearing housings are arranged in alignment with the ends of the spindle, the front housing consisting of a tubular body of a centering piece containing two or more axial roller bearings or similar bearings arranged opposite to the load moving in a press, each bearing contained in a separate housing which in turn engages in the tubular body of the centering piece arranged around the spindle, two or more outer discs protruding outwards from the separate housings make it possible to distribute part of the load borne by the axial bearings to an inner sleeve having two or more openings equipped with linear bearings for the passage and guidance of a rod parallel to the spindle. The bearings and the separate housings are connected to each other by a connection piece so that axial movement in the direction of load movement is limited by means of a locking washer and a front closing cover. The centering piece has a fastening device for fastening to the inner sleeve so that the rod passing through the centering piece cannot rotate around the shaft spindle, which limits the rotation of the planetary nut connected to the thrust connection piece.

[0020] The interior of the front housing is kept completely sealed against leaks by seals placed on the front and rear openings.

[0021] The rear housing is composed of an outer rear housing formed by a tubular body equipped with two or more discs making it possible to distribute part of the loads borne by the axial bearing to the inner sleeve, wherein the rearmost disc has a diameter greater than that of the remaining discs and has holes on its periphery for fastening to a flange of the inner sleeve, through which the majority of the load distributed by the axial bearing is transmitted to the inner sleeve. The tubular body of the outer rear housing in turn houses an inner rear housing containing the irreversible system and the axial bearings, the inner rear housing having a tubular structure with internal circular ribs acting as spacers between at least one axial bearing located in the front section of the inner rear housing, the at least one axial bearing being arranged opposite to the compression movement load, if the inner rear housing contains more than one axial bearing, these in turn are contained separately in separate housings connected to each other by a connection, and at least one axial bearing in its rear section being arranged opposite to the retraction movement load, if the inner rear housing contains more than one axial bearing, these in turn are contained separately in separate housings connected to each other by a connection. The outer rear housing is sealed by seals located in the front and rear openings of the housing.

[0022] This arrangement and construction of the rod, front and rear housings, axial bearings, thrust connections and load distribution flanges makes it possible to extend the load capacity and stroke of the actuator and to improve the absorption of buckling loads with a smaller diameter rod, thereby reducing costs and simplifying the solution.

[0023] The device has an irreversible system comprising a drive shaft with two keys connected to a driven shaft (extension of the main shaft) and a C-shaped spring with a certain preload in the rest state, a trigger attached to each end enclosed in a rotating cylindrical piece and fixed by a locking washer, the rotation and movement of the rotating cylindrical piece being limited by means of a cover with a projection whose geometry engages and complements that of the rotating cylindrical piece. The C-shaped spring is coupled to the drive shaft so that the plate of the rotating cylindrical piece comes into contact with the trigger, which in turn must engage with the key of the driven shaft. Based on this structure, the mechanism allows bidirectional movement if the movement is initiated on the drive shaft when the preload of the spring is reduced, and locks the system if the movement is initiated on the driven shaft when the load of the preloaded spring increases.

[0024] Compared to a helical spring, the use of a C-shaped spring allows, on the one hand, to establish the actuating mechanism for the irreversible system for actuating the movement from the driven shaft on the same plane, whether the movement is clockwise or counterclockwise, shortening the length of the rotating element that accommodates the irreversible system, simplifying the structure of the system and its installation, and thus shortening the overall length of the actuator. On the other hand, the greater friction surface of the C-shaped spring and the specific structure of the system increase the resistance to the reverse movement to the point where the actuator fails, and only then allows the main shaft to move in the reverse direction.

[0025] According to another characteristic or advantage of the invention, the inner sleeve has four elements screwed thereto, with adjusting nuts and sealing O-rings, for which purpose the inner sleeve has four or more threaded boreholes for implementing the elements screwed thereto, so that they are aligned with the intended guides connected to the planetary nuts in a so-called parking position or operating position that allows replacement of spare parts, wherein the elements screwed thereto are tangential to the inner diameters of the adjusting nuts and the inner sleeve, thereby sealing the system for normal operation.

[0026] As for the load-distributing pads associated with the opposite end of the rod connected to the planetary nut that moves the spindle through the thrust connection, they consist of a cylindrical tube with an internal thread rigidly connected to a load-distributing flange, which is fastened to a cap-like part of the outer sleeve at the free end of the actuator, thereby limiting the relative movement of the outer sleeve with respect to the rod.

[0027] For the rods involved in the device, they are connected together at the end opposite to the planetary nut by means of a load-distributing pad and two or more outer discs of the centering piece fastened to the cap-like piece of the outer sleeve, so that the last or rearmost of the said discs defines a contact surface with the inner sleeve, with an angled bevel, and the first or foremost of the said discs has a diameter greater than the diameter of the remaining discs, and has holes on its outer periphery for fastening to a flange arranged on the inner and outer housings. It is this first outer disc that transmits most of the load transmitted by the axial bearing to the separate housing and from the separate housing to the centering piece and then to the inner sleeve through the fastening flange.

[0028] Finally, as mentioned above, the actuator can be assisted by two servomotors connected to any type of gearing, so that the torque delivered to the main shaft is the sum of the torques delivered by each servomotor individually, and connected in "load sharing" mode, sharing the load as required.

[0029] It only needs to be explained that the tube forming the inner sleeve can have any cross section, circular as described above, or square, rectangular, oval, etc. Therefore, the shape or cross section of all elements that can be assembled to the inner sleeve must correspond to the shape or cross section of the inner sleeve. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] As a supplement to the description that will be provided herein, and for the purpose of helping to make the features of the invention more easily understood, said description is accompanied by a set of drawings forming a part hereof, according to a preferred practical exemplary embodiment of the invention, in which, by way of illustration and not limitation, the following are presented:

[0031] Figure 1 A cross-sectional view and enlarged detail views N and O of the apparatus of the invention according to one embodiment are shown, wherein the apparatus adopts a configuration in which a single servomotor is connected by a direct coupling.

[0032] Detail N shows an isometric cross section of the front bearing housing of the apparatus of the invention.

[0033] Detail O shows an isometric cross section of the rear bearing housing of the apparatus of the invention.

[0034] Figure 2 An isometric exploded perspective view showing the internal components of the device of the present invention and the connections therebetween.

[0035] Figure 3 An isometric perspective cross section of the disassembly of the bearing housing shown in detail views N and O is shown.

[0036] Figure 4 A side view of the device according to the invention in order to position the cross section LL and an enlarged detail view U of the cross section LL are shown, wherein the propulsion device is not shown.

[0037] The cross section LL shows a cross section in the “parking position” using the position plane of the connection element fixed by screws.

[0038] Detail U shows an enlarged detail of the cross section LL at the level of one of the screw-fixed connections.

[0039] Figure 5 An isometric view is shown with the spindle and nut removed as support material to illustrate replacement of the spindle nut.

[0040] Figure 6 An isometric view showing the assembly of a new spindle and nut using two or more rods prior to insertion of a closing sleeve.

[0041] Figure 7 An isometric view of the method described in the specification for centering a spindle and a nut by means of a screw-fixed unit is shown.

[0042] Figure 7.1 Shows Figure 7 The outline of the assembly at the free end of the spindle and the corresponding detail of the front elevation are shown.

[0043] Figure 8 An exploded view of the elements that make up the mobile irreversible system is shown.

[0044] Fig. 9 A side view showing the positioning MM cross section required for the device of the present invention.

[0045] Cross section MM shows a cross section of the irreversible system.

[0046] Fig.10 A diametric cross section of the device is shown for positioning the R detail and the S detail.

[0047] Detail R shows the stress distribution of the axial bearing in the front housing.

[0048] Detail S shows the stress distribution in the axial bearing in the rear housing.

[0049] Preferred embodiments of the present invention

[0050] According to the figures shown, it can be seen that the device of the invention comprises a main shaft (11) connected to a planetary roller nut (13), a ball or the like, which main shaft is driven by at least one servomotor (40) connected by a direct coupling or a chain drive, wherein, if the two drive units are mechanically connected, they are both connected to the same shaft or to different shafts so that the torque transmitted to the main shaft is the sum of the torques generated by each servomotor (solution not shown in the figures).

[0051] A servomotor (40) actuates a spindle (11) connected to a nut (13), the rotation of which is limited by means to be described hereinafter, so that it moves longitudinally in two directions on an axial axis, and the entire assembly is enclosed and closed in all directions by an inner sleeve (14), a front cover (26) and a rear cover (25).

[0052] The two ends of the main shaft (11) are supported by two front and rear bearing housings, as shown in detail N, detail R and detail O, detail S.

[0053] The front housing, which is subjected to the greatest axial load in the direction opposite to the pressing movement, consists of a tubular body (30) of a centering piece (16), which contains two or more axial roller bearings (28), which are identical or different, according to the specific design criteria in each case, arranged opposite to the pressing movement load, and are separately contained in a separate housing (19), which in turn is engaged in the tubular body (30) of the centering piece (16) arranged around the main axis (11), two or more outer disks (31) protrude outwards from the separate housing to transfer the load borne by the axial bearings (28) to the inner sleeve (14), having two or more openings (16A) for the passage of a rod (2) parallel to the main axis, the opening (16A) of the frontmost outer disk (31) being equipped with a linear bearing (27) for guiding the rod (2). The axial bearing (28) and the separate housing (19) are connected to each other by a connecting piece (20) so that the axial movement in the load movement direction is limited by means of a locking washer (29) and a front closing cover-like piece (26). The centering piece has a fastening device for fastening to the inner sleeve so that the rod (2) passing through the centering piece (16) cannot rotate around the main axis, which limits the rotation of the nut (13) connected to the thrust connection piece (1).

[0054] The choice of axial bearing and its corresponding configuration of the front and rear housings is not only a design choice, but also depends on the type of specific loads to which the actuator is subjected and the manner in which they are distributed and transmitted to the inner sleeve (14). More specifically, the actuator is subjected to two axial stresses in the direction opposite to the movement of the actuator, namely the compression movement load (CP) and the retraction movement load (CR). The stresses are transmitted in a manner as shown by the arrows in the details R and S, namely by the axial bearing (28) arranged opposite to the axial load to be borne, obliquely transmitting the load toward the area outside the area of ​​larger diameter through the geometry of the axial bearing itself, and then transmitting the load to the inner sleeve (14) in the following manner toward the surface of larger diameter.

[0055] The front housing exclusively receives the compressive displacement load (CP), which is axially transmitted to the foremost axial bearing (28) via the locking washer (29) and the connecting piece (47), which transmits it obliquely to the corresponding separate housing (19) and to the corresponding connecting piece (20) connected to the next axial bearing. The oblique load transmitted to the separate housing (19) is transmitted to the tubular body (30) via the same component and to the next separate housing (19). The oblique load of the tubular body (30) transmitted to the centering piece (16) is transmitted to the inner sleeve (14) via the outer disc (31), while the load transmitted to the connecting piece is axially transmitted to the next axial bearing (28). This load transfer process is repeated systematically until the rearmost axial bearing (28) of the front housing is reached, which transfers the axial loads it bears obliquely and directly to the end section of the tubular body (30) of the centering piece (16), which forms the housing of the axial bearing, and then transfers them to the inner sleeve (14) through the outer disc (31) and axially through the flange of the inner sleeve connected to the frontmost outer disc (31) of the centering piece. Finally, the interior of the tubular body (30) of the front housing is kept completely sealed against leakage by the front seal (46) of the front opening and the rear seal (45) of the rear opening.

[0056] The rear housing is loaded in both directions (compression movement load (CP) and retraction movement load (CR)). On the one hand, the retraction movement load (CR) is entirely due to friction and the friction occurring between the workpieces and the weight of the block to be moved, on the other hand, the compression movement load (CP) is largely relieved by the front housing. Therefore, the rear housing is subject to lower loads even in both directions. Due to this and its position inside the inner sleeve (14), and the need to accommodate the irreversible system, the construction of the rear housing differs from that of the front housing.

[0057] In particular, the rear housing is composed of an outer rear housing (17) formed of a tubular body, with an integrated front cover-like member, equipped with two or more outer discs (24) that make it possible to distribute part of the load borne by the axial bearing (28) to the inner sleeve (14), the rearmost of these discs having a diameter greater than that of the remaining discs and having a flange (15) on its outer periphery for fastening to the inner sleeve (14) and a hole fastened to the rear cover-like member (25), through which most of the load distributed by the axial bearing (28) is transmitted to the inner sleeve (14). The tubular body of the outer rear housing in turn houses the irreversible system and the inner rear housing (41) of the axial bearings enclosed in the outer shell (49), the latter having a tubular structure with an inner circular rib (38), on each side of which constitutes the housing of at least one axial bearing (28), which is arranged opposite to the pressure displacement load (CP) located in the front of the inner rear housing (41), if it contains more than one axial bearing (28), these axial bearings are in turn contained separately in a single housing connected to each other by a connection, and for at least one axial bearing (28) located in the rear thereof, this axial bearing is arranged opposite to the retraction displacement load (CR), if it contains more than one axial bearing (28), these axial bearings are in turn contained separately in a single housing connected to each other by a connection. The front part of the outer rear housing (17) is sealed by a front seal (21) and the rear part is sealed by a rear sealing cap (25) and a rear seal (22).

[0058] Specifically, in the actual embodiment shown in the figure, the pressing movement load (CP) is transmitted to the axial bearing (28) of the front section through the connecting piece (39), and then the load is obliquely transmitted to the inner rear housing (41), which distributes it in the outer rear housing (17) and the outer shell (49), and then transmitted to the outer rear housing (17) through the sealing cover (25), preventing the load from affecting the irreversible system, thereby finally transmitting the load to the inner sleeve (14) through the outer disc (24) and flange of the outer rear housing (17). As for the retraction movement load (CR), it is transmitted to the axial bearing (28) of the rear section through the connecting piece (32), and the axial bearing then transmits the load obliquely to the inner rear housing (41), which transmits it to the outer rear housing (17), and the outer rear housing transmits it to the inner sleeve (14) through the outer disc (24) and flange of the outer rear housing (17). Finally, the locking washer (48) limits the axial movement of the elements contained in the rear section of the inner rear housing (41), preventing compression loads (CP) and retraction loads (CR) from affecting the irreversible system.

[0059] Finally, the remaining load is released into the machine through the fastening means used to fasten the actuator to the machine.Axial bearings can only transfer load in one direction, hence their place in the design.

[0060] The nut (13) is housed in a cylindrical closed housing (5) whose internal geometry is complementary to the external geometry of the nut (13) in order to prevent the nut (13) from rotating inside the closed housing (5). As for the closed housing (5), it has a flange (6) in its outer central area, which is used to attach the closed housing to the thrust connection (1) via a flange (7), and in the middle a guide (8) made of self-lubricating technical plastic is provided to avoid heating and minimize friction losses, as well as to secure the so-called "parking" system to facilitate maintenance or rapid replacement described below. Finally, the assembly formed by the above-mentioned elements is closed by means of a closing cover (10) which is fixed or attached to the closed housing (5) by any conventional means by screws, so that relative movements between the elements forming the assembly are impossible.

[0061] The thrust connection (1) is provided with at least two tubular housings (1C) with internal threads, in which two or more rods (2) are housed, both ends of which are threaded and designed to distribute the load through the threads, which rods can be equipped with an axial movement stop (Z) of the actuator, which consists of a machined or welded peripheral ring, which is arranged close to the threaded end (A), which is screwed into the tubular housing (1C) connected to the thrust connection (1) and abuts against the rearmost outer disc (31) of the centering piece (16) in the event of an operating abnormality. The free end of each rod passes through a corresponding opening of the outer disc (31) of the centering piece (16), the limit of which is set by the axial movement stop (Z). The load distribution pad (9) consists of an internally threaded tube rigidly connected to a load distribution flange, so that the freely threaded end (A) of each rod-like member is screwed into the threaded tube of the load distribution pad (9) connected to each rod (2), and the flange of each load distribution pad is fixed to the cover-like member (3) of the outer sleeve at the free end of the actuator by screws, preventing the outer sleeve (14) from relative movement with respect to the rod, thereby rigidly connecting the assembly.

[0062] According to one of the features of the invention, the threads on the rod are designed to distribute the load on the threads by increasing the contact surface, thereby reducing the buckling length and allowing a smaller diameter to withstand high loads. In addition, the rod is guided by a centering piece (16) which, as explained above, has openings arranged circumferentially in the outer disk (31) of the centering piece (16), which are perfectly aligned with the position of the rod (2) and facilitate the transmission of loads to the sleeve (14). These openings serve as housings for linear bearings (27) made of self-lubricating material with a low friction coefficient. The centering piece (16) significantly reduces the possible buckling of the rod (2) by transmitting the forces to the sleeve (14) connected to its flange.

[0063] The cover (3) of the outer sleeve (12) enables the entire system to be attached to the block to be moved by means of anchoring means to the block (4), which can take different forms depending on the anchoring requirements of the block to be moved.

[0064] As mentioned above, this type of solution relates to the frames of recycling and hay baling machines, which are often exposed to extreme working environments of corrosive liquids, dust and dirt. In the present invention, as an improvement over the prior art mentioned in the background, two or more rods increase the possibility of introducing unwanted substances into the system by two or more times, thereby shortening the life of the various components constituting the actuator, or even causing damage, making the entire system unusable.

[0065] This problem is solved by means of an outer sleeve (12) fastened by any conventional attachment means for attachment to a cover (3) of the outer sleeve, the outer sleeve having a larger diameter than the inner sleeve (14), arranged to cover all dust and waste entry zones at all locations, since the outer sleeve slides on the outside of the inner sleeve (14). It has a flexible rubber lip at its end which fits the outside of the inner sleeve (14), preventing particles from entering by entrainment, covering the only particle entry formed by the inlet and outlet of the system of axially moving parts formed by the nut (13), the thrust connection (1), the rod (2), the load distribution pad (9) and the outer sleeve (12) itself.

[0066] In order to allow the system to be anchored to a machine, a support structure (18) is provided, which includes fastening means for fastening to different parts of the machine in the shape required by the machine, the support structure being rigidly connected to the inner sleeve (14) by flanges or any other conventional means. Specifically, in the case of this practical embodiment, the support structure (18) is formed by one or more anchoring flanges (18A) for anchoring to the machine, one or more reinforcing flanges (18B) and one or more anchoring flanges (18C) for anchoring to the rear part of the inner sleeve (14), so that the outer sleeve (12) can slide under the anchoring flanges (18A) and reinforcing flanges (18B) of the machine. These flanges (18A, 18B and 18C) are attached to each other by various tubular parts (18D) arranged circumferentially around the inner sleeve (14), so that the outer sleeve (12) can pass from under it.

[0067] The design of the support structure (18) may consist of a second outer sleeve such that the outer sleeve (12) slides over the inner sleeve (14) and under the second outer sleeve, the second outer sleeve having a flexible rubber lip that fits over the outside of the outer sleeve (12), thereby further minimizing the possibility of particles entering the actuator through entrainment.

[0068] According to another feature of the invention, in order to reuse most of the workpieces in the actuator at the end of its service life, four threaded bores (14A) are provided in the inner sleeve (14), such as Figure 4 As shown in the cross-section LL and in the detail view U, there are four or more connecting parts fixed by screws, including a screw (44), an adjusting nut (43) and an O-ring (42), and the screw (44) is defined with a contact surface (44A), defining an upper left fixing element (44SI), an upper right fixing element (44SD), a lower left fixing element (44II) and a lower left fixing element (44ID) formed by the corresponding screws, nuts and O-rings.

[0069] These elements allow two positions: a working position, in which the surface (44A) is tangential to the inner diameter of the inner sleeve (14) and the adjusting nut (43) compresses the O-ring (42) against the outer wall of the inner sleeve (14) to ensure tightness against leakage; and a parking position, which is marked by the threaded bore (14A), in which the nut (13) is moved longitudinally on the spindle to a position in which the surface (44A) of the screw (44) is aligned with the surface (8A) of the recess arranged in the guide (8), in which the adjusting nut (43) compresses the O-ring (42) to ensure tightness of the system against leakage, so that by turning the screw (44) clockwise, the surface (44A) of the screw (44) presses against the surface (8A) of the recess arranged in the guide (8), locking the actuator in what is called a parking position, as Figure 4 The cross section LL is shown.

[0070] The parking position is arranged as close as possible to the center of gravity of the system to provide support so that the main shaft (11) can be tightened in a completely centered position so that the axial bearing (28) and any components located in the front and rear bearing housings can be replaced, such as Figure 5 shown.

[0071] The invention also makes it possible to completely replace the spindle (11), the nut (13) and all their associated components in a simple manner. Figure 6 and Figure 7 For explaining the method. In order to replace the spindle (11) and the nut (13), it is necessary to first remove the various elements contained in the front and rear housings using the method described above. The nut (13) is then released from the above-mentioned "parking position" by rotating the screw (44) counterclockwise to the above-mentioned operating position. Once the nut (13) has been released from its support, due to the clearance relative to the inner diameter of the sleeve (14), the nut rests on its inner diameter through the guide (8), the center of gravity of the assembly, which makes it possible to completely extract the spindle (11), the nut (13) and all the parts associated therewith by sliding the guide (8) across the inner diameter of the inner sleeve (14).

[0072] Once the spindle (11) is free from the inner sleeve (14), the thrust connection (1), the guide (8) and the closing housing (5) can be released, and then the closing cap (10) can be removed and the nut (13) released, as shown in FIG. Figure 5Subsequently, the new spindle (11) and nut (13) and the remaining parts associated with the nut (13) to be replaced are reassembled on the new nut (13), and then the new spindle (11) is inserted into the nut (13), and the nut (13) is moved along the spindle (11) to a position where two or more rods (2) can be screwed in, and the centering piece (16) is positioned so that the spindle passes through the tubular body (30) and the rod passes through the opening (16A) of the centering piece (16), as shown. Figure 6 As shown. The assembled assembly is then slid along the inner diameter of the inner sleeve (14) on the guide (8) towards the rear part of the inner sleeve (14) until the threaded bore (14A) of the sleeve (14) is aligned with the surface (8A) of the guide (8). In this position, the nut (13) is centered and rests on the inner wall of the sleeve (14), so the screw (44) is turned clockwise until the spindle nut assembly is centered in the parking position, the centering piece is slid to its corresponding fastening flange by the rod for fastening to the inner sleeve (14) and it is fixed there by the screw. When this happens, the system is considered to be centered and in a balanced state, so that the remaining elements are inserted until the front and rear housings are completed, as shown Figure 3 shown.

[0073] Regarding the irreversible system, the low friction of the planetary roller system combined with the size of the channel makes it possible to transmit the movement from one side of the spindle to the other side of the motor. To solve this problem, a method described in Figure 8 A system consisting of a preloaded C-shaped spring (33) attached to a Z-shaped trigger system (37) or having another equivalent geometry, a spindle (11) (driven shaft) having two keys arranged at 90° or other angles, which in turn correspond to the angle of the trigger (37), the trigger being attached to the preloaded spring, the preloaded spring having a drive shaft with two plates (35A and (35B) fixed by screws or welding arranged at 90° or other angles so that they correspond to the angle of the spring trigger and the position of the keys. The system has a locking washer (23) and a rotating element (36) enclosing the spring and a closing cover with a protrusion (25A) having a geometry that engages with a cutout (36A) to prevent the rotating element (36) from rotating.

[0074] The driven shaft (11) is connected to the driven shaft (35) via an adjustment device for adjusting between the two moving parts to be adjusted. As for the spring (33), it is inserted into the rotating element (36) with a pre-applied load setting so that a force is applied on its inner diameter. Fig. 9The cross section MM of the trigger (37) is arranged to be aligned with the plates (35A and 35B) on its outer surface, and the trigger (37A and 37B) is aligned with the keys (34A and 34B) of the main shaft (11) or the driven shaft.

[0075] The assembly is axially constrained in the direction of the drive shaft. More specifically, the washer (23) prevents the spring from leaving in the direction of the driven shaft. The cover (25) closes the assembly and holds it in place, preventing the rotating element (36) from rotating by means of a recess (25A) that fits perfectly in the cutout (36A).

[0076] A preloaded spring (33) presses against the wall of the rotating element (36), so that the system is locked if no movement of the drive shaft occurs.

[0077] If the motor stops and the system attempts to rotate clockwise and counterclockwise, the key (34A or 34B) pushes the trigger (37A or 37B) depending on the direction of rotation, causing the spring (33) to rotate in the direction of the preload, increasing the pressure on the wall of the rotating element (36), thereby locking the system.

[0078] The greater the torque when the engine is stopped, the greater the locking force of the system.

[0079] Furthermore, if the movement comes from the motor rotating in a clockwise or counterclockwise direction, the drive shaft pushes the trigger (37A or 37B) with the aid of plates (35A and 35B), which in turn pushes the key (34A or 34B), pulling the driven shaft and causing the spring (33) to rotate in the direction opposite to the preload, shortening its length so that there is no pressure on the walls of the rotating element (36), allowing the system to rotate.

[0080] Since the element or trigger (37) acting on the end of the C-shaped spring (33) is located in the same plane, this saves axial space compared to other mechanisms such as the mechanism described in German Patent DE3444946A1, and this construction also makes it easier to assemble the mechanism.

Claims

1. An electromechanical actuator comprising a spindle (11) connected to a nut (13) actuated by one or more servomotors (40), two or more rods (2) rigidly connected to the nut (13), the two or more rods defining a retractable arm of the actuator, the assembly being enclosed in an inner sleeve (14), characterized in that: a) on the front face of the nut (13), in the thrust direction of the load, a thrust connector (1) is connected around the spindle (11), the thrust connector being provided with a tubular housing (1C) with an internal thread, into which one of the threaded ends (A) of the rod (2) is screwed, while at its opposite threaded end (A) a load distribution pad (9) is screwed, the load distribution pad being attached together by means of a flange to a cover (3) of an outer sleeve (12), the outer sleeve having a larger diameter than the inner sleeve (14), The inner sleeve is provided with a fastening structure (18) for fastening the actuator to a related machine, the thrust connection (1) and the nut (13) being intended to comprise attachment means for attaching two elements and limiting relative movement between them. b) it comprises a respective end housing containing two or more axial bearings (28), One of the axial bearings is formed by a tubular body (30) of a centering piece (16) arranged around the main shaft (11), in which two or more linear bearings (27) are housed for guiding the rod (2) passing therethrough, comprising fastening means for fastening to the inner sleeve (14), preventing all elements connected to the rod (2) from rotating, and having sealing means. c) it comprises an irreversible system comprising a drive shaft (35) connected to said main shaft (11), or driven shaft, the driven shaft is equipped with two keys (34A and 34B) and a C-shaped spring (33), the C-shaped spring is pre-loaded and enclosed in a rotating element (36), wherein the rotation and movement of the rotating element are limited by means of the cover (25) and the locking washer (23). d) comprising an easy assembly / disassembly system, wherein a series of right and left fixing elements, upper and lower fixing elements (44SI, 44SD, 44ID, 44II) are screwed to the inner sleeve (14) by means of screws (44), adjusting nuts (43) and sealing O-rings (42), passing through threaded bores (14A) in the inner sleeve (14) so ​​as to align with the surface (8A) of the recess of the guide device (8) in a predefined position for replacement of spare parts or in an operating position, wherein the surface (44A) of the screw (44) is tangential to the inner diameter of the adjusting nut (43) and the inner sleeve (14), thereby sealing the system.

2. The electromechanical actuator according to claim 1, characterized in that The rod (2) comprises a stop (Z) for the axial movement of the actuator, consisting of a ring machined or welded to the rod (2).

3. The electromechanical actuator according to claim 1, characterized in that The load distribution pad (9) is formed of a cylindrical tube with internal threads and a load distribution flange and is fastened to the cover (3) of the outer sleeve (12), restricting relative movement of all the elements connected thereto.

4. The electromechanical actuator according to claim 1, characterized in that The centering element (16) comprises one or more discs (31) or contact surfaces, wherein the inner sleeve (14) is rigidly connected to the tubular body (30), the foremost disc having a hole at its periphery and the rearmost disc being provided with an angled bevel.

5. The electromechanical actuator according to claim 1, characterized in that The irreversible system comprises a drive shaft (35) with two plates attached to both ends (35A and 35B), a main shaft (11) or a driven shaft with two keys (34A and 34B), a C-shaped spring (33) which has a preload in a static state, two triggers (37) attached to both ends, fixed in place by locking washers (23) and encapsulated in a rotating element (36), and axial and rotational restrictions are performed by means of a rear cover (25); the spring (33) is arranged to be coupled to the drive shaft so that the plates (35A and 35B) are in contact with the trigger (37A and 37B), and the trigger is then able to engage with the keys (34A and 34B) of the driven shaft, so that if a movement is initiated on the drive shaft (35), movement in two directions can be achieved, and if a movement is initiated on the driven shaft, the system is locked.

6. An electromechanical actuator according to claims 1 and 5, characterized in that The geometric structure (36A) of the rotating element (36) engages in the projection (25A) of the closing cover (25), thereby forming a limiting device for limiting rotation and axial movement.

7. The electromechanical actuator according to claim 1, characterized in that The electromechanical actuator comprises more than one servomotor (40) coupled via a mechanical transmission or mechanical element, wherein the input torque of the main shaft is the sum of the torques provided by each servomotor individually.

8. The electromechanical actuator according to claim 1, characterized in that The fastening structure (18) for fastening the actuator to the associated machine comprises several flanges (18A, 18B and 18C) for fastening to different parts of the machine and a preferably tubular structure (18D) fastened to the sleeve by means of one of the flanges (18C).

9. The electromechanical actuator according to claim 1, characterized in that The thrust connection (1) comprises a fastening flange (7) for fastening to the flange (6) of the closing cover (5) which accommodates the nut (13), wherein a guide (8) is located between the two flanges and the assembly is closed by the closing cover (10) so as to completely restrict relative movements between the elements of the assembly.

10. The electromechanical actuator according to claim 1, characterized in that The axial bearings (28) of the front housing are contained in a separate housing (19) connected by a connection (20), arranged in line in the direction opposite to the compression displacement load (CP), and these in turn are contained in the tubular body (30) of the centering piece (16).

11. An electromechanical actuator according to claims 1 and 10, characterized in that The axial movement of the axial bearing (28) in the load movement direction in the area of ​​the front housing is limited by means of a front closing cover (26) and a locking washer (29); the entire housing is kept sealed to prevent leakage by means of a front seal (46) of the front opening and a rear seal (45) of the rear opening.

12. The electromechanical actuator according to claim 1, characterized in that The rear housing has at least two axial bearings (28), the foremost axial bearing is arranged in the direction opposite to the compression movement load (CP), and the rearmost axial bearing is arranged in the direction opposite to the retraction movement load (CR), and both axial bearings are accommodated in an inner rear housing (41) separated by a circular inner rib (38), and the inner rear housing (41) is then accommodated in the tubular body of the outer rear housing (17), and the outer rear housing is equipped with two or more contact surfaces or discs (24) that contact the inner sleeve (14), wherein the rearmost disc has a diameter greater than the diameter of the remaining discs and has a flange (15) on its outer periphery for fastening to the inner sleeve (14) and a hole for fastening to the rear cover (25).

13. An electromechanical actuator according to claims 1 and 12, characterized in that Each section separated by the circular inner rib (38) and the inner rear shell (41) may include more than one axial bearing, and the more than one axial bearings are separately contained in separate shells connected in a straight line, the axial bearing of the front section is located in the opposite direction of the compression movement load (CP), and the axial bearing of the rear section is located in the opposite direction of the retraction movement load (CR).

14. An electromechanical actuator according to claims 1 and 12 to 13, characterized in that The front of the outer rear housing is sealed by a front seal (21) and the rear thereof is sealed by a rear closing cover (25) and a rear seal (22).

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