Linear electro-mechanical actuator

Abstract

Described is a linear electro-mechanical actuator (E) comprising a containment frame (100) comprising a side wall (100a) and a first and a second closing wall (100b, 100c) coupled to opposite ends of the side wall (100a). The actuator (E) comprises an actuation shaft (200) translating along a longitudinal axis (X) and comprising a threaded zone (300). The actuator (E) comprises a lead nut (400) rotatable about the longitudinal axis (X) and engaged with the actuation shaft (200) by means of a recirculating ball threaded connection (C). The actuator (E) comprises a first and a second bushing (600a, 600b) mounted on opposite sides of the containment frame (100) for guiding by translation respective portions of the actuation shaft (200). The first and the second bushing (600a, 600b) are configured to be removable from the containment frame (100) by axially extracting from the outside of a containment space defined by the containment frame (100) without requiring the extraction of the actuation shaft (200) from the respective closing wall (100b, 100c).

Description

[0001] LINEAR ELECTRO-MECHANICAL ACTUATOR

[0002] DESCRIPTION

[0003] The present invention relates to a linear electro-mechanical actuator that is widely used in the field of the so-called “steer-by-wire” systems.

[0004] Linear electro-mechanical actuators are currently known comprising a containment frame, an actuation shaft extending between a first end and a second end protruding outside the containment frame and a motorized mechanism for moving the shaft by axial translation along both directions.

[0005] The prior art actuators also comprise a lead nut connected to an electric motor and rotatable about the longitudinal axis and engaged with the actuation shaft by means of a recirculating ball threaded connection.

[0006] The prior art actuators further comprise a first and a second bushing mounted on opposite sides of the containment frame for guiding by translation respective portions of the actuation shaft, supporting them by sliding.

[0007] The first and the second bushing are axially spaced so that the lead nut is interposed between the first and the second bushing.

[0008] As a rule, the first and the second bushing are entirely enclosed by the containment frame so that they are positioned inside a containment space defined by the containment frame itself. An example of such a structure is described in patent document US 11685427.

[0009] Disadvantageously, the above-mentioned electro-mechanical actuators have drawbacks related to the difficulty and complexity of their maintenance.

[0010] In particular, when there is a need to carry out maintenance and / or checks on the actuator, the latter needs to be completely disassembled. In particular, the removal of the bushings (which is necessary for their replacement or for the replacement of the respective seals) necessarily requires the disassembly of the end walls of the containment frame and then the removal of the bushings from the containment walls.The technical purpose of the present invention is thus to provide a linear electromechanical actuator which is able to overcome the drawbacks of the prior art. An aim of the present invention is thus to provide a linear electro-mechanical actuator that is simple to maintain.

[0011] A further aim of the present invention is thus to provide a linear electro-mechanical actuator that is practical to maintain.

[0012] The technical purpose indicated and the aims specified are substantially achieved by a linear electro-mechanical actuator comprising the technical features described in claim 1 and / or in one or more of the claims dependent thereon.

[0013] In particular, the electro-mechanical actuator according to the present invention comprises a containment frame comprising a side wall and a first and a second closing wall coupled to opposite ends of the side wall and acting in conjunction with the side wall to internally define a containment space.

[0014] Preferably, each closing wall is removable.

[0015] More preferably, each closing wall is formed by, or comprises, a closing cover. The actuator also comprises an actuation shaft extending along a longitudinal axis between a first end and a second end protruding outside the containment frame. The actuation shaft is configured to translate along the longitudinal axis and comprises a threaded zone, in particular in a relative central portion positioned inside the containment space.

[0016] The actuator also comprises a lead nut rotatable about the longitudinal axis (but axially fixed) and engaged with the threaded portion of the actuation shaft by means of a recirculating ball threaded connection.

[0017] The lead nut is connected or connectable to an electric motor.

[0018] According to an aspect of the invention, the actuator comprises an electric motor connected to the lead nut.

[0019] Preferably, the electric motor is inserted inside the containment space.

[0020] More preferably, the magnets of the rotor of the electric motor are integrated with the lead nut.

[0021] Alternatively, the electric motor is positioned outside the containment space and operatively connectable to the lead nut, by means of a power pick-up.According to an aspect of the invention, the actuator also comprises a pair of bearings interposed between the containment frame and the lead nut, and integral with the lead nut. In particular, one between the inner ring and the outer ring of the bearings is formed integrally with the lead nut.

[0022] Preferably, it is the inner ring that is integrated with the lead nut.

[0023] Preferably, the bearings of the pair are of the so-called ‘four-contact’ type, that is, the balls inside the bearing are positioned so that there are four points of contact between the balls and the outer and inner rings of the bearing. This allows both radial and axial loads to be withstood.

[0024] Preferably, the bearings of the pair are heterogeneous with respect to each other. More preferably, one bearing of the pair is a roller bearing and the other bearing of the pair is a ball bearing.

[0025] According to an aspect of the invention, the actuator further comprises a first and a second bushing mounted on opposite sides of the containment frame for guiding by translation respective portions of the actuation shaft.

[0026] The first and the second bushing are axially spaced so that the lead nut is interposed between the first and the second bushing. In particular, each bushing is mounted on a respective closing wall of the containment frame.

[0027] Preferably, each closing wall comprises a through-hole, in particular circular, coaxial to the longitudinal axis and within which the respective bushing is at least partially inserted axially.

[0028] According to the invention, the first and the second bushing are configured to be removable from the containment frame by axially extracting from the outside of the containment space without requiring the extraction of the actuation shaft from the respective closing wall. In other words, the removal of the bushings can take place by means of axial withdrawal relative to the respective closing wall and the actuation shaft, which can remain in position.

[0029] The actuator according to the invention can, for example, be used for steering devices for vehicles, in particular for “steer-by-wire” apparatuses. In this situation, the actuator is mounted on the vehicles, for example by means of mounting holes formed in the closing walls of the containment frame, and the first and the secondend of the actuation shaft are engaged with the steering arms of the vehicle. In this situation, in order to disassemble the bushings from the containment frame, there is no need to remove (that is, disassemble) the actuator from the vehicle, as it is sufficient to disengage the steering arms from the ends of the actuation shaft and axially remove the bushings.

[0030] According to an embodiment, the first and the second bushing are made of an antifriction material. Preferably, said material is also a stainless material.

[0031] According to an alternative embodiment, the first and the second bushing are made of a surface-treated material so as to give the material an anti-friction effect.

[0032] According to one aspect of the invention, the actuator comprises fixing means configured to removably fix each bushing to the respective closing wall.

[0033] Preferably, the fixing means are accessible along an axial direction parallel to the longitudinal axis.

[0034] Preferably, the actuator comprises a mechanical seal, in particular an O-ring, interposed between a closing wall and the respective bushing. In particular, the mechanical seal is housed in a groove or seat formed on an outer surface of the bushing.

[0035] According to an embodiment of the invention, each bushing comprises a main portion with a tubular shape positioned between the actuation shaft and the inner wall of a corresponding hole in the closing wall.

[0036] Each bushing also comprises a flanged portion, axially adjacent to the main portion and positioned outside the containment space in such a way as to be in contact with an outer surface of the respective closing wall.

[0037] Preferably, the fixing means are positioned on the flanged portion.

[0038] Preferably, the flanged portion is operatively positioned in a position projecting outside an outer surface of the respective closing wall.

[0039] Preferably, the axial extension of the main portion is greater than the axial extension of the flanged portion.

[0040] Preferably, the main portion and the flanged portion are defined by a single monolithic body.

[0041] According to one aspect of the invention, the actuator comprises at least a first sealand at least a second seal positioned around the actuation shaft in an axially spaced position so that the lead nut is interposed between the seals. In this situation, each bushing is provided internally with a respective groove configured to house a respective seal.

[0042] Preferably, each groove is formed in the respective flanged portion and faces the actuation shaft.

[0043] According to a preferred embodiment, the actuator comprises a pair of first seals and a pair of second seals. In this situation, each groove comprises an annular rib configured to divide the groove into two seats, each configured to house a respective seal of the corresponding pair.

[0044] Further features and advantages of the present invention are more apparent in the illustrative and therefore non-limiting description of an embodiment of a linear electro-mechanical actuator.

[0045] The description is set out below with reference to the accompanying drawings which are provided solely for purposes of illustration without restricting the scope of the invention and in which:

[0046] Figure 1 shows a perspective view of the actuator according to the present invention;

[0047] Figure 2 is a cross section view of the actuator of Figure 1;

[0048] Figure 3 shows an enlarged detail of Figure 2;

[0049] Figures 4 shows an exploded view of a portion of the actuator of Figure 1; Figure 5A shows a cross section view of a bushing of the actuator of Figure 1 in which the seals have been removed;

[0050] Figure 5B show a cross section view of the bushing of Figure 5A in which seals have been added.

[0051] With reference to the accompanying drawings, the label “E” indicates an electromechanical actuator comprising a containment frame 100, which comprises a side wall 100a and first and a second closing wall 100b, 100c positioned at opposite ends of the side wall 100a and acting in conjunction with the side wall 100a to internally define a containment space.

[0052] In the embodiment shown in Figure 1, each closing wall 100b, 100c is removable.Preferably, each closing wall 100b, 100c is formed by, or comprises, a closing cover.

[0053] Preferably, the closing cover is coupled to a respective end of the side wall 100a in a reversible manner, for example by means of threaded elements.

[0054] The actuator "E" comprises an actuation shaft 200 extending along a longitudinal axis "X" between a first end 200a and a second end 200b protruding outside the containment frame 100.

[0055] The first and the second end 200a, 200b can be engaged by respective operating elements that, in the embodiment described and illustrated, are steering arms of a vehicle. According to this embodiment, the actuator ”E” is therefore used as an actuator for steering devices of vehicles, in particular for “steer-by-wire” apparatuses. However, the actuator “E” could find further different uses. For example, the actuator “E” could be used as a generator. In this situation, a movement of the actuation shaft 200 corresponds to a generation of power (this operation as a generator can also carried out in the context of a "steer-by-wire" actuator).

[0056] The actuation shaft 200 is configured to translate along the longitudinal axis “X” and comprises a threaded zone 300 defining an axial section, preferably central, of the shaft 200 itself.

[0057] The actuator “E” also comprises a lead nut 400 rotatable about the longitudinal axis “X” and engaged with the actuation shaft 200 by means of a recirculating ball threaded connection “C”. The lead nut is formed in the shape of a hollow tubular body, which has an inner surface engaged with the outer surface of the actuation shaft 200 by means of the above-mentioned recirculating ball threaded connection “C”.

[0058] The lead nut 400 is connected or connectable to an electric motor "M".

[0059] In the embodiment shown in the accompanying drawings, the actuator “E” comprises an electric motor “M” connected to the lead nut 400 and inserted in the containment space. Preferably, the motor “M” is coaxial to the lead nut 400 and positioned in a position radially external to it.

[0060] In the embodiment shown in the accompanying drawings, the magnets of the rotorof the electric motor “E” are fixed to the lead nut 400, in particular by means of gluing.

[0061] Again with reference to the embodiment illustrated in the accompanying drawings, the actuator ”E” comprises a pair of bearings 500a, 500b interposed between the containment frame 100 and the lead nut 400 and supporting the lead nut 400 in rotation so that the lead nut 400 has just a rotational movement about the axis ”X”. Preferably, at least one of the bearings 500 (preferably both) is integral with the lead nut 400. In other words, one of the inner / outer rings of the bearing 500 is formed directly by a part of the lead nut 400 itself.

[0062] More preferably, it is the inner ring of the bearing 500 that is directly formed by a part of the lead nut 400 itself.

[0063] Preferably, the bearings 500a, 500b are positioned on opposite ends of the lead nut 400.

[0064] Preferably, the bearings 500a, 500b of the pair are heterogeneous with respect to each other.

[0065] More preferably, one bearing of the pair is a roller bearing 500a and the other bearing of the pair is a ball bearing 500b.

[0066] Preferably, at least one of the closing walls (the one on the left, 100b, according to the embodiment illustrated in Figures 2 and 3) has a front relief, facing towards the containment space “V”, so as to come into contact with the outer ring of the bearing 500a, thereby causing a stable locking of the outer ring against a corresponding stop abutment, thus defining a packing element of the bearing 500a. Preferably, the front relief has an annular profile.

[0067] Further, in the specific embodiment illustrated and as visible in Figure 2, the other bearing 500b is axially packed between a front abutment of the second closing wall 100c and a retaining ring (for example a Seeger ring) inserted into a dedicated hollow of the closing wall 100c. This may be appropriate depending on the specific layout of the actuator ‘E’ in order to allow an insertion and extraction of the electric motor ”M”.

[0068] The actuator “E” also comprises a first and a second bushing 600a, 600b mounted on opposite sides of the containment frame 100 for guiding by translation respectiveportions of the actuation shaft 200.

[0069] The first and the second bushing 600a, 600b are thus fitted around the actuation shaft 200.

[0070] Preferably, the first and the second bushing 600a, 600b are made of an anti-friction material. Preferably, the material is also a stainless material, for example bronze or brass.

[0071] The first and the second bushing 600a, 600b are configured to be removable from the containment frame 100 by axially extracting from the outside of the containment space without requiring the extraction of the actuation shaft 200 from the respective closing wall 100b, 100c.

[0072] In other words, the first and the second bushing 600a, 600b can be removed from the containment frame 100 by means of a sliding along the longitudinal axis “X” towards the outside of the containment space without the actuation shaft 200 having to be “removed” from the closing walls 100b, 100c which can therefore remain engaged with the side wall 100a.

[0073] As shown in the accompanying drawings, the actuator “E” also comprises fixing means 700 configured to removably fix each bushing 600a, 600b to the respective closing wall 100b, 100c.

[0074] Preferably, the fixing means 700 are accessible along an axial direction parallel to the longitudinal axis “X”.

[0075] Thus, in use, if there is a need to carry out maintenance of the actuator "E", the fixing means 700 are released so as to allow a removal of the first and of the second bushing 600a, 600b with respect to the respective closing walls 100b, 100c. In this situation, the first and the second bushing 600a, 600b are removed, being slid along the longitudinal axis “X” towards the outside of the containment space, that is, away from the respective closing walls 100b, 100c. During the extraction of the first and of the second bushing 600a, 600b, the actuation shaft 200 can remain in its position along the longitudinal axis “X” without it also having to be removed from one of the two closing walls 100b, 100c and, therefore, without the need to intervene on the above-mentioned recirculating ball threaded connection “C”.

[0076] Advantageously, even if the actuator “E” is mounted on a vehicle, in order toremove the first and the second bushing 600a, 600b from the actuator “E” itself, there is no need to disassemble the actuator “E” from the vehicle, it being sufficient that the first and the second end 200a, 200b are disengaged from the respective operating elements which, in the embodiment described and illustrated, are steering arms of a vehicle.

[0077] Preferably, only one bushing 600a, 600b is provided on each side of the actuation shaft 100 (that is, for each closing wall 100b, 100c).

[0078] Preferably, each closing wall 100b, 100c comprises a through hole, in particular, circular. This hole is coaxial to the longitudinal axis "X". Within this hole, the respective bushing 600a, 600b is at least partially inserted axially.

[0079] In the embodiment illustrated, by way of example and without limiting the scope the invention, in the accompanying drawings, for example in Figure 3 and Figure 4, each bushing 600a, 600b comprises a main portion 600a’, 600b’ configured with a tubular shape.

[0080] The main portion 600a’, 600b’ is positioned between the actuation shaft 200 and the inner wall of a corresponding hole of the closing wall 100b, 100c.

[0081] As shown, for example, in Figures 2 and 3, wherein each closing wall 100b, 100c is formed by a closing cover, the main portion 600a’, 600b’ is inserted into the hole formed in the respective closing cover so that the latter fits around the main portion 600a’, 600b’.

[0082] Each bushing 600a, 600b also comprises a flanged portion 600a”, 600b” axially adjacent to the first portion 600a’, 600b’ and positioned outside the containment space in such a way as to be in contact with an outer surface of the respective closing wall 100b, 100c. This outer surface may be defined by a recess or a recessed seat, or may be defined by the normal outer profile of the closing wall 100b, 100c. Preferably, each flanged portion 600a”, 600b” is operatively positioned in a position projecting outside the outer surface of the respective closing wall 100b, 100c. This means that the flange 600a, 600b may be gripped manually to carry out its removal during maintenance activities.

[0083] In accordance with one aspect of the invention, each flanged portion 600a", 600b" is provided with gripping means that can be engaged by a tool so as to facilitate theaxial extraction of the flange 600a, 600b.

[0084] By way of example, and without limiting the scope of the invention, the gripping means are made in the form of extraction holes.

[0085] As shown, for example, in Figure 2 and in Figure 3, wherein each closing wall 100b, 100c is formed by a closing cover, the flanged portions 600a”, 600b’ ’ are in contact with the outer surface of the respective closing cover.

[0086] In the preferred embodiments, the fixing means 700 are positioned on the flanged portion 600a” , 600b” and are engaged with the outer surface of the respective closing wall 100b, 100c.

[0087] According to the embodiments illustrated in the accompanying drawings, the fixing means 700 are angularly distributed around the axis “X”.

[0088] Each main portion 600a’, 600b’ is made as one piece with the corresponding flanged portion 600a”, 600b”.

[0089] Preferably, the main portion 600a’, 600b’ has a diameter smaller than the diameter of the flanged portion 600a”, 600b”.

[0090] Preferably, the axial extension of the main portion 600a’, 600b’ is greater than the axial extension of the flanged portion 600a”, 600b”.

[0091] More preferably, the main portion 600a’, 600b’ extends through the entire thickness of the closing wall 100b, 100c.

[0092] Alternatively, the axial extension of the main portion 600a’, 600b’ is substantially identical to the axial extension of the flanged portion 600a”, 600b”.

[0093] Alternatively, the axial extension of the main portion 600a’, 600b’ is less than the axial extension of the flanged portion 600a”, 600b”.

[0094] Preferably, the actuator "E" comprises a mechanical seal 900c, in particular an Ciring, interposed between a closing wall 100b, 100c and the respective bushing 600a, 600b.

[0095] Preferably, between each closing wall 100b, 100c and the respective bushing 600a, 600b, the actuator “E” comprises a corresponding mechanical seal 900c.

[0096] In particular, the mechanical seal 900c is housed in a groove or seat 900b formed on an outer surface of the bushing 600a, 600b.

[0097] In the accompanying drawings, each bushing 600a, 600b has, on a relative outersurface, a groove or seat 900b for the mechanical seal 900c.

[0098] Preferably, according to the embodiment of the actuator “E” shown in the accompanying drawings, each main portion 600a’, 600b’ comprises, on a relative outer surface facing the containment frame 100, the groove or seat 900b configured to receive the mechanical seal 900c, and in particular an O-ring.

[0099] Preferably, and according to the embodiment of the actuator “E” shown in the accompanying drawings, the actuator “E” comprises at least a first seal 800a and at least a second seal 800b positioned around the actuation shaft 200 in an axially spaced position so that the lead nut 400 is interposed between the seals 800a, 800b. In this situation, each bushing 600a, 600b is provided internally with a respective groove 900 configured to house one of the seals 800a, 800b.

[0100] In other words, each bushing 600a, 600b is provided, on a relative inner surface and facing towards the actuation shaft 200, with a groove 900 for housing a seal 800a, 800b. In this situation, the seals 800a, 800b are interposed between the corresponding bushing 600a, 600b and the actuation shaft 200.

[0101] The groove 900 of each bushing 600a, 600b is a circumferential groove.

[0102] Preferably, the groove 900 is formed in the flanged portion 600a”, 600b”.

[0103] More preferably, the groove 900 is formed in the inner surface of the flanged portion 600a”, 600b”. According to the embodiment shown in the accompanying drawings, the actuator “E” comprises a pair of first seals 800a and a pair of second seals 800b.

[0104] Each groove 900 comprises an annular rib 900a configured to divide the groove 900 into two seats "SI", "S2" each configured to house a respective seal 800a, 800b of the corresponding pair.

[0105] As shown, for example, in Figures 5 A and 5B, the first bushing 600a has the groove 900 divided by the rib 900a so as to define two seats, “SI” and “S2”, each configured to house one seal 800a of the first pair of seals. In the same way, the second bushing 600b has the groove 900 divided by the rib 900a so as to define two seats “S 1”, “S2”, each configured to house one seal 800b of the second pair of seals. Advantageously, the fact of locating the seals 800a, 800b inside a suitable seat 900 formed on the bushings 600a, 600b reduces the overall dimensions of theactuator “E”, but, at the same time, increases the contact surface of the bushings 600a, 600b with the actuation shaft 200, so that the bushings 600a, 600b effectively counteract the bending of the actuation shaft 200 itself.

[0106] Preferably, the actuator “E” also comprises an encoder configured to detect an angular position of the lead nut 400 around the longitudinal axis “X”.

[0107] Preferably, the sensor of the encoder (not illustrated) is integrated with one of the closing walls 100b, 100c of the containment frame 100.

[0108] According to the views of Figures 2 and 3, an encoding band 400a of the encoder is applied to a member 400b (preferably annular in shape) integral with the lead nut 400, in particular fitted at an end thereof. In the embodiment of Figure 3, the member 400b is connected to the lead nut 400 by means of threaded fixing means. Alternatively, the encoding band 400a of the encoder is integrated with the lead nut 400.

[0109] The present invention achieves the preset aims eliminating the drawbacks of the prior art.

[0110] In particular, the structure of the bushings 600a, 600b and their location in the actuator "E" allow a simple maintenance, as well as a facilitated disassembly, of the actuator "E" which can be subjected to overhaul without the need for a complete disassembly, in particular without the need to remove the closing walls and the actuation shaft.

[0111] Further, if the actuator “E” is mounted on a vehicle, the bushings 600a, 600b can be disassembled from the actuator “E” without it being decoupled from the vehicle.

Claims

CLAIMS1. A linear electro-mechanical actuator (E), comprising:- a containment frame (100), comprising a side wall (100a) and a first and a second closing wall (100b, 100c) coupled at opposite ends of said side wall (100a) and acting in conjunction with said side wall (100a) to define internally a containment space;- an actuation shaft (200), extending along a longitudinal axis (X) between a first end (200a) and a second end (200b) protruding outside the containment frame (100), said actuation shaft (200) being configured for translating along said longitudinal axis (X) and comprising a threaded zone (300);- a lead nut (400), rotatable about the longitudinal axis (X) and engaged with the actuation shaft (200) by means of a recirculating ball threaded connection (C), said lead nut (400) being connected or connectable to an electric motor (M);- a first and a second bushing (600a, 600b) mounted on opposite sides of the containment frame (100) for guiding by translation respective portions of the actuation shaft (200),wherein the first and second bushings (600a, 600b) are axially spaced in such a way that said lead nut (400) is interposed between the first and second bushings (600a, 600b), andwherein said first and second bushings (600a, 600b) are configured to be removable from the containment frame (100) by axially extracting from the outside of the containment space without requiring the extraction of the actuation shaft (200) from the respective closing wall (100b, 100c).

2. The actuator (E) according to claim 1, comprising fixing means (700) configured for removably fixing each bushing (600a, 600b) to the respective closing wall (100b, 100c), preferably said fixing means (700) being accessible along an axial direction parallel to the longitudinal axis (X).

3. The actuator (E) according to claim 1 or 2, wherein each bushing (600a, 600b) comprises:- a main portion (600a’, 600b’), configured to be tubular in shape and positioned between the actuation shaft (200) and the inner wall of a corresponding hole of the closing wall (100b, 100c);- a flanged portion (600a”, 600b”), axially adjacent to the first portion (600a’, 600b’) and positioned outside the containment space in such a way as to be in contact with an outer surface of the respective closing wall (100b, 100c); preferably, said fixing means (700) being positioned on the flanged portion (600a”, 600b”).

4. The actuator (E) according to claim 3, wherein the axial extension of said main portion (600a’, 600b’) is greater than the axial extension of the flanged portion (600a”, 600b”).

5. The actuator (E) according to any one of the preceding claims, comprising at least a first seal (800a) and at least a second seal (800b) positioned around said actuation shaft (200) in a position axially spaced in such a way that the lead nut (400) is interposed between said seals (800a, 800b), each bushing (600a, 600b) being provided internally with a respective groove (900) configured to house a respective one of said seals (800a, 800b).

6. The actuator (E) according to claim 5, comprising a pair of first seals (800a) and a pair of second seals (800b) and wherein each groove (900) comprises an annular rib (900a) configured to divide said groove (900) into two seats (SI, S2) each configured to house a respective seal (800a, 800b) of the corresponding pair.

7. The actuator (E) according to claim 5 or 6 when they depend on claim 3, wherein said groove (900) is formed in said flanged portion (600a”, 600b”).

8. The actuator (E) according to any one of claims 3 to 7, wherein each flanged portion (600a’ ’ , 600b” ) is operatively positioned in a position projecting externally from an outer surface of the respective closing wall (100b, 100c).

9. The actuator (E) according to any one of the preceding claims, wherein each closing wall (100b, 100c) is removable, preferably each closing wall (100b, 100c) being formed by, or comprising, a closing cover.

10. The actuator (E) according to claim 9, wherein each closing wall (100b, 100c) comprises a through hole, in particular circular, coaxial to said longitudinal axis (X) and within which the respective bushing (600a, 600b) is at least partially axially inserted.

11. The actuator (E) according to any one of the preceding claims, comprising a mechanical seal (900c), in particular an O-ring, interposed between a closing wall (100b, 100c) and the respective bushing (600a, 600b), in particular said mechanical seal (900c) being housed in a groove or seat (900b) formed on an outer surface of the bushing (600a, 600b).

12. The actuator (E) according to any one of the preceding claims, comprising an electric motor (M) connected to the lead nut (400), preferably said electric motor (M) being inserted in the containment space.

13. The actuator (E) according to any one of the preceding claims, wherein the first and second bushings (600a, 600b) are made of an anti-friction material, preferably said material also being a stainless material.

14. The actuator (E) according to any one of the preceding claims, comprising a pair of bearings (500a, 500b) interposed between the containment frame (100) and the lead nut (400) and integral with said lead nut (400), preferably the bearings (500a, 500b) of said pair being heterogeneous to each other, more preferably a bearing of said pair being a roller bearing (500a) and the other bearing of said pair being a ball bearing (500b).

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