Hydraulic rotary actuator

Abstract

The invention concerns a hydraulic rotary actuator (1) comprising a body with a cylindrical cavity (14) with an axis Xc, a piston (30), adapted to separate said cavity (14) into two chambers (20, 21) that can be supplied with a pressurised hydraulic fluid, in which a through seat (35) is obtained, and a shaft (40), housed in the seat (35) of the piston (30) and rotatably mounted in the body (10) around an axis of rotation Xa; said shaft carries at the end at least one connection flange (46), in which a section (41) of the shaft (40) has on the outer surface a first thread (42) adapted to engage a corresponding second thread (36) obtained on the surface of the seat (35) of the piston (30) and in which the axis of rotation Xa of the shaft is arranged eccentric with an eccentricity Ec with respect to the axis Xc of the cylindrical cavity (14).

Description

[0001] The present invention concerns a hydraulic rotary actuator, in particular a helical hydraulic rotary actuator.

[0002] Helical rotary actuators are hydraulic actuators configured to convert the linear displacement of a piston into rotary movement, by means of helical gears. They are compact, simple and efficient. They produce a high instant torque in both directions of rotation.

[0003] These helical actuators are generally used for the movement of parts in the sector of agricultural and earth moving machines, in the maritime sector, in lifting systems, for controlling valves and, more generally, for applications requiring rotation of members along a limited and predefined arc of rotation. In fact, since the angle of rotation is determined by the length of the actuator, in general said actuators can provide in output a rotation of 90°, 180° or, in some cases, up to 360°.

[0004] Examples of helical rotary actuators manufactured according to a particularly widespread production method are described in US 4313367 A and US 2012263616 A1.

[0005] Said actuators generally comprise an outer cylindrical-shaped casing, a shaft and a piston integral with a cylindrical sleeve. The piston is mounted sliding in the cylindrical casing while the shaft is mounted rotatably with respect to the casing and is housed passing through the piston and the cylindrical sleeve.

[0006] On the outer surface of a section of the shaft, a helical toothing is obtained which engages a first corresponding helical toothing obtained on the inner surface of the piston sleeve. The outer surface of the piston sleeve carries a second helical toothing that engages a crown wheel integral with the housing.

[0007] The piston sleeve is hydraulically sealed between the housing and the shaft. When a hydraulic pressure is applied to an inlet in the casing, the piston sleeve is axially displaced and rotates in a first direction of rotation since the toothing on its outer diameter and the crown wheel of the housing force said piston sleeve to rotate.

[0008] At the same time, the toothing on the inner diameter of the piston sleeve, in turn, forces rotation of the shaft in the above-mentioned first direction of rotation.

[0009] The application of hydraulic pressure to another inlet of the casing causes the piston to retract, and the sleeve and therefore the shaft to rotate in a second direction of rotation opposite to the first direction.

[0010] The helical rotary actuators conceived as above, although efficient, nevertheless have some limitations.

[0011] Of these, the main limitation is their complicated construction and the consequent cost of producing said devices. In fact, the helical toothings provided on the piston sleeve, on the shaft and on the outer casing require particularly accurate and complex machining operations. The presence of a double pair of toothings (shaft / sleeve and sleeve / casing) on the one hand is necessary in order to transmit the rotation to the shaft, but on the other it makes these elements fairly costly to produce.

[0012] Hydraulic rotary actuators having the same technical features mentioned in the pre-characterizing portion of the appended claim 1 are already known from patent documents, WO 87 / 00590 A1, GB 470099 A and JP S51 17786A for examples.

[0013] In this context, the object of the present invention is to propose a hydraulic rotary actuator that overcomes the drawbacks of the known art cited above.

[0014] In particular, an object of the present invention is to provide a hydraulic rotary actuator which is simpler to produce in construction terms, and is therefore also cheaper than the known ones.

[0015] A further object of the present invention is to provide a more compact and more lightweight hydraulic rotary actuator than those of the known art.

[0016] The above-mentioned objects are achieved by a hydraulic rotary actuator in accordance with the attached claim 1.

[0017] In detail, according to the present invention the actuator comprises a body that defines at least one cylindrical inner cavity with an axis Xc.

[0018] The cylindrical cavity houses in a sliding manner a piston which defines and separates, inside said cavity, a first chamber and a second chamber that can be supplied with a pressurized hydraulic fluid, through respective passages obtained in the body, to cause displacement of the piston in the cylindrical cavity.

[0019] The piston comprises in general a substantially cylindrical body. The length of the piston is less than the length of the cylindrical cavity; the difference between the two lengths is therefore equal to the maximum stroke that can be performed by the piston in the cavity.

[0020] On the outer surface of the piston at least one seat is obtained adapted to house a seal that co-acts with the inner surface of the cavity of the body to provide the seal between the first chamber and the second chamber.

[0021] The piston is also provided with a through seat which extends between a first end and a second end.

[0022] In the above-mentioned seat a shaft is inserted which is rotatably mounted in the body around an axis of rotation Xa. Said shaft carries at least at one of its ends a connection flange, obtained in the same piece as the shaft or made integral with it by means of screws or other fastening means, which allows connection of the actuator to a part of the device / apparatus in which it is used.

[0023] According to the invention, a section of the outer surface of the shaft is provided with a first threading or toothing adapted to engage a corresponding second threading or toothing obtained on the surface of the piston seat.

[0024] According to the invention, the axis of rotation Xa of the shaft, which coincides with the axis of the seat obtained in the piston, is arranged eccentric with respect to the axis Xc of the cylindrical cavity, which coincides with the axis of the piston body.

[0025] Said characteristic, together with the presence of the two reciprocally engaged threadings / toothings, allows the translation movement of the piston in the cylindrical cavity to be converted into a rotation movement of the shaft.

[0026] In fact, if the above-mentioned axes of the shaft and of the cavity coincided, by applying a hydraulic pressure in one of the two chambers of the cylindrical cavity, the piston would move forward in one direction and simultaneously, due to the threading-toothing pair, it would rotate around the shaft which would remain substantially stationary. For this reason, in the actuators of the known art, a double pair of helical toothings are provided, where the outermost pair allows the outer casing to work as a reaction element and therefore rotate the shaft.

[0027] In the actuator according to the present invention, due to the eccentric positioning of the shaft with respect to the cavity and the piston, the latter is not able to rotate in the cylindrical cavity. By applying a hydraulic pressure in one of the two chambers, the piston moves in the cylindrical cavity, rotating the shaft due to the coupling of the two toothings / threadings obtained respectively on the shaft and on the surface of the piston seat.

[0028] In practice, the eccentric arrangement of the shaft means that the body can be made to work as a reaction element which, preventing the piston from rotating, allows transmission of the rotary movement to the shaft.

[0029] The configuration of the actuator described above has various advantages compared to that of the actuators of the known art described above.

[0030] Firstly, as is evident, the structure of the actuator is simpler due to the presence of one single threading / toothing pair, compared to the two helical toothing pairs of the actuators of the known art.

[0031] Furthermore, in the variation in which threadings are used, it is possible to produce the two parts, shaft and piston, with traditional and not particularly sophisticated machine tools.

[0032] Another advantage is that the actuator body can be lighter. In the known actuators, in fact, the body is generally made of steel since it has to carry on the inner surface, or in any case on a collar welded to the inner surface, the helical toothing that co-acts with the toothing of the piston sleeve.

[0033] In the actuator according to the invention, since no toothings or threads are provided on the inner surface of the cavity, it is possible to produce the body with materials having a lower mechanical resistance and also a lower specific weight, like aluminium or other light alloys.

[0034] Although the actuator according to the present invention can be produced using a pair of helical toothings on the piston and on the shaft, in the description below reference will be made to a preferred embodiment in which a pair of threadings is used.

[0035] According to an aspect of the invention, the ratio Ec / Dp between the eccentricity Ec1 and the diameter of the piston Dp is between 1 / 12 and 1 / 8.

[0036] These eccentricity values allow for limitation / reduction of the friction losses between the shaft and the piston and, on the other hand, limitation of the actuator radial dimensions.

[0037] According to another aspect of the invention, the threading obtained on the shaft and the threading obtained on the piston have a helix angle (φ) preferably equal to or greater than 20°, more preferably between 25° and 35°.

[0038] The choice of the helix angle depends essentially on the desired characteristics of the actuator in terms of reactivity, maximum arc of rotation and dimensions of the body (length).

[0039] The number of leads of the shaft and piston threadings varies according to the diameter of the piston and the helix angle.

[0040] According to another aspect of the invention, on the outer surface of the piston at least two seats are obtained adapted to each house an annular guide element adapted to co-act with the surface of the cylindrical cavity.

[0041] In further detail, said guide elements are interposed between the piston body and the surface of the cylindrical cavity and slide in contact with the latter, preventing direct contact with the piston body.

[0042] In fact, since the eccentric coupling between shaft and piston causes a radial thrust on the latter, the sliding in contact on the cylindrical surface would cause significant friction with dissipation of power and considerable wear of the parts.

[0043] Said annular guide elements preferably have a substantially rectangular flattened section. According to an aspect of the invention, said guide elements are preferably made of reinforced composite materials such as, for example, Bearite ™< or other equivalent polymer materials, with a similar or higher pressure resistance value.

[0044] According to the invention, the actuator body comprises a central part, with an annular wall that defines the inner cylindrical cavity, and two closing elements, adapted to close respective open ends of the annular wall.

[0045] The central part is typically a machined monolithic element. The closing elements are connected to said central part by means of screws or similar.

[0046] The ends of the shaft are rotatably housed in the respective closing elements. Preferably, the shaft is supported in said closing elements by bearings, for example ball or roller bearings, or similar.

[0047] According to the invention, each of the two chambers can be connected to a pressurised hydraulic fluid source by means of specific hydraulic passages. Each hydraulic passage comprises a first section, produced in the annular wall of the central part, and a second section, produced in the corresponding closing element, where said second section emerges on an inner face of said corresponding closing element facing the corresponding chamber.

[0048] This configuration allows the maximum piston stroke to be obtained (which in turn is proportional to the available arc of rotation) with the same length of the actuator body and without arranging fittings, couplings and the like on said closing elements.

[0049] According to another aspect of the invention, the actuator body is provided with fastening means for connecting the actuator to a support structure of the device or of the apparatus in which it is used.

[0050] According to a variation, said fastening means comprise holes, if necessary threaded, obtained in one or both the closing elements or, if necessary, also on the central part of the body.

[0051] The above-mentioned objects of the present invention are further achieved by an actuator assembly comprising two actuators according to one or more of the variations described above. In detail, the actuator assembly comprises one single common body for the two actuators, the two cylindrical cavities of which are arranged with the respective axes Xc, Yc perpendicular to each other.

[0052] According to a preferred variation, said axes Xc, Yc of the first cavity and the second cavity are respectively arranged on parallel planes and are offset from each other.

[0053] This variation is designed for applications comprising an articulation that requires a double rotation on two axes perpendicular to each other. Said articulation is applied, for example, in lifting equipment, in particular in systems for the movement of baskets, aerial platforms or equivalent equipment, where a rotation around a first horizontal axis is required to regulate the "pitch" of the basket / platform and a second rotation around a vertical axis to orient said basket / platform in the horizontal plane.

[0054] The structure of the two actuators is substantially identical in terms of operating concept.

[0055] In further detail, the second cylindrical cavity houses a second piston of the second actuator with a through seat which houses a second shaft, the rotation axis Ya of which is perpendicular to the axis Xa of the first shaft of the first actuator. The surfaces of the shaft and of the seat are provided with respective reciprocally engaged threads.

[0056] Also in this case, the axis of rotation Ya of the second shaft is arranged eccentrically, with an eccentricity Ec2, with respect to the axes Yc of the cylindrical cavity and Yp of the piston.

[0057] The characteristic dimensions of the two actuators (diameter of the piston, length of the threads on shaft and seat of the piston, helix angle, eccentricity, maximum angle of rotation, etc.) can be the same or different according to requirements.

[0058] According to a preferred embodiment, the body of the two actuators (more precisely the respective central parts that define the cylindrical cavities) is made in one single piece.

[0059] Alternatively, said body can be formed of two separate elements made integral by means of screws, or similar, and if necessary interlocking and / or centring means.

[0060] Further characteristics and advantages of the present invention will become clearer from the description of an example of a preferred, but not exclusive, embodiment of a hydraulic rotary actuator, as illustrated in the attached figures in which: figure 1 is a perspective view of a hydraulic rotary actuator according to an embodiment of the invention; figure 2 is an exploded perspective view of the actuator of figure 1; figure 3 is a section view, along a longitudinal plane, of the actuator of figure 1; figure 4 is a section view, along a transverse plane, of the actuator of figure 1; figure 5 is a perspective view of a hydraulic rotary actuator according to another embodiment of the invention; figure 6 is a section view, along a longitudinal plane, of the actuator of figure 5; figure 7 is a perspective view of the actuator of figure 5 provided with connection means; figure 8 is a perspective view of an actuator assembly according to an embodiment of the invention; figure 9 is a section view, along a first longitudinal plane, of the actuator assembly of figure 8; figure 10 is a section view, along a longitudinal plane, of the actuator assembly of figure 8.

[0061] With reference to the attached figures from 1 to 6, the number 1 indicates overall a hydraulic rotary actuator according to the present invention.

[0062] The actuator comprises a body 10, a shaft 30 and a piston 40.

[0063] The body 10 comprises in turn a central part 11 and two closing elements 12, 13.

[0064] The central part 11 of the body 10 comprises an annular wall that defines within it a cylindrical cavity 14 with axis Xc. Said cavity 14 is delimited at the ends by the closing elements 12, 13. Said closing elements 12, 13 are fixed to the central part 11 by means of screws 15.

[0065] Preferably, an annular gasket 16 is interposed between each closing element 12, 13 and an end face 11a of the central part 11, which acts as an abutment for said closing elements.

[0066] Preferably, the central part 11 and the closing elements 12, 13 of the body 10 are made of aluminium or other light alloys.

[0067] The piston 30 and the shaft 40 are typically made of steel.

[0068] The piston 30 comprises a cylindrical body with axis Xp slidingly housed in the cylindrical cavity 14 of the body 10. Said piston 30 defines and separates two chambers 20, 21 in said cylindrical cavity 14. Each of the two chambers 20, 21 can be connected to a pressurised hydraulic fluid source by means of specific hydraulic passages obtained in the annular wall or, as in the example illustrated, also in the closing elements.

[0069] In detail, according to the embodiment illustrated in figures 1 to 4, a first section 22 of the hydraulic passage is obtained in the annular wall of the central part 21 and a second section 23 of the hydraulic passage is obtained in the closing elements. In further detail, the first section 22 extends between the outer surface 11b of the annular wall 11 and the end faces 11a of said central part 11.

[0070] The second section 23 extends between an abutment area 12b,13b of the closing elements 12, 13 and the inner face 12a, 13a of said closing elements, facing the cavity 14 and the chambers 20, 21 respectively.

[0071] The first section 22 and the second section 23 of the hydraulic passage are obtained in the central part 11 and in the closing elements 12, 13 so that when said parts are assembled, the end of the first section 22 that emerges on the abutment face 11a of the central part 11 is aligned with the end of the second section 23 that emerges on the abutment area 12b, 13b of the closing elements 12, 13.

[0072] Said configuration allows for optimisation of the actuator dimension in the longitudinal direction (parallel to the axis Xc of the cavity 14). In fact, unlike the known actuators in which the hydraulic fluid inlets into the chambers are obtained in the wall of the cylindrical cavity, with this configuration it is possible to bring said inlets to the head areas (in the closing elements 12, 13), so that the piston 30 can exploit the whole length of the cylindrical cavity 14 for its stroke. This is possible without having to connect in the area of the closing elements 12, 13 couplings or pipes which, in some cases, can interfere with the connection of the actuator to the relative device / apparatus.

[0073] Preferably, according to the invention, the body of the piston 30 has a diameter slightly smaller than that of the cylindrical cavity. In general the difference between said diameters is a few tenths of a millimetre.

[0074] To guide the sliding of the piston 30 in the cavity 14, guide elements 32 are provided housed in respective seats 31 obtained on the outer surface of the piston.

[0075] Said guide elements 32 comprise flat annular bands made of Bearite ™< or equivalent materials.

[0076] The thickness of the guide elements 32 is calibrated so that their outer surface protrudes beyond the outer surface of the piston 30, thus the sliding by contact occurs only between said guide elements 32 and the surface 14a of the cylindrical cavity 14.

[0077] According to the invention, at least one pair of guide elements 32 is provided, each of which is arranged in the area of an end of the piston 30. According to the length of the piston 30, there can be four of said guide elements, as in the example of the figures from 1 to 4, or more.

[0078] To guarantee the hydraulic seal between the two chambers 20, 21, on the outer surface of the piston 30 a seat 33 is obtained adapted to house an annular gasket 34 which slides in contact with the surface 14a of the cavity 14. Said gasket 34 is arranged roughly in the area of the centre line of the piston 30, between the guide elements 32.

[0079] In the body of the piston, a seat 35 is obtained in which the shaft 40 is rotatably housed. Said seat 35 comprises a cylindrical hole, the axis of which coincides with the axis Xa of the shaft 40 and is parallel to the axis Xc of the cylindrical cavity 14. The hole extends throughout the length of the piston 30.

[0080] The shaft 40 is rotatably supported by the closing elements 12, 13. In detail, each closing element 12, 13 is provided with a seat 17 in which an end of the shaft 40 is housed, preferably by means of bearings 27, for example oblique ball bearings or tapered roller bearings.

[0081] To guarantee the hydraulic seal between the two chambers 20, 21, on a cylindrical section 37 of the seat 35 at least one seat 38 is obtained which houses an annular gasket 39 adapted to co-act with a corresponding cylindrical section 43 of the shaft 40. Preferably, in the seat 35, two seats 38 and two respective gaskets 39 are obtained.

[0082] A section 41 of the shaft 40 has a thread 42 adapted to engage a corresponding threading 36 (nut screw) obtained on a section of the seat 35. The threadings 36, 42 have square or, if necessary, trapezium-shaped helix profile. The helix angle φ of the threadings 36, 42 is typically approximately 25°-30°.

[0083] As mentioned above, said value of the helix angle can be lower or higher according to the operating parameters of the actuator; these can include, for example, the available arc of rotation, the longitudinal dimension (length) of the actuator and the reactivity, namely the rotation speed given the same fluid pressure supplied and torque required.

[0084] According to the invention, the axis of rotation Xa of the shaft 40 is eccentric with respect to the axes Xc of the cylindrical cavity 14 and Xp of the piston 40.

[0085] As explained above, by applying a pressure to the hydraulic fluid in one of the two chambers 20, 21, the piston 30 is pushed in a direction along the axis Xp. The coupling between the threads 36, 42 of the shaft and the piston, followed by displacement of the piston 30, causes rotation of the shaft 40. Thanks to the eccentricity Ec between the shaft 40 and the piston 30, the piston cannot rotate on itself, discharging the reaction of the central part 11 of the body 10 onto the shaft 40.

[0086] The value of the eccentricity Ec is parameterized according to the diameter of the piston.

[0087] An optimal eccentricity value Ec that limits the diameter of the piston and at the same time minimizes the friction losses between the threads and does not produce an excessive radial stress on the guide elements 32 of the piston 30, is approximately one tenth of the diameter Dp of said piston 30.

[0088] In the embodiment illustrated in figures 1 to 4, the shaft 40 is provided at its ends with two flanges 46, 47 which allow connection of the actuator to one of the parts (fixed or mobile) of the device / apparatus. In practice, said flanges 46, 47 protrude beyond the seats 17 of the closing elements 12, 13.

[0089] In detail, a flange 46 is made in one piece with the shaft 40 while a second flange 47 is fixed to the opposite end of the shaft 40 by means of screws 47a and if necessary drive pins.

[0090] According to this variation, also the closing elements 12, 13 are provided with connection means, holes 18 in the example illustrated, which allow the body 10 of the actuator to be fixed to the other part of the device / apparatus.

[0091] Figures 5, 6 and 7 illustrate an actuator 1 according to another embodiment of the present invention. The operation and particular characteristics are the same as those described for the variation of figures 1 to 4.

[0092] Unlike the previous one, in this variation the shaft 40 has only one connection flange 46, preferably integral with it. The opposite end of the shaft 40 is covered with a cover 25 fixed to the closing element 13 in the area of the seat 17.

[0093] According to this variation, furthermore, both the closing elements 12, 13 and the central part 11 of the body are provided with connection means, for example in the form of holes 18, 19, for connecting the actuator to a part of the device / apparatus.

[0094] According to a preferred variation, said holes 18, 19 are provided in the area of seats 26, obtained on said central part 11 and said closing elements 12, 13, for the positioning and centring of a bracket 60 or equivalent fastening means, as illustrated in figure 7.

[0095] Figures 8 to 10 illustrate an actuator assembly 200 that comprises a first actuator 1 and a second actuator 100 produced according to the inventive concepts described for the previous variations.

[0096] According to this particular embodiment, the actuator assembly 200 comprises a single monolithic body 210 in which both the cavities 14, 114 that house the respective pistons 30, 130 are obtained. In practice, said body 210 comprises two central parts 11, 111 of the respective first and second actuators.

[0097] According to this variation, the axes Xc, Yc of the first cavity 14 and second cavity 114 respectively are perpendicular to each other; likewise, the axes Xa, Ya of the respective shafts 40, 140 of the first actuator 1 and second actuator 100 are perpendicular.

[0098] In the example of the figures, both the shaft 40 of the first actuator 1 and the shaft 140 of the second actuator 100 are provided with two connection flanges 46, 47, 146, 147.

[0099] This embodiment is applied particularly effectively for the movement of baskets or aerial platforms connected to a lifting arm.

[0100] The first actuator 1, generally having larger dimensions and therefore providing a higher torque, has the task of controlling the pitch movement (rotation around a horizontal axis Xa) of the basket or platform to keep the support surface parallel to the ground during deployment of the lifting arm.

[0101] The second actuator 100 has the task of controlling rotation of the basket or platform around a vertical axis Ya to orient them in the horizontal plane.

[0102] Said actuator assembly allows considerable simplification of the movement system used in lifting systems of the known art, where in general the pitch movement is governed by a linear hydraulic piston and the rotation movement is governed by a helical rotary actuator of the known art like those described above.

[0103] The invention has been described for illustrative non-limiting purposes, according to some preferred embodiments. A person skilled in the art can find numerous other embodiments and variations, all falling within the protective scope of the following claims.

Claims

1. A hydraulic rotary actuator (1) comprising: - a body (10) comprising a central part (11) with an annular wall that defines at least one cylindrical cavity (14) with an axis (Xc) and two closing elements (12, 13), adapted to close respective open ends of said annular wall; - a piston (30), housed moving in the cylindrical cavity (14) and adapted to separate, in said cavity (14), a first chamber (20) and a second chamber (21) which can be supplied with a pressurized hydraulic fluid, said piston (30) having a through seat (35) between a first end and a second end; and - a shaft (40), housed in the trough seat (35) of the piston (30) and mounted rotatable in the body (10) about an axis of rotation (Xa), said shaft (40) carrying at the end at least one connection flange (46); wherein the ends of the shaft (40) are rotatably housed in seats (17) produced in the closing elements (12, 13), wherein a section (41) of the shaft (40) is provided on the outer surface with a first thread (42) adapted to engage a corresponding second thread (36) produced on the surface of the seat (35) of the piston (30), wherein the axis of rotation (Xa) of the shaft is arranged eccentric with an eccentricity (Ec) with respect to the axis (Xc) of the cylindrical cavity (14); wherein each of the two chambers (20, 21) is connectable to a source of a pressurized hydraulic fluid by means of specific hydraulic passages (22, 23), the actuator (1) being characterized in that each hydraulic passage comprises a first section (22) produced in the annular wall of the central part (11) and a second section (23) produced in the corresponding closing element (12, 13), said second section emerging on an inner face of said corresponding of closing element (12, 13) facing the corresponding chamber (20, 21).

2. The actuator (1) according to claim 1, wherein the ratio Ec / Dp between the eccentricity (Ec) and the diameter of the piston (Dp) is comprised between 1 / 12 and 1 / 8.

3. The actuator (1) according to claim 1 or 2, wherein the thread (42) produced on the shaft and the thread (36) produced on the seat (36) of the piston (30) have a helix angle (φ) equal to or greater than 20°.

4. The actuator (1) according to any one of the preceding claims, wherein on the outer surface of the piston (30) there are produced at least two seats (31) adapted to each house an annular guide element (32) adapted to coact with the surface of the cylindrical cavity (14) slidably resting thereon to prevent direct contact between said surface of the cylindrical cavity (14) and the piston (30).

5. The actuator according to any one of the preceding claims, wherein said closing elements (12, 13), or optionally also the central part (11), are provided with holes (18, 19) which allow fixing of the actuator (1) to a part of a device or apparatus in which it is used.

6. An actuator assembly (200) comprising a first actuator (1) and a second actuator (100) according to any one of the preceding claims, wherein there is provided a single body (210) in which there is produced a first cylindrical cavity (14) and a second cylindrical cavity (114), wherein the axis (Xc) of the first cylindrical cavity (14) is perpendicular to the axis (Yc) of the second cavity (114).

7. The actuator assembly according to claim 6, wherein the axes (Xc, Yc) of the first cavity (14) and of the second cavity (114) are respectively arranged on a plane parallel and staggered in relation to each other.

8. The actuator (1) according to claim 1, wherein the central part (11) and the two closing elements (12, 13) are made of aluminium or other equivalent light alloys.

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