WO2024236435A1

WO2024236435A1 - Centering unit with anti-rotation group

Info

Publication number: WO2024236435A1
Application number: PCT/IB2024/054551
Authority: WO
Inventors: Rossella BOTTACINI
Original assignee: Pneumax S.P.A.
Priority date: 2023-05-15
Filing date: 2024-05-10
Publication date: 2024-11-21

Abstract

The present invention relates to a centering unit (10) comprising a housing body (11) inside which a centering rod (13) is at least partially housed in a linearly movable manner along an actuation axis (A) between a first minimum extraction position from the housing body (11) and a second maximum extraction position from the housing body (11); and an anti-rotation group (40) configured to prevent rotation of the centering rod (13) about the actuation axis (A) during its movement between the first and second positions, characterized in that the anti-rotation group (40) comprises a sliding block (41) fixedly connected to the centering rod (13) and a guide (42) fixedly connected to the housing body (11), wherein the sliding block (41) is constrained to slide along the guide (42) along a direction parallel to the actuation axis (A) by means of the interposition of at least a pair of rollers (46) arranged side by side, with the respective roller axes comprised in parallel planes and transverse one with respect to the other.

Description

CENTERING UNIT WITH ANTI-ROTATION GROUP

TECHNICAL FIELD

The present invention generally relates to a centering unit with an anti-rotation group. In particular, the present invention relates to centering units typically used in the field of sheet metal working, for example for the construction of motor vehicle bodies.

STATE OF THE ART

In the construction of motor vehicle bodies, it is well known to use centering units, for example, to make special references to ensure the correct positioning of sheets on the machining equipment.

For this purpose, known centering units are configured to linearly move a centering rod along an actuation axis, between two end positions, a first rest position, in which the centering rod is predominantly retracted into the body of the centering unit, and a second operating position, in which the centering rod protrudes more from the body of the centering unit. The centering units are generally controlled through a pneumatic or electric actuator which acts on an element that is axially movable between two end positions and through which the actuator acts on the centering rod to move it between the rest position and the operating position.

In order to implement an accurate position reference when the rod is in its operating position, it can, for example, have an asymmetrical shape at its free end, thus creating an abutment surface. In such a configuration, it is essential that the centering rod reaches the operating position in the absence of any rotation about its actuation axis. Otherwise, the abutment surface would provide an inaccurate reference to the desired positioning.

Known centering units implement various solutions to maintain the angular position of the centering rod.

Document EP 1132628 describes the use of a connecting pin between the actuator piston and the centering rod. The pin extends off-axis, parallel to the actuation axis.

Document US 8 366 085 describes the use of a pair of rollers arranged in diametrically opposing positions with respect to the rod, each of which runs along a respective longitudinal track parallel to the actuation axis.

Documents DE102018003877 and EPl 123779 describe the use of a pin connected to the centering rod and constrained to slide in an axial guide parallel to the actuation axis.

Known solutions, on the one hand, do not always offer an adequate degree of accuracy in maintaining the angular position of the centering rod. Some solutions are not even able to offer the same reliability with reference to both possible directions of rotation of the centering rod. On the other hand, known solutions can lead to strong friction when sliding the rod between the rest position and the operating position and vice versa, resulting in the dissipation of part of the actuation thrust provided by the actuator.

In order to facilitate maintenance of the centering units, there is also a particular need to design the unit in such a way that the actuator, whether pneumatic or electric, can be replaced. Particularly in electrically powered actuation units, the replacement of the actuator can be complex and difficult. In fact, due to the nature of the drives traditionally used in electrically powered centering units, the action is imparted through a rotationally driven rod, thus requiring special gears to transform the rotary motion into a linear translation of the centering rod. The structural complexity of such actuators and the number of gears involved generally makes it difficult to construct a connection interface that facilitates disassembly and reassembly of the actuator. Furthermore, in order to ensure maximum operating efficiency, the assembly and disassembly of the actuator must not alter the coaxial arrangement between the stator and rotor.

OBJECTS AND SUMMARY OF THE INVENTION

In light of the above, the problem underlying the present invention is that of devising a centering unit capable of overcoming the drawbacks of the prior art.

In the context of this problem, an object of the present invention is to provide a centering unit capable of effectively preventing rotation of the centering rod about the actuation axis without, however, generating significant friction that could lead to dissipation of a large part of the actuation thrust supplied to the centering unit.

Another object of the present invention is to design a centering unit that can effectively counteract a rotation of the centering rod in both rotation directions.

Yet another object of the present invention is to devise a centering unit that allows an actuator to be connected to and removed from it without affecting its performance and wear.

In accordance with a first aspect thereof, the invention thus relates to a centering unit comprising a housing body, inside which a centering rod is at least partially housed in a linearly movable manner along an actuation axis between a first minimum extraction position from the housing body and a second maximum extraction position from the housing body; and an anti-rotation group configured to prevent rotation of the centering rod about the actuation axis during its movement between the first and second positions.

According to the present invention the anti-rotation group comprises a sliding block fixedly connected to the centering rod and a guide fixedly connected to the housing body, wherein the sliding block is constrained to slide along the guide along a direction parallel to the actuation axis by means of the interposition of at least a pair of rollers arranged side by side, with the respective roller axes comprised in parallel planes and transverse one with respect to the other.

The Applicant has found that the use of the special anti-rotation group provided with a sliding block and guide coupled by rollers, effectively prevents rotation of the centering rod about the actuation axis, while generating only minimal or essentially zero friction. This allows maximum exploitation of the actuation thrust provided by the relevant actuator.

In particular, each roller of the pair of side-by-side rollers, arranged with their respective roller axes in parallel planes and transverse to each other, is capable of counteracting torsion each in a specific rotation direction, thus preventing rotation of the rod effectively in both directions.

The present invention may have at least one of the preferred following features; the latter may in particular be combined with one another as desired in order to meet specific application needs.

Preferably, the sliding block is coupled to the guide by at least a plurality of rollers arranged side by side with the respective roller axes comprised in parallel planes, where, alternately, the roller axes are transverse to the adjacent roller axes.

In a variant of the invention, the rollers of the at least one pair of rollers are constrained to rotate, each about its own roller axis, inside a longitudinal seat which extends parallel to the actuation axis, the longitudinal seat being defined by a pair of longitudinal halfseats, where a first half-seat of the pair of longitudinal half-seats is made on a wall of the sliding block facing the guide and a second half-seat of the pair of half-seats is made on a wall of the guide facing the pad.

Preferably, each longitudinal half-seat has a V-shaped or substantially triangular crosssection open on one side.

In a variant of the invention at least two connecting elements project transversely from the pad, towards the inside of the housing body, configured to engage in a group of respective housing seats present on the sleeve of the centering rod. Alternatively, the sliding block is made integral with the centering rod.

Preferably, on the sleeve of the centering rod there are at least two groups of housing seats for housing the connecting elements, each group of housing seats comprising a plurality of seats aligned along a direction parallel to the actuation axis, each group of housing seats being provided on the sleeve of the centering rod at a different angular position.

In a variant of the invention, the centering unit comprises an actuator provided with an actuator body connected to the housing body and configured to act on a control rod in turn constrained to the centering rod, wherein the actuator is configured to move the control rod linearly along a control axis between two end positions, of which a first position of maximum insertion in the actuator body and a second position of minimum insertion in the actuator body.

Preferably, the actuator body is removably connected to the housing body at a bottom wall thereof.

The Applicant has identified that the removable connection between the actuator body and the housing body facilitates maintenance and replacement of the electric actuator.

In a variant of the invention, a head wall of the actuator body acting as a connection interface with the housing body and a bottom wall of the housing body acting as a connection interface with the actuator body are shaped in a complementary manner so as to implement a relative positioning guide between the actuator body and the housing body such that the drive axis substantially coincides with the actuator control axis.

The Applicant has identified that the particular conformation of the head wall of the actuator body which acts as a connection interface with the housing body and the bottom wall of the housing body which acts as a connection interface with the actuator body, such as to implement a relative positioning guide between the actuator body and the housing body, ensures precise positioning with respect to the actuation axis of the closing device, coinciding with the actuator control axis, thus resulting in a minimization of the friction involved.

In a variant of the invention, the actuator body comprises a guiding and centering protrusion which protrudes at least partially towards the outside of the actuator body from the head wall of the actuator body which acts as a connection interface with the housing body.

Correspondingly, the housing body comprises a guide mouth made on the bottom wall of the housing body which acts as a connection interface with the actuator body, the guide mouth being configured to accommodate within it and cooperate with the guiding and centering protrusion so as to implement the relative positioning guide.

Advantageously, the presence of the guiding and centering protrusion on the actuator body makes it easier for the user during assembly to position it centered and coaxial to the housing of the closing device. This is further supported by the presence of a guide mouth on the bottom wall of the housing body, which is configured to accommodate the guiding and centering protrusion within it and cooperate with it in such a way as to guide the relative positioning between the actuator body and the housing body.

Preferably, the guide mouth has at least one portion with a section complementary to at least one section of the guiding and centering projection transverse to the actuation axis.

More preferably, the at least one complementary section portion of the guide mouth can be coupled by interference or substantially no play with the guiding and centering protrusion.

Advantageously, an interference fit or substantially zero play between the guide moth and the guiding and centering protrusion ensures a high degree of precision in the relative positioning between the housing body and the actuator body so as to guarantee substantial coaxiality between the actuation axis of the closing device and the actuator drive axis.

In a variant of the invention, the actuator is of the electric type and comprises a cylindrical electromagnetic stator and a cylindrical hollow magnetic rotor inside and coaxial to the electromagnetic stator, the actuator control axis being an axis of rotation of the hollow magnetic rotor.

Preferably, a first termination of the magnetic rotor protrudes from the actuator body at the guiding and centering protrusion.

Preferably, the guide mouth is shaped in such a way that it accommodates the first protruding termination free to rotate.

Preferably, the guiding and centering protrusion has an extension surrounding the protruding termination of the magnetic rotor, more preferably an extension with axial symmetry with respect to the actuation axis.

In a variant of the invention, the magnetic rotor is constrained to the actuator body in a rotatable manner about the control axis of the electric actuator by the interposition of a pair of bearings.

Preferably, a head wall of the actuator body defines a housing seat for a first bearing of the pair of bearings facing towards the inside of the actuator body.

Preferably, the bearings of the pair of bearings are arranged substantially at or in proximity to a head end and a bottom end of the actuator body.

Preferably, the head wall of the actuator body is delineated by a head cover of the actuator body.

More preferably, the housing seat of the first bearing is made at the guiding and centering protrusion.

This makes it advantageously possible to construct the actuator in a particularly compact manner.

In a variant of the invention, the control rod is threaded and engages a nut fixedly connected with the magnetic rotor, wherein the nut has a thread internally configured to engage a thread of the control rod such that a rotation of the nut results in a translation of the threaded rod.

Preferably, the nut is essentially entirely housed within a defined volume inside the hollow magnetic rotor, more preferably at its first termination protruding from the actuator body.

Advantageously, the internal arrangement of the nut fixedly connected and/or made as a single piece with respect to the hollow magnetic rotor facilitates the implementation of a strictly coaxial arrangement of the rotor/nut assembly with respect to the stator, thus minimizing friction and allowing maximum exploitation of the torque offered by the electric actuator. In fact, the location of the nut inside the rotor prevents any microdisplacement of the nut that may occur when assembling the actuator to the housing body.

In addition, due to the internal arrangement of the nut with respect to the hollow magnetic rotor, it is also possible to support the rotor through the pair of bearings.

In a variant of the invention, the bottom wall of the housing body comprises a pair of screwing seats arranged symmetrically according to a central symmetry with respect to a point of intersection of the actuation axis on the bottom wall.

Similarly, the actuator body comprises a pair of screws that pass through it parallel to the actuation axis and are arranged at opposing angular positions with respect to this actuation axis.

Advantageously, such symmetrical arrangements of the screwing seats and screws make it possible to mount the electric actuator to the housing body either with a first orientation or with a second orientation rotated by 180° with respect to the first, thus allowing the drive electronics to be housed on a first or second side with respect to the drive body.

Preferably, the control rod thread is configured to allow reversibility of control rod rotation in the absence of a command imparted by the electric actuator.

Conveniently, the suitable thread to allow for a reversible rotation of the control rod facilitates the manual opening operations of the actuation unit in addition to the mounting operations of the electric actuator to the housing body.

In a variant of the invention, the first termination of the hollow magnetic rotor is made in the form of a crown gear with a conical conformation.

Preferably, the unit also comprises manual drive means configured to impart a rotation to the crown gear termination of the magnetic rotor.

Advantageously, the shape of the first termination of the crown gear rotor and the presence of manual drive means configured to impart a rotation to this crown gear, allow manual action directly on the rotor, facilitating the disassembly and reassembly of the electric actuator to the housing body, imparting a perfectly coaxial action to the actuation and rotation axes.

More preferably, the first manual drive means comprise at least one toothed element housed in the housing body in proximity to a bottom wall of the housing body, the toothed element being arranged in the housing body in a manner rotatable about an axis transverse to the actuation axis and translatable along said transverse axis so as to selectively engage the crown gear termination, the toothed element being configured such that, when engaged with the crown gear termination, a rotation imparted to the toothed element about the transverse axis causes a rotation of the magnetic rotor about the axis of rotation of the electric actuator.

Preferably, the toothed element comprises a toothed conical head.

More preferably, an elastic return means acts on at least one toothed element to return the toothed element to a disengaged position from the crown wheel termination when not forced to assume the engaged position.

The special shape of the manual drive means allows for easy and convenient operation of the rotor, possibly using conventional tools such as an electric screwdriver or the like. The action on the rotor can in fact be imparted by acting on the toothed element transverse to the actuation axis, so as to bring it into engagement with the rotor, and imparting a rotation to the rotor. Advantageously, once the action on the transverse element is finished, thanks to the elastic return means, the toothed element independently returns to a rest position where it does not engage the rotor.

In a variant of the invention, the bearings of the pair of bearings are both radial and axial thrust bearings.

Preferably, the bearings of the pair of bearings comprise a plurality of balls housed in a crown shaped seat, the seat forming both an upper and a lower abutment against which the balls engage.

Conveniently, in this way, the bearings allow the magnetic rotor to rotate, while maintaining its position perfectly coaxial to the actuation axis and counteracting the axial forces at play, particularly when reaching the end positions of the drive rod.

In a variant of the invention, the electromagnetic stator comprises a plurality of coils with a winding axis which is arranged radially with respect to the axis of rotation and the hollow cylindrical magnetic rotor comprises a plurality of permanent magnets arranged on a rotor sleeve, parallel to the axis of rotation and with alternating polarity with respect to adjacent magnets.

In a variant of the invention, the unit comprises an encoder associated with the hollow cylindrical magnetic rotor and configured to monitor the instantaneous position of the rod as a function of the number of revolutions performed by the rotor.

BRIEF DESCRIPTION OF THE DRAWINGS

Further characteristics and advantages of the present invention will become clearer from the following detailed description of some preferred embodiments thereof, made with reference to the appended drawings.

The different features in the individual configurations may be combined with one another as desired according to the preceding description, should there be advantages specifically resulting from a specific combination.

In these drawings,

- Figure 1 is a perspective view of a centering unit according to a first preferred embodiment of the present invention;

- Figure 2 is a sectional view of the centering unit in Figure 1;

- Figures 2a and 2b are sectional views along section lines B-B and C-C in Figure 2, respectively;

- Figures 3 and 3a are a partial exploded view of the centering unit in Figure 1 and an enlarged detail of it;

- Figure 4 is a perspective view of the centering unit of Figure 1 in a partially disassembled configuration; and

- Figure 5 is a perspective view from below of the housing body of the centering unit in Figure 1 in a disassembled configuration from the electric actuator;

- Figures 6a and 6b are partially cross-sectional views of the centering unit in accordance with a second preferred embodiment in which the actuating electronics are mounted on a first and second side, respectively;

- Figure 7 is a sectional view of a centering unit according to a third preferred embodiment of the present invention; and

- Figures 8, 8a, 9 and 9a are partial sectional views along section lines a-a and b-b in Figure 7 and enlarged details respectively.

DETAILED DESCRIPTION OF THE INVENTION

For the illustration of the drawings, use is made in the following description of identical numerals or symbols to indicate construction elements with the same function. Moreover, for clarity of illustration, certain references may not be repeated in all drawings.

While the invention is susceptible to various modifications and alternative constructions, certain preferred embodiments are shown in the drawings and are described hereinbelow in detail. It must in any case be understood that there is no intention to limit the invention to the specific embodiment illustrated, but, on the contrary, the invention intends covering all the modifications, alternative and equivalent constructions that fall within the scope of the invention as defined in the claims.

The use of "for example", "etc.", "or" indicates non-exclusive alternatives without limitation, unless otherwise indicated. The use of “comprises” and “includes” means “comprises or includes, but not limited to”, unless otherwise indicated.

With reference to Figures 1-5, a first preferred embodiment of a centering unit according to the present invention is illustrated, overall indicated by number 10.

The centering unit 10 comprises a housing body 11 inside which a centering rod 13 is at least partially housed in a movable manner. The centering rod 13 is linearly movable along an actuation axis A between two end positions, a first minimum extraction position from the housing body 11 and a second maximum extraction position from the housing body 11.

The centering unit 10 also comprises an actuator 20 provided with an actuator body 23 removably connected to the housing body 11 at a bottom wall 11c of the housing body 11.

The actuator 20 is configured to act on a control rod 14 which in turn is constrained to the centering rod 13. In particular, the actuator 20 is configured to move the control rod 14 linearly along a control axis which, specifically, coincides with the actuation axis A, between two end positions, of which a first position of maximum insertion in the actuator body 23 and a second position of minimum insertion in the actuator body 23.

In order to prevent a rotation of the centering rod 13 about the actuation axis A, the centering rod 13 is slidably coupled to the housing body 11 by means of an anti -rotation group 40, shown in detail in Figures 2a, 2b, 3 and 3a. The anti-rotation group 40 comprises a sliding block 41 fixedly connected to the centering rod 13 and a guide 42 fixedly connected to the housing body 11, whereby the sliding block 41 is constrained to slide inside the guide 42.

In the first embodiment illustrated, the centering rod 13 is connected to the sliding block 41 by a plurality of fastening means 45, such as screws that engage the sliding block 41 and fit into corresponding threaded seats 45a made in the centering rod 13. In addition, there are at least two connecting elements 43 which protrude from the sliding block 41 transversely to the direction of the actuation axis A, towards the inside of the housing body 11 and are spaced apart from each other along a direction parallel to the actuation axis A. The connecting elements 43 may, for example, be made in the form of pivots, pins or plates, or their equivalent.

The connecting elements 43 are configured to engage in a group of respective seats 44 accessible from the sleeve of the centering rod 13 and extending towards the inside of the centering rod 13 along a direction transverse to the direction of the actuation axis A. The seats 44 of the connecting elements are also spaced apart from each other along a direction parallel to the actuation axis A, in particular by the same distance by which the connecting elements 43 are spaced apart, thereby enabling engagement of each of the elements 43 in a respective seat 44. In this way, the connection between the sliding block 41 and the centering rod 13 is stronger than any torque to which the rod 13 is subjected.

In particular, the centering rod 13 comprises at least two groups of seats 44 complementary to the connecting elements 43. Preferably, each group of seats 44 is provided on the sleeve of the centering rod 13 at a different angular position, such as a first position rotated by 90° about the actuation axis A with respect to a second position. In this way, the centering rod 13 can be coupled to the sliding block 41 in at least two predefined orientations, e.g. a first orientation whereby the centering rod 13 is turned by 90° about the actuation axis A with respect to a second orientation. Correspondingly, there are also at least two groups of threaded housings 45a for the engagement of the fastening means 45 in at least two predefined orientations.

The sliding block 41 is coupled to the guide 42 in a slidable manner along a direction parallel to the actuation axis A by the interposition of at least one pair of rollers 46.

Preferably, the sliding block 41 is coupled to the guide 42 by the interposition of at least one plurality of rollers 46 or, as shown in detail in Figure 3a, by the interposition of two pluralities of rollers 46.

In the first embodiment of the invention, the sliding block 41 is coupled to the guide 42 by the interposition of two pluralities of rollers 46 and the guide 42 comprises a pair of semi-guides 42a. In each plurality of rollers, the rollers 46 are arranged side by side with their respective roller axes comprised in parallel planes where, in an alternating manner, the roller axes are transverse, e.g. orthogonal, to the adjacent roller axes.

The rollers of each of the plurality of rollers 46 are constrained to rotate, each about its own roller axis, inside a respective longitudinal seat 47 which extends parallel to the actuation axis A. Each the longitudinal seat 47 is defined by a pair of longitudinal halfseats 47a, 47b having a V-shaped or substantially triangular cross-section open on one side, where a first half-seat 47a of the pair of half-seats is made on a respective side wall of the sliding block 41 facing the guide 42 and a second half-seat 47b of the pair of halfseats is made on a respective inner wall of the guide 42 facing the sliding block 41. In the embodiment illustrated, the semi-guide 42a of the guide 42 defines a respective longitudinal seat 47 with the sliding block 41.

The actuator 20 is generally of the pneumatic or electric type. In the specific case of the embodiment illustrated, the actuator 20 is of the electric type. However, the principles of the present invention are equivalently applicable to centering units operated by means of a pneumatic actuator.

The electric actuator 20 is of the hollow-shaft type, such as a torque motor, and comprises a cylindrical electromagnetic stator 21 that is fixedly constrained to the actuator body 23. The electromagnetic stator 21 cooperates with a corresponding hollow magnetic rotor 24, which therefore also has a cylindrical shape and is arranged internally to the electromagnetic stator 21 in a coaxial arrangement. The magnetic rotor 24 is configured to rotate about the control axis of the electric actuator 20. The electromagnetic stator 21 is powered via drive electronics 30 mounted on the side of the actuator body 23.

Preferably, the electromagnetic stator 21 comprises a plurality of coils (not illustrated) with a winding axis which is radial with respect to the actuation axis A. The hollow magnetic rotor 24 comprises a plurality of permanent magnets (not illustrated) with an elongated shape, for example, of the tile or parallelepiped type, arranged on the cylinder sleeve, parallel to the actuation axis A and with alternating polarity with respect to the adjacent magnets.

The magnetic rotor 24 is axially constrained to the actuator body 23 by the interposition of a pair of bearings 31,32 arranged substantially at or near a head end and a bottom end of the body 23. Each end of the actuator body 23 is preferably closed by a respective head cover 25 and bottom cover 27 wherein the head cover 25 defines a head wall 25b that externally delimits the actuator body 23 at the top, while the bottom cover 27 defines a bottom wall that externally delimits the actuator body 23 at the bottom.

A nut 22 is also provided, fixedly constrained to the hollow magnetic rotor 24. The nut 22 has an internal thread configured to engage the control rod 14 so that a rotation of the nut 22 induced by the cylindrical rotor 24 causes a translation of the threaded control rod 14. For this purpose, the control rod 14 has a thread on its outer sleeve.

Conveniently, the nut 22 is housed internally in the hollow magnetic rotor 24, preferably in such a way that it remains substantially completely enclosed in the hollow magnetic rotor 24.

In the embodiment illustrated, the nut 22 is arranged internally to the hollow magnetic rotor 24, at a first termination 24a thereof protruding from the actuator body 23 and is retained inside the rotor 24 by a ring nut 26. In particular, the first termination 24a of the rotor 24 protrudes from the actuator body 23 at the head cap 25, which closes this body 23 at the top and acts as the connection interface to the housing body 11.

In a possible variant of the invention not illustrated, the hollow magnetic rotor 24 has an internal thread configured to engage the threaded control rod 14, itself acting as a nut.

The threaded control rod 14 is permanently and coaxially connected to a first end of the centering rod 13. In alternative embodiments, not illustrated, the control rod 14 is made as a single piece with the centering rod 13.

The housing body 11 and the actuator body 23 are advantageously shaped in a complementary manner so as to form a centering guide of one on the other, thereby facilitating the mounting or replacement of the electric actuator 20 on the body 11.

To this end, as is clearly visible in Figure 4, the head wall 25b of the actuator body 23 has at least one guiding and centering protrusion 25a extending towards the outside of the actuator body 23. Preferably, the guiding and centering protrusion 25a has an extension with axial symmetry with respect to the actuation axis A, such as, for example, a cylindrical extension centered on the actuation axis A or an extension with concentric cylinders of different diameters centered on the actuation axis A. The guiding and centering protrusion 25a extends around the protruding termination 24a of the magnetic rotor 24, preferably substantially in contact therewith.

In a complementary manner, the housing body 11 has a guide mouth 37 (shown in Figure 5) made on its bottom wall 11c which acts as a connection interface with the actuator body 23. The guide mouth 37 is shaped to accommodate both the first protruding termination 24a of the magnetic rotor 24 and at least a portion of the guiding and centering protrusion 25a. In particular, the first protruding termination 24a of the magnetic rotor 24 can be housed - and in an assembled configuration, is housed - in the guide mouth 37 without contact in order to be free to rotate. In contrast, the guiding and centering protrusion 25a can be housed - and in an assembled configuration, is housed - in the guide mouth 37 with interference or substantially no play in order to act as a substantially precise centering between the actuation axis A and the actuator control axis 20.

In the first embodiment illustrated, the head cover 25 advantageously defines a housing seat for a first bearing 31, of the pair of bearings 31,32. In particular, the housing seat of the first bearing 31 is advantageously located at the guiding and centering projection 25a, but is arranged on the opposite side with respect to the head wall 25b delineated externally by the cover 25, i.e. it faces towards the inside of the actuator body 23.

The first bearing 31 is therefore arranged substantially in proximity to the first termination 24a of the magnetic rotor 24. The first bearing 31 is accommodated in the seat defined by the head cover 25 by the interposition of a gasket 38 to increase the degree of insulation and protection of the actuator body 23.

Similarly to the first bearing 31, a second bearing 32 of the pair of bearings 31,32 is placed at a second termination 24b of the magnetic rotor 24 opposite the first termination 24a, substantially at the bottom end of the actuator body 23.

Preferably, both the first 31 and the second 32 bearings are of the radial and axial thrust type. In the embodiment illustrated, the bearings 31,32 comprise a plurality of balls 33 housed in a seat 34 shaped like a crown and in such a way as to create both an upper and a lower abutment against which the balls 33 engage.

The bottom cover 27 of the actuator body 23 carries an encoder 28 for monitoring the instantaneous position of the control rod 14, depending on the number of revolutions made by the rotor 24 and detected by the encoder 28. To this end, the magnetic rotor 24 carries a magnet 29 at its second termination 24b opposite the first 24a.

The centering unit 10 also comprises manual means 16 for driving the rotor 24. To this end, the first termination 24a of the rotor 24 protruding from the actuator body 23 is made in the form of a crown gear with a conical shape, and the manual drive means 16 are configured to impart a rotation to the crown gear termination 24a of the magnetic rotor 24. In particular, in the illustrated embodiment, the manual drive means 16 comprise a toothed element 16a housed in the body 11, in proximity to the bottom wall 11c thereof.

The toothed element 16a is housed in the housing body 11 in such a manner that one of its first ends substantially terminates at the toothed crown element 24a and a second end thereof faces laterally from an opening 1 lb provided on the housing body 11. At its first end, the toothed element 16a is provided with a toothed conical head configured to engage with the toothed crown termination 24a of the rotor 24.

The toothed element 16a is arranged in the housing body 11 in a movable manner along a direction transverse to the actuation axis A, between a position of disengagement from the toothed crown termination 24a and a position of engagement with the toothed crown termination 24a. In the engaged position, a rotation of the toothed element 16a about the transverse axis causes a rotation of the rotor 24 about the actuation axis A and, consequently, a translation of the control rod 14 along this actuation axis A.

A respective elastic return means (not shown) acts on the toothed element 16a to bring the toothed element 16a to the position of disengagement from the rotor 24 when not forced to assume the engagement position.

Figure 4 shows the centering unit 10 according to the first embodiment disassembled, i.e. with the electric actuator 20 removed from the housing body 11, e.g. for replacement or maintenance of the electric actuator 20. As can be seen in this figure, the control rod 14 can be removed from the electric actuator 20, remaining constrained to the housing body 11. The removal of the rod 14 is achieved by rotating the magnetic rotor 24 and, in this way, determining the relative translation between the rod 14 and the rotor 24. This rotation can easily be imparted by means of the toothed element 16a once it is brought into engagement with the toothed crown termination 24a of the rotor 24. Mounting the electric actuator 20 on the housing body 11 also requires turning the magnetic rotor 24. Once the maximum insertion position has been reached, the protrusion 25a has as a guiding and centering role between the housing body 11 and the electric actuator 20, allowing the two elements to be fixed together in a configuration of perfect alignment between the control rod 14 and the control axis of the actuator 20.

In accordance with a second embodiment of the invention, the electric actuator 20 can be mounted on the housing body 11 according to two distinct configurations, i.e. with the drive electronics 30 arranged, with respect to the drive body 11, on a first side or on a second side opposite the first side, as shown in Figures 6a and 6b. For this purpose, the actuating body 11 comprises two screwing seats l id arranged symmetrically on its bottom wall 11c according to a central symmetry with respect to the point of intersection of the actuation axis A on the bottom wall 11c. This allows a pair of screws 27b to be screwed into the screwing seats l id which pass through the actuator body 23 parallel to the actuation axis A and are arranged in positions equidistant from that actuation axis A, but offset from it by 180°.

Figures 7, 8, 8a, 9 and 9a show a third embodiment of the invention of a centering unit 10 in which the centering rod 13 is slidably coupled to the housing body 11 by means of an anti-rotation group 40 comprising a sliding block 41 fixedly connected to the centering rod 13 and a guide 42 fixedly connected to the housing body 11, wherein the sliding block 41 is constrained to slide along the guide 42.

In particular, the sliding block 41 is coupled to the guide 42 by means of the interposition of a single plurality of rollers 46, e.g. a pair of rollers 46, arranged side by side with their respective roller axes comprised in parallel planes, where, in an alternating manner, the roller axes are transverse, e.g. orthogonal, to the adjacent roller axes as can be seen from a comparison of Figures 8a and 9a.

Also in this case, the rollers of the plurality of rollers 46 are constrained to rotate, each about its own roller axis, inside a longitudinal seat 47 that extends parallel to the actuation axis A.

As shown in Figures 8 and 9, the longitudinal seat 47 is defined by a pair of longitudinal half-seats 47a, 47b having a V-shaped or substantially triangular cross-section open on one side, where a first half-seat 47a of the pair of half-seats is made on a side wall of the sliding block 41 facing the guide 42 and a second half-seat 47b of the pair of half-seats is made on a wall of the guide 42 facing the sliding block 41.

In the third embodiment of the invention, the guide 42 is interposed between a wall of the housing body 11 and the sliding block 41, while the sliding block 41 is interposed between the guide 42 and the centering rod 13 to which it is constrained.

Claims

1. Centering unit (10) comprising

- a housing body (11) inside which a centering rod (13) is at least partially housed in a linearly movable manner along an actuation axis (A) between a first minimum extraction position from the housing body (11) and a second maximum extraction position from the housing body (11); and

- an anti-rotation group (40) configured to prevent rotation of the centering rod (13) about the actuation axis (A) during its movement between the first and second positions; characterized in that the anti-rotation group (40) comprises a sliding block (41) fixedly connected to the centering rod (13) and a guide (42) fixedly connected to the housing body (11), wherein the sliding block (41) is constrained to slide along the guide (42) along a direction parallel to the actuation axis (A) by means of the interposition of at least a pair of rollers (46) arranged side by side, with the respective roller axes comprised in parallel planes and transverse one with respect to the other.

2. Centering unit (10) according to claim 1, wherein the sliding block (41) is coupled to the guide (42) by at least a plurality of rollers (46) arranged side by side with the respective roller axes comprised in parallel planes, where alternately, the roller axes are transverse to the adjacent roller axes.

3. Centering unit (10) according to claim 1 or 2, wherein the rollers of the at least one pair of rollers (46) are constrained to rotate, each about its own roller axis, inside a longitudinal seat (47) which extends parallel to the actuation axis (A), the longitudinal seat (47) being defined by a pair of longitudinal half-seats (47a, 47b), where a first half-seat (47a) of the pair of longitudinal half-seats is made on a wall of the sliding block (41) facing the guide (42) and a second half-seat (47b) of the pair of half-seats is made on a wall of the guide (42) facing the sliding block (41).

4. Centering unit (10) according to claim 3, wherein each longitudinal half-seat (47a, 47b) has a V-shaped or substantially triangular cross-section open on one side.

5. Centering unit (10) according to any one of the preceding claims, wherein which at least two connecting elements (43) project transversely from the sliding block (41), towards the inside of the housing body (11), configured to engage in a group of respective housing seats (44) present on the sleeve of the centering rod (13).

6. Centering unit (10) according to claim 5, wherein on the sleeve of the centering rod (13) there are at least two groups of housing seats (44) for housing the connecting elements (43), each group of housing seats (44) comprising a plurality of seats aligned along a direction parallel to the actuation axis (A), each group of housing seats (44) being provided on the sleeve of the centering rod (13) at a different angular position.

7. Centering unit (10) according to any one of claims 1 to 4, wherein the sliding block (41) is made as a single piece with the centering rod (13).

8. Centering unit (10) according to any one of the preceding claims, comprising an actuator (20) provided with an actuator body (23) connected to the housing body (11) and configured to act on a control rod (14) in turn constrained to the centering rod (13), wherein the actuator is configured to move the control rod (14) linearly along a control axis between two end positions, of which a first position of maximum insertion in the actuator body (23) and a second position of minimum insertion in the actuator body (23).

9. Centering unit (10) according to claim 8, wherein the actuator body (23) is removably connected to the housing body (11) at a bottom wall (11c) thereof.

10. Centering unit (10) according to claim 8 or 9, wherein a head wall (25b) of the actuator body (23) acting as a connection interface with the housing body (11) and a bottom wall (11c) of the housing body (11) acting as a connection interface with the actuator body (23) are shaped in a complementary manner so as to implement a relative positioning guide between the actuator body (23) and the housing body (11) such that the drive axis (A) substantially coincides with the actuator control axis (20).

11. Centering unit (10) according to any one of claims 8 to 10, wherein the actuator body (23) comprises a guiding and centering protrusion (25a) which protrudes at least partially towards the outside of the actuator body (23) from the head wall (25b) of the actuator body (23) which acts as a connection interface with the housing body (H).

12. Centering unit (10) according to claim 11, wherein the housing body (11) comprises a guide mouth (37) made on the bottom wall (11c) of the housing body (11) which acts as a connection interface with the actuator body (23), the guide mouth being configured to accommodate within it and cooperate with the guiding and centering protrusion (25a) so as to implement the relative positioning guide.

13. Centering unit (10) according to claim 12, wherein the guide mouth (37) has at least one section portion complementary to a section of the guiding and centering protrusion (25a) transverse to the actuation axis (A).

14. Centering unit (10) according to claim 13, wherein the at least one complementary section portion of the guide mouth (37) is coupled by interference or substantially no play with the guiding and centering protrusion (25a).

15. Centering unit (10) according to any one of claims 10 to 14, wherein the bottom wall (11c) of the housing body (11) comprises a pair of screwing seats (l id) arranged symmetrically according to a central symmetry with respect to an intersection point of the actuation axis (A) on the bottom wall (11c).

16. Centering unit (10) according to any one of claims 8 to 15, wherein the actuator body (23) comprises a pair of screws (27b) which pass through it parallel to the actuation axis (A) and, with respect to said actuation axis (A), are arranged in opposing angular positions.

17. Centering unit (10) according to any one of claims 8 to 16, wherein the actuator (20) is of the electrical type and comprises a cylindrical electromagnetic stator (21) and a cylindrical hollow magnetic rotor (24) inside and coaxial to the electromagnetic stator (21), the actuator control axis being an axis of rotation of the hollow magnetic rotor.

18. Centering unit (10) according to claim 17, wherein a first termination (24a) of the magnetic rotor (24) protrudes from the actuator body (23) at the guiding and centering protrusion (25a).

19. Centering unit (10) according to claim 18, wherein the guide mouth (37) is shaped to accommodate the first termination (24a) protruding from the magnetic rotor (24) in a rotationally free manner.

20. Centering unit (10) according to claim 18, wherein the magnetic rotor (24) is constrained to the actuator body (23) in a rotatable manner about the control axis of the electric actuator by the interposition of a pair of bearings (31,32), wherein a head wall (25) of the actuator body (23) defines a housing seat of a first bearing (31), of the pair of bearings (31,32), facing internally to the actuator body (23), the housing seat of the first bearing preferably being made at the guiding and centering protrusion (25a).