ES2310436A1 - Push button switch unit - Google Patents

Abstract

The invention relates to a push button switch unit including: a base body (1) with a shaft (2) which passes through an opening (3) in a panel (4) and which is fixed thereto, a support (6) which is fixed to the shaft (2) and which bears a switch (7), and an actuator assembly (8) mounted such that it can be moved by the shaft (2) from an extended position to a retracted position against the force of a spring (9) in order to actuate the switch (7). First and second coupling flanges (11, 13) project out from the shaft (2) and the support (6) respectively. Said first and second flanges (11 and 13) are adapted to be coupled to one another by moving the support (6) axially in relation to the base part (1) and subsequently rotating the support (6) in relation to the base part (1). In addition, stop elements (14, 15) limit the rotation of the support (6) in relation to the base part (1).

Description

Push button switch unit.

Technical sector

The present invention concerns a unit of push button switch incorporating a base body, a support carrier of a switch and an actuator assembly. The base body and the support are provided with respective elements of mutual coupling to make a releasable connection between the support and base body.

Prior art

Pushbutton switch units are known in which a base body has a rod adapted to be passed to through an opening of a panel, said rod having a exterior configuration, such as thread thread, adapted for coupling a fixing element, such as by example a nut, for joining said base body to said panel.  An actuator assembly that defines a push button and a stem is mounted on the base body so that it can be displaced from an extended position to a retracted position against the thrust of an elastic element for actuating an actuator of a switch mounted on a bracket fixed to the lower end of said rod by means of mutual coupling elements.

By patent EP-A-1087414 is known a unit of push-button switch of the type described above in which said mutual coupling elements comprise arms transversely elastic formed in the support, with a projection cross section provided at the end of each of said arms elastic, and corresponding openings formed at one end of a cane of the base body. The transverse projections are capable  to fit tightly in said openings by deformation elastic of the mentioned transversely elastic arms.

The patent US-A-4251703 describes a button push button applicable to a push button switch. The push button comprises an outer part mounted in a guided way to be axially displaced, and an inner part fixed to said part exterior, said inner part being adapted to receive the force of a spring and to press an actuator of the switch when the button is pressed against the force of said dock. The inner piece can be inserted in the outer piece from above and fixed to it by a type closure bayonet that involves an axial displacement followed by a turn of the inner piece in relation to the outer piece. About the piece Outside a lid is arranged. The purpose of the inner piece Detachable is to allow a spring change to adapt the force from spring thrust to different needs.

Exhibition of the invention

The present invention provides a unit of push button switch of the type comprising a base body, a carrier support of at least one switch and an actuator assembly. The mentioned base body has a rod adapted to be passed to through an opening of a panel, and said rod has a exterior configuration adapted for joining the base body to the aforementioned  panel. The said support is fixed at one end of the rod of the base body, and said actuator assembly is mounted so that can be moved through said rod from a position extended to a retracted position against the thrust of an element elastic to actuate an actuator of said switch. In the support and at said end of the rod are arranged about respective mutual coupling elements to effect a releasable connection of the support to the base body. The unit of push button switch according to the present invention is characterized in that said mutual coupling elements they comprise first coupling tabs that extend cantilever formed at the end of the base body shank, and second coupling tabs that extend in cantilever formed in the support, said first and second tabs being of coupling arranged substantially at the same distance from a longitudinal axis of the shank and of the support and adapted for engage each other by an axial displacement of the support in relationship with the base piece followed by a rotation of the support in relationship with the base piece, at least one first being arranged stop to limit said rotation of the support in relation to the piece base in an angular position of coupling.

In an embodiment, the cane of the body base incorporates a number of first pins distributed regularly around a central axis, extending the corresponding first coupling tabs from about ends of said first pins. In a similar way, the support It has an equal number of second pins distributed regularly around a central axis, and the second tabs coupling extend from ends of said second sideburns.

In another embodiment, the first coupling tabs extend from the first pins formed at the end of the shank of the base body while the second coupling tabs extend directly from a peripheral outer surface of the support.

In both cases, the tabs of coupling provide a robust and secure connection that can be established or released in an easy and fast way. Also, at said connection of the elastic deformation of the elements that integrate it, as with some of the units of state of the art switch, there is no risk of fatigue breakage of such mutual coupling elements or of failure due to elastic deformation thereof.

The push button switch unit of the The present invention also provides, according to another example of realization, slits formed in the cane of the base body for define elastic tabs, each of which has a wedge surface adapted to cooperate with an edge of a opening of the panel to elastically deform said tongue and a retaining surface adapted to engage the panel after the  elastic recovery of the tongue in order to join the body panel base. In addition, the unit includes a supplementary element provided with an opening adapted to the outer contour of the rod and an outer perimeter surface adapted to a surface exterior of the base body, more specifically, a surface exterior of a perimeter wall that defines a bowl in a base body end. This bowl is adapted to receive the push button and has an outer surface adapted to lean on the panel. The mentioned opening of the element supplementary has a first edge adapted to cooperate with said wedge surface to elastically deform said tongue and a second opposite edge adapted to mate with said tongue retention surface.

The distance between the mentioned surface of tongue retention and an outer supporting surface of said bowl is substantially equivalent to the sum of the thicknesses of the panel and said supplementary element. With it, the supplementary element can be installed interchangeably in a exposed side of the panel, to provide a profile bowl high, and on a hidden side of the panel, to provide a bowl Low profile

Brief description of the drawings

The advantages and characteristics of this invention will be more fully understood from the following detailed description of an exemplary embodiment with reference to the attached drawings, in which:

Fig. 1 is a perspective view in explosion of a push button switch unit according to a exemplary embodiment of the present invention;

Fig. 2 is a bottom perspective view which shows an actuator assembly and a base part that are part of the unit of Fig. 1 ready to be assembled;

Fig. 3 is a top perspective view. showing a support that is part of the unit of Fig. 1, which carries a switch and a lighting element;

Fig. 4 is a top plan view of the push button switch unit of Fig. 1 assembled;

Fig. 5 is a cross-sectional view taken along the plane V-V of Fig. 4;

Fig. 6 is a cross-sectional view taken by plane VI-VI of Fig. 4;

Fig. 7 is a bottom perspective view of a base piece and a support that are part of a unit of push button switch according to another embodiment of the present invention, ready to be assembled;

Fig. 7A is a detailed sectional view. cross section illustrating the mutual coupling of first and second tabs to make a releasable connection of a support to a base body in the unit of Fig. 7;

Fig. 8 is a top perspective view of a base piece and a supplementary element that are part of a push button switch unit according to yet another exemplary embodiment of the present invention, in disposition of be assembled to a panel according to a first variant of mounting;

Fig. 9 is a side view of the one unit of the push-button switch of which the parts of Fig. 8 assembled to a panel according to said first variant of assembly, showing the panel in cross section; Y

Fig. 10 is a side view of the one unit of the push-button switch of which the parts of Fig. 8 assembled to said panel according to a second variant of assembly, showing the panel in cross section.

Detailed description of an embodiment example

In the different figures that accompany the following description the same references have been used numeric to designate equal or equivalent elements. The "superior" and "inferior" terms and their derivatives make reference to the position of the elements in the figures. The "axial" and "radial" terms refer to an axis central longitudinal in whose direction the button moves button and in relation to which the Main elements

Referring first to Figs. 1 to 6, a push button switch unit is described according with an exemplary embodiment of the present invention, which it comprises a base body 1 which in its upper part includes a perimeter wall 47 defining a bowl 20, and a rod 2, hollow, which extends inferiorly from said bowl 20. The mentioned rod 2 is adapted to be passed through a opening 3 of a panel 4 (Figs. 5 and 6) until a surface outer support 43 of said bowl 20 makes contact with a exposed side of panel 4. Reed 2 has a configuration exterior adapted for joining said base body 1 to said panel 4. In this exemplary embodiment, said configuration Outside the rod 2 includes two alternative fixing means. One such fixing means is an external thread thread 21 (Fig. 2) adapted for coupling an element of fixing 5, such as a nut, which has a corresponding threaded internal thread 35 (Fig. 1) and a support surface 36 adapted to make contact with panel 4 or with an element interposed, such as a washer (not shown). The other of sayings alternative fixing means comprises a pair of tabs elastic 40 defined in the reed 2 by means of slits 37. Each of said tabs 40 is provided with a surface in wedge 41 adapted to cooperate with an edge of the opening 3 of the panel 4 to elastically deform said tongue 40 and a retaining surface 42, preferably stepped, adapted to engage with panel 4 after the elastic recovery of the tab 40. With these alternative fixing means, the unit Push button switch can be fixed to panel 4 by insertion under pressure from the exposed side of panel 4. The fixing can be released by pressing on the tabs 40 to force its elastic deformation

Optionally, said outer surface of support 43 of the bowl 20 of the base body 1 rests on a base 26 arranged between the base body 1 and the panel 4. The mentioned base 26 has a corresponding outer surface of support to rest on the panel 4 and an opening 27 for the step of the reed 2 of the base body 1. The unit includes a support 6 in which at least one switch 7 and at least one lighting element 17 arranged in a central area. This support 6 is adapted to be fixed at a lower end of the rod 2 of the base body 1 with said lighting element 17 inserted inside the reed 2 of the base body 1. Finally, the unit includes an actuator assembly 8 that defines a push button 22 at the top and a hollow rod 23 that is extends downward from said push button 22. In the example of embodiment shown in Figs. 1 to 6, the mentioned set actuator 8 is formed by a base piece 24 that defines the mentioned rod 23 and a widened upper part 34 in which fits a cover 25 of a translucent or transparent material. In an interior space of said cover 25 a sheet 26 of a translucent or transparent material that can carry graphic or written information.

Actuator assembly 8 is mounted on the body base 1 with the part that forms the push button 22 housed in the bowl 20 and rod 23 inserted in rod 2, so that the actuator assembly 8 can axially slide a path limited between an extended position and a retracted position. A elastic element 9 (Figs. 5 and 6) is arranged to push the actuator assembly 8 towards its extended position, so that the actuator assembly 8 can be displaced through said rod 2 from the extended position to said position retracted against the thrust of said elastic element 9 to actuate an organ actuator of said switch 7. The lighting element 17 remains further inserted into the rod 23 of the actuator assembly 8, of so that the light coming from the lighting element 17 is emitted through sheet 26 and cover 25 of the push button 22. However, it should be noted that the inclusion of the element of lighting 17 is optional, and its presence is not essential for the present invention

In relation to Figs. 2 and 3 are described to then some mutually coupled elements arranged respectively on said support 6 and on said lower end of the rod 2 to make a releasable connection of the support 6 to the base body 1. These mutual coupling elements comprise, on the one hand, first pins 10 that project axially of the end of the reed 2 of the base body 1 (Fig. 2). The mentioned first pins 10, in number of four, are distributed regularly around a longitudinal axis of rod 2 and arranged at a first distance from it. From the ends of the first pins 10 extends radially cantilever towards were corresponding first coupling tabs 11. On the other hand, the mutual coupling elements comprise some second pins 12 protruding axially from the support 6 (Fig. 3). These second pins 12 are in the same number, that is, in number of four, spread regularly around an axis longitudinal of the support 6, which is aligned with the mentioned longitudinal axis of the rod 2, and arranged at a second distance thereof, said second distance being greater than said first distance. From the ends of the second pins 12, radially cantilever inward corresponding ones  second coupling tabs 13.

The second coupling tabs 13 of the support 6 are adapted to be arranged adjacent to the first coupling tabs 11 of the base body 1 by means of a approach in the axial direction of the support 6 to the base body 1 until you put them in touch. Such an approach is made with the support 6 arranged in an angular release position in relationship with the base body 1. From this position, the second coupling tabs 13 of the support 6 are adapted to be superimposed and coupled with said first tabs coupling 11 of the base body 1 for subsequent rotation of the support 6 in relation to the base part 1 from said position angular release to an angular coupling position. To separate the support 6 from the base body 1, it is enough to perform some reverse operations. Although an example is shown in the figures of realization with four first and four second pins 10, 12, it is obvious that for the purposes of the present invention any other number of first and second pins 10, 12 different from four It would give an equivalent result.

As shown in Fig. 3, each of the second pins 12 is attached to one end of a partition peripheral 18 formed in the support 6, and between the opposite end of each of said peripheral partitions 18 and the second pin 12 adjacent thereto is formed a space 19 adapted to allow insertion in the axial direction of a corresponding first pin 10 and first coupling flange 11 of the body base 1. This space 19 is delimited axially by a insertion boundary surface that limits the insertion of first coupling tabs 11 in the axial direction. In a area of the inner support 6 to the mentioned peripheral partitions 18 other partitions are formed that have a defining end a first stop 14 adapted to interfere with the first pins 10 in order to limit said rotation of the support 6 in relationship with the base part 1 in said angular position of coupling, and another end defining a second stop 15 arranged to interfere with the first pins 10 in order to limit the rotation of the support 6 in relation to the base part 1 in the angular position of release.

Obviously, for the purpose of the present invention a single first stop 14 and a single second stop would suffice 15, and / or optionally the first and second stops 14, 15 could be configured in other ways than shown in the figures or willing to interfere with other parts of the body base 1 to limit its rotation as they might occur to Those skilled in the art. In the embodiment example shown in Fig. 3, there is one of said partitions with the first and second stops 14, 15 arranged between each of the second adjacent pins 12, except between two of them. This is so because in an area of the support 6 that would otherwise occupy the missing partition there is an opening 16 through which the actuator assembly 8 accesses said actuator of the switch 7.

Turning on Fig. 2, the displacement axial towards said extended position, that is, towards outside, of the actuator assembly 8 in relation to the base body 1 is limited by the interference of nails 28 formed in the base body 1 with the ends of corresponding holes elongated 29 formed in the actuator assembly 8. Those mentioned nails 28 extend radially inward from an edge of a opening 31 formed in a bottom wall 33 at the lower end of the cane 2 of the base body 1, while said holes elongated 29 are formed in respective elastic tabs 30 defined by pairs of axial slits 32 formed in the rod 23 of the actuator assembly 8. The aforementioned tabs elastic 30 are elastically deformed when the assembly actuator 8 is inserted into the base body 1 at the time of the assembly, until the nails 28 are inserted in the holes elongated 29, from which moment, an elastic recovery of the elastic tabs 30 keeps the actuator assembly 8 retained with respect to the base body 1 with the possibility of a limited axial displacement.

In Fig. 4 a top view of the assembled push button switch unit on which they are indicated lines V-V and VI-VI that  define the planes of the cross-sectional views shown in Figs. 5 and 6, respectively.

In Figs. 5 and 6 are shown in section transverse assembly of the push button switch unit to panel 4 using one of the mentioned fixing means alternatives, that is, the nut 5 coupled to the threaded thread 21 of the reed 2 of the base body 1 to keep it fixed to the panel 4. The elastic element 9 is in the form of a spring compression helical disposed between the base body 1 and the actuator assembly 8 to push the latter into position extended. In Fig. 5 you can see the second tabs of coupling 13 extending from the ends of the second pins 12 of support 6 coupled with the first tabs of coupling 11 extending from the ends of the first pins 10 of the base body 1 to make a releasable connection from support 6 to the base body 1. In Fig. 6 you can see the nails 28 of base body 1 inserted in elongated holes 29 formed on the elastic tabs 30 of the actuator assembly 8 for limit axial displacement out of actuator assembly 8 pushed by the spring 9.

In relation to Fig. 7, a another embodiment of the present invention follows in relation to the elements of mutual coupling to effect the releasable connection of the support 6 to the base body 1. For the purpose of more clarity, only the base body 1 is shown in Fig. 7 and the support 6, which carries the switch 7 and the element of Illumination 17. Obviously, the push button switch unit will include an actuator assembly 8 analogous or equivalent to that described above in relation to the exemplary embodiment of Figs. one to 6.

In the exemplary embodiment of Fig. 7, from the lower end of the reed 2 of the base body 1 project axially down a few first pins 10 from whose ends extend radially inward the first tabs of coupling 11, while the second tabs of coupling 13 extend radially outward directly from an outer surface of the support 6. To one of the sides of each first pin 10 and corresponding first tab of coupling 11 is attached a wall that has a first face inside which constitutes the first stop 14 to limit the rotation of the support 6 in relation to the base part 1 in the angular position of coupling and a second outer face, opposite, which provides the second stop 15 arranged to limit the rotation of the support 6 in relationship with the base part 1 in the angular position of release.

Between the free side of each first pin 10 with its corresponding first coupling tab 11 and each second stop 15 attached to the first pin 10 and corresponding first adjacent coupling tab 11 there is a space 39 adapted for insertion in the axial direction of a corresponding second coupling tab 13 of the support 6. The  mentioned space 39 is axially delimited by a surface insertion limit against which the second ones make contact coupling tabs 13 of the support 6 when the support 6 is approximate to base body 1 in angular release position prior to the rotation of the support 6 from the angular position of release to angular coupling position.

In the exemplary embodiment of Fig. 7, some respective mutual contact surfaces of the first and second coupling tabs 11, 13 comprise some retention configurations intended to retain support 6 in the angular position of coupling in relation to the base body 1. Thus, as shown in greater detail in Fig. 7A, in said contact surface of one or more of the first tabs of coupling 11 is formed a hole 48 adapted to receive a projection 38 formed on the contact surface of the corresponding second coupling tab 13. The insert of said projection 38 in said hole 48 is effected by virtue of a small elastic deformation of the corresponding first and / or second coupling tab 11, 13. Obviously, for the purpose of present invention the projection 38 could be formed in the first coupling tab 11 and hole 48 in the second coupling tab 13 with an equivalent result.

In relation to Figs. 8 to 10 describes then another example of embodiment of the switch unit button of the present invention in which the mentioned external configuration of the rod 2 includes fixing means Alternative In Fig. 8 only the base body 1 of that of the push button switch unit of this exemplary embodiment, which includes first 10 pins and first tabs of coupling 11 for coupling with a support similar to support 6 shown in the exemplary embodiment of Fig. 7. In this example of embodiment, the base body 1 is associated with an element supplementary 44 provided with an opening 45 adapted to the contour outside of the reed 2 and an outer perimeter surface 46 adapted to an outer surface of the perimeter wall 47 which defines the bowl 20 at one end of the base body 1. The element supplementary 44 has a suitable thickness to provide a high profile bowl 20 when installed between bowl 20 of the base body 1 and the panel 4, as shown in Fig. 9.

In the reed 2 of the base body 1 they are formed slits 37 defining a pair of elastic tabs 40 in opposite sides of the reed 2. Each of said tabs 40 has a prominent portion comprising a wedge surface 41 adapted to cooperate with an edge of the opening 3 of the panel 4 in order to elastically deform said tongue 40 when the base body 1 is inserted under pressure through the opening 3 of panel 4, and a retaining surface 42 adapted to engage with the edge of the opening 3 of the panel 4 after the elastic recovery of the tongue 40. The distance between said retention surface 42 of the tongue 40 and the surface outer support 43 of said bowl 20 is substantially equivalent to the sum of the thicknesses of panel 4 and the element supplementary 44. Preferably, the retention surface 42 of tongue 40 is staggered to accommodate a range of panel 4 thicknesses and / or dimensional tolerances of panel 4 and of the supplementary element 44.

In the assembly example of Fig. 9, the supplementary element 44 is installed between the bowl 20 of the base body 1 and panel 4, with rod 2 of base body 1 passed first through the opening 45 of the supplementary element 44 and then through the opening 3 of the panel 4. The surfaces of retention 42 of the tabs 40 is coupled to the hidden face of panel 4 next to the edge of its opening 3. With this arrangement, the bowl 20 has a high profile.

The opening 45 of the supplementary element 44 it has a first edge, or upper edge, adapted to cooperate with said wedge surface 41 of the tabs 40 to deform elastically said tongue 40 and a second edge, or edge opposite bottom, adapted to engage with said surface of retention 42 of the tongue 40, analogously to how they would the edges of the opening 3 of the panel 4. Thus, the element supplementary 44 can be installed alternately adjacent to the hidden face of panel 4 to provide a bowl 2 of low profile, as shown in Fig. 10.

In the assembly example of Fig. 10, the supplementary element 44 is installed between panel 4 and the tabs 40 of the base body 1, with the reed 2 of the base body 1 passed first through opening 3 of panel 4 and then to through the opening 45 of the supplementary element 44. The retention surfaces 42 of the tabs 40 are coupled to a lower face of the supplementary element 44 next to the edge of its opening 45. With this arrangement, the bowl 20 has a low profile.

Thus, the supplementary element 44 may be installed interchangeably on the exposed side of panel 4, to provide a high profile bowl 20, and on a hidden side of panel 4, to provide a low profile bowl 20.

A subject matter expert will be able to introduce variations and modifications in the example of embodiment shown and described without departing from the scope of the present invention as defined in the claims attached.

Claims (16)

1. Push button switch unit, of the type comprising a base body (1) with a reed (2) adapted to be passed through an opening (3) of a panel (4), said reed (2) having a exterior configuration adapted for joining said base body (1) to said panel (4); a support (6) carrying at least one switch (7) fixed at one end of the shaft (2) of the base body (1); and an actuator assembly (8) mounted so that it can be moved through said rod (2) from an extended position to a retracted position against the thrust of an elastic element (9) to drive an actuator member of said switch (7 ), being arranged in said support (6) and at said end of the rod (2) respective mutual coupling elements to effect a releasable connection of the support (6) to the base body (1), characterized in that said mutual coupling elements they comprise first coupling tabs (11) that extend in a cantilever formed in the reed (2) of the base body (1), and second coupling tabs (13) that extend in a cantilever formed in the support (6), said first and second coupling tabs (11, 13) being arranged substantially at the same distance from a longitudinal axis of the rod (2) and the support (6) and adapted to engage each other by an axial displacement of the s oportion (6) in relation to the base part (1) followed by a rotation of the support (6) in relation to the base part (1), at least a first stop (14) being arranged to limit said support rotation (6 ) in relation to the base part (1) in an angular coupling position. 2. Unit according to claim 1, characterized in that the first and second coupling tabs (11, 13) extend from the ends of corresponding first and second pins (10, 12) projecting axially from the end of the rod (2) of the base body (1) and of the support (6), respectively. 3. Unit, according to claim 2, characterized in that it comprises a number of said first pins (10) arranged at a first distance from said longitudinal axis and regularly distributed around it, the first coupling tabs (11) extending radially in cantilever outward from the ends of the first pins (10), and an equal number of said second pins (12) are arranged at a second distance from the longitudinal axis and regularly distributed around it, said second distance being greater than said first distance , the second coupling flanges (13) extending radially cantilever inwardly from the ends of the second pins (12). Unit, according to claim 3, characterized in that it comprises at least a second stop (15) arranged to limit the rotation of the support (6) in relation to the base piece (1) in an angular position of release. 5. Unit, according to claim 4, characterized in that said first and second stops (14, 15) are materialized by the ends of partitions formed in the support (6). 6. Unit, according to claim 5, characterized in that it includes several of said partitions arranged around the longitudinal axis, each between two adjacent second pins (12), except in an area of the support (6) in which a opening (16) for access of the actuator assembly (8) to said actuator of said switch (7). 7. Unit, according to claim 3, characterized in that each of said second pins (12) is connected to one end of a peripheral partition (18), being formed between the opposite end of each of said partitions (18) and the second pin (12) adjacent thereto a space (19) adapted for insertion in the axial direction of a corresponding first pin (10) and corresponding first coupling flange (11) of the base body (1), said space being (19) axially delimited by an insertion boundary surface. 8. Unit according to claim 1, characterized in that the first coupling tabs (11) extend radially inwardly from the ends of corresponding first pins (10) projecting axially from the end of the shaft (2) of the body base (1), and the second coupling tabs (13) extend radially outwardly from an outer surface of the support (6). Unit according to claim 8, characterized in that said first stop (14) is provided by a first face of a wall laterally attached to each first pin (10) and corresponding first coupling flange (11), and because a second opposite face of said wall provides a second stop (15) arranged to limit the rotation of the support (6) in relation to the base piece (1) in an angular position of release. 10. Unit according to claim 9, characterized in that between each first pin (10) and corresponding first coupling tabs (11) and each second stop (15) there is a space (39) adapted for insertion in the axial direction of a corresponding second coupling flange (13) of the support (6), said space (39) being axially delimited by an insertion boundary surface. Unit according to claim 1, characterized in that the first and second coupling tabs (11, 13) have respective mutual contact surfaces, said contact surface being formed of at least one of the first coupling tabs (11) a hole (48) adapted to receive a corresponding projection (38) formed on the contact surface of at least one of the second coupling tabs (13), or vice versa. 12. Unit according to claim 1, characterized in that the support (6) is adapted to further support at least one lighting element (17) arranged in a central area and adapted to be inserted inside the reed (2 ) and of said actuator assembly (8). 13. Unit according to claim 1, characterized in that said external configuration of the shaft (2) adapted for joining the base body (1) to the panel (4) comprises an external thread thread (21) adapted for coupling a fixing element (5) provided with an internal thread thread (35) and a support surface (36) adapted to make contact with the panel (4) or with an interposed element. 14. Unit according to claim 1, characterized in that said outer configuration of the shaft (2) adapted for joining the base body (1) to the panel (4) comprises slits (37) defining at least one elastic tongue ( 40) provided with a wedge surface (41) adapted to cooperate with an edge of said opening (3) of the panel (4) to elastically deform said elastic tongue (40) and a retaining surface (42) adapted to engage with the panel (4) after elastic recovery of the elastic tongue (40). 15. Unit according to claim 14, characterized in that it comprises a supplementary element (44) provided with an opening (45) adapted to the outer contour of the shaft (2) and an outer perimeter edge (46) adapted to an outer surface of a perimeter wall (47) defining a bowl (48) at one end of the base body (1), wherein said opening (45) has a first edge adapted to cooperate with said wedge surface (41) to elastically deform said tongue elastic (40) and a second opposite edge adapted to engage said retention surface (42) of the elastic tongue (40), a distance between said retention surface (42) of the elastic tongue (40) and an outer surface of support (43) of said bowl (48) substantially equivalent to the sum of the thicknesses of the panel (4) and of said supplementary element (44), whereby the supplementary element (44) can be installed interchangeably on one side exposed from the panel (4), to provide a bowl (48) of high profile, and on a hidden side of the panel (4), to provide a bowl (48) of low profile. 16. Unit according to claim 14 or 15, characterized in that said retention surface (42) of the elastic tongue (40) is stepped to accommodate a range of panel thicknesses (4).