WO2014009977A1

WO2014009977A1 - Valve unit for controlling the fluid supply of an actuator of a mobile device

Info

Publication number: WO2014009977A1
Application number: PCT/IT2012/000210
Authority: WO
Inventors: Giuseppe Balotelli
Original assignee: Giuseppe Balotelli
Priority date: 2012-07-10
Filing date: 2012-07-10
Publication date: 2014-01-16

Abstract

A valve unit (1,100) for controlling the fluid supply of an actuator (2) of a mobile device (3) comprises a unit body (10), at least two valve seats (12) with an axial extension made in said unit body, and at least two valves (14a, b) housed in the respective valve seats. Each valve comprises a valve obturator (16) axially mobile in its respective seat between a rearward position, wherein it prevents the transit of fluid towards a respective actuation chamber or from at least one actua- tion chamber to a discharge duct, and a forward position wherein it permit said passage of fluid. Said obturator has a proximal end (12') engageable by a presser organ (210) of a fluid supply unit (200).

Description

"Valve unit for controlling the fluid supply of an actuator of a mobile device"

DESCRIPTION

[001] . The present invention relates to a valve unit for controlling the fluid supply of an actuator of a mobile device operable by a pres surised _. fluid, a mobile device fitted with said valve unit, and a fluid supply assembly of said mobile device.

[002] The present invention is aimed in particular at the sector of piece processing machines and assembly machines, where gripping organs of the pieces which must be moved to subject the pieces to various processes or to transfer the pieces from one station to another are for example present.

[003] As is known, the gripping organs comprise at least one mobile part suitable for moving closer to/away from a fixed part or another mobile part for the support and release of a piece. To move such mobile parts, each gripping organ is provided with at least one actuator which can be supplied with a pressurised fluid, such as compressed air in the case of assembly machines and oil in the case of processing machines. One of the drawbacks of these machines, especially in the case of large scale plants, consists of the fact that the mobility of the gripping organ is obstructed and limited by the need to supply the relative actuators through supply and/or discharge tubes which must remain connected to the gripping organs. To try and overcome such drawback, some machines are fitted with distribution organs of the supply fluid which substantially reduce the distance between the source of the pressurised fluid and the mobile devices to be supplied. Even though the mobility of the mobile devices is slightly improved thanks to such distributors, the drawbacks caused by the fact of having to keep at least one tube permanently connected to the mobile device remain.

[004] The purpose of the present invention is to propose a valve unit and fluid supply assembly able to definitively eliminate the drawbacks complained of above, related to the fluidic connection of the mobile devices to a fixed fluid supply source.

[005] Such purpose is achieved by a valve unit according to claim 1, by a mobile device according to claim 13 and by a fluid supply assembly according to claim 16. The dependent claims describe preferred or advantageous embodiments of the invention.

[006] The characteristics and advantages of the valve unit, mobile device and fluid supply assembly according to the invention will be more clearly comprehensible from the description given below of its preferred embodiments, made by way of a non-limiting example, with reference to the appended drawings , wherein:

[007] - figure 1 shows, in cross-section, a valve unit according to the present invention, in a first embodiment;

[008] - figures 2a -2f show the same number of steps of a fluid supply cycle of a mobile device performed with the valve unit in figure 1;

[009] - figure 3 shows, in cross-section, a fluid supply assembly comprising a fluid supply unit and a valve unit, in a second embodiment;

[0010] - figures 4a -4d show the same number of steps of a fluid supply cycle of a mobile device performed with the valve unit in figure 3;

[0011]- figure 5 shows, in cross-section, a fluid supply assembly comprising the fluid supply unit in figure 3 and a fluid supply unit in an embodiment variation, particularly suitable when the fluid supplied is not dispersible in the atmosphere;

[0012] - figure 6 is a partial cross-section view of the fluid supply assembly in figure 3 or 5;

[0013]- figure 7 shows, in cross-section, the actuator means of the fluid supply unit in figure 3 or 5;

[0014] - figure 8 show the discs of the shovel valves in figures 3 or 5 or 6; and [0015] - figures 9 and 9a show an example of a mobile device supplied by a fluid supply assembly according to the invention, with a mobile device in two operating positions .

[0016] In said drawings, reference numeral 1; 100 globally denotes a valve unit for controlling the fluid supply of an actuator 2 of a mobile device 3 operable by a pressurised fluid, according to the invention. For example said mobile device 3 is a gripping device of a piece of a processing machine or assembly machine. In this case, at least one arm of the gripping organ is movable in relation to the other and the movement of said arm is provided by a respective actuator 2, such as a hydraulic or pneumatic cylinder. The pressurised fluid is supplied to the valve unit 1; 100 by a fluid supply unit 200, described in more detail below.

[0017] In the description which follows, the elements common to or equivalent elements of the various embodiments of the invention have been indicated with the same reference numerals.

[0018] According to a general embodiment, the valve unit 1; 100 comprises a unit body 10 wherein at least two valve seats 12 having an axial extension and preferably parallel to each other are made Each of said valve seats 12 has a proximal end 12' open to the outside and a fluid supply aperture 12A", 12B" in fluidic communication with a respective actuation chamber 2a, 2b of the actuator 2 of the mobile device 3.

[0019] Each valve seat 12 houses a respective control valve 14A, 14B of the flow of pressurised fluid to and from a respective actuation chamber 2a, 2b. In particular each valve comprises a valve obturator 16 axially mobile in its respective seat 12 between a rearward position, in which it prevents the transit of fluid from said fluid supply unit 200 to a respective actuation chamber 2a, 2b or from at least one actuation chamber 2a, 2b to a discharge duct 18; 218, and a forward position, in which it permits said transit of fluid. Said valve obturator 16 has a proximal end 16' engageable by a presser organ 210 of the fluid supply unit 200. In other words, the valve obturator 16 ends with a proximal end 16' facing the open proximal end 12' of the valve seat 12 and therefore accessible by the presser organ 210. As will be described below, it is said presser organ 210 which moves the valve obturator 16 from the rearward position to the forward position .

[0020] According to a preferred embodiment, each valve obturator 16 is crossed by a chamber supply duct 20 suitable for placing the fluid supply unit 200 in fluidic communication with a respective chamber 2a, 2b of the actuator 2 of the mobile device 3.

[0021] In one embodiment, the proximal end 12' of each valve seat supports a sealing element 22 axially distanced outwards in relation to the proximal end 16' of the valve obturator 16 and suitable for forming a radial seal with the outer surface of an end portion of the presser organ 210. In other words, when the valve obturator 16 is in a rearward position, its proximal end 16' is inside the valve seat distanced in relation to the open end 12' of said valve seat. Consequently, the proximal end 12' of the valve seat 12 defines an intake aperture 12" for the end portion of the presser organ 210, in such a way that said end portion of the presser organ 210 is inserted in a sealed manner in said intake aperture 12" even without pressing on the valve obturator 16. For example the sealing element 22 is supported by an entrance bush 24 inserted in the proximal end 12' of the valve seat 12.

[0022] In a preferred embodiment, each valve 14 comprises a fixed abutment element 26 defining an axial cavity 26' through which the valve obturator passes 16. Said abutment element 26 provides a radial distal surface 28, that is facing opposite the open proximal end 12' of the valve seat 12 and substantially orthogonal to the main axis of said seat, suitable for cooperating with an obturator sealing element 30 borne by the distal end 16" of the valve obturator projecting axially from said axial cavity 26' . When the valve obturator 16 is in a rearward position, said obturator sealing element 30 is in contact with said radial distal surface 28 so as to prevent the passage of pressurised fluid from the supply unit 200 to a distal portion 32 of the valve seat 12 in communication with an actuation chamber 2a, 2b. When the valve obturator 16 is in a forward position, said obturator sealing element 30 is axially distanced from said radial distal surface 28 so as to permit the passage of pressurised fluid from the supply unit 200 to said distal portion 32 of the valve seat 12. It is to be noted that the presence of pressurised fluid in the distal portion 32 of the valve seat 12 facilitates the sealing action exerted by the obturator sealing element 30.

[0023] For example in the case in which the pressurised fluid circulates through the chamber supply duct 20 made in the valve obturator 16, as in the example shown, the outer lateral surface of the valve obturator 16 and the inner lateral surface of the abutment element 26 define between them an inner annular chamber 34 in fluidic communication with the chamber supply duct 20. So, when the valve obturator 16 is in the forward position, said inner annular chamber 34 is in fluidic communication with the distal portion 32 of the valve seat 12.

[0024] In a preferred embodiment, the fixed abutment element 26 further defines a proximal radial support surface 36 of an elastic means 38, for example a helical spring, acting on the valve obturator 16 so as to keep it or bring it back to a rearward position, when it is not pressed by the presser element 210.

[0025] Figures 1 and 2a-2e show a valve unit 1 in a particularly suitable embodiment for the supply of compressed air. In the body 10 of the unit a discharge duct 18 is made communicating with at least one of the valve seats 12 for the discharge of at least one actuation chamber 2a, 2 of the actuator 2. In this embodiment, the two valve seats 12 communicate fluidically with the same actuation chamber 2a, for example through a shared first exit duct 4 OA communicating with the distal portions 32 of the valve seats 12. A first valve 14A (the one on the right in the drawings) is operable to place the supply unit 200 in fluidic communication with said actuation chamber 2a; a second valve 14B (the one on the left in the drawings) is operable to place said actuation chamber 2a in fluidic communication with the discharge duct 18.

[0026] In addition, said second valve 14B is suitable for placing a second actuation chamber 2b in fluidic communication with the supply unit 200 while the first actuation chamber 2a is being discharged. In this case, the second valve 14B has a different configuration from the first. In particular the fixed abutment element 26 of the second valve 14B defines, with the inner wall of the valve seat 12, an outer annular chamber 42 communicating with the discharge duct 18 and with the inner annular chamber 34. Consequently, when the valve obturator 16 is in the forward position, a first actuation chamber 2a is placed in fluidic communication with the discharge duct 18 through said inner 34 and outer 42 annular chambers.

[0027] At the axial portion of valve seat 12 between the fixed abutment element 26 and the proximal end 12', the valve obturator 16 forms, with the inner lateral wall of the valve seat 12, a proximal annular chamber 44which places the chamber supply duct 20 made in the valve obturator 16 with a second exit duct 12B" connected to the second actuation chamber 2b.

[0028] In one embodiment shown in figures 3 and 4a-4d, the second valve 14B is the same as the first valve 14A and each is in communication with a respective actuation chamber 2a, 2b, through a respective exit duct 40A, 40B. In this case, therefore, said exit duct 40A, 40B is used both to supply the respective actuation chamber with the pressurised fluid, and to discharge said actuation chamber, in both cases, through the valves 14A, 14 and the associated supply unit 200. The valves and supply unit are to such purpose alternatively connectable to a source of pressurised fluid 212 and to a drain 218.

[0029] As anticipated above, each valve obturator 16 is engageable by a presser organ 210 of a supply unit 200 associable with the valve unit 1; 100 described.

[0030] One aspect of the invention relates therefore to a fluid supply assembly of an actuator of a mobile device operable with a pressurised fluid, comprising a valve unit 1; 100 as described above and a fluid supply unit 200 which can be placed alongside the body 10 of the valve unit.

[0031] Said supply unit 200 comprises, for each of the valves of the valve unit, a presser organ 210 movable between a forward position, in which it is suitable for pressing a relative valve obturator 16 into a forward position, and a rearward position, in which it disengages from said valve obturator 16.

[0032] In a preferred embodiment, each presser organ 210 is crossed by a valve supply duct 214 suitable for fluidically communicating with a respective chamber supply duct 20 of the valve obturator 16 when said presser organ 210 is in a forward position, that is when the distal end 210' of the presser organ is inserted so as to be sealed in the intake aperture 12" of the valve seat 12. Said valve supply duct 214 is alternatively fluidically connectable to a source of pressurised fluid 212 or to a drain 218.

[0033] In a preferred embodiment, the supply unit 200 comprises a supply unit body 216 in which two chambers 220 are made, in each of which a piston 222 is housed, axially movable between a rearward position and a forward position. Each piston has a stem which, projecting from the body of the supply unit 216, forms the presser organ 210 suitable for engaging a respective valve obturator 16. Each chamber with the respective piston forms a supply cylinder 202 of the supply unit 200. Each chamber of said supply cylinder 202 is in fluidic communication with pressurised fluid actuator means 230 operable by a user for a contemporary or independent movement of said stems forming the presser organs 210 between the rearward position and the forward position.

[0034] In a preferred embodiment, said actuator means 230 comprise a shovel valve 232 controlled by a lever 234. Preferably, the shovel valve 232 with relative lever 234 is part of the supply unit 200 and is integral with the body of the supply unit 216. For example said body and shovel valve form a pistol-shaped device easy to transport and operate manually by the user. [0035] In one embodiment, each valve supply duct 214 is connected to a filler valve 240 operable by a user to connect one valve supply duct 214 to the supply source 212 of the pressurised fluid and the other valve supply duct 214 to a drain 218, or vice versa. To such purpose for example the proximal end of each stem forming the presser organ 210 projects rearwards from the body of the supply unit 216 so as to permit the valve supply duct 214 made axially inside said stem to be fluidically connected to the filler valve 240.

[0036] In a preferred embodiment, the adjacent ends of the supply unit 200 and of the valve unit 1; 100 are suitable for forming a reciprocal slotted coupling, so as to discharge onto the relative bodies the reaction generated by the thrust of the presser organs on the respective valve obturators. For example the body of the supply unit 200 ends, at the end of each presser organ 210 facing the respective valve obturator 16, with a hammer head 216' suitable for being inserted with a shaped coupling in a corresponding hammer seat 10' made in the body of the valve unit 10.

[0037] In an embodiment particularly suitable for the use of oil as the pressurised fluid, shown in figure 5, a check valve 250 is inserted either in said valve supply duct 214 of the presser organ 210 or in the supply duct of the valve obturator 16 suitable for opening when said presser organ 210 engages said valve obturator 16 and for closing as soon as said presser organ disengages from said valve obturator. This way, the moment the presser organ 210 detaches from the respective valve obturator 16, any oil still circulating in the valve supply duct does not leak outwards towards the free end of the presser organ 210. In the meantime, the valve 14A, 14B has already closed.

[0038] Figure 6 is an end view in partial cross-section of the supply assembly in figure 5, which shows an example of a filler valve 240 made with a shovel valve controlled by a butterfly lever 242.

[0039] Figure 7 shows, in cross-section, the shovel valve 232 which operates the supply unit 200 in figures 3 and 5. In the case of the supply unit in figure 5, the functioning of such shovel valve 232 is the same as that of the filler valve 240.

[0040] Figure 8 shows the arrangement of the passages made in the shovel valve 232 or 240. A first and a second supply hole PI and P2 diametrically opposite each other, and a discharge slot 261 angularly distanced by an angle a in relation to a supply hole, for example the first supply hole PI, are made in the rotating disc 260. The rotating disc 260 rotates in relation to a fixed disc 262, in which a third supply hole C, C; P_AR a fourth supply hole D, D'; P_B, and a discharge hole 263 are made. In the case of the actuation valve 232 of the valve unit 200, the third supply hole C, C is in fluidic communication with the front chambers of the supply cylinders 202, while the fourth supply hole D, D' is in fluidic communication with the rear chambers of the supply cylinders 202. In the case of the filler valve 240, the third and fourth supply holes P_A, P_B are in fluidic communication with the respective valve supply ducts 214 made in the presser organs 210.

[0041] When the shovel valve 232; 240 is in the rest position, the third supply hole C, C ¹ ; P_A, communicates with the first supply hole PI, while the fourth supply hole D, D ¹ ; P_B, communicates with the discharge slot 261. Upon rotation of the rotating disc 260 by an angle a, the second supply hole P2 will coincide with the fourth supply hole D, D'; P_B while the first hole C, C ' ; P_A will be placed in communication with the discharge slot 261.

[0042] Returning to the valve unit 1; 100, according to a preferred embodiment the body 10 of the unit is integral with the mobile device 3 to be supplied with a fluid.

[0043] One aspect of the invention relates therefore to a mobile device 3 operable by a pressurised fluid, comprising at least one mobile organ 4, at least one actuator 2 having at least two actuation chambers 2a, 2b which can be supplied with a pressurise fluid for the movement in at least two directions of said mobile organ 4 , and a valve unit 1; 100 as described in fluidic communication with said actuation chambers. Preferably, the mobile device 3 comprises a device body 3' which supplements the valve unit 1; 100.

[0044] In one advantageous embodiment, wherein the pressurised fluid is compressed air, the discharge duct 18 made in the body 10 of the valve unit 1 is directed towards the at least one mobile organ 4. This way, the compressed air discharged by an actuation chamber can be used to keep the mobile organ clean.

[0045] The functioning of the supply assembly in the embodiments described above will now be described.

[0046] With reference to the embodiment shown in figures 1 and 2a-2e, and relative to the version with one actuation chamber 2b, the second, communicating with the outside, starting from a rest configuration of the supply assembly, wherein both valves (figure 2e) are closed, the first actuation chamber is supplied by making a presser organ 210 interact with the valve obturator 16 of the first valve 14A and sending the pressurised flow into said valve, for example through the valve supply duct 20 made in the presser organ 16 (figure 2a) . The first ! 6

actuation chamber 2a is then pressurised, while the second chamber 2b is in communication with the outside through the second valve Γ4Β. Consequently, the actuator 2 of the mobile device 3 is commanded to perform a oneway movement .

[0047] Recalling the presser organ 210 to the rearward position causes the closure of the first valve 14Ά (figure 2b) . Thanks to the fact that the presser organ remains sealed in the intake aperture of the valve seat even after the valve has closed, it is possible to remove the fluid supply from the presser organ with the valve closed. Consequently, the valve unit remains exactly in the condition of pressurisation of the first chamber even when the supply unit is removed. The valve unit can thus be moved freely, for example together with the mobile device which it is an integral part of.

[0048] In the subsequent step illustrated in figure 2c, a presser organ 210 is commanded to act on the second valve 14B. The advancement of the valve obturator makes it possible to connect the first actuation chamber 2a to the discharge duct 18. In this step, the second valve 14B is not yet supplied by the supply unit and the two chambers are therefore both unpressurised . Subsequently, the supply unit 200 supplies the second valve 14B, and thereby the second actuation chamber 2b, while the first chamber is still discharging (figure 2d) . Consequently, the actuator of the mobile device inverts its stroke. By removing the supply unit, the second chamber is also discharged and the valve unit is rearmed for a new cycle ( figure 2e ) .

[0049] It is to be noted that in this implementation of the supply assembly according to the invention, the two presser organs 210 are commanded in subsequent steps of the command cycle of the actuator of the mobile device. For example if the two actuation chambers are pressurised in two separate work stations, each work station may be provided with a supply unit, which in this case may be fitted with a single supply cylinder 202.

[0050] In the embodiment shown in figures 3 and 4a-4d, relative to the version with both actuation chambers 2a, 2b closed by the respective valves 14A, 14B of the valve unit 100, and preferably utilisable with compressed air as the command fluid, the pistol body 216, 232 of the supply unit 200 is engaged in the two hammer seats 10' of the valve unit 100. For example alignment means 203, for example of the "snap" type, may be envisaged between the body 10 of the valve unit 100 and the body 216 of. the supply unit 200, suitable for ensuring the correct reciprocal positioning of said bodies in such a way that the presser organs 210 are perfectly coaxial with the respective valve obturators 16 (figure 4a) .

[0051] By operating the shovel valve 232 the insertion of the presser organ 210 in the valve unit 100 is caused and thereby the aperture of the valves 14A, 14B. At this point the filler valve 240 may be actuated, for example commanding it by pressure of the thumb. By means of said valve, one of the two actuation chambers (in the drawing the chamber 2b) is connected to a source of compressed air 212, such as a compressor, while the other is connected to a drain 218 (figure 4b) .

[0052] When the lever 234 of the shovel valve 232 is released, the front chambers of the two supply cylinders 202 are supplied, so as to recall the presser organs 210 to a rearward position. As soon as each presser organ 210 has detached itself from the relative valve obturator 16, the filler valve 240 can also be released. At this point, since the presser organs 210 are still sealed on the valve unit 100 when the two valves 14A, 14B are closed, the actuation chambers 2a, 2b remain in the desired position. By disengaging the supply unit 200 from the hammer seats 10', the mobile device 3 is left free to move, for example with the valve unit 100 integrated into it, where commanded, without any connection tube.

[0053] It is to be noted that once the actuator 2 of the mobile device 3 has been operated, it is possible to invert its movement by keeping the lever 234 of the shovel valve rotated and acting merely on the filler valve 240. The chamber which was discharging will be pressurised, while the pressurised chamber will be connected to the drain (figure 4c) .

[0054] With reference to the embodiment shown in figure 5, particularly suitable for use in a processing machine working on pressurised oil, at the end of a work cycle the supply unit 200 is inserted, in the form of a pistol device, in the hammer seats 10' of the valve unit 100. The choice of which of the two actuation chambers 2a, 2b to supply is made by rotating the butterfly of the filler valve 240. It is to be noted that, thanks to the presence of the check valve 250, no fluid leaks out of the supply unit 200.

[0055] The rear chambers of the supply cylinders 202 are supplied by the rear supply ducts D, D¹ by rotating the lever 234 of the shovel valve 232 by an angle a, letting the presser stems 210 slowly enter the respective valves 14A,14B. During the aperture of the valves 14A, 14B the check valves 250 are forced to open, thereby placing the actuation chambers 2a, 2b in communication with the ducts of the filler valve 240, which injects the pressurised fluid in the valve previously selected, while the other is left connected to the drain 218. [0056] Once the actuator 2 of the mobile device 3 has been operated, it is possible to invert its movement by keeping the lever 234 of the shovel valve rotated and acting merely on the filler valve 240. The chamber which was discharging will be pressurised, while the pressurised chamber will be connected to the drain.

[0057] When the lever 234 of the shovel valve is released, the front chambers of the supply cylinders are supplied by the front supply ducts C, C, making the presser stems move rearwards. Before said stems have come out of the valve unit 100 completely, that is have passed outside the sealing gaskets 22 of the intake apertures 12", the valves 14A, 14B have closed, as have the check valves 250. As a result, the ducts which were previously communicating are again sealed.

[0058] By detaching the supply unit 200 from the hammer seats 10' of the valve unit 100 the mobile device with the respective valves is rendered free again to be brought into the working position, without the constraint of connection tubes .

[0059] It is to be noted that in an embodiment variation, the actuation valves of the supply unit 232 and the filler valve 240 may be replaced by two solenoid valves and the cycle described above may be controlled by a control unit such as a PLC. [0060] Thanks to the valve unit and the supply assembly described above, it is thereby possible to remote an actuator of a mobile device in any position, without the limitation of constrained univocal fluid supplies.

[0061] A person skilled in the art may make modifications and adaptations to the embodiments of the invention, replacing elements with others functionally equivalent, so as to satisfy contingent requirements, while remaining within the sphere of protection of the following claims. Each of the characteristics described as belonging to a possible embodiment may be realised independently of the other embodiments described.

Claims

1. Valve unit for controlling the fluid supply of an actuator of a mobile device operable with a pressurised fluid coming from a supply unit, said valve unit comprising :

- a unit body;

- at least two valve seats with an axial extension made in said unit body, each of said valve seats having a proximal end open towards the outside and a supply aperture in fluidic communication with a respective actuation chamber of said actuator;

- at least two valves housed in the respective valve seats, each valve comprising a valve obturator axially mobile in its respective seat between a rearward position, wherein it prevents the transit of fluid from said supply unit to a respective actuation chamber or from at least one actuation chamber to a discharge duct, and a forward position, in which it permits said transit of fluid, said obturator having a proximal end engageable by a presser organ of the supply unit.

2. Valve unit according to the previous claim, wherein each valve obturator is traversed by a supply duct suitable for placing the supply unit in fluidic communication with the chambers of the actuator of the mobile device.

3. Valve unit according to claim 1 or 2, wherein each valve obturator is elastically influenced to return to a rearward position.

4. Valve unit according to any of the previous claims, wherein the proximal end of each valve seat supports a sealing element axially distanced outwards of the proximal end of the valve obturator and suitable for forming a radial seal with the outer surface of an end portion of the presser organ.

5. Valve unit according to any of the previous claims, wherein in the body unit a discharge duct is made communicating with at least one of the valve seats for the discharge of at least one actuation chamber of the actuator.

6. Valve unit according to the previous claim, wherein two valve seats communicate fluidically with the same first actuation chamber, wherein a first valve is operable to place the supply unit in fluidic communication with said actuation chamber, and wherein a second valve is operable to place said actuation chamber in fluidic communication with the discharge duct.

7. Valve unit according to the previous claim, wherein said second valve is suitable for placing a second actuation chamber in fluidic communication with the supply unit while the first actuation chamber is in discharge .

8. Valve unit according to any of the previous claims, wherein each valve comprise a fixed abutment element defining an axial cavity through which the valve obturator passes, said abutment element providing a radial distal surface suitable for cooperating with an obturator sealing element borne by the distal end of the valve obturator projecting axially from said axial cavity .

9. Valve unit according to the previous claim, wherein when the valve obturator is in a rearward position , said obturator sealing element is in contact with said radial distal surface so as to prevent the passage of the pressurised fluid from the supply unit to a distal portion of the valve seat in communication with an actuation chamber, and wherein when the valve obturator is in a forward position , said obturator sealing element is axially distanced from said radial distal surface so as to permit the passage of the pressurised fluid from the supply unit to said distal portion of the valve seat.

10. Valve unit according to claim 7 and 8, wherein said fixed abutment element defines an outer annular chamber communicating with the discharge duct, and wherein the mobile obturator of said second valve forms an inner annular chamber communicating with said outer annular chamber so that, when the valve obturator is in the forward position, one actuation chamber is placed in fluidic communication with the discharge duct through said inner and outer annular chambers.

11. Valve unit according to any of the claims 8-10, wherein said fixed abutment element defines a proximal radial support surface of a helical spring acting on the valve obturator.

12. Valve unit according to any of the previous claims, wherein the unit body is integral with the mobile device.

13. Mobile device operable by a pressurised fluid, comprising at least one mobile organ, at least one actuator having at least two actuation chambers which can be supplied with pressurised fluid for the movement in at least two directions of said mobile organ, and a valve unit according to any of the previous claims in fluidic communication with said actuation chambers .

14. Mobile device according to the previous claim, comprising a device body, wherein said valve unit is built into said device body.

15. Mobile device according to the previous claim, wherein said pressurised fluid is compressed air, and wherein the discharge duct made in the body of the valve unit is directed towards the at least one mobile organ.

16. Supply assembly of an actuator of a mobile device operable by a pressurised fluid, comprising a valve unit according to any of the claims from 1 to 12 and a supply unit which can be placed alongside the body of the valve unit and comprising, for each of the valves of said valve unit, a presser organ movable between a forward position, in which it is suitable for pressing a relative valve obturator into a forward position, and a rearward position, in which it disengages from said valve obturator .

17. Assembly according to the previous claim, wherein each presser organ is traversed by a valve supply duct suitable for fluidically communicating with a respective chamber supply duct of the obturator when said presser organ is in a forward position, said valve supply duct being alternatively fluidically connectable to a source of pressurised fluid or to a drain.

18. Assembly according to the previous claim, wherein said presser organ is in the form of a stem of a piston of a respective supply cylinder, the chambers of each supply cylinder being in fluidic communication with pressurised fluid actuator means operable by a user for a contemporary movement of said stems between the rearward position and the forward position.

19. Assembly according to the previous claim, wherein said actuator means comprise a shovel valve controllable by a lever.

20. Assembly according to any of the claims 17-19, wherein each valve supply duct is connected to a filler valve operable by a user to connect a valve supply duct to a supply source of the pressurised fluid and the other valve supply duct to a drain 218, or vice versa.

21. Assembly according to any of the claims 17-20, wherein the supply unit ends, at the end of each presser organ facing the respective valve obturator, with a hammer head suitable for being inserted with a shaped coupling in a corresponding hammer seat made in the body of the valve unit.

22. Assembly according to any of the claims 17-21, wherein a check valve is inserted in either said valve supply duct of the presser organ or in the supply duct of the valve obturator suitable for opening when said presser organ engages said valve obturator and to close as soon as said presser organ disengages from said valve obturator .