DESCRIPTION "A bleed device and an actuating tool for said device" [0001] . The subject of the present invention is a bleeding device for brake fluid, specifically a bleeding device suitable for being held in a calliper body comprised in a brake system of a vehicle such as a motor vehicle. [0002] . The invention further regards a bleeding tool suitable for operating said bleeding device. [0003] . Also forming part of the invention is a bleeding kit for hydraulic circuits comprising said bleeding device and/or said bleeding tool. [0004] . As is known, the hydraulic circuit of a braking system, usually on each brake, comprises at least one bleeding device usually formed by a threaded cap screwed into an opening of the hydraulic circuit and having a conical end which, when the cap is tight in the opening, closes an opening site acting as a valvular element. [0005] . A bleed channel is incised axially to the cap and is hydraulically connected to the hydraulic circuit when the cap is loosened. [0006] . The first filling of the hydraulic circuit with brake fluid is normally performed under vacuum, to avoid the need to bleed the circuit by loosening the bleed cap. [0007] . Subsequently, during brake maintenance and checking operations, the brake circuit is bled by- connecting the bleed channel to a bleed tube, which collects the bled fluid in a container, and pressurising the circuit with the cap closed, after which the cap is loosened to expel the air bubbles through the bleed channel, following which the cap and thus the circuit is re-closed. [0008] . The operation is repeated more than once for each brake, until the air or any other gases which might impede the braking operation are completely removed from the circuit. [0009] . Said brake fluid is usually an extremely aggressive and corrosive fluid, and it is thus necessary to take careful precautions during the bleeding operation to avoid ruining work surfaces or parts of, for example, the brake system, such as the calliper body, or parts with a surface finish such as varnish, or to avoid harming sensitive parts, for example the hands of any worker. [0010] . During these operations, in particular while unscrewing the cap, the hydraulic circuit fluid may leak through the seal of the bleed tube. [0011] . Furthermore, if the bleeding operation is performed under conditions of high stress, such as during a sports race, the bleed tube may come undone from the cap, provoking a harmful leaking of extremely corrosive and aggressive liquid. [0012] . The operation is also made more complex by the fact that the bleed tube must be connected to the cap every time, and the cap then acted on using a tool, for example a key, to loosen it. [0013] . Furthermore, said devices, often using a standardised Allen key, are operable with common keys accessing them through the wheel's spokes, which makes the brake plant's safety vulnerable in the case of any tampering. [0014] . Said bleeding devices also protrude noticeably from the calliper body surface and are thus excessively obstructive. [0015] . In addition, in the case of motor vehicles, said bleeding devices make the bleeding operation using a key and bleed tube very uncomfortable, specifically due to possible interference with the wheel rim. [0016] . The notable protrusion can also constitute a risk in the case of accidental collisions with blunt objects, such as stones. [0017] . An air bleeding device is known from document JP03009178 associated with a tool for operation of said bleeding device; however, this proposed solution does not guarantee the safety required of the bleeding operation, specifically in its hydraulic seal. [0018] . It is clear that there is a high risk of fluid loss and/or leakage through the coupling surface, as the tool must simultaneously apply twisting torque and guarantee the hydraulic seal. [0019] . Furthermore, there are notable risks deriving from any mechanical uncoupling, as this would provoke considerable fluid leakage. [0020] . In addition, any breakage of the coupling surface, due to the continuous torque stresses to which it is subjected, also carries with it a loss of the hydraulic seal, undoubtedly constituting a risk to the worker's safety. [0021] . The scope of the present invention is to realise a bleeding device which overcomes the limits of the known technique. [0022] . Said scope is reached by a device realised in accordance with claim 1. The claims dependent on this describe embodiments of the invention. [0023] . The characteristics and advantages of the present invention are in any case evident from the description reported below of a preferred, indicative and non limiting embodiment, with reference to the attached drawings, wherein: [0024] . - figure 1 represents a sectional view of a bleeding device inserted in a calliper body according to the known technique; [0025] . - figure 2 shows a sectional view of a bleeding device according to the present invention; [0026] . - figure 2a shows a sectional view of a bleeding device according to the present invention, inserted into a calliper body and coupled to a bleeding tool; [0027] . - figure 3 shows a sectional view of an embodiment of a bleeding device according to the present invention, [0028] . - figure 3a shows a sectional view of an embodiment of a bleeding device according to the present invention, inserted into a calliper body and coupled to a bleeding tool; [0029] . - figure 3b shows a sectional view of a further embodiment of a bleeding device according to the present invention, inserted into a calliper body,- [0030] . - figure 4 shows a sectional view of a breeding tool according to the present invention; [0031] . - figure 5 shows a sectional view of an embodiment of a bleeding tool according to the present invention; [0032] . - figure 6 shows an exploded perspective view of a bleeding device, a protective cap and a bleeding tool; [0033] . - figure 7 shows an exploded perspective view of an embodiment of a bleeding device, a protective cap and an embodiment of a bleeding tool. [0034] . With reference to the attached drawings, and solely for a possible embodiment, the number 1 indicates (fig. 2, 2a) a brake fluid bleeding device. [0035] . Favourably, said bleeding device 1 is suitable for being held in a bleed channel 2 of a hydraulic circuit 3 of a calliper body 4. [0036] . Said bleed channel 2 is also preferably internally threaded. [0037] . Furthermore, said bleeding device 1 is externally threaded, so that it can be easily screwed into said internally threaded bleed channel 2. [0038] . Furthermore, said bleeding device 1 is suitable, in a closed configuration, for impeding the passage of said fluid through said bleed channel 2 and in an open configuration for allowing the passage of said fluid through said bleed channel 2. [0039] . In a preferred embodiment said bleeding device 1 remains at least partially held in said bleed channel 2. [0040] . Favourably, said bleeding device 1 comprises a first end 5 suitable for impeding in said closed configuration the passage of said fluid through said bleed channel 2. [0041] . Said bleeding device 1 also comprises a second end 6 opposite said first end. [0042] . Furthermore, said bleeding device 1 comprises an intermediate portion 7 suitable for fluid connection of said first end 5 to said second end 6. [0043] . Advantageously, said bleeding device 1 comprises at least one control surface 8 comprised in said second end 6 suitable for realizing a shape coupling with at least one portion of bleeding tool 9 (fig. 4) to receive a twisting torque. [0044] . Advantageously, said bleeding device 1 comprises at least one sealing surface 10 distinct from said control surface 8 suitable for hydraulic coupling with at least one portion of said bleeding tool 9. [0045] . Said sealing surface 10 should be understood as being distinct from said control surface 8, as said sealing surface 10 is separated from said control surface 8 by a discontinuity 30, for example an outline, a wane, or a step. [0046] . In a preferred embodiment said distinct sealing surface is inside said bleeding device 1. [0047] . Furthermore said distinct sealing surface 10 is comprised in said intermediate portion 7. [0048] . In an alternative embodiment said distinct sealing surface 10 is comprised at least partially in said second end 6. [0049] . Favourably said distinct sealing surface 10 is substantially cylindrical in shape and, for example, delimits a volume comprising a drainage channel 27. [0050] . In a preferred embodiment said distinct sealing surface 10 is suitable for achieving the seal with sealing means 11, such as an O-ring. [0051] . Furthermore said control surface 8 is inside said bleeding device 1. [0052] . Furthermore, said control surface 8 comprises an outline 12 with a polygonal cross section (fig. 6) . [0053] . Advantageously, said outline 12 has a square cross section. [0054] . In a preferred embodiment said second end 6 comprises at least one site 13 with a polygonal cross section (fig. 2) . [0055] . In a favoured embodiment said site 13 is inside said second end 6. [0056] . [0057] . Favourably, said site 13 has a square cross section. [0058] . Furthermore, said site 13 comprises said outline 12. [0059] . In an alternative embodiment said site 13 has a hexagonal cross section. [0060] . Favourably, said first end 5 comprises a shutter 14. [0061] . In a preferred embodiment said shutter 14 moves axially within said bleed channel 2, selectively engaging a sealing surface 32 of said bleed channel 2. [0062] . Favourably, said shutter 14 comprises at least one portion of conical surface 15 and at least one portion of cylindrical surface 16. [0063] . Advantageously, said cylindrical surface 16 comprises at least one passing aperture 28, suitable for fluid connection of said drainage channel 27 to said bleed channel 2, in said open configuration. [0064] . In a preferred embodiment said second end 6 of said bleeding device 1 is also suitable for reception of a protective cap 17 for said bleeding device 1 (fig. 6) . [0065] . Furthermore, in reference to figures 2a, 4, 6, said bleeding tool 9 suitable for actioning said bleeding device 1 is shown. [0066] . Favourably, said bleeding tool 9 allows the passage of bleeding device 1 from a closed configuration, wherein fluid passage through said bleed channel 2 is impeded, to an open configuration, wherein fluid passage through said bleed channel 2 is permitted. [0067] . Advantageously, said bleeding tool 9 comprises at least one collection channel 18. [0068] . Furthermore, said bleeding tool 9 comprises at least one connecting channel 19. [0069] . Favourably, said collection channel 18 and said connecting channel 19 are connected through a through hole 33 (figs. 2a, 3a, 4, 5) . [0070] . In a preferred embodiment, said collection channel 18 comprises a control counter-surface 20 suitable for realisation of a shape coupling with said bleeding device 1 to transmit twisting torque. [0071] . Favourably, said collection channel 18 comprises a sealing counter-surface 21, distinct from said control counter-surface 20, suitable for realisation of a fluid connection with said bleeding device 1. [0072] . Said sealing counter-surface 21 should be understood as being distinct from said control counter- surface 20, as said sealing counter-surface 21 is separated from said control counter-surface 20 by a discontinuity 31, such as an edge, a wane, or a step. [0073] . In a preferred embodiment said connecting channel 19 is suitable for coupling with a bleed extension (not shown in drawings) for connection to a bleed tank (not shown in drawings) of said bleeding tool 9 with fluid connection to said bleeding device 1. [0074] . Favourably, said bleeding tool 9 comprises at least one handpiece 22 suitable for operating said bleed tool 9. [0075] . Furthermore, said handpiece 22 comprises at least one control end 23. [0076] . Preferably, said collection channel 18 and said connecting channel 19 are aligned. [0077] . Advantageously, said collection channel 18 and said connecting channel 19 are transversal with respect to handpiece 22. [0078] . Alternatively, said collection channel 18 and said connecting channel 19 are aligned with said handpiece 22. [0079] . In a preferred embodiment said collection channel 18 and said connecting channel 19 are formed on said control end 23. [0080] . Favourably, said sealing counter-surface 21 suitable for hydraulic coupling with said distinct sealing surface 10 of said bleeding device 1 is substantially cylindrical. [0081] . Favourably, said sealing counter-surface 21 is outside said collection channel 18. [0082] . Advantageously, said control counter-surface 20 comprises a coupling outline 24 with a polygonal cross section. [0083] . Favourably, said coupling outline 24 has a square cross section. [0084] . In an alternative embodiment said coupling outline 24 has a hexagonal cross section. [0085] . Furthermore, said coupling outline 24 is aligned with said connection tube 18. [0086] . In a preferred embodiment said collection channel 18 comprises a sealing means 11 suitable for realisation of a seal with said sealing surface 10 distinct from said control surface 8 of bleeding device 1. [0087] . Advantageously, said sealing means 11 comprises an O-ring. [0088] . Furthermore, said connecting channel 19 comprises a connection means 26 (figs. 2a, 3a, 4, 5) suitable for fluid connection of said connecting channel 19 with a fluid collection extension (not shown in drawings) . [0089] . Favourably, said connecting means 26 comprises a connector. [0090] . In the normal maintenance phase of the braking system and thus in the bleeding operation, it is intended that the bleeding tool 9 be connected to said bleeding extension, for example made of transparent plastic, using said connection means 26, such as a connector. [0091] . Furthermore, said bleeding extension is connected to a bleed fluid collection container. [0092] . It is also intended that the hydraulic circuit 3 be pressurised through pressure on a brake pedal. [0093] . Subsequently a shape coupling is achieved between the bleeding tool 9 and the bleeding device 1. [0094] . Favourably, said shape coupling is realised by inserting said collection channel 18 into said bleeding device, specifically in said site 13, using a light pressure on the bleeding tool 9 to obtain the complete insertion of said collection channel 18 into site 13. [0095] . Said shape coupling specifically permits mechanical coupling between said control surface 8 and said control counter-surface 20. [0096] . Simultaneously with said mechanical coupling, said sealing surface 10 is hydraulically coupled with said sealing counter-surface 21. [0097] . Thanks to the structure of the bleeding device 9 and bleeding device 1 in said closed configuration, as previously described, the shape coupling allows fluid connection between said drainage channel 27 and said bleed fluid collection container. [0098] . Furthermore, said bleeding tool 9 and said bleeding device 1 form a united system. [0099] . Proceeding in the bleeding operation, said bleeding device 1 is loosened and screwed into said internally threaded bleed channel 2 by rotating said bleeding tool 9 coupled in unity with said bleeding device 1; favourably, said bleeding tool 9 is operated using handpiece 22. [00100] . In this way twisting torque is transmitted to said bleeding device 1 through control surface 8 of bleeding device 1 and the control counter-surface 20 of bleeding tool 9, avoiding the application of significant twisting torque to sealing surface 10 and sealing counter-surface 21. [00101] . Correspondingly, said shutter 14 is axially displaced in said bleed channel 2 and frees said sealing surface 32, taking bleeding device 1 to said open configuration and simultaneously achieving fluid connection between said bleed channel 2 and said drainage channel 27. [00102] . In this way the bleed fluid, previously pressurised, flows from hydraulic circuit 3 through bleed channel 2, drains along the drainage channel 27 of said passing aperture 28, and passes into said collection channel 18 comprised in said bleeding tool 9. [00103] . The bleed fluid then flows into connection tube 19 with fluid connection to said collection channel 18 and then proceeds along the bleed extension to be deposited in said bleed fluid collection container. [00104] . Advantageously, a worker performing the above described bleeding operation steps can simultaneously visually check the passage of any air bubbles and brake fluid through the transparent bleed extension, thus evaluating the efficacy of the bleeding operation. [00105] . The worker then returns said bleeding device 1 to the closed configuration using the opposite rotation to that previously used on said .bleeding tool 9 through said handpiece 22. [00106] . Favourably, said bleeding operation is repeated until all air or other gases have been completely bled from said hydraulic circuit 3. [00107] . At the end of the bleeding operation it is sufficient to place said bleeding device 1 in the closed configuration by suitable rotation of the bleeding tool 9 coupled in unity, and then to uncouple said bleeding tool 9 from said bleeding device 1. [00108] . Advantageously, in this way a completely safe bleeding operation is achieved: in fact, said bleeding tool 9 has the dual purpose of mechanical coupling suitable for transmitting said twisting torque and hydraulic coupling suitable for fluid connection of said bleeding device 1 to said bleeding extension. [00109] . This dual purpose is performed by two pairs, exclusively associated, of completely distinct surfaces, that is the control surface 8 and counter-control surface 20 adapted to withstanding the applied twisting torque, and the sealing surface 10 and counter-sealing surface 21, suitable for achieving the seal without being greatly influenced by the mechanical actions applied between the first two surfaces (fig. 2a,4) . [00110] . This favoured situation allows any event related to the mechanical coupling to be independent of phenomena related to the hydraulic coupling; in this way, in the case of, for example, a crack and/or breakage of the control surface 8 or control counter-surface 20 due to continued stress from the applied twisting torque, this will have no effect on the fluid connection between the sealing surface 10 and the counter-sealing surface 21. [00111] . The possibility of harmful loss or leakage due to accidental events such as breakage is thus averted. [00112] . Furthermore, there is the advantageous fact that an intimate hydraulic coupling is achieved between said sealing surface 10 and said sealing counter-surface 21 through said sealing means 11; in fact, said intimate hydraulic coupling acts synergistically with said mechanical coupling, essentially impeding a dangerous uncoupling of said tool 9 from said bleeding device 1. [00113] . Also advantageous is the use of a single bleeding device 9, which achieves both mechanical and hydraulic coupling with said bleeding device 1 through two completely distinct surface pairs, permits a quicker bleeding operation, obtaining a notable time saving and increased safety and efficiency of the bleeding operation, important results in for example high stress situations such as a motor vehicle race, such as with motor cars . [00114] . Also advantageous is that the realisation of a bleeding device 1 as described involves the use of a bleeding tool 9 exclusively constructed for operation of said bleeding device 1; in this way the possibility of any tampering using common keys is avoided, increasing the safety of the brake plant and thus also of the motor vehicle's user. [00115] . Surprisingly, realisation of a bleeding device 1 as described permits a drastic reduction in the size of the protruding portion of the bleeding device 1 itself from the calliper body, as can be seen for example by comparing fig. 1 of the known technique with fig. 2 of the present invention. [00116] . The bleeding operation is also advantageously facilitated by the bleeding tool 9 coupled to the bleeding device 1, specifically by notably reducing interference with the vehicle's wheel rim and more generally by reducing the space occupied by said bleeding device. [00117] . Furthermore, the reduced protrusion minimises the risks deriving from any accidental collisions with blunt objects, such as stones. [00118] . Described below is an embodiment of said bleeding device 1 associated with said bleeding tool 9. [00119] , With reference to figures 3, 3a, the number 101 indicates a bleeding device realised in an alternative embodiment, wherein the elements equal to those in the previously described embodiment are indicated with the same numerical reference, whose functioning is essentially equal to said bleeding device 1, comprising a first end 105, a second end 106 and an intermediate portion 107, all analogous to said first end 5, second end 6 and intermediate portion 7. [00120] . Furthermore, said second extremity 106 comprises a control surface 108. [00121] . Favourably, said control surface 108 is also outside said bleeding device 101. [00122] . Furthermore, said control surface 108 comprises an outline 112 with a polygonal cross section (fig. 7) . [00123] . Advantageously, said outline 112 has a hexagonal cross section. [00124] . Alternatively, said outline 112 has a square cross section. [00125] . Favourably, said bleeding device 101 comprises at least one sealing surface 110 distinct from said control surface 108 suitable for hydraulic coupling with at least one portion of said bleeding tool 109. [00126] . In a preferred embodiment said distinct sealing surface 110 is inside said bleeding device 101. [00127] . Favourably, said distinct sealing surface 110 is comprised at least partially in said second end 106. [00128] . Favourably, said sealing surface 110 has a cylindrical form. [00129] . Advantageously, said sealing surface 110 delimits a drainage channel 27. [00130] . Favourably, said bleeding device 101 is operated by a suitable bleeding tool 109 (figs. 3a, 5, 7) alternative to the previously described embodiment, whose functioning is completely analogous to that of said bleeding tool 9 (the elements equal to those in the previously described embodiment are indicated in figs. 3a, 5, 7 with the same numeric reference) . [00131] . Furthermore, said bleeding tool 109 comprises at least one collection channel 118. [00132] . Furthermore, said bleeding tool 109 comprises at least one connecting channel 119. [00133] . Favourably, said collection channel 118 and said connecting channel 119 are connected by a through hole 33. [00134] . In a preferred embodiment, said collection channel 118 comprises a control counter-surface 120 suitable for realisation of a shape coupling with said bleeding device 101 to transmit twisting torque. [00135] . Favourably, said collection channel 118 comprises a sealing counter-surface 121, distinct from said control counter-surface 120, suitable for realisation of a fluid connection with said bleeding device 101. [00136] . Advantageously, said control counter-surface 120 comprises a coupling outline 124 with polygonal cross section. [00137] . Favourably, said coupling outline 124 has a hexagonal cross section. [00138] . Alternatively, said outline 124 has a square cross section. [00139] . Furthermore, said coupling outline 124 is aligned with said connection tube 118. [00140] . Furthermore, said control counter-surface 120 is suitable for realisation of a shape coupling to transmit twisting torque to said bleeding device 101 comprising a site 125. [00141] . Advantageously, said site 125 is ring-shaped. [00142] . In a favoured embodiment said site 125 has a polygonal cross section. [00143] . Furthermore, said site 125 has a hexagonal cross section. [00144] . Alternatively, said site 125 has a square cross section. [00145] . Favourably, said site 125 is aligned with said collection channel 118. [00146] . Advantageously, the bleeding operation using the embodiment represented by bleeding device 101 associated with bleeding tool 109 is completely analogous to that previously described, being a mechanical coupling between said hexagonal control surface 108 and said hexagonal control surface 120, suitable for transmitting twisting torque, and the hydraulic coupling between said distinct sealing surface 110 and said distinct sealing surface 121 suitable for realisation of a fluid connection between said bleeding device 101 and said bleeding tool 109. (fig. 3a) . [00147] . Furthermore, said bleeding device 101 is protected by a cap 117 which closes said second end 106. [00148] . It is also possible to realise a further embodiment of said bleeding device 101. [00149] . With reference to figure 3b, wherein the elements equal to those in the embodiment described above are indicated with the same numerical reference, the number 201 indicates a further embodiment of said bleeding device 101 whose functioning is essentially analogous to said bleeding device 101, comprising a first end 205, a second end 206 and an intermediate portion 207, all analogous to said first end 105, second end 106 and intermediate portion 107. [00150] . Favourably, a site 225 is realised in said calliper body 4. [00151] . Said site 225 is suitable for holding and partially building in said second end 206. [00152] . Advantageously, said site 225 comprises a first surface 226 and a second surface 227 distinct from said first surface 226. [00153] . Said bleed channel 201 is operated by a tool 109 appropriately sized to allow the desired shape coupling with said bleed channel 201. [00154] . [00155] . In a preferred embodiment said tool realises a contact with at least said second surface 227 during the above described bleeding operation. [00156] . tool [00157] . Advantageously, the size of the part of bleed channel 201 protruding from calliper body 4 is further reduced. [00158] . Furthermore, said bleed channel 201 is protected by a cap 217 which closes said second end 206.