CONNECTION UNIT FOR A FAST-COUPLING SAFETY JOINT

Abstract: Connection unit (4) for a fast-coupling safety joint (1), provided with a main, hollow body (10) which can be connected to a first distribution pipe (2) for a pressurised fluid, a valve element (11), which is mounted such as to slide inside the main body (10), and is maintained by a spring (13) in a first operative position, in which it separates the first pipe (2) from the outer environment in a fluid-tight manner, first releasable stop means (15), which in use define an advanced coupling position of a terminal (5) of a second pipe (3) inside the connection unit (4), in order to permit fluid connection between the first and the second pipe (2, 3) itself, and second releasable stop means (16), which define a withdrawn, safety position of the terminal (5), in which the valve element (11) is disposed in the first operative position, and permits venting of the operative fluid which is disposed beyond the first pipe (2), towards the terminal (5) itself; the first stop means (15) are interposed between the main body (10) and the valve element (11), and the second stop means (16) can co-operate with the terminal (5) in order to render it integral with the valve element (11), during its own displacement between the safety and coupling positions.

Description: CONNECTION UNIT FOR A FAST-COUPLING SAFETY JOINT TECHNICAL FIELD The present invention relates to a connection unit for a fast-coupling safety joint, which can connect in a fluid-tight manner to one another two distribution pipes for a pressurised operative fluid, and in particular air or compressed gas . BACKGROUND ART Fast-coupling joints without the safety function are known, which substantially comprise a connection unit which can be connected to a first one of said distribution pipes, and a terminal which can be connected to a second one of said distribution pipes , and can be connected such that it can be released, inside the connection unit in a coupling position. The connection unit comprises a main, hollow body which can be connected to the first pipe, a slide-valve element which is mounted axially such as to slide inside the main body, a cylindrical, helical spring which is interposed between the main body and the valve element, and can exert axial thrust on the valve element itself, in order to maintain it in a first operative position, of sealed separation of the first pipe from the outer environment , and releasable stop means , in order to constrain the terminal against the connection unit in the coupling position, in which the terminal exerts on the valve element thrust, which is opposite and prevalent relative to the thrust exerted by the spring, and thus maintains the valve element itself in a second operative position of opening of the fluid connection between the first and the second pipe . These joints have the following disadvantage. During the disconnection step, the terminal, which is thrust by the pressure of the operative fluid and by the reaction of the spring, tends to be detached from the connection unit in an extremely violent manner, with the possibility of striking, and in some cases wounding the operator, or at least of damaging machinery or objects which are disposed in the vicinity. In order to eliminate this disadvantage, fast- coupling safety joints have been produced, in which the main body of the connection unit is provided with first and second releasable stop means, which are disposed axially spaced from one another. In particular, the first stop means can cooperate with the terminal in order to lock it in the coupling position, whereas the second stop means can cooperate with the terminal in order to retain it , after release of the first stop means and during the step of disconnection from the connection unit, in a withdrawn, safety position, in which the terminal itself is mechanically connected to the main body, and the valve element is disposed in the first operative position, in which it isolates the first pipe in a fluid-tight manner, and permits drawing towards the exterior of the operative fluid which is present inside the joint, beyond the first pipe, towards the second pipe. These stop means generally consist of mobile engagement elements, which can be deactivated manually from the exterior, project inside the main body, and can cooperate with a retention groove provided on a radially external surface of the terminal . In order for these joints to function correctly, the first and second stop means must be disposed at a pre- determined axial distance from one another, and thus the retention groove of the terminals , which can be connected to said connection units, must have a corresponding axial length, which is normally relatively long. Consequently, the use of connection units of the above-described type makes it impossible to use the standard terminals which are available on the market, which are provided with an annular retention groove with a short axial length, and are normally used in fast-coupling joints which do not have a safety function. DISCLOSURE OF INVENTION The object of the present invention is to provide a connection unit for a fast-coupling safety joint, which is suitable for being fitted with the standard terminals which are available on the market, and are normally used in fast-coupling joints which do not have a safety function. This object is achieved by the present invention, in that it relates to a connection unit which can be connected to a first distribution pipe for a pressurised operative fluid, and can be connected such that it can be released, to a terminal of a second distribution pipe for said operative fluid, in order to form a fast-coupling safety joint, said connection unit having a longitudinal axis, and comprising: a main, hollow body which can be connected to said first pipe; a slide valve element, mounted such that it can slide axially inside said main body; first resilient means, which exert axial thrust on said valve element, in order to maintain it in a first operative position, in which said valve element separates said first pipe from the external environment in a fluid- tight manner; first releasable stop means , which in use define an advanced coupling position of said terminal inside said connection unit , in which said terminal exerts on said valve element thrust, which is opposite and prevalent relative to the thrust exerted by said first resilient means, and maintains the valve element itself in a second operative position, of opening of the fluid connection between said first and second pipe; - second releasable stop means, which can cooperate with said terminal in order to retain it, after release of said first stop means and during the step of disconnection of the terminal itself from said connection unit, into a withdrawn, safety position, in which said terminal is mechanically connected to said connection unit, and the valve element is disposed in said first operative position, and permits drawing towards the exterior of the operative fluid which is present beyond the first pipe, towards the terminal itself; characterised in that said first stop means comprise releasable connection means, between said main body and said valve element, and said second stop means comprise releasable constraint means , which are supported by said valve element and can cooperate with said terminal in order to render it integral with the valve element itself, during its own displacement between said withdrawn safety position, and said advanced coupling position. Thus, the safety position is obtained by rendering the terminal and the valve element integral with one another by means of the releasable constraint means , whereas the coupling position is obtained by constraining the valve element itself to the main body, by means of the releasable connection means. Consequently, with appropriate geometric, but not functional modifications, the connection unit according to the present invention can accept a great variety of terminal profiles, which must simply be provided with an annular groove with a short axial length, of the type normally fitted on the standard terminals which are available on the market, and are used in fast-coupling joints which do not have a safety function. Said first stop means preferably comprise first, manually actuated selection means, in order to command release of said connection means, and said second stop means comprise second, manually actuated selection means, in order to command release of said constraint means, said connection unit comprising means to inhibit actuation of said second selection means, which are active in the coupling position of said terminal, and can be deactivated after actuation of said first selection means . This prevents any possibility of deactivating the second stop means before the first stop means are released, and thus by-passing the safety function of the joint. BRIEF DESCRIPTION OF DRAWINGS Further characteristics and advantages of the present invention will become apparent from the following description of two preferred embodiments, provided purely by way of non-limiting example, with reference to the attached drawings, in which: figure 1 illustrates in axial cross-section a fast- coupling safety joint, which is provided with a connection unit according to the present invention, and a terminal which is connected to the connection unit itself in a coupling position; figure 2 is a cross-section on an enlarged scale according to line II-II in figure 1; figure 3 illustrates in axial cross-section the connection unit and the terminal in figure 1, disconnected from one another; figure 4 illustrates in axial cross-section the joint in figure 1, in a safety configuration; figures 5-7 illustrate a lateral view of the joint in figure 1, during successive steps of a manoeuvre of disconnection of the terminal from the connection unit; figure 8 illustrates a lateral view of a different embodiment of a connection unit for a fast-coupling safety joint according to the present invention, connected to a corresponding terminal in a coupling position; figure 9 is a cross-section according to line IX-IX in figure 8, with parts removed for the sake of clarity; figure 10 illustrates in axial cross-section the connection unit and the terminal in figure 8, in the coupling step; and figure 11 illustrates in axial cross-section the connection unit and the terminal in figure 8 connected to one another in a safety configuration. BEST MODE FOR CARRYING OUT THE INVENTION With reference to figure 1 and figures 4 to 6 , 1 indicates as a whole a fast-coupling safety joint for fluid-tight connection to one another of two pipes 2, 3, for distribution of a pressurised operative fluid (figure 1), in particular air or compressed gas. The joint 1 has a longitudinal axis A, and comprises a connection unit 4, produced according to the present invention, and suitable for being connected to the pipe 2, and a terminal 5 (which is of a known type and is not part of the present invention) , which is connected to the pipe 3 , and can be connected such that it can be released, to the connection unit 4. With reference to figures 1, 3, 4 and 7, the terminal 5 has a substantially tubular shape with an axis A, and comprises a main, cylindrical portion 6, which in use is connected to the pipe 3 , and has on its exterior an annular retention groove 7, and a free end portion 8, which has a diameter which is smaller than the portion 6, and is connected to the portion 6 itself. With reference to figure 1 and figures 3 to 7, the connection unit 4 comprises a main, hollow body 10 which is substantially cylindrical, and can be connected at one of its own ends to the pipe 2; a slide valve element 11, which is mounted axially such that it can slide inside the body 10, and defines with the body 10 itself a substantially cylindrical chamber 12, which in use communicates with the pipe 2; a cylindrical, helical spring 13 with an axis A, which is accommodated in the chamber 12 and can exert axial thrust on the valve element 11, in order to maintain it in a first operative position (figures 3 and 4) , in which the valve element 11 itself abuts a radially inner annular projection 14 of the body 10, and separates the chamber 12 and the pipe 2 in a fluid-tight manner from the external environment; in use a first releasable stop mechanism 15 , defines an advanced, coupling position (figures 1 and 5) of the terminal 5 inside the connection unit 4, in which the terminal 5 itself exerts on the valve element 11 thrust, which is opposite and prevalent relative to the thrust exerted by the spring 13 , and thus maintains the valve element 11 in a second operative position (figure 1) of opening of the fluid connection between the pipes 2 and 3; and a second releasable stop mechanism 16, which cooperates with the terminal 5 in order to retain it, after the release of the stop mechanism 15, and during the step of disconnection of the terminal 5 itself from the connection unit 4, in a withdrawn, safety position (figures 4 and 6) , in which the terminal 5 is mechanically connected to the connection unit 4 , and the valve element 11 is disposed in the first operative position, and permits drawing towards the exterior of the operative fluid which is present beyond the projection 14 , towards the pipe 3. According to the present invention, the stop mechanism 15 comprises releasable connection means 17, between the body 10 and the valve element 11, and the stop mechanism 16 comprises releasable constraint means 18, which are supported by the valve element 11, and can cooperate with the groove 7 of the terminal 5, in order to render the terminal 5 itself integral with the valve element 11, between the withdrawn, safety position and the advanced, coupling position. With reference to figures 1, 3 and 4, the body 10 consists of a pair of substantially tubular elements 19, 20 with an axis A, which are screwed to one another. The element 19 is substantially in the shape of a beaker, and comprises two substantially cylindrical portions 21, 22 with different diameters, which are connected to one another by a substantially circular intermediate wall 23 , and can be connected respectively to the element 20 and to the pipe 2. More specifically, the portion 21 has a diameter which is larger than the diameter of the portion 22, and is threaded internally; in addition, the wall 23 has a central through hole 24 with an axis A, in order to permit in use passage of the operative fluid from the pipe 2 to the chamber 12. The element 20 has a substantially cylindrical shape, an end portion 25 which is threaded externally and is engaged inside the portion 21 of the element 19, and is integral with the projection 14; in particular, the projection 14 has a cylindrical surface 26 with an axis A, which defines a sliding seat for the valve element 11, and is delimited towards the wall 23 by a frusto-conical surface 27 with an axis A, with concavity which faces the wall 23 itself, and on the opposite side is delimited by a circular surface 28, which also has an axis A. The chamber 12 is thus delimited by the wall 23 , by the portions 21, 25 of the body 10 screwed together, by the surface 27 of the projection 14, and by the valve element 11. Again with reference to figures 1, 3 and 4, the valve element 11 has an elongate cup shape with an axis A, and is defined by a wall 29 with a substantially circular base, and by a lateral wall 30 which consists of a plurality of substantially cylindrical portions 33, 34, 35, with an outer diameter which decreases towards the wall 29 itself; the walls 29 and 30 also delimit a cavity 36. In particular the wall 29 is provided externally with a sealing ring 38 with an axis A, which, in the first operative position of the valve element 11, abuts the surface 27 of the projection 14, separating the chamber 12 and the pipe 2 in a fluid-tight manner from the cavity 36, and thus from the external environment. The wall 29 also has an axial seat substantially in the shape of a cup, which faces towards the interior of the chamber 12, and is engaged by a corresponding end of the spring 13 , the other end of which is engaged inside a similar seat provided in the wall 23 of the element 19. Out of the portions 33, 34, 35 of the wall 30, the portion 35 is adjacent to the wall 29, and has an outer diameter which is substantially the same as the outer diameter of the wall 29 itself; in addition, the portion 35 is engaged in an axially sliding manner inside the cylindrical surface 26 of the projection 14, and has a cylindrical section 41 which is adjacent to the portion 34, and has an outer diameter which is substantially the same as the outer diameter of the wall 29, a bladed section 42 with an outer diameter which is smaller than the outer diameter of the wall 29 itself, and in the second operative position of the valve element 11 can permit fluid connection between the chamber 12 and the cavity 36, and a lowered intermediate section 43 which connects the sections 41 and 42. Between the portion 1 35 of the valve element 11 and the projection 14, there is interposed a sealing ring 44, which is engaged in a corresponding annular groove provided in the surface 26. In the first operative position of the valve element 11, the ring 44 is positioned between the projection 14 and the lowered section 43 of the portion 35, such as to permit drawing of operative fluid from the cavity 36 towards the exterior, whereas in the second operative position of the valve element 11, the ring 44 is compressed between the projection 14 and the section 41 of the portion 35, such as to ensure sealing between the body 10 and the valve element 11 itself. The portion 34 is disposed adjacent to the portion 35, engaged in an axially sliding manner inside an end portion 45 of the element 20 of the body 10, opposite the portion 25, and defines internally an annular shoulder 46, the function of which will be explained hereinafter. Finally, the portion 33 is disposed on the side opposite the portion 34, relative to the portion 35, has a length which is longer than the portions 34, 35 themselves, extends outside the body 10, and ends in a radially annular flange 47, which projects towards the exterior. The valve element 11 is also provided integrally with a cylindrical rod 48 with an axis A, which extends inside the cavity 36 of the wall 29, as far as the connection area of the portions 33 and 34 of the wall 30. The constraint means 18 comprise a plurality of spheres 50, which are accommodated in a sliding manner in respective radial through seats 51 provided in the portion 45 of the element 20 of the body 10, are regularly distributed around the axis A, and are mobile between a position of engagement with the groove 7 of the terminal 5 , in which they form a mechanical connection between the valve element 11 and the terminal 5 itself, and a position of disengagement from the groove 7. The stop mechanism 16 additionally comprises a manually actuated selection ferrule 52 with an axis A, which is mounted such as to slide axially along a radially outer surface of the portion 33 of the valve element 11, and can command displacement of the spheres 50 from the position of engagement to the position of disengagement, and thus can give rise to disconnection of the terminal 5 from the valve element 11, and a retention element 53, which is mounted such as to slide axially inside the portion 33 of the valve element 11, can be engaged in use by the end portion 8 of the terminal 5, and, when it is disconnected from the terminal 5 itself, can be disposed in a position of internal closure of the seats 51 of the spheres 50. In particular, the spheres 50 have a diameter which is larger than the radial dimension of the respective seats 51, and thus, in the engagement position, project radially inside the portion 33 of the valve element 11, and engage the groove 7 of the terminal 5, whereas in the position of disengagement, they are disposed such that they abut the retention element 53 radially, and consequently project radially outside the valve element 11 itself. Along its own inner surface, the selection ferrule 52 has an annular groove 54 , which can be engaged by the spheres 50, when the latter are disengaged from the groove 7 of the terminal 5, and is loaded by a cylindrical helical spring 55 with an axis A, which is wound around the portion 33 itself; more specifically, the spring 55 is interposed between one end 76 of the selection ferrule 52, opposite the flange 47, and a resilient ring 56 which is fitted on the exterior of the portion 33, in the vicinity of the portion 45 of the element 20 of the body 10. In its own position of engagement with the groove 7, the selection ferrule 52 is thrust by the spring 55 against the flange 47, whereas, in their own position of disengagement from the groove 7, the spheres 50 keep the selection ferrule 52 axially spaced from the flange 47 itself . The retention element 53 consists of a cylindrical cup tubular portion 57, engaged in an axially sliding manner inside the portion 33 of the valve element 11, and by a rim portion 60, which extends in a projecting manner from a base wall of the portion 56 which faces the shoulder 46, and is engaged in a sliding manner along the outer surface of the rod 48. In particular, between the portion 33 of the valve element 11, and the portion 57 of the retention element 53, there is interposed a sealing ring 61, which is accommodated in a corresponding annular groove provided on a radially inner surface of the portion 33 itself. With reference to figures 1 to 4 , the portion 60 comprises a pair of elongate arms 62 (figure 2) , which are disposed facing one another, and extend axially in a projecting manner on diametrically opposite parts of the base wall of the portion 57, relative to the axis A, and a connection element 63 which is transverse relative to the axis A, connecting the free ends of the arms 62 , and having a through hole 63a which is engaged in a sliding manner by the rod 48. The retention element 53 is loaded by a cylindrical helical spring 64 with an axis A, which extends between the portion 57 and the shoulder 46 of the portion 34 of the valve element 11; on a free end of the rod 48, there is also mounted a resilient ring 65, which is interposed between the arms 62, and cooperates with the lateral edge of the hole 63a of the connection element 63, in order to prevent extraction of the retention element 53 from the cavity 36 of the valve element 11, and thus from the connection unit 4, in the direction opposite the wall 29. The portion 57 of the retention element 53 can be engaged in use, by means of interposition of a sealing ring 66, by the portion 8 of the terminal 5, which, during the step of introduction inside the cavity 36 of the valve element 11, can exert on the retention element 53 axial thrust, which is opposite and prevalent relative to the thrust of the spring 64 , in order to displace the retention element itself axially towards the wall 29, and release the spheres 50, such as to permit subsequent engagement with the groove 7; more particularly, the ring 66 is accommodated in a corresponding annular groove provided on a radially inner surface of the lateral wall of the portion 57 of the retention element 53. Similarly, the connection means 17 comprise a plurality of spheres 67, which are accommodated in a sliding manner in respective radial through seats 68 provided in the portion 45 of the element 20, are regularly distributed around the axis A, and are mobile between a connection position, in which they engage an annular groove 69 provided in the radially outer surface of the portion 34 , and define the second operative position of the valve element 11, and thus the position of engagement of the terminal 5, and a release position, in which they are disconnected from the groove 69 itself. The stop mechanism 15 additionally comprises a manually actuated selection ferrule 70 with an axis A, which is mounted such as to slide axially along respective radially outer surfaces of the body 4 and of the selection ferrule 52, and can command displacement of the spheres 67 from the position of connection to the position of release, and thus can give rise to displacement of the valve element 11 from the second to the first operative position. In particular, the spheres 67 have a diameter which is larger than the radial dimension of the respective seats 68, and thus in the connection position, they project radially inside the element 20 of the body 10, and engage the groove 69 of the valve element 11, whereas in the disconnection position, they are disposed such that they abut radially a cylindrical section of the portion 34 of the valve element 11 adjacent to the groove 69, and thus project radially outside the element 20 itself . Along its own radially inner surface, the selection ferrule 70 has an annular groove 71 which can be engaged by the spheres 67 when the latter are disconnected from the groove 69, and loaded by a cylindrical helical spring 72 with an axis A, which is wound around the element 20 of the body 10, and is interposed between a radially outer projection 73 of the element 20, and a first inner shoulder of the selection ferrule 70 itself. According to an important feature of the connection unit 4, the selection ferrule 70 has an end portion 75, which, owing to the effect of the thrust of the spring 72, and in the position of coupling of the terminal 5, can be disposed such that it covers completely the selection ferrule 52, such as to prevent the latter from being actuated before the selection ferrule 70 itself is actuated, and thus by-passing the safety function of the joint 1. For the sake of greater clarity, in the position of connection of the spheres 67 to the groove 69, the selection ferrule 70 is thrust by the spring 72, such that its own second inner shoulder abuts the end 76 of the selection ferrule 52, which in turn abuts the flanges 47, and covers the ferrule 52 itself with its own portion 75, whereas in the position of disconnection of the spheres 67 from the groove 69, the selection ferrule 70 is axially spaced from the flange 47. Assembly of the joint 1 is described on the basis of an initial configuration (figure 3), in which the terminal 5 is fully extracted from the connection unit 4, the valve element 11 is disposed in its own first operative position, and by means of the ring 38, separates in a fluid-tight manner the chamber 12 from the cavity 36, the spheres 67 are disposed in their own disconnection position, and keep the selection ferrule 70 spaced from the flange 47, and the retention element 53 is thrust by the spring 64 in the direction opposite the wall 29, and forms a radial stop for the spheres 50, which are thus disposed in the disengaged position, and also keep the selection ferrule 52 axially spaced from the flange 47. The terminal 5 is connected to the connection unit 4 by means of single manoeuvre of insertion of the terminal 5 itself inside the cavity 36 of the valve element 11. In this step, the end portion 8 of the terminal 5 engages in the portion 57 of the retention element 53 , and thrusts the latter towards the wall 29 of the valve element 11, thus compressing fully the spring 64, the resilient rigidity of which is lower than the resilient rigidity of the spring 13 ; as soon as the groove 7 of the terminal 5 is in the position of the spheres 50, under the effect of the thrust of the spring 55 on the selection ferrule 52, the spheres slide inside the corresponding seats 51, and are thrust such that they engage with the groove 7 itself, giving rise to a mechanical connection between the terminal 5 and the valve element 11 (figure 4) . Simultaneously, owing to the disengagement of the spheres 50 from their own groove 54, and again as a result of the thrust of the spring 55, the selection ferrule 52 is thrust against the flange 47. The valve element 11, which continues to thrust the terminal 5 axially inside the connection unit 4 , moves integrally with the terminal 5 itself from the first operative position towards the second operative position, giving rise to compression of the spring 13, and gradually moving the ring 38 away from the surface 27 of the projection 14, such as to put the chamber 12 into communication with the cavity 36, via the bladed section 42 of the valve element 11. As soon as the groove 69 of the valve element 11 is in the position of the spheres 67, the latter, owing to the effect of the thrust of the spring 72 on the selection ferrule 70, slide inside the corresponding seats 68 and are thrust into engagement with the groove 69 itself, thus locking the valve element 11 in the second operative position, in which it opens the fluid connection between the pipes 2 and 3 , and defining the advanced position of coupling of the terminal 5 inside the connection unit 4 (figure 1) . Simultaneously, owing to the disengagement of the spheres 67 from their own groove 71, and again under the effect of the thrust of the spring 72, the selection ferrule 70 is thrust against the end 76 of the selection element 52, and covers it completely with its own end portion 75. In this step, the operative fluid which comes from the pipe 2, passes through the bladed section 42, which is disposed such as to project inside the chamber 12, and flows into the terminal 5 , and thus into the pipe 3 , passing through the cavity 36 and the rim portion 60 of the retention element 53. In this operative configuration, the rings 38, 44, 61 and 66 ensure that the joint 1 is perfectly sealed from the interior towards the exterior. The terminal 5 is disconnected from the connection unit 4 by acting separately and in succession on the selection ferrules 70 and 52. In particular, in the position of coupling of the terminal 5, the ferrule 52 is inaccessible, since it is fully covered by the end portion 75 of the selection ferrule 70 (figures 1 and 5) . Thus, the selection ferrule 70 must be displaced axially towards the pipe 2, until the groove 71 is in the position of the spheres 67; at this point, owing to the effect of the thrust of the spring 13 and of the pressurised fluid, the spheres 67 slide inside the corresponding seats 68, and are thrust into engagement with the groove 71 itself, thus releasing the valve element 11, which is displaced from the second to the first operative position, in which, by means of the contact of the ring 38 with the surface 27 of the projection 14, it separates in a sealed manner the chamber 12 , and thus the pipe 2 , from the remaining part of the joint 1. In this step, the terminal 5 is still connected to the valve element 11, by means of the engagement of the spheres 50 in the groove 7 (figures 4 and 6) . On completion of displacement of the valve element 11 into the first operative position, the ring 44 is positioned between the lowered section 43 of the valve element 11 and the surface 26 of the projection 14 of the body 10, thus allowing the operative fluid which is contained between the projection 14 itself and the pipe 3 to be drawn towards the exterior. At this point, it is possible to act on the selection ferrule 52, by displacing it axially towards the pipe 2; when the groove 54 of the ferrule 52 is in the position of the spheres 50, the latter, owing to the effect of the thrust of the spring 64, slide inside the corresponding seats 51, and are thrust into engagement with the groove 54 itself, thus releasing the terminal 5, detachment of which takes place in a perfectly controlled manner, owing to the lack of pressure inside the cavity 36 of the valve element 11 (figures 3 and 7) . In figures 8 to 11, 1' indicates as a whole a fast- coupling safety joint, which comprises a connection unit 4 ' , produced according to a different embodiment of the present invention; this connection unit is described hereinafter only to the extent that it differs from the connection unit 4, and the same reference numbers indicate parts which are the same as, or correspond to, parts which have already been described. The connection unit 4 ' comprises a stop mechanism 15 ' , which differs from the stop mechanism 15 in that instead of the selection ferrule 70 and the spheres 67, it comprises a trigger element 80, which is supported by the element 20 of the body 10, and is mobile in the direction at right-angles to the axis A, inside a corresponding seat 81 of the element 20 itself, between a connection position (figures 8 and 9) , in which it cooperates in engagement with the groove 69 of the valve element 11, thus defining the second operative position of the latter, and therefore the position of coupling of the terminal 5, and a release position (figures 10 and 11) , in which it is disconnected from the groove 69 itself. In particular, the trigger element 80 comprises a ring portion 82, which is accommodated in a sliding manner in the seat 81, and is mounted with radial play on the exterior of the portion 34 of the lateral wall 30 of the valve element 11, and an actuation portion 83, which has a substantially rectangular profile, and extends in a projecting manner from the ring portion 82, which is accommodated in a recess 84 in the element 20 of the body 10, which communicates with the seat 81. The trigger element 80 is loaded in the direction at right-angles to the axis A by a spring 85, which is interposed between an end surface of the recess 84 and the actuation portion 83, such that the ring portion 82 is kept continually in contact with the outer surface of the portion 34 of the valve element 11, on the side which is diametrically opposite the actuation portion 83 itself . The stop mechanism 16 comprises a selection ferrule 86, which is similar to the ferrule 52, and differs from the latter in that it has a larger size, and comprises a first portion 87, which corresponds entirely to the ferrule 52, and cooperates in a sliding manner with an outer surface of the portion 35 of the wall 30 of the valve element 11, and a second portion 88, which cooperates in a sliding manner with an outer surface of the element 20 of the body 10. The portion 88 of the ferrule 86 also has a through slot 89, with a substantially rectangular profile, which can be engaged, by means of the thrust of the spring 85, by the actuation portion 83 of the trigger element 80, in the position of connection of the latter with the groove 69 of the valve element 11, corresponding to the position of coupling of the terminal 5; by this means, the selection ferrule 86 is prevented from being actuated before the trigger element 80 is displaced into the release position, by this means by-passing the safety function of the joint 1'. The portion 87 of the ferrule 86 is provided with the annular groove 54 , which can be engaged by the spheres 50, and is loaded by the spring 55, which, instead of the ring 56, cooperates with a projection 93, which extends integrally from the portion 35 of the wall 30 of the valve element 11. In its own position of engagement with the groove 7 of the terminal 5, the ferrule 86 is thrust by the spring 55 against a ring 92, which is mounted externally on a free end of the portion 35 of the valve element 11, and to all effects replaces the flange 47. In the release position, the ring portion 82 of the trigger element 80 cooperates with the portion 34 of the wall 30 of the valve element 11, and has dimensions together with the latter, such that the outer surface of the actuation portion 83 is disposed perfectly in line with the outer surface of the element 20 of the body 10, in the vicinity of the recess 84, in order to permit axial sliding of the ferrule 86 relative to the body 10 itself. Finally, the element 20 of the body 10 is provided externally in a projecting manner with a radial peg 90, which cooperates in a sliding manner with a longitudinal groove 91 of the ferrule 86, and has the function of keeping the ferrule 86 itself in a pre-determined angular position relative to the axis A, such that the slot 89 is always aligned with the actuation portion 83 of the trigger element 80. The assembly of the joint l 1 is altogether similar to the assembly of the joint 1, and is also described on the basis of an initial configuration (figure 10) in which the terminal 5 is disconnected from the connection unit 4 ' , the valve element 11 is disposed in its own first operative position, the trigger element 80 is disposed in its own release position, and the retention element 53 is thrust by the spring 64 in the direction opposite the wall 29, and forms a radial stop for the spheres 50, which are thus disposed in the position of disengagement, and also keep the selection ferrule 86 axially spaced from the ring 92. In this case also, the terminal 5 is connected to the connection unit 4 by means of a single manoeuvre of insertion of the terminal 5 itself inside the cavity 36 of the valve element 11. In this step, as soon as the groove 7 of the terminal 5 is in the position of the spheres 50, by means of the effect of the thrust of the spring 55 on the selection ferrule 86, the spheres slide inside the corresponding seats 51, and are thrust into engagement with the groove 7 itself, thus forming a mechanical connection between the terminal 5 and the valve element 11 (figure 11) . Simultaneously, owing to the disengagement of the spheres 50 from their own groove 54, and again owing to the effect of the thrust of the spring 55, the selection ferrule 86 is thrust against the ring 92, thus covering partially the actuation portion 83 of the trigger element 80. The valve element 11, which continues to thrust the terminal 5 axially inside the connection unit 4, is displaced integrally with the terminal 5 itself, from the first operative position towards the second operative position, thus giving rise to compression of the spring 13, and gradually moving the ring 38 away from the surface 27 of the projection 14, such as to put the chamber 12 into communication with the cavity 36, via the bladed section 42 of the valve element 11. Owing to the presence of the ring 92, the ferrule 86 is also displaced integrally with the valve element 11. As soon as the groove 69 of the valve element 11 is in the position of the ring portion 82 of the trigger element 80, and simultaneously the slot 89 is aligned with the actuation portion 83, owing to the effect of the thrust of the spring 85, the trigger element 80 slides in the seat 81, and is thrust into the position of connection with the groove 69 itself, thus locking the valve element 11 in the second operative position, in which it opens the fluid connection between the pipes 2 and 3 , and defines the advanced position of coupling of the terminal 5 inside the connection unit 4 (figures 8 and 9) ; in this position, the actuation portion 83 of the trigger element 80 engages the slot 89. The terminal 5 is disconnected from the connection unit 4 ' by acting separately and in succession on the trigger element 80 and on the selection ferrule 86. In particular, in the position of engagement of the terminal 5, the ferrule 86 cannot be displaced axially, since the actuation portion 83 of the trigger element 80 engages the slot 89 (figures 8 and 9) . It is therefore necessary to exert pressure on the actuation portion 83, in the direction at right-angles to the axis A, such as to disengage the ring portion 82 from the groove 69; at this point, by means of the effect of the thrust of the spring 13 and of the pressurised fluid, the valve element 11 is displaced from the second to the first operative position, in which, by means of the contact of the ring 38 with the surface 27 of the projection 14, it separates the chamber 12, and thus the pipe 2 , in a sealed manner from the remaining part of the joint 1. In this step, the terminal 5 still abuts the valve element 11, by means of the engagement of the spheres 50 in the groove 7 (figure 11) . On completion of displacement of the valve element 11 to the first operative position, the ring 44 is positioned between the lowered section 43 of the valve element 11, and the surface 26 of the projection 14 of the body 10, thus allowing the operative fluid which is contained between the projection 14 itself and the pipe 3 to be drawn towards the exterior. At this point, it is possible to act on the selection ferrule 86, by displacing it axially towards the pipe 2; when the groove 54 of the ferrule 86 is in the position of the spheres 50, the latter, owing to the effect of the thrust of the spring 64, slide inside the corresponding seats 51, and are thrust into engagement with the groove 54 itself, thus releasing the terminal 5, detachment of which takes place in a perfectly controlled manner, owing to the lack of pressure inside the cavity 36 of the valve element 11 (figure 10) . Finally, it is apparent that modifications and variants can be made to the connection units , 4 ' produced according to the present invention, without departing from the scope of protection of the claims .

Claims: CLAIMS 1. Connection unit (4, 4') which can be connected to a first distribution pipe (2) of a pressurised operative fluid, and can be connected such that it can be released, to a terminal (5) of a second pipe (3) for distribution of said operative fluid, in order to form a fast-coupling safety joint (1, 1'), said connection unit (4, 4') having a longitudinal axis (A) , and comprising: - a main, hollow body (10) which can be connected to said first pipe (2) ; a slide valve element (11) , mounted such that it can slide axially inside said main body (10) ; first resilient means (13) , which exert axial thrust on said valve element (11) , in order to maintain it in a first operative position, in which said valve element (11) separates said first pipe (2) from the external environment in a fluid-tight manner; - first releasable stop means (15, 15'), which in use define an advanced coupling position of said terminal (5) inside said connection unit (4, 4'), in which said terminal (5) exerts on said valve element (11) thrust, which is opposite and prevalent relative to the thrust exerted by said first resilient means (13) , and maintains the valve element (11) itself in a second operative position, of opening of the fluid connection between said first and second pipe (2, 3) ; second releasable stop means (16) , which can cooperate with said terminal (5) in order to retain it, after release of said first stop means (15, 15') and during the step of disconnection of the terminal (5) itself from said connection unit (4, 4'), into a withdrawn, safety position, in which said terminal (5) is mechanically connected to said connection unit (4, 4'), and said valve element (11) is disposed in said first operative position, and permits drawing towards the exterior of the operative fluid which is present beyond said first pipe (2) , towards the terminal (5) itself; characterised in that said first stop means (15, 15') comprise releasable connection means (17; 69, 82), between said main body (10) and said valve element (11) , and said second stop means (16) comprise releasable constraint means (18) , which are supported by said valve element (11) and can cooperate with said terminal (5) in order to render it integral with the valve element (11) itself, during its own displacement between said withdrawn safety position, and said advanced coupling position. 2. Connection unit according to claim 1, characterised in that said first stop means (15) comprise first, manually actuated selection means (70) , in order to command release of said connection means (17) , and said second stop means (16) comprise second, manually actuated selection means (52) , in order to command release of said constraint means (18) , said connection unit (4) comprising means (75) to inhibit actuation of said second selection means (52) , which are active in the coupling position of said terminal (5) , and can be deactivated after actuation of said first selection means (70) . 3. Connection unit according to claim 2 , characterised in that said connection means (17) comprise first engagement means (69) , which are supported by said valve element (11) , and second engagement means (67) , which are supported by said main body (10) , and are mobile, under the command of said first selection means (70) , between a position of connection to said first engagement means (69) , in order to define said second operative position of said valve element (11) , and said advanced position of coupling of said terminal (5) , and a position of release from the first engagement means (69) themselves. 4. Connection unit according to claim 3 , characterised in that said first engagement means comprise an annular groove (69) , which is provided on an outer surface of said valve element (11) , and said second engagement means comprise a plurality of first spheres (67) , which are mounted such as to slide in respective radial through seats (68) provided in said main body (10) . 5. Connection unit according to any one of claims 2 to 4, characterised in that said valve element (11) has an internal cavity (36) , which can be engaged in use by said terminal (5) , and said constraint means (18) comprise a plurality of second spheres (50) , which are mounted such as to slide in respective radial through seats (51) , which are provided in a lateral wall (30) of said valve element (11) and delimit said cavity (36) , and are mobile, under the command of said second selection means (52) , between a position of engagement with a corresponding annular groove (7) of said terminal (5) , in order to form a mechanical connection between said valve element (11) and the terminal (5) itself, and a position of disengagement from said groove (7) of said terminal (5) . 6. Connection unit according to claim 5 , characterised in that said second stop means (16) comprise a retention element (53) , which is mounted such as to slide inside said cavity (36) of said valve element (11) , and can be engaged in use by said terminal (5) , one-way constraint means (65) , which are interposed between said retention element (53) and said valve element (11) , in order to prevent extraction of the retention element (53) itself from said connection unit (4) , and second resilient means (64) , which are accommodated in said cavity (36) of said valve element (11) , and exert axial thrust on said retention element (53) , in order to place it, when it is disconnected from the terminal (5) itself, in a position of inner closure of said seats (51) of said second spheres (50) . 7. Connection unit according to claim 5 or claim 6, characterised in that said valve element (11) has a portion (33) which projects axially from said main body (10) , said first selection means comprising a first selection ferrule (70) , which is mounted such as to slide axially along a radially outer surface of said main body (10) , having at least one seat (71) for said first spheres (67) in said release position, and is actuated by third resilient means (72) , said second selection means comprising a second selection ferrule (52) , which is mounted in an axially sliding manner along a radially outer surface of said projecting portion (33) of said valve element (11) , having at least one seat (54) for said second spheres (50) in said position of disengagement, and is actuated by fourth resilient means (55) , said inhibition means being defined by an end portion (75) of said first selection ferrule (70) , which is disposed, in said position of coupling of said terminal (5) , such that it is covered radially, and covers fully said second selection ferrule (52) . 8. Connection unit according to claim 1, characterised in that said first stop means (15') comprise at least one trigger element (80) which is supported by said main body (10) , is mobile in a radial direction relative to said longitudinal axis (A) , and is loaded in said radial direction by fifth resilient means (85) which are interposed between said main body (10) and the trigger element (80) itself, said connection means comprising third engagement means (69) which are supported by said valve element (11) , and fourth engagement means (82) , which are supported by said trigger element (80) and are mobile between a position of connection to said third engagement means (69) , in order to define said second operative position of said valve element (11) , and said advanced position of coupling of said terminal (5) , and a position of release from the third engagement means (69) themselves . 9. Connection unit according to claim 8, characterised in that said trigger element (80) comprises a ring portion (82) , which defines said fourth engagement means, and is disposed with radial play on the exterior of said valve element (11) , and inside a corresponding seat (81) of said main body (10) , and an actuation portion (83) , which extends in a projecting manner from said ring portion (82) , and is loaded by said fifth resilient means (85) , such that said ring portion (82) is maintained constantly in contact with the outer surface of said valve element (11) , on the side diametrically opposite the actuation portion (83) itself, said third engagement means comprising an annular groove (69) provided on an outer surface of said valve element (11) . 10. Connection unit according to claim 9, characterised in that said second stop means (16) comprise third, manually actuated selection means (86) , in order to command release of said constraint means (18) , said third selection means comprising a third ferrule (86) for selection (52) , which is mounted in an axially sliding manner along a radially outer surface of said valve element (11) , is actuated by sixth resilient means (55) , and can determine release of said constraint means (18) , by means of the effect of its own axial displacement in the direction opposite the thrust exerted by the sixth resilient means (55) themselves, said third ferrule (86) having a slot (89) which can be engaged, by the effect of the thrust of said sixth resilient means (55) , by said actuation portion (83) of said trigger element (80) , in said position of connection of said ring portion (82) to said third engagement means (69) of said valve element (11) , such as to inhibit actuation of said third ferrule (86) in this position, before the trigger element (80) is displaced into the position of release, between said ring portion (82) and said third engagement means (69) . 11. Connection unit according to any one of the preceding claims, characterised in that said connection unit (4, 4') comprises first and second sealing means (38, 44), which are interposed between said main body (10) and said valve element (11) , said second sealing means (44) being positioned on the side opposite said first sealing means (38) , relative to said first pipe (2) , said first sealing means (38) being active in said first operative position of said valve element (11) , and deactivated in said second operative position of the valve element (11) itself, said second sealing means (44) being active in said second operative position of said valve element (11) , and deactivated in the first operative position of the valve element (11) itself.

Inventors: NICOLINO ALDO, NICOLINO, ALDO
Applicants: NICOLINO ALDO, PRES BLOCK S R L, NICOLINO, ALDO, PRES BLOCK S.R.L.
Application year: 1998
Main classification: F16L37
IPC codes: F16L37