Manually-operated valve particularly for gas, with means for limiting the opening stroke of the actuation handwheel

A manually-operated valve particularly for gas, with elements for limiting the opening stroke of an actuation handwheel, which comprises a valve body which internally forms a gas passage duct being controlled by a flow control element which can be actuated by a handwheel which can perform a translational motion by turning. Elements for limiting the opening stroke of the handwheel are further provided. The stroke limiting elements comprise a locking element which can move substantially at right angles to the axis of the rotation thread of the handwheel, the locking element engaging, at an opening stroke limit of the handwheel, an abutment for stopping the rotation of the handwheel.

DESCRIPTION OF THE PREFERRED EMBODIMENTS With reference to the figures, the manually-operated valve particularly for gas, with means for limiting the opening stroke of the actuation handwheel, generally designated by the reference numeral 1 , comprises a valve body 2 having a mouth 3 for the connection of a bottle of gas and the like and a mouth 4 for dispensing the gas. Inside the valve body 2 a duct 5 is provided for connection between the mouth 3 and the mouth 4 being controlled by a flow control element 10 which can move hermetically in a chamber 11 formed in the valve body and is actuated by a handwheel 15 which can perform a translational motion by turning. In greater detail, the handwheel has a shank 16 being arranged inside the valve body and has a male thread 17 which engages a female thread 18 formed in the chamber 11 . The shank 16 is connected to a knob 19 which is external to the valve body 2 . Means for limiting the opening stroke are provided on the handwheel 15 and limit the stroke of the handwheel in order to prevent its extraction. The stroke limiting means comprise at least one locking element which can move substantially at right angles to the axis of the handwheel rotation thread. With reference to FIGS. 1 to 4 , the locking element, generally designated by the reference numeral 20 , has an elastic ring 21 which externally surrounds the valve body and acts on a locking pin 22 which can move radially with respect to the chamber in which the shank 16 of the handwheel can perform a translational motion. The shank of the handwheel, as shown more clearly in FIGS. 3 and 4 , is provided along its circumference with recesses 25 which gradually increase in depth and define, at the deepest end, an abutment 26 for stopping rotation by engaging the locking pin 22 . With the described arrangement, the locking pin is pushed elastically in a radial direction by the elastic ring and performs its insertion when the hole 23 , in which it is slidingly supported, is located in front of a recess 25 , allowing its insertion. The engagement between the locking pin 22 and the abutment 26 blocks the rotation of the handwheel 15 in the opening direction without however creating any forcing in an axial direction. According to a different embodiment, which is conceptually similar and is shown in FIGS. 5 and 6 , the locking element has an annular element 30 which ends with a locking pin 31 which also can slide in a radial direction and is accommodated in a hole 23 formed in the valve body 2 . As in the preceding example, there are recesses 25 with the corresponding abutment 26 . According to a kinematically reversed embodiment, the locking ring can be fitted on the handwheel, as shown in FIGS. 7 and 8 . In this case, there is a pin spring 40 which is provided with two locking ends 41 which can slide in a radial direction with respect to radial holes 42 provided in the handwheel and can be inserted in recesses 43 formed correspondingly on the internal surface of the valve body. The recesses 43 gradually increase in depth and have, at their deeper ends, an abutment which is again designated by the reference numeral 26 . FIGS. 9 and 10 illustrate a locking element which is fitted on the handwheel 15 and is provided by means of an internal ring 50 which lies circumferentially in a groove 51 formed in the handwheel. In the groove there is a radial stop element 52 for one end of the internal ring having at its other end a locking tip 53 which enters a recess, again designated by the reference numeral 43 , which gradually increases in depth and has the abutment 26 at its deeper end. With reference to FIGS. 11 and 12 , another embodiment is illustrated being based on the same innovative concept and in which the locking element is supported by the handwheel. In the specific embodiment, the locking element is constituted by a piston 80 being pushed by a helical pusher spring 81 which is accommodated in a slot 82 which is formed inside the knob 19 . The piston 80 is pushed against the body 2 of the valve in the region where the shank 16 of the handwheel 15 is inserted. In this region, the body 2 is provided with outer recesses 83 which gradually increase in depth along its circumference and form, at the deeper end, an external abutment 84 against which the piston 80 engages, locking the rotation of the knob in the extraction direction. With reference to FIGS. 13 and 14 , another embodiment is illustrated in which the locking element is associated with the knob 19 of the handwheel 15 . The locking element is provided by means of a pin spring 90 supported by a protrusion 91 formed on the knob 19 and provided with a first arm 92 which abuts against the internal surface of the knob and a second arm 93 which engages the external recesses, again designated by the reference numeral 83 . In this embodiment, the pin spring 90 has excellent resistance to the unscrewing torque produced by the load applied axially in an upward region with respect to the spring. The embodiments illustrated in FIGS. 11 to 14 are particularly advantageous, since in practice they allow to avoid substantially modifying the manufacture of the existing valve by adopting a few structural modifications on the knob of the handwheel and on the outer surface of the valve body. To complete the assembly, it is noted that for safety reasons it is possible to maintain the traditional locking ring, designated by the reference numeral 60 , which engages by abutment against a shoulder 62 formed on the handwheel. The arrangement is such that engagement between the shoulder 62 and the locking ring 60 is provided only in case of failure of the locking performed by the locking element that is movable at right angles to the axis of the rotation thread of the handwheel, i.e., the axis formed by the male thread 17 provided on the handwheel and the female thread 18 provided on the surface of the chamber formed inside the valve body. With the described arrangement, therefore, the locking element, by performing a translational motion in a radial direction, does not generate axial components on the handwheel which might lead to jamming of the rotation of the handwheel due to the friction generated on the rotation thread; furthermore, the described arrangement allows to achieve automatic engagement and disengagement of the locking element without producing force components which might lead to jamming. The invention thus conceived is susceptible of numerous modifications and variations, all of which are within the scope of the appended claims. All the details may further be replaced with other technically equivalent elements. In practice, the materials used, as well as the contingent shapes and dimensions, may be any according to requirements. The disclosures in Italian Patent Application No. MI2000A002578 from which this application claims priority are incorporated herein by reference.