PERON, Luca (Via Desman, 133, Borgoricco, I-35010, IT)
PLAIAN, Teodora (Via Leandro Faggin 26, Ponte San Nicolo', I-35020, IT)
BORTOLIERO, Michele (Via Pio X 20, Monselice, I-35043, IT)
PERON, Luca (Via Desman, 133, Borgoricco, I-35010, IT)
PLAIAN, Teodora (Via Leandro Faggin 26, Ponte San Nicolo', I-35020, IT)
| CLAIMS 1. A system for connecting a gas flow cut-off device in a gas meter (1), for protection against excess temperatures, to a structure of the meter, the structure comprising a boxlike casing (3) of the meter in which a gas inlet section (4) is formed, and the device comprising a plug element (7) associated with a valve seat (6) formed in the inlet section (4), the plug being provided with a operating rod (8) slidably mounted on a support (9) fastened to the boxlike casing (3), with a spring (13) acting on the plug (7) in such a way that the latter tends to close the seat (6), a fusible element (15) being interposed between the support (9) and the plug (7) to keep the plug in a position distant from the seat (6) in opposition to the resilient action of the spring (13), the plug (7) being movable to close the seat (6) under the resilient action as a result of the fusion of the fusible element (15), thus causing the gas flow to be cut off in the inlet section (4), characterized in that it comprises means and counter- means for fixing the support (9) to the meter structure, the fixing means and counter-means comprising at least one appendage (18) projecting into the meter from a wall (16) of the boxlike casing (3) and at least one corresponding seat (19) provided in the support (9) and engageable by the at least one appendage (18), means being provided to lock the appendage (18) in the seat (19) in order to secure the support (9) to the boxlike casing (3). 2. A connecting system according to Claim 1, wherein a plurality of appendages (18) projecting from the wall (16) into the boxlike casing (3) is provided, the appendages (18) being engageable with corresponding seats (19) provided in the support (9), the locking between the appendages (18) and the corresponding engagement seats (19) being provided by the chamfering or rolling back of the free ends of the appendages (18), to ensure their retention with respect to the corresponding seats (19). 3. A system according to Claim 2, wherein the appendages (18) are produced on the wall (16) of the boxlike casing (3) by localized deformation of the wall (16) of the boxlike casing (3), without any through holes formed in the wall, such that no gas sealing means are required in the fastening of the support (9) to the wall (16) of the meter. 4. A system according to Claim 3, wherein the support (9) comprises a platelike base (9a) interacting, by a substantially positive connection, with a recess (20) formed in the wall (16), the appendages (18) projecting from a surface of the recess (20) to engage in corresponding through holes which are made in the base (9a) and which form the seats (19) for engaging the appendages (18). 5. A system according to Claim 4, wherein the operating rod (8) of the plug (7) is slidably mounted in the support (9) coaxially with the valve seat (6), which in turn is coaxial with the gas inlet section (4) of the meter, the rod (8) carrying the plug (7) at one of its ends and having a bearing point (14) at its other end, the fusible element being made in the form of a sleevelike spacer (15) which is fitted on the rod (8) between the support (9) and the bearing point (14) so as to retain the plug (7) in a position distant from the valve seat (6) with consequent compression of the return spring (13), the spring being positioned between the plug (7) and the support (9), on the opposite side of the support (9) from the spacer (15). |
Technical field
The present invention relates to a system for connecting a gas flow cut-off device in a gas meter, for protection against excess temperatures, the system having the features described in the preamble of Claim 1 which is the principal claim.
Technological background
In the technical field of the present invention, which is concerned with gas meters for monitoring the consumption of gas supplied to a user, there is a known way of using valve devices which can cut off the gas flow, for protection against excess temperatures.
Such a device normally uses a cut-off plug associated with a corresponding valve seat, in the gas inlet section of the meter, the plug being normally kept in the open position of the seat in opposition to a resilient return action, where this return action is, for example, obtained by keeping a spring in compression with the interposition of a fusible element having a relatively low specified melting point. When this element is melted as a result of a critical occurrence caused for example by the overheating of the meter in the presence of excess temperatures or fire, the plug can be freely moved to close the valve seat by the action of the return spring, thus cutting off the main gas supply path.
An example of a cut-off device of this kind is known from FR 2736431.
Such a cut-off device is typically mounted inside the boxlike casing of the meter by screw or similar fastening means, which require special working of the fastening surfaces with the provision of fixing bases or piercings for the engagement of the fastening screws. Since this fastening is also provided in a space in which gas is present and flowing, it is necessary to ensure sufficient gas-tightness between the surfaces which are joined in this space.
Description of the invention
The object of the invention is to provide a system for connecting cut-off devices of the aforesaid type in gas meters which is structurally and functionally designed so as to overcome the constraints described with reference to the cited prior art.
This problem is resolved by the invention by means of a connection system made in accordance with the following claims.
Brief description of the drawings
Other features and advantages of the invention will become clear from the following detailed description of a preferred example of embodiment thereof, illustrated, for the purpose of illustration and in a non-limiting way, in the attached drawings, in which :
Figure 1 is a schematic perspective view of a gas meter provided with a cut-off device connected to it by the system according to the invention,
Figure 2 is a cross-sectional view of the meter of Figure 1, with the cut-off device shown in an inoperative condition in which the gas path is open,
Figure 3 is a cross-sectional view of the meter of Figure 1, with the cut-off device shown in an operating condition in which the gas path is closed,
Figure 4 is a sectional view, on an enlarged scale, of a detail of the connection system of the preceding figures.
Preferred embodiment of the invention
With reference to the above drawings, the number 1 indicates the whole of a gas meter provided with a gas path cut-off device 2, for protection against excess temperatures, the device being connected to the device with a connection system constructed according to the invention.
The meter 1 is of the type comprising a boxlike casing 3 in which a gas inlet section 4 and a gas outlet section 5 are provided.
The casing 3 is formed by a first part 3a, in which the sections 4 and 5 are formed, and which is connected in a gas-tight way to a second part 3b.
The inlet section 4 is made in the form of a sleeve 4a fixed in a gas-tight way in an aperture formed in the part 3a of the boxlike casing, on which the main gas path cut-off device 2 acts directly, as is made clear in the remainder of the description.
A valve seat 6 intended to interact with a plug 7 of the safety device is formed in the sleeve 4a.
The plug 7 is fixed to an operating rod 8 guided coaxially with the valve seat, by means of a slidable engagement in a support 9, the support comprising a platelike base 9a for attachment to the boxlike casing of the meter, a thin- walled frame 10 projecting from this base and being pierced by a pair of holes 11, 12 which are coaxial with each other and spaced apart, in which the rod 8 is slidably guided. A return spring 13 acts between the plug and the wall 10a of the frame 10 facing it. The rod 8 is provided with a bearing point 14 at the end opposite the plug. Between the bearing point and the wall 10b of the structure 10 facing it there is a sleevelike spacer 15 made of low-melting-point material, the presence of which causes the plug 7 to be kept in a distant position from the corresponding valve 6, with the spring 13 in compression. If the spacer 15 of low-melting-point material melts in critical conditions, for example if the meter overheats because of the presence of excess temperatures or fire, the return action of the spring 13 makes the plug 7 tend to close the seat 6 as a result of the free sliding of the rod, in the absence of the spacer, thus causing the main gas path to be cut off in the inlet section 4.
The plug 7 is provided with a plug head formed by a plate 7a with a lateral edge 7b bent back and having a predetermined taper, this shape causing the plug to be self-centring with respect to the valve seat associated therewith.
The connection system according to the invention includes fixing means and counter-means located between the base 9a and the wall 16 for the connection of the support 9 to the wall 16 of the part 3b of the boxlike casing. In greater detail, the wall 16 is provided with appendages 18 which project from the wall towards the inside of the boxlike casing 3, and which can engage in corresponding through holes 19 formed in the base 9a of the support, with mutual locking with these holes, for example by means of an operation of chamfering or rolling back the ends of the appendages 18 in the corresponding seats formed by the holes 19, in order to ensure their permanent fitting.
The appendages 18 are advantageously formed in a recess 20 in the wall 16, created by pressing, as shown clearly in Figure 4, this recess being formed by a kind of boss in the wall 16, provided for a different function in the assembly of the meter. The base 9a is also made in a shape such that it engages by superimposition, with a substantially positive connection, with the surface 20a of the recess which faces the base, thus ensuring a precise fit between the joined parts.
The appendages 18 can be formed conventionally by the localized deformation of the wall 16 in the area of the recess 20. It should be noted that the preparation of the wall 16 for the fixing of the support 9 makes use of a structure which is already present and intended for a different function, thus limiting the amount of work done on the boxlike casing, while also requiring no apertures or piercings through the wall 16 of the meter, and thus requiring no provision of gas-tight sealing means in the connection system of the cut-off device for protection against excess temperatures, on the side facing the wall 16 of the meter.
It should also be noted that the gas path cut-off device 2 is designed as a structure wholly independent of the valve unit (not shown) which is provided in the meter and which is placed downstream of the device 2 with respect to the direction of flow of the gas.
It also makes it possible to provide a downstream valve unit with components made from plastics materials, since protection against excess temperatures is provided by the device 2.
It should also be understood that the spacer 15 of fusible material, required for protection against excess temperatures, can have a different shape from that described above. For example, it can be made as a spacer having a C-shaped cross section, enabling it to be freely fitted on the operating rod of the plug once the latter has been fitted and its capacity for the sealed closure of the valve seat under the resilient action of the spring has been verified.
It should also be noted that the cut-off device acts directly on the inlet section 4 of the meter, which can be made independently of the boxlike casing for subsequent assembly, thus facilitating the machining of the corresponding components.
Thus the invention achieves the proposed object and provides the aforementioned advantages with respect to the known art.