SYSTEM"

DESCRIPTION

[0001]The present invention relates to the field of valves for fuel cell vehicle systems, and in particular to the field of valves for managing the flow of hydrogen between a tank and the fuel cells. In particular, the present invention relates to a sealing assembly for a valve.

[0002]In a fuel cell vehicle system, hydrogen is stored in a high-pressure tank, typically 700 or 350 bar. A multifunction valve is applied to the tank, usually called OTV (On-Tank-Valve), which allows the introduction of hydrogen into the tank (refilling function) and the release of hydrogen towards the downstream user devices (fueling function). The multifunction valve is provided with numerous functional devices, such as a solenoid opening device, a thermal safety device and manual shut off taps.

[0003]The components of these functional devices, which must ensure excellent sealing against gas leaks, are typically subject to the high pressures of hydrogen. There is therefore the need to adopt reliable technical solutions, such as to ensure gas tightness under pressure for the entire programmed life of the multifunction valve. [0004]The object of the present invention is that of implementing a multifunction valve provided with a sealing assembly capable of meeting the above mentioned requirements . [0005]Such an object is achieved by a multifunction valve according to claim 1. The dependent claims disclose further advantageous embodiments of the invention.

[0006]The features and the advantages of the multifunction valve according to the present invention appear more clearly from the following description, made by way of an indicative and non-limiting example with reference to the drawings of the accompanying figures, in which:

- Figure 1 is a sectional view of a region of a multifunction valve according to the present invention; - Figure 2 shows a region of a first functional device of the multifunction valve, i.e. a thermal safety device;

Figure 3 shows a stem of the first functional device; - Figure 4 shows an enlargement of the panel IV of

Figure 3, which highlights a junction portion of the stem;

- Figure 5 shows a front view of an anti-extrusion ring of a sealing assembly according to the present invention; - Figure 6 is a sectional view of the anti-extrusion ring, according to the section plane VI-VI of Figure 5;

- Figure 7 shows a region of a second functional device of the multifunction valve, i.e. a manually operated shut-off tap.

[0007]A multifunction valve according to the invention comprises a valve body 2, for example made of a single piece of metal material, for example of aluminum, having a first compartment 4 for a first functional device 10 which operates, for example, as a bulb-shaped heat safety device.

[0008]For example, the first functional device 10 comprises a stem 12 slidably housed in the first compartment 4 along a first direction XI. The stem 12 comprises a guide segment 14, sealingly slidable in a sealing section 16 of the first compartment 4 having a lateral surface 16a. The guide segment 14 comprises a first portion 14a having a first diameter Dl, a second end portion 14b having a second diameter D2, wherein the first diameter Dl is greater than the second diameter D2 (D1>D2), and a junction portion 14c which joins the first portion 14a to the second portion 14b, having a frustoconical lateral surface 14d converging towards the second portion 14b. [0009]The lateral surface 14d of the junction portion 14c has an opening angle B comprised between 45 and 55°, preferably between 48 and 50°, preferably equal to 49°. [0010]A first sealing assembly 18 is applied to the guide section 14 which ensures sealing with the lateral surface 16a of the sealing section 16.

[0011]In the sealing section 16, upstream of the first sealing assembly 18, which defines a high-pressure side, there is a high pressure pi of the hydrogen; downstream of the first sealing assembly 18, on the other hand, a free side is defined.

[0012]From the high-pressure side towards the free side, the first sealing assembly 18 preferably comprises a positioning ring 20, fitted onto the second portion 14b of the guide segment 14 and having a clearance with respect to the lateral surface 16a of the sealing section 16.

[0013]Preferably, the positioning ring 20 has a square or rectangular cross section, circumferentially continuous and homogeneous. [0014]Preferably, the positioning ring 20 is made of PTFE

(Polytetrafluoroethylene ).

[0015]The first sealing assembly 18 also comprises a primary O-ring 22, placed by the side of the positioning ring 20 and in contact therewith, fitted with interference on the second portion 14b of the guide segment 14 and in compression against the lateral surface

16a of the sealing section 16, so as to achieve the seal to gas under pressure.

[0016]Preferably, the primary O-ring 22 is made of silicone or VMQ (Vinyl-Methyl-Silicone).

[0017]Finally, the sealing assembly 18 comprises an anti ^¬ extrusion ring 24, placed by the side of the primary 0- ring 22 and in contact therewith, fitted on the junction portion 14c of the guide segment 14 and in compression against the lateral surface 16a of the sealing section 16.

[0018]Preferably, the anti-extrusion ring 24 is made of PTFE (polytetrafluoroethylene).

[0019]The anti-extrusion ring 24 consists of an annular unit body 26 having a ring axis Z which, when the ring is fitted onto the guide segment 14, is coaxial to the first direction XI. The unit body 26 has a cylindrical external lateral surface 28, coaxial to the ring axis Z, a front surface 30 consisting of a flat circular crown lying on an imaginary plane orthogonal to the ring axis Z having an inner diameter Dmax, and a rear surface 32 consisting of a flat circular crown lying on an imaginary plane orthogonal to the ring axis Z having an inner diameter

Dmin. [0020]The inner diameter Dmax of the front surface 30 is greater than the inner diameter Dmin of the rear surface

32.

[0021]Internally, between the front surface 30 and the rear surface 32, the unit body 26 has a frustoconical inner lateral surface 34, coaxial to the ring axis Z. The opening angle A of the inner lateral surface 34 is comprised between 50 and 70°, preferably between 60 and 65°, preferably equal to about 62°. In any case, the opening angle A of the inner lateral surface 34 of the unit body 26 is greater than the opening angle B of the lateral surface 14d of the frustoconical portion 14c on which the anti-extrusion ring is fitted (A>B).

[0022]After having applied the anti-extrusion ring 24 to the guide segment 14, the inner lateral surface 34 is facing and in contact with the lateral surface 14c of the frustoconical segment 14b of the guide segment 14.

[0023]Preferably, moreover, between the inner lateral surface 34 and the rear surface 32, connected thereto, there is an auxiliary cylindrical surface 36, coaxial to the ring axis Z. In this variant, the transverse section of the unit body 26 therefore has the shape of a rectangle trapezoid having the major base on the front surface 30 and the minor base at the junction with the auxiliary surface 36. [0024]Furthermore, the multifunction valve preferably has a second compartment 104 for a second functional device which operates, for example, as a manually operable shut off tap.

[0025]For example, the second functional device comprises a stem 1012 housed in the second compartment 104 so as to be translatable along a second direction X2.

[0026]A second sealing assembly 1018 is applied to the stem 1012 of the second functional device, comprising the possible positioning ring 1020, the primary O-ring 1022 and the anti-extrusion ring 1024. The stem 1012 and the second sealing assembly 1018 are structurally and functionally similar to the stem 12 and the first sealing assembly 18 of the first functional device 10.

[0027]Preferably, moreover, the multifunction valve has a further compartment for a further functional device which operates, for example, as a temperature sensor for detecting the temperature in a predefined region inside the valve body.

[0028]Innovatively, the multifunction valve according to the present invention allows the needs of the field to be met, since the high pressure of the hydrogen operates on the anti-extrusion ring in the sense of deforming it and considerably increasing the gas tightness.

[0029]It is clear that a person skilled in the art may make changes to the multifunction valve described above in order to meet incidental needs, all falling within the scope of protection defined in the following claims.