"TANK UNIT FOR A HYDROGEN FUEL CELL AUTOMOTIVE SYSTEM"

[0001]The present invention belongs to the field of hydrogen-powered fuel cell automotive system components. In particular, the present invention relates to a tank unit for storing the hydrogen on board the vehicle.

[0002]Most hydrogen-powered fuel cell automotive systems include a single tank in which the hydrogen is stored at high pressure; a multifunction valve (OTV valve), for hydrogen fueling and supplying a fuel cell supply line, provided with numerous accessory devices, such as cut-off valves, vent valves, thermal safety devices etc., is applied to one flange of the tank.

[0003]Recently, the need has arisen to use a plurality of smaller tanks to replace a single larger tank, in order to conveniently take advantage of some spaces of the vehicle.

[0004]Such smaller tanks have some drawbacks. For example, it is not possible to apply a traditional OTV valve of the type described above thereto, due to the overall dimensions which do not allow it to be applied to the flange.

[0005]Therefore, there is the need to create a tank unit, comprising a plurality of tanks, which is suitable for fueling and supplying hydrogen to usage devices, and provided with the aforesaid accessory devices.

[0006]It is the object of the present invention to provide a tank unit capable of meeting the needs of the field and overcoming the aforementioned drawbacks. [0007]Such an object is achieved by a tank unit according to claim 1. The dependent claims identify further advantageous embodiments of the invention.

[0008]The features and advantages of the tank unit according to the present invention will become apparent from the following description, given by way of non limiting example, according to the accompanying drawings, in which:

[0009]- Figure 1 shows a front view of a tank unit according to an embodiment of the present invention; [0010]- Figure lb shows a side view of the tank unit in

Figure la;

[0011]- Figure 2 shows a sectional view of a main inlet unit of the tank unit, obtained according to the section plane II-II in Figure la; [0012]- Figure 3 shows a sectional view of a top unit of the tank unit, obtained as an enlargement of box III in Figure lb;

[0013]- Figure 4 shows a sectional view of a top unit of the tank unit, obtained as an enlargement of box IV in Figure la; [0014]- Figure 5 shows a sectional view of a bottom unit of the tank unit, obtained as an enlargement of box V in Figure la;

[0015]- Figure 6 shows a sectional view of a main outlet unit of the tank unit, obtained according to the section plane VI-VI in Figure la;

[0016]- Figure 7 shows a tank pack with a general discharge pipe in a top manifold, according to an embodiment of the invention; [0017]- Figure 8 shows an enlargement of box VIII in

Figure 7;

[0018]- Figure 9 shows a section of a bottom manifold and of bottom units of the tank pack, according to an embodiment; [0019]- Figure 10a shows a bottom unit in Figure 9;

[0020]- Figure 10b shows a three-dimensional section of a bottom manifold and of bottom units of the tank pack, according to a further embodiment;

[0021]- Figure 11 shows a tank pack with a casing, according to a further embodiment of the invention;

[0022]- Figure 12 shows an enlargement of box VIII in

Figure 11.

[0023]With reference to the accompanying Figures, reference numeral 1 indicates as a whole a tank unit for a hydrogen-powered fuel cell automotive system, according to an embodiment of the present invention.

[0024]The tank unit 1 comprises at least one module 2a; for example, according to the embodiment described, the tank unit 1 comprises a first module 2a and a second module 2b, operatively connected to each other to ensure the passage of hydrogen.

[0025]The module 2a comprises at least two tanks 4a, 4b; for example, in the embodiment described, the module 2a comprises five tanks 4a-4e. [0026]Each tank 4a - 4e comprises a tank body 6, extending between a top end 6a and a bottom end 6b, a top flange 8a applied to the top end 6a of the tank body 6 and a bottom flange 8b applied to the bottom end 6b. Each flange 8a, 8b is provided with a respective threaded hole; preferably, the threaded holes are coaxial and define a tank axis X.

[0027]Preferably, the tank axes X of all the tanks 4a-4e are parallel to one another and the top flanges 8a of all the tanks 4a-4e are arranged on the same side, as, obviously, all the bottom flanges 8b.

[0028]Each module 2a, 2b further comprises a top manifold 10a, arranged on the side of the top flanges 8a and operatively connected to the top flanges 8a of all the tanks 4a-4e of the module 2a, 2b. [0029]The top manifold 10a internally has a top pipe 12a, extending transversely to the tank axes X, intercepting each of these, for example, orthogonally. Pressurized hydrogen is supplied to one end IN of the top pipe 12a of the first module 2a for fueling the tanks of the entire tank unit 1.

[0030]The tank unit 1 comprises a main inlet unit 200 (Figure 2), placed at the end IN, integrated with the top manifold 10a of the first module 2a.

[0031]The main inlet unit 200 comprises a main inlet body 201, preferably in a single piece with the top manifold

10a. In the main inlet body 201, a main inlet port 202 is obtained, in which a main inlet junction 204 is preferably housed for the connection with a fueling device for the supply of pressurized hydrogen. [0032]In the main inlet body 201, a main inlet pipe 206 is further obtained, being connectable to the top pipe 12a. [0033]The main inlet unit 200 further comprises a main cut-off valve 208, which is manually operated and normally open. Said main cut-off valve 208 may be closed manually to close the communication between the main inlet pipe 206 and the top pipe 12a, for example, so as to perform maintenance interventions.

[0034]At the tanks, a top unit 20 (Figures 3 and 4), operatively connected to the top pipe 12a of the top manifold 10a, is applied to each top flange 8a. [0035]The top unit 20 comprises a top body 22, preferably in a single piece, for example made of aluminum, comprising an attachment portion 24 which is screwable to the flange 8a, and a main portion 26 which, when the top unit 20 is applied to the flange 8a, is external thereto.

[0036]In the top body 22, an inlet pipe 28 is obtained, having an inlet port 30 on the external surface of the main portion 26, an upstream branch 30 which starts from the inlet port 30 and extends into the main portion 28, and a downstream branch 32 which is adjacent to the upstream branch 30 and extends into the attachment portion 24, preferably parallel to the tank axis X, up to an outlet port 34 in the tank body 6.

[0037]Preferably, along the inlet pipe 28, a non-return valve 40 is placed, which is normally closed, opened by the hydrogen being fueled and suitable for preventing the return of the hydrogen from the tank body towards the inlet port 30. Preferably, said non-return valve 40 is placed close to the outlet port 34. [0038]According to an embodiment, an end section 36 of the inlet pipe 28 is obtained in an ejector 38, being applicable to the attachment portion 24, on which the outlet port 34 is obtained. In such embodiment, the non return valve 40 is placed between the ejector 38 and an end region of the attachment portion 26, to which the ejector 38 is applied.

[0039]The top unit 20 further comprises a first inlet junction 44, on one side at least partially inserted into the inlet port 30 of the top body 22, an intermediate pipe 46 applied on the other side of the first inlet junction 44, and a second inlet junction 48, applied to the intermediate pipe 46 and to the top manifold 10a.

[0040]The system, consisting of the first inlet junction 44, intermediate pipe 46, and second inlet junction 48, allows the fluid connection between the top pipe 12a and the inlet pipe 28.

[0041]Furthermore, preferably, the top unit 20 comprises an inlet filter 50 which intercepts the inlet pipe 28, preferably placed in an initial section of the upstream branch 30, for example inserted into the first inlet junction 44.

[0042]The top unit 20 further comprises a thermal safety device 60 with a breakable bulb 62, housed in a safety port 64 of the main portion 26 of the top body 22, and a piston 66.

[0043]In the top body 22, a safety pipe 68 is obtained, comprising an upstream branch 70, obtained in the attachment portion 24, preferably parallel to the tank axis X, in communication with the internal space of the tank body 6, and a downstream branch 72, obtained in the main portion 26, which leads to the outside by means of a vent opening 74.

[0044]The piston 66 of the thermal safety device 60 intercepts the safety pipe 68, for example between the upstream pipe 70 and the downstream pipe 72, preventing, under normal operating conditions, the escape of hydrogen. When the bulb 62 breaks, the piston 66 frees the safety pipe 68, so that the hydrogen may escape from the vent opening 74. [0045]Each module 2a, 2b further comprises a bottom manifold 10b, arranged on the side of the bottom flanges 8b and operatively connected to the bottom flanges 8b of all the tanks 4a-4e of the module 2a, 2b.

[0046]The bottom manifold 10b internally has a bottom pipe 12b, extending transversely to the tank axes X, intercepting each of these, for example, orthogonally. At an end OUT of the bottom pipe 12b of the last module 2b, the pressurized hydrogen coming from all the tanks 4a - 4e of the tank unit 1, towards the usage devices, flows out.

[0047]A bottom unit 61 (Figure 5) is applied to each bottom flange 8b, operatively connected to the bottom pipe 12b of the bottom manifold 10b.

[0048]The bottom unit 61 comprises a bottom body 63, preferably in a single piece, for example made of aluminum, comprising a tank portion 65, screwed to the bottom flange 8b and ending with a free internal surface 67 in the space delimited by the tank body 6, and a manifold portion 69 applied to the bottom manifold 10b. [0049]In the bottom body 63, a sensor pipe 71 is obtained, for example parallel to the tank axis X, extending into the tank portion 65, opening onto the internal surface 67 with a sensor opening 73, and into the manifold portion 69, opening, for example, onto an external surface of the manifold portion 69.

[0050]The sensor pipe 71 houses a temperature sensor device 75 comprising a protection bulb 77 inserted in the sensor opening 73 and protruding from the internal surface 67, and a temperature sensor 79 housed in the protection bulb 77 and connected to a signal wire 81 of the temperature sensor 79, said signal wire 81 being arranged in the sensor pipe 71.

[0051]In the bottom body 63, an outlet pipe 80 is further obtained, for example parallel to the tank axis X, extending into the tank portion 65, opening onto the internal surface 67 with an inlet opening 82, and into the manifold portion 69, opening, for example, onto a side surface of the manifold portion 69 so as to intercept the bottom pipe 12b. [0052]The bottom unit 61 further comprises an excess flow valve 90, normally open, which operates along the outlet pipe 80; said valve 90 is suitable for obstructing the outlet pipe 80 if the outgoing hydrogen flow exceeds a predefined threshold value. Preferably, said excess flow valve 90 is arranged in an initial section of the outlet pipe 80, close to the outlet opening 82.

[0053]The tank unit 1 further comprises a main outlet unit 100 (Figure 6), integrated in the bottom manifold 10b of the last module 2b. [0054]The main outlet unit 100 comprises a main outlet body 102, for example in a single piece with the bottom manifold 10b, preferably made of aluminum, in communication with the bottom pipe 12b of the bottom manifold 10b. [0055]The main outlet body 102 has a main outlet pipe 104 having a first branch 106 in direct communication with the bottom pipe 12b, a second branch 108 which is connectable to the first branch 106, and a third branch 110 which is connectable to the second branch 108 and ends with a main outlet port 112 at the end OUT for the outflow of hydrogen towards the usage devices.

[0056]A main outlet junction 114 is preferably inserted into the main outlet port 112.

[0057]The main outlet unit 100 comprises a first electromagnetically operated cut-off valve 116, operating between the first branch 106 and the second branch 108 normally closed and openable with an electric command for the outflow of the hydrogen towards the usage devices. [0058]The cut-off valve 116 comprises a solenoid 118, a piston 120 which obstructs the passage between the first branch 106 and the second branch 108, which is magnetically operable by the solenoid 118, and an electrical socket 122 for the electrical supply of the solenoid 118 and preferably for the connection to the temperature sensor devices 72 of the tanks of the tank unit 1.

[0059]The main outlet unit 100 further comprises a second manually operated cut-off valve 128, operating along the main outlet pipe, downstream of the region in which the first cut-off valve 116 operates, which is normally open and closable to permanently obstruct the passage of hydrogen from the bottom pipe 12b towards the main outlet port 114, for example, so as to perform maintenance work. [0060]Furthermore, the main outlet body 102 has a by-pass pipe 124, which creates a connection between the bottom pipe 12b and the main outlet port 112.

[0061]The main outlet unit 100 further comprises a third manually operated cut-off valve 130, operating along the by-pass pipe 124, which is normally closed and openable to by-pass the first cut-off valve 116 and to directly discharge the hydrogen from the bottom pipe 12b towards the main outlet port 114.

[0062]According to an embodiment of the invention, the tank unit 1 comprises an external discharge pipe 300 which puts all the vent openings 74 for the thermal safety device 60 in communication with a discharge area, for example, the external environment.

[0063]For example, the discharge pipe 300 comprises a main discharge branch 302 and secondary discharge branches 304, in which each secondary discharge branch 304 is connected to a respective vent opening 74 and to the main discharge branch 302.

[0064]According to an embodiment of the invention, some top units 20 lack the thermal safety device 60 and each module 2a, 2b comprises a secondary thermal safety device 400 (Figure 1).

[0065]The secondary thermal safety device 400 comprises a detection unit 402, arranged outside the tanks 4a-4e, in an intermediate position between the top end 6a and the bottom end 6b in the axial direction, for example in a center position.

[0066]The detection unit 402 comprises a breakable bulb and a cut-off piston, similar to the description of the thermal safety device 60, and is connected, by means of secondary safety pipes 404, to the respective safety port 64, which is permanently in communication with the safety pipe 68 and therefore with the tank internal space, since the thermal safety device 60 is not present.

[0067]When a threshold temperature is exceeded in the region in which the detection unit 402 is located, the bulb of said detection unit breaks and the piston frees the seat thereof, discharging each secondary safety pipe 404.

[0068]Preferably, the detection unit 402 is also connected to the discharge pipe 300, so that the secondary safety pipes are discharged in connection with said discharge pipe 300.

[0069]According to a further embodiment of the invention, the discharge of the hydrogen following the intervention of a thermal safety device 60 occurs by means of the top manifold (Figures 7 and 8).

[0070]In such embodiment, the top body 22 of the top unit 20 internally has a general discharge pipe, preferably parallel to the top pipe 12a, to which the vent openings 74 of the top units 20 of all the tanks 4a-4e of a module 2a, 2b are operatively connected.

[0071]For example, said connection is obtained by means of an auxiliary discharge pipe 500 which connects each vent opening 74 with the general discharge pipe inside the top manifold 10a. [0072]According to a further embodiment, a plurality of tanks 4a-4e of a predefined module 2a, and preferably all the tanks of a predefined module, are connected to one another so that the intervention of the thermal safety device of a tank causes all the connected tanks to be emptied (Figures 9 and 10a).

[0073]In such embodiment, the bottom body 63 of the bottom unit 61 has an auxiliary discharge pipe 600, extending from an auxiliary inlet opening 602 on the internal surface 67, in the internal space of the tank body 6, to an auxiliary outlet opening 604 on a side surface of the manifold portion 69 of the bottom body 63.

[0074]Furthermore, in such embodiment, the bottom manifold 10b has a general auxiliary pipe 606, for example parallel to the bottom pipe 12b, which puts all the auxiliary outlet openings 604 in communication.

[0075]Advantageously, in such embodiment, the activation of the thermal safety device 60 of a predefined tank causes the sudden escape of the hydrogen from the vent opening 74 of said predefined tank, the pressure drop in the latter and the recall therein of the hydrogen of the other tanks, by means of the auxiliary discharge pipe 600 of the predefined tank, the general auxiliary pipe 606 of the bottom manifold 10b and the auxiliary discharge pipes 600 of the other tanks. [0076]According to a variant of such embodiment (Figure 10b), the bottom manifold 10b comprises at least one general thermal safety device 700 configured to intercept the general auxiliary pipe 606 of the bottom manifold 10b, adapted to discharge in a discharge region the general auxiliary pipe 606, if it detects a temperature higher than a threshold temperature.

[0077]For example, the general thermal safety device 700 is integrated in the bottom manifold 10b. [0078]For example, said bottom manifold 10b internally has a general safety branch 702, which branches off from the general auxiliary pipe 606, and a general discharge branch 704 ending with a general discharge opening 706 on the external surface of the bottom manifold 10b, in communication with the discharge region, being fluidly connectable with the general safety branch 702. The general thermal safety device 700 is operative between the general safety branch 702 and the general discharge branch 704. [0079]According to a further embodiment (Figures 11 and

12), the module 2a, 2b is provided with a casing 700 applied outside the bottom manifold 10b, for example to a lower face 10c thereof.

[0080]Inside the casing 700, the signal wires 81 of all the temperature sensor devices 75 are housed, which come out from the manifold portion 69 of the respective bottom body 61 by means of the opening of the sensor pipe 71. [0081]Preferably, the casing 700 comprises a multipole connector 702 for detecting the signals coming from said temperature sensor devices 75.

[0082]Preferably, in such embodiment, the multipole connector 702 is electrically connected to the solenoid 118 of the first cut-off valve 116, for the electrical supply of said solenoid 118. [0083]According to an alternative embodiment (not shown), the main inlet unit comprises a plurality of main cut-off valves, each capable of closing the supply of hydrogen to a respective tank 4a-4e of the module.

[0084]According to a still further alternative embodiment (not shown), the main outlet unit comprises a main outlet body structurally separated from the bottom manifold and applied thereto.

[0085]According to a further alternative embodiment (not shown), the main inlet unit comprises a main inlet body structurally separated from the top manifold and applied thereto.

[0086]According to a still further alternative embodiment (not shown), at least one thermal safety device, or at least one secondary thermal safety device, or at least one general thermal safety device is activated by a trigger consisting of a wire made of a shape-memory material (SMA) or of a wire comprising a plurality of sections, in series or parallel, in which at least one section is made of a shape-memory material. Said wire is subject to shortening due to an increase in temperature. [0087]It is apparent that, in order to meet contingent needs, those skilled in the art may make changes to the tank unit described above, all contained within the scope of protection as defined by the following claims.