HYDROGEN FUEL CELL ELECTRIC VEHICLE INCLUDING HYDROGEN DISTRIBUTION COMPONENTS HOLDED IN A HOUSING

Abstract

This hydrogen-powered electric vehicle comprises an electric powertrain for driving at least one drive wheel of the vehicle, at least one electrical energy storage battery, at least one fuel cell module, a hydrogen tank (15) for the fuel cell, and a hydrogen circuit (16) connected to the tank. The hydrogen circuit includes a high-pressure section (20) corresponding to the pressure of the tank, which includes components through which the hydrogen circulates. It comprises a non-hydrogen-tight housing (30) equipped with a hydrogen sensor (31) in which said components of the hydrogen circuit are placed. (See Figure 4 for abbreviations.)

Description

Title of the invention: HYDROGEN FUEL CELL ELECTRIC VEHICLE INCLUDING HYDROGEN DISTRIBUTION COMPONENTS PLACED IN A HOUSING technical field

[0001] The present invention relates to an electric motor vehicle with a hydrogen fuel cell. Prior art

[0002] Electric vehicles currently in circulation are mainly vehicles whose powertrain energy source is a battery. They are commonly called BEVs (English acronym for "Battery Electric Vehicles").

[0003] In parallel with BEVs, some motor vehicle manufacturers are beginning to develop electric vehicles with two energy sources: a battery and a fuel cell (FC) powered by hydrogen from a hydrogen tank. These vehicles are commonly called "hydrogen fuel cell electric vehicles," or FCEVs (for "Fuel Cell Electric Vehicle").

[0004] By incorporating hydrogen in addition to a battery, FCEVs offer a long range while optimizing the capacity of the onboard traction battery, thereby controlling its size and associated weight. Furthermore, refueling with hydrogen is as quick as refueling with conventional carbon-based fuels, taking only a few minutes.

[0005] Whatever the operating temperatures of these vehicles, the thermal management between the traction battery and the heat produced by the operation of the fuel cell makes it possible to guarantee stable and repeatable range and motor power despite a very variable temperature range which is penalizing for simple electric vehicles, i.e. not equipped with a fuel cell.

[0006] An example of FCEV vehicle architecture can be seen in [Fig.1].

[0007] In the example shown in [Fig. 1], which depicts a chassis 1, the vehicle comprises a high-pressure hydrogen tank 2 (e.g., 700 bar) supplied from a filling pipe 3 (Arrow F1) which opens onto the vehicle body, a fuel cell 4 supplied with hydrogen from the tank 2 (arrow F2), and a battery 5 supplied with electrical energy from the fuel cell. fuel 4 and which powers an electric motor 6 which drives at least one wheel of the vehicle, for example the two rear wheels (arrow F3).

[0008] In order to increase the vehicle's range, it is desirable to be able to house a large hydrogen tank inside the vehicle.

[0009] One of the main problems associated with introducing hydrogen into a vehicle is related to safety management. Indeed, the hydrogen molecule (H2, dihydrogen) is the smallest existing molecule. The risk of leakage is therefore higher than for other gases.

[0010] Hydrogen is a highly flammable and reactive gas. It forms explosive mixtures with air above a low volume concentration, on the order of 4% (Lower Explosive Limit - LEL; Lower Flammable Limit - LFL).

[0011] The amount of energy required to ignite hydrogen (minimum ignition energy - MIE) is low, on the order of 0.01 mJ. For comparison, the energy of an electrostatic discharge is on the order of 10 mJ.

[0012] It is therefore necessary to avoid the risks of leakage and to avoid the lack of ventilation, in particular around the so-called "high pressure" part of the hydrogen circuit, which is the most critical.

[0013] Indeed, the hydrogen circuit includes a first portion 7 extending from the filling pipe to the tank (the so-called filling or "refuelling" part) and a second portion 8 extending from the tank to the fuel cell (the so-called distribution or "defuelling" part).

[0014] The distribution portion itself comprises three parts, each characterized by a different pressure level between the reservoir and the fuel cell.

[0015] It comprises a high-pressure section in which, in operation, the hydrogen stored in the tank is distributed at a high nominal pressure, for example 700 bar, and reaches a main pressure regulator (not shown); a medium-pressure section between the main pressure regulator and an internal expansion valve in the fuel cell module, in which the hydrogen is then distributed between 12 and 20 bar, depending on the characteristics of the fuel cell; and a low-pressure section between the expansion valve of the fuel cell module and the stack of electrochemical cells of the fuel cell, in which the hydrogen is finally distributed at a pressure of less than 3 bar.

[0016] In the event of a leak, the mass flow rate of hydrogen released into the atmosphere is directly proportional to the gas pressure in the pipes. Consequently, the high-pressure section of the circuit is by far the most dangerous in the event of a leak.

[0017] However, in the event of a frontal collision that would involve displacement of the hydrogen tank, fixed to a cradle of the vehicle, the components, pipes and Fittings that make up the high-pressure hydrogen circuit may become deformed or torn off, leading to a risk of leakage.

[0018] Under normal operating conditions, in the absence of a frontal impact or "crash," the hydrogen circuit is very rigid and prone to displacement due to its manufacturing process. It is made up of stainless steel pipes, some of which are bent, and joined together by fittings. In order to eliminate assembly stresses and movement during operation, it is desirable to reduce the number of parts used in the hydrogen circuit and to secure the assembly consisting of the tank and the hydrogen circuit in such a way as to account for dimensional variations during assembly and to eliminate differential displacements during operation.

[0019] Furthermore, since the hydrogen molecule is the smallest, the hydrogen circuit can be subject to permeation, i.e., hydrogen leaks even when the vehicle is at rest, or in the worst-case scenario, to a leak. As absolute leak-tightness cannot be guaranteed or demonstrated, it is essential to detect even the slightest hydrogen leak as early as possible. Description of the invention

[0020] In view of the foregoing, the object of the invention is to enable the detection of any hydrogen leak likely to occur in a hydrogen circuit, as soon as the leak appears.

[0021] The invention therefore relates to a hydrogen electric vehicle, comprising an electric powertrain intended to drive at least one drive wheel of the vehicle, at least one electrical energy storage battery, at least one fuel cell module, a hydrogen tank for the fuel cell and a hydrogen circuit connected to the tank, the hydrogen circuit comprising a high-pressure part corresponding to the pressure of the tank comprising components in which the hydrogen circulates.

[0022] It comprises a non-hydrogen-tight housing equipped with a hydrogen sensor in which said hydrogen circuit components are placed.

[0023] For example, the housing is equipped with hydrogen dilution holes.

[0024] In one embodiment, said high-pressure part is fixed to the tank.

[0025] According to one feature of the invention, the part of the hydrogen circuit attached to the tank is comprised between a control valve for opening and closing the tank and a non-return valve for filling the tank on the one hand, and between said tank valve and a distribution regulator on the other hand.

[0026] In one embodiment, the distribution regulator is fixed on a part of the tank intended to deliver hydrogen to the fuel cell module.

[0027] In addition, the tank valve can be fixed to a part of the tank intended for filling the tank. Brief description of the drawings

[0028] Other objects, features and advantages of the invention will become apparent from the following description, given solely by way of non-limiting example, and made with reference to the accompanying drawings in which:

[0029] - Fig. 1 is a perspective view of the chassis of a vehicle according to the state of the technique;

[0030] - Fig. 2 is a perspective view of a vehicle chassis from one aspect of the invention, showing the placement of the hydrogen tank, fuel cell, traction battery and powertrain;

[0031] - Figure 3 illustrates the mounting of the hydrogen circuit on the tank, in accordance with to another aspect of the invention;

[0032] - Figures [Fig. 4] and [Fig. 5] are detailed views of the hydrogen tank showing the housing in which the components of the hydrogen circuit are contained; and

[0033] - Fig. 6 illustrates the mounting of the hydrogen tank on a cradle. Detailed description

[0034] Figure 2 shows an electric hydrogen fuel cell motor vehicle according to the invention and in particular the chassis 10 of the vehicle on which is fixed a powertrain 11 of the vehicle intended to drive at least one drive wheel of the vehicle, here the two rear wheels of the vehicle.

[0035] The powertrain includes in particular an electric machine and an inverter positioned at the rear axle 12 of the vehicle.

[0036] The vehicle is a "hydrogen fuel cell electric vehicle", or FCEV. The powertrain thus comprises two energy sources, namely at least one high-voltage battery 13 and at least one fuel cell module (FC) 14, the battery being able to be recharged either from the fuel cell, while driving the vehicle, or from an electrical power supply network, while parked.

[0037] The high-voltage battery 13 is advantageously located under the floor of the vehicle.

[0038] The fuel cell module 14 is located under the rear seats, i.e. under the second row seats. It is supplied with hydrogen from a high-pressure hydrogen tank 15 integrated transversely in the front compartment of the vehicle and in a position set back from the front face which is more exposed to crash stresses.

[0039] The tank is thus located in an advanced position relative to the vehicle's passenger compartment, at the level of the front axle, while being positioned further back relative to the front of the vehicle exposed to frontal impacts.

[0040] The hydrogen tank 15 is connected to a hydrogen circuit 16, which supplies the hydrogen stored at high pressure in the tank 15 to the fuel cell module.

[0041] With reference to [Fig.3] which shows the hydrogen tank 15, the hydrogen circuit includes a first portion 17 extending from a filling pipe 18 (or "refuelling" pipe) to the tank 15 and a second distribution portion 19 extending from the tank 15 to the fuel cell (or "defuelling" pipe).

[0042] The first distribution portion includes a high-pressure section 20 in which, in operation, the hydrogen stored in the tank is distributed at a nominal high pressure, for example 700 bar, and reaches a distribution regulator 21 consisting of a main pressure regulator; a medium-pressure section 22 between the main pressure regulator and an internal expansion valve in the fuel cell module, in which the hydrogen is then distributed between 12 and 20 bar, depending on the characteristics of the fuel cell; and a low-pressure section (not shown) between the expansion valve of the fuel cell module and the stack of electrochemical cells of the fuel cell, in which the hydrogen is finally distributed at a pressure of less than 3 bar.

[0043] The hydrogen circuit 16, in particular the high-pressure portion, is designed to minimize the risk of leakage in the event of a frontal impact, by fixing said high-pressure portion corresponding to the pressure of the tank to the tank.

[0044] Thus, the components, pipes and fittings of the hydrogen circuit in which hydrogen is distributed at high pressure are fixed to the tank.

[0045] All components, pipes and fittings located between an "OTV" (On Tank Valve) control valve 24 of the tank, which provides the interface between the tank and the hydrogen circuit, and the main pressure regulator 21 which reduces the pressure from "high" (up to 700 bar) to "medium" pressure (approximately 16 bar) on the second portion of distribution or "defueling" of the circuit, in which hydrogen moves from the tank to the fuel cell, are fixed to the tank.

[0046] Similarly, all components, pipes and fittings located between the "OTV" valve 24 and a filling non-return valve 25, located on the distribution or "refueling" part of the circuit, in which hydrogen moves from the refueling nozzle to the tank, are fixed to the tank.

[0047] The components are preferably attached to the tank by a plate 26 which is fixed to one of the straps 27 that secure the tank to the vehicle. Alternatively, the plate with the components can be attached to a dedicated strap encircling the tank.

[0048] The high-pressure components and pipes are thus protected in the event of a frontal impact.

[0049] Firstly, the high-pressure components and pipes, which are fragile, are mechanically protected by the tank located in front of them. This tank, due to applicable regulations, is resistant to the most severe impacts.

[0050] In the event of a frontal impact that would cause the hydrogen tank to move, the high-pressure pipes and fittings, being attached to it, will move with the tank. Consequently, they will not break or deform, thus preventing a dangerous hydrogen leak.

[0051] In addition, by fixing the components of the high-pressure part 20 of the tank, the length of the high-pressure part 20 of the hydrogen circuit, the most dangerous in case of leakage, is reduced to the maximum.

[0052] This makes it possible to reduce the amount of hydrogen stored in the pipes that would be released in the event of a leak, regardless of the detection and reaction time of the system, and therefore to reduce the associated risk.

[0053] Assembling the components and pipe on a reduced number of parts on the tank with recovery of dispersions at assembly makes it possible to cancel the stresses in the components at assembly and eliminates the travel and displacement during the operation of the vehicle.

[0054] Furthermore, all the components and fittings that could be the source of leaks are grouped and confined so as to channel and concentrate the gas towards a detector including here a hydrogen sensor, without the containment area being sealed to prevent any volume of hydrogen from exceeding the explosive limit.

[0055] Thus the area in which the various components or fittings in which hydrogen circulates or which handle hydrogen are located are covered with a non-sealed compartment or cover equipped with a hydrogen sensor.

[0056] Preferably, all the components and fittings of the high-pressure part are placed in a housing that is not sealed against hydrogen and air and is equipped with a hydrogen sensor.

[0057] With reference to Figures 4 and 5 and to [Fig. 6], which shows the hydrogen tank mounted on a cradle B, the components of the high-pressure section between the tank's "OTV" valve 24 and the main pressure regulator 21 are housed in a non-sealed casing 30 equipped with a hydrogen sensor 31. The "OTV" valve is a control valve for opening and closing the tank, which is controlled in the open position during tank filling and during The hydrogen distribution system to the fuel cell, which is normally controlled in the closed position outside of these phases, particularly when the vehicle is stopped, must present the lowest possible risk of leakage.

[0058] The housing 30 is in particular perforated with holes configured to allow dilution of hydrogen in case of leakage.

[0059] Such compartmentalization makes it possible, in the event of a hydrogen leak, to define a controlled ATEX Zone.

[0060] It enables rapid and robust leak detection. The hydrogen sensor is positioned in a compartmentalized area designed to direct hydrogen towards the sensor. Thus, in the event of a leak, a local concentration of hydrogen is rapidly created around the sensor thanks to the compartmentalization, which can then be quickly detected by the sensor.

[0061] After the detection and stopping of the leak by closing solenoid valves, in particular that of the "OTV" valve, the hydrogen present in the compartmentalized area is diluted outwards.

[0062] Furthermore, the fact that the compartmentalized area is not airtight allows, in addition to the dilution of hydrogen, for safety in the event of a fire. Indeed, in this way, the temperature around the Thermal Pressure Relief Devices (TPRDs) located in the OTV valve remains close to that around the hydrogen tank. Since the compartmentalization is not airtight, the TPRDs are therefore not "blinded" in the event of a fire starting around the tank but outside the compartmentalized area.

[0063] Finally, no energy source is present in the compartmentalized area that could ignite hydrogen in the event of a leak.

[0064] In the event of a leak in the distribution line, the hydrogen tank is immediately isolated by the filling check valve 25. This drastically limits the amount of hydrogen released into the atmosphere because only the very small quantity present in the filling line will be released. This is advantageous because the filling line is the outermost part of the hydrogen circuit, as the filling pipe is fixed to the surface of the body to allow for hydrogen refueling. Consequently, the filling line is the part of the hydrogen circuit most exposed to impacts that could damage the circuit and cause a hydrogen leak.

Claims

Demands

1. Hydrogen electric vehicle, comprising an electric powertrain (11) for driving at least one drive wheel of the vehicle, at least one battery (13) for electrical energy storage, at least one fuel cell module (14), a hydrogen tank (15) for the fuel cell and a hydrogen circuit (16) connected to the tank, the hydrogen circuit (16) comprising a high-pressure part (20) corresponding to the pressure of the tank comprising components through which hydrogen flows, characterized in that it comprises a non-hydrogen-tight housing (30) equipped with a hydrogen sensor (31) in which said components of the hydrogen circuit are placed.

2. Hydrogen vehicle according to claim 1, wherein the housing (30) is provided with hydrogen dilution holes.

3. Hydrogen vehicle according to any one of claims 1 and 2, wherein said high-pressure part is attached to the tank.

4. Hydrogen electric vehicle according to claim 2, wherein the part of the hydrogen circuit attached to the tank is comprised between a tank opening and closing control valve (24) and a tank filling check valve on the one hand, and between said tank valve (24) and a distribution regulator on the other hand.

5. Motor vehicle according to claim 4, wherein the distribution regulator is fixed on a part of the tank (15) intended to deliver hydrogen to the fuel cell module.

6. Motor vehicle according to any one of claims 4 and 5, wherein the tank valve (24) is fixed to a part of the tank intended for filling the tank.

7.

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