powertrain system for a motor vehicle comprising a fuel cell and an internal combustion engine

Abstract

Powertrain system for a motor vehicle comprising a fuel cell and an internal combustion engine. Powertrain system (1) for a motor vehicle, comprising: - a tank (5) for holding hydrogen, - a fuel cell (7) comprising an anode circuit having a first inlet (11), and a cathode circuit having a second inlet (13), - an internal combustion engine (4), the internal combustion engine comprising a first inlet (41) and a second inlet (42), - a first air compressor (30), and - a second air compressor (44) comprising an inlet (79) configured to draw air from an environment external to the powertrain system, and an outlet (80) configured to supply the second inlet (42) of the internal combustion engine (4) and the second inlet (13) of the fuel cell (7) with compressed air. Figure for the abstract: Figure 1

Description

Title of the invention: Powertrain system for a motor vehicle comprising a fuel cell and an internal combustion engine Technical field of the invention

[0001] The invention relates to a powertrain system for a motor vehicle, the powertrain operating on hydrogen. More specifically, the invention relates to a powertrain system comprising a fuel cell and an internal combustion engine, the fuel cell and the internal combustion engine being designed to consume hydrogen. The invention further relates to a motor vehicle comprising such a powertrain system. The invention also relates to a method of using such a powertrain system. Prior art

[0002] Motor vehicles equipped with a powertrain system comprising a hydrogen tank, a fuel cell, an electrochemical battery, and an electric motor coupled to the vehicle's drive wheels are known. The fuel cell is capable of producing an electric current through a redox reaction between hydrogen from the tank and oxygen from the ambient air. The electric current produced by the fuel cell is used to charge the electrochemical battery. The electrochemical battery can then supply the electric motor with electric current to produce mechanical torque that drives the drive wheels. The advantages of such a solution are very high efficiency at low power and the absence of polluting emissions.

[0003] Motor vehicles equipped with a powertrain system comprising a hydrogen tank and an internal combustion engine coupled to the vehicle's drive wheels are also known. In this case, the hydrogen from the tank is used as fuel to power the internal combustion engine and thus generate engine torque driving the vehicle's drive wheels. The advantages of such a solution are the ability to generate high power output with high efficiency. Furthermore, such an internal combustion engine produces low pollutant emissions compared to an internal combustion engine running on gasoline or diesel fuel.

[0004] Publication CN106541816A also discloses a motor vehicle comprising both a fuel cell and an internal combustion engine, both the fuel cell and the internal combustion engine being intended to consume hydrogen. However, this system offers insufficient performance. In particular, the fuel cell in such a powertrain is generally incapable of producing a high-intensity electrical current. Thus, the electrochemical battery recharges slowly and / or the electric motor powered by the fuel cell produces relatively low torque. One possible solution to increase the intensity of the electrical current produced by the fuel cell is to increase its size. However, in this case, the fuel cell becomes expensive and / or cannot be easily integrated into a motor vehicle and / or occupies too large a volume, thus reducing the space available for other equipment and passengers. Presentation of the invention

[0005] The object of the invention is to provide a powertrain system that remedies the above disadvantages and improves upon known prior art powertrain systems.

[0006] More specifically, a first object of the invention is a powertrain system equipped with a fuel cell capable of producing a higher intensity electric current while remaining compact and simple to manufacture. Summary of the invention

[0007] The invention relates to a powertrain system for a motor vehicle, comprising: - a tank designed to hold hydrogen, - a fuel cell designed to produce an electric current by chemical reaction between hydrogen from the reservoir and oxygen, the fuel cell comprising an anodic circuit having a first inlet to supply hydrogen, a cathodic circuit having a second inlet to supply oxygen-rich air, - an internal combustion engine intended to produce driving torque by chemical reaction between hydrogen from the tank and oxygen, the internal combustion engine comprising a first inlet to supply hydrogen, a second inlet to supply oxygen-rich air, - a first air compressor comprising an inlet configured to draw air from an environment external to the powertrain, and an outlet configured to supply the second inlet of the fuel cell with compressed air, - a second air compressor comprising an inlet configured to draw air from an environment external to the powertrain system, and an outlet configured to supply the second inlet of the internal combustion engine and the second inlet of the fuel cell with compressed air.

[0008] The powertrain system may further include an electric motor for producing drive torque, the electric motor being intended to be powered directly or indirectly by an electric current produced by the fuel cell. The powertrain system may, in particular, include an electrochemical battery intended to be recharged by an electric current produced by the fuel cell, and the electric motor may be intended to be powered by an electric current from the electrochemical battery.

[0009] The powertrain system according to this may include: - a first valve comprising a first inlet hydraulically connected to an outlet of the second compressor, a second inlet hydraulically connected to an environment external to the powertrain system, and an outlet hydraulically connected to the second inlet of the fuel cell, and / or - a second valve comprising an inlet hydraulically connected to the outlet of the second compressor, a first outlet hydraulically connected to the second inlet of the internal combustion engine and a second outlet hydraulically connected to the second inlet of the fuel cell.

[0010] The outlet of the second compressor can be hydraulically connected to the inlet of the first compressor.

[0011] The first compressor can be an electric air compressor. The second compressor can be a turbocharger configured to be driven by exhaust gases from the internal combustion engine.

[0012] The powertrain system may include a first cooler comprising an inlet hydraulically connected to the outlet of the first compressor, the first cooler comprising an outlet hydraulically connected to the second inlet of the fuel cell. The powertrain system may include a second cooler comprising an inlet hydraulically connected to the outlet of the second compressor, the second cooler comprising an outlet hydraulically connected to the second inlet of the internal combustion engine.

[0013] The powertrain system may include a first air filter having an inlet hydraulically connected to an environment external to the powertrain system, the first air filter having an outlet hydraulically connected to the inlet of the first compressor. The powertrain system may include a second air filter having an inlet hydraulically connected to an environment external to the powertrain system, the second air filter having an outlet hydraulically connected to the inlet of the second compressor.

[0014] The fuel cell may include a proton exchange membrane, the membrane comprising a hydrocarbon polymer.

[0015] The invention also relates to a method of using a powertrain system as defined above, in which the first compressor and the second compressor operate simultaneously, the first compressor and the second compressor both contributing to increasing the air pressure at the second inlet of the fuel cell.

[0016] The invention also relates to a motor vehicle comprising a powertrain system as defined above. Presentation of the figures

[0017] These objects, features and advantages of the present invention will be described in detail in the following description of a particular embodiment, given by way of non-limiting example, with reference to the accompanying figures, among which:

[0018] Fig. 1 is a schematic view of a powertrain system according to one embodiment of the invention.

[0019] Fig. 2 is a schematic view of a fuel cell of the powertrain system. Detailed description

[0020] Figure 1 schematically illustrates a powertrain system 1 for a motor vehicle according to an embodiment of the invention. The powertrain system 1 may, for example, be intended to equip a passenger car, a commercial vehicle, a truck, or even a bus. The powertrain system 1 is intended to provide mechanical torque to rotate the drive wheels of the vehicle to move the vehicle forward (or backward). To this end, the powertrain system 1 comprises at least one rotating shaft 2 intended to be coupled to the drive wheels of the vehicle.

[0021] The powertrain system 1 comprises two motors: on the one hand, the powertrain system 1 comprises an electric motor 3, that is to say, a motor intended to be supplied with electrical energy to produce a rotational torque. On the other hand, the powertrain system 1 comprises an internal combustion engine 4, that is to say, an engine capable of transforming the energy produced by the combustion of a gas into a rotational torque.

[0022] According to the embodiment presented, the electric motor 3 and the internal combustion engine 4 are coupled to the same rotating shaft 2, itself mechanically connected to two drive wheels (front or rear), or even to four drive wheels of the vehicle. According to an alternative embodiment, the electric motor 3 and the internal combustion engine 4 could be coupled to different drive wheels. For example, the electric motor 3 could be coupled to wheels The front-wheel drive and the internal combustion engine 4 could be coupled to the rear-wheel drive, or vice versa. In a preferred embodiment, the torques produced by the two engines 3 and 4 are intended to be added together to obtain a higher resulting torque. Alternatively, the powertrain 1 could be configured so that only one of the two engines 3 or 4 drives the vehicle's drive wheels at any given time.

[0023] Furthermore, the powertrain system 1 includes a hydrogen tank 5 (in particular in the form of dihydrogen). The hydrogen contained in the tank 5 is intended to be used directly or indirectly as an energy source to operate the engines 3 and 4. The tank 5 may, for example, take the form of one or more cylinders carried on board the vehicle. The hydrogen may be stored under pressure in the tank 5.

[0024] The powertrain system 1 also includes a fuel cell 7. The fuel cell 7 is an electrochemical generator producing an electrical voltage through the oxidation on one electrode of a reducing fuel (in this case hydrogen) coupled to the reduction on the other electrode of an oxidant (in this case oxygen).

[0025] The powertrain system 1 also includes an electrochemical battery 23, for example of the lithium-ion type, intended to be recharged by an electric current produced by the fuel cell 7. The electric motor 3 can be powered by an electric current from the electrochemical battery 23. This allows the fuel cell 7 to operate at an optimal speed, independent of the torque required by the electric motor 3. The fuel cell 7 can thus be electrically connected to the electrochemical battery 23 by means of a first electrical converter 24, in particular of the DC / DC type. The electrochemical battery 23 can be electrically connected to the electric motor 3 by means of a second electrical converter 25, in particular of the DC / AC type.In addition, the first converter 24 can also be directly connected to the second converter 25 so that the electric current produced by the fuel cell 7 is directly consumed by the electric motor 3. According to an alternative embodiment of the invention, the powertrain system 1 could be without an electrochemical battery 23. The electric motor 3 would then be powered directly by an electric current from the fuel cell, without prior storage of the electrical energy produced by the fuel cell in chemical form. In this scenario, the two converters 24, 25 could be replaced by a single converter, in particular of the DC / AC type, interposed between the fuel cell 7 and the electric motor 3.

[0026] The fuel cell 7 is advantageously of the proton exchange membrane fuel cell (PEMFC) type. The fuel cell 7 is schematically represented in [Fig. 2]. It comprises an anodic circuit with a first inlet 11 for supplying hydrogen and a first outlet 12 for removing excess hydrogen. The fuel cell 7 also comprises a cathodic circuit with a second inlet 13 for supplying oxygen-rich air and a second outlet 14 for removing oxygen-depleted air and water.

[0027] The first inlet 11 is hydraulically connected to the reservoir 5, and the second inlet 13 is hydraulically connected to the ambient air around the powertrain 1. Note that when two components are said to be "hydraulically connected" to each other, it is understood that there is a fluidic connection means between these two components. This fluidic connection means is capable of transporting a fluid or a gas, in particular air or hydrogen. This fluidic connection means is preferably implemented by one or more conduits. A first component and a second component are hydraulically and directly connected when there is a conduit having a first end hydraulically connected to the first component and a second end hydraulically connected to the second component. A first component and a second component are hydraulically and indirectly connected when they are hydraulically connected to each other via at least one third component.In [Fig. 1], the different organs are schematically represented by rectangles and the ducts are schematically represented by segments connecting the different organs.

[0028] Furthermore, the excess hydrogen at the first outlet 12 can advantageously be reinjected into the fuel cell 7 through the first inlet 11 by a recirculation unit 19, for example a pump.

[0029] The fuel cell 7 comprises a stack of cells in series, generally referred to by the English term "stack". Figure 2 illustrates one embodiment of a cell of the fuel cell 7. Each cell comprises an anode 15 in contact with the anodic circuit, a cathode 16 in contact with the cathodic circuit, and a membrane 17 separating the anode 15 and the cathode 16. The membrane 17 is permeable to protons (H+) but impermeable to electrons. The anode 15 and the cathode 16 of each cell are connected in series to an electrical circuit 18.

[0030] When hydrogen and oxygen are supplied to the fuel cell 7 respectively through the first inlet 11 and the second inlet 13, an oxidation reaction of hydrogen occurs on the one hand at the level of the anodic circuit whose chemical formula is: H2 -> 2H+ + 2e The H+ protons resulting from this oxidation reaction cross the membrane 17 of each cell and combine with electrons and oxygen to form water molecules according to the following chemical reaction: 4H+ 4e+ O2 2 H2O The anode of each cell thus reaches a negative electrical potential, while the cathode of each cell reaches a positive electrical potential. This creates a potential difference between the anode and cathode of each cell. Since the cells are connected in series, the potential differences between their anode and cathode are added together. This allows for the establishment of an electrical voltage of several hundred volts across the terminals of the electrical circuit 18. The electrical current produced by the fuel cell 7 can be used to directly power the electric motor 3 and / or to recharge an electrochemical battery 23. In [Fig. 2], the path of hydrogen is indicated by the first arrow Fl, the path of air by the second arrow F2, and the path of protons H+ by the third arrow F3.

[0031] The membrane 17 must perform several functions: it must conduct hydrogen ions (protons), but not electrons, which would create a short circuit in the fuel cell 7. The membrane 17 must also prevent the passage of gases from one side of the fuel cell to the other, to avoid the phenomenon known as "gas crossover." Finally, the membrane must withstand a reducing environment at the anode and, at the same time, an oxidizing environment at the cathode. The membrane 17 can be, for example, a polymer membrane.

[0032] In one embodiment, the membrane 17 comprises perfluorinated and polyfluorinated alkyls (PFAS). The membrane 17 may, for example, be a NAFION® membrane or equivalent. Such a membrane has the advantage of being easy to manufacture and supply. In another embodiment, the membrane 17 may advantageously comprise a hydrocarbon polymer, in particular one without PFAS. This latter material has the advantage of being more resistant to high temperatures. Hydrocarbon polymer membranes 17 can, in particular, withstand temperatures of around 100°C to 150°C, which allows the fuel cell 7 to operate at a higher temperature. This offers numerous advantages, as we will see later.

[0033] The powertrain system 1 further includes a first air compressor 30. The first compressor 30 includes an inlet 71 configured to draw air from an environment external to the powertrain system, and an outlet 72 configured to supply the second inlet 13 of the fuel cell 7 with compressed air. The first compressor 30 is advantageously a compressor electric. The first compressor 30 is thus equipped with an electric motor 73 coupled to a set of blades 74. The electric motor 73 is intended to be supplied with electrical energy to drive the set of blades 74 in rotation, which creates an airflow. This airflow is directed towards the second inlet 13 of the fuel cell 7.

[0034] The amount of air entering the fuel cell 7 through its second inlet 13 determines the fuel cell's operating power. The greater the amount of air, the more oxygen there is in the cathode circuit, the more chemical reactions occur between protons H+ and oxygen O2, and the higher the intensity of the electric current produced by the fuel cell. A high-intensity electric current is particularly useful for generating high torque with the electric motor 3. Along with the increase in the intensity of the electric current produced by the fuel cell, the increase in the amount of oxygen in the cathode circuit can lead to a rise in the fuel cell's temperature.

[0035] It is therefore understood that the use of a membrane 17 more resistant to high temperatures, in particular a hydrocarbon polymer membrane, allows the fuel cell to operate with a greater quantity of oxygen in the cathode circuit, and thus to produce a higher intensity electric current. Furthermore, a higher maximum operating temperature of the fuel cell also has the advantage of facilitating its cooling. Indeed, if the fuel cell temperature is high, the temperature difference between the fuel cell and the ambient air is greater, and the heat produced by the fuel cell is more easily dissipated.

[0036] Furthermore, the powertrain system 1 includes a first air filter 29. The first air filter 29 includes an inlet 75 hydraulically connected to an environment external to the powertrain system, and an outlet 76 hydraulically connected to the inlet 71 of the first compressor 30. In other words, the first air filter 29 is positioned upstream of the first compressor 30, following the direction of airflow through the first compressor. The first air filter 29 is intended to filter the air coming from outside the powertrain system 1 to prevent contamination of the fuel cell 7 with unwanted particles.

[0037] The powertrain system 1 also includes a first cooler 31. The first cooler 31 includes an inlet 77 hydraulically connected to the outlet 72 of the first compressor 30, and an outlet 78 hydraulically connected to the second inlet 13 of the fuel cell 7. In other words, the first cooler 31 is positioned downstream of the first compressor 30, following the direction of airflow through the first compressor. The first cooler 31 is intended to cool the air entering the fuel cell through the second inlet 13. The air The air entering the fuel cell not only supplies oxygen but also cools the fuel cell. The first cooler may consist of a set of cooling fins and / or it may work in conjunction with an on-board cooling system in the vehicle, such as a closed-loop water or oil cooling system.

[0038] The internal combustion engine 4 comprises a set of combustion chambers 6, for example, three combustion chambers as shown in [Fig. 1], or alternatively any other number of combustion chambers. The internal combustion engine 4 includes a first inlet 41 for supplying hydrogen to each combustion chamber 6. The first inlet 41 is connected to the reservoir 5 by a hydraulic line. The internal combustion engine 4 may include hydrogen injection devices capable of injecting a given quantity of hydrogen at a precise time into each combustion chamber. The internal combustion engine 4 also includes a second inlet 42 for supplying oxygen-rich air (in particular in the form of dioxygen) to each combustion chamber.The second inlet 42 is hydraulically connected to the air surrounding the powertrain system 1, since ambient air naturally contains a significant proportion of oxygen.

[0039] The first inlet 11 of the fuel cell 7 and the first inlet 41 of the internal combustion engine 4 are both hydraulically connected to the tank 5. The powertrain system 1 includes a valve 8 comprising an inlet connected to the tank 5, a first outlet connected to the first inlet 41 of the internal combustion engine, and a second outlet connected to the first inlet 11 of the fuel cell. The valve 8 can be controlled to supply hydrogen only to the fuel cell 7, only to the internal combustion engine 4, or simultaneously to both the fuel cell and the internal combustion engine.

[0040] Each combustion chamber 6 can also be equipped with an ignition device such as a spark plug. Each combustion chamber is thus intended to be the site of the following exothermic chemical reaction: 2H2 + O2 → 2H2O + energy The energy generated by this chemical reaction allows a piston to move within the combustion chamber. The movement of each piston causes the rotation of a crankshaft attached to the rotating shaft 2, via a connecting rod.

[0041] The internal combustion engine 4 therefore has a completely different operation from the fuel cell since it is intended to produce a mechanical force or torque, and not an electric current.

[0042] In addition to energy production, the combustion of hydrogen also produces water (H2O). The water is mixed with the exhaust gases and discharged. The exhaust gases are expelled from the internal combustion engine 4 through an exhaust outlet 45. These gases consist mainly of oxygen-depleted air and water, particularly in the form of vapor. The exhaust gases can then be released into the atmosphere.

[0043] The powertrain system 1 also includes a second air compressor 44. The second compressor 44 includes an inlet 79 configured to draw air from an environment external to the powertrain system, and an outlet 80 configured to supply the second inlet 42 of the internal combustion engine 4

[0044] According to the invention, the second compressor 44 cooperates not only with the internal combustion engine 4 but also with the fuel cell 7. In particular, the second compressor 44 is configured to supply the second inlet 13 of the fuel cell 7 with compressed air. The powertrain therefore includes a hydraulic line 100 connecting an outlet of the second compressor 44 to the second inlet of the fuel cell 7. The second compressor 44 thus has a dual function of supplying air to both the internal combustion engine 4 and the fuel cell 7. The fuel cell 7 therefore benefits from two stages of air compression: the first air compressor 30 described above and the second air compressor 44.This allows for an increase in air pressure in the fuel cell's cathode circuit, thereby increasing the fuel cell's operating power compared to a fuel cell with only one air compressor. This increase in air pressure at the fuel cell inlet 7 is achieved without increasing the size of the first compressor 30. Thus, the invention can also be applied to reduce the capacity of the first compressor 30. The first compressor can therefore be more compact and simpler to manufacture.

[0045] The integration of a two-stage air compression system allows the fuel cell 7 to be used at higher power. It is therefore particularly advantageous to combine the two-stage air compression system with a fuel cell 7 equipped with hydrocarbon polymer-based membranes 17, since such membranes allow the fuel cell to be used at higher temperatures, particularly between 100°C and 150°C.

[0046] Furthermore, to maintain their proper functioning, the membranes 17 need to be moistened with liquid water. For this purpose, the powertrain system may advantageously include a humidifier (not shown) positioned upstream of the second inlet 13 of the fuel cell. When the operating temperature of the fuel cell exceeds 100°C, the water at ambient pressure vaporizes, which could impair the proper humidification of the membranes. Advantageously, the increased air pressure in the cathode circuit allows the water to remain in a liquid state, even at operating temperatures above 100°C. The double-stage compression provided by the combination of the two compressors 30 and 44 thus enables better humidification of the fuel cell membranes 17.

[0047] According to the embodiment presented, the second compressor 44 is an air turbocharger: the kinetic energy of the exhaust gases of the combustion engine is suitable for use in operating the second compressor 44. For this purpose, the second compressor 44 comprises a first set of rotating blades 81, a second set of rotating blades 82, and a coupling means 83 arranged between the first set of blades 81 and the second set of blades 82. The kinetic energy of the exhaust gases of the combustion engine is suitable for driving the second set of blades 82 in rotation, which in turn drives the first set of blades 81 in rotation via the coupling means 83. The rotation of the first set of blades 81 generates an airflow directed towards the second inlet 42 of the internal combustion engine and towards the second inlet 13 of the fuel cell.

[0048] Alternatively, the compressor 44 could be an electric compressor, that is to say a compressor equipped with an electric motor coupled to a set of blades.

[0049] Furthermore, the powertrain system 1 can also be equipped with a silencer 33 mounted downstream of the outlet 45 and the second set of blades 82.

[0050] Furthermore, the powertrain system 1 also includes a second air filter 43. The second air filter 43 comprises an inlet 84 hydraulically connected to an environment external to the powertrain system, and an outlet 85 hydraulically connected to the inlet 79 of the second compressor 44. In other words, the second air filter 43 is positioned upstream of the second compressor 44, following the direction of airflow through the second compressor. The second air filter 43 is intended to filter the air coming from outside the powertrain system 1 to prevent contamination of the combustion chambers 6 of the internal combustion engine with unwanted particles.

[0051] The powertrain system 1 also includes a second cooler 32. The second cooler 32 includes an inlet 86 hydraulically connected to the outlet 80 of the second compressor 44, and an outlet 87 hydraulically connected to the second inlet 42 of the internal combustion engine. In other words, the second cooler 32 is positioned downstream of the second compressor 44, following the direction of airflow through the second compressor. The second cooler 32 is intended to cool the air entering the internal combustion engine through the second inlet 42. The second cooler 32 may include a set of fins cooling and / or it can cooperate with an on-board cooling system in the vehicle, including a cooling system comprising a closed water or oil circuit.

[0052] Advantageously, the powertrain system 1 includes a first valve 91 and a second valve 92 for controlling the hydraulic connection between the second compressor 44 and the fuel cell 7. The two valves 91, 92 can be solenoid valves intended to be controlled by an electronic control unit to which they are electrically connected.

[0053] The first valve 91 includes a first inlet 93 hydraulically connected to the outlet 80 of the second compressor 44, a second inlet 94 hydraulically connected to an environment external to the powertrain system, and an outlet 95 hydraulically connected to the second inlet 13 of the fuel cell 7. The first valve 91 can be controlled so that only its second inlet 94 is open, or so that both its inlets 93, 94 are open simultaneously.

[0054] The second valve 92 comprises an inlet 96 hydraulically connected to the outlet 80 of the second compressor 44, a first outlet 97 hydraulically connected to the second inlet 42 of the internal combustion engine 4, and a second outlet 98 hydraulically connected to the second inlet 13 of the fuel cell 7. The second valve 92 can be controlled so that only its first outlet 97 is open, or so that only its second outlet 98 is open, or even so that both its outlets 97 and 98 are open simultaneously. In this last configuration, the airflow exiting the second valve is shared between the internal combustion engine 4 and the fuel cell 7. Advantageously, the second valve is configured to allow adjustment of the proportion of the airflow between the internal combustion engine 4 and the fuel cell 7.

[0055] More specifically, according to the illustrated embodiment, the first inlet 93 of the first valve 91 is directly connected to the second outlet 98 of the second valve 92. The second inlet 94 of the first valve 91 is directly connected to the outlet 76 of the first air filter 29. The outlet 95 of the first valve 91 is directly connected to the inlet 91 of the first compressor 74. The inlet 96 of the second valve 92 is directly connected to the outlet 80 of the second compressor 44. The first outlet of the second valve 92 is directly connected to the inlet 86 of the second cooler 32.

[0056] Alternatively, other arrangements could be considered: for example, the second outlet 98 of the second valve 92 could be connected directly to the inlet 75 of the first air filter 29. The air present in the cathode circuit of the fuel cell would thus be doubly filtered by the second air filter 43, then the first air filter 29.

[0057] The outlet 80 of the second compressor 44 is hydraulically connected to the inlet 71 of the first compressor 30. The second compressor 44 is therefore positioned in series with the first compressor and upstream of the first compressor 30, according to the direction of airflow. Alternatively, the outlet 80 of the second compressor 44 could be hydraulically connected to the outlet 72 of the first compressor 30, with the two compressors 30 and 44 then being mounted in parallel.

[0058] Different operating modes of the powertrain system 1 can be envisaged. According to a first operating mode, only the internal combustion engine 4 operates. The fuel cell 7 is then at rest and produces no electrical current. In this case, the second valve 92 is controlled so that only its first outlet 97 is open. The entire airflow generated by the second compressor 44 is then directed to the second inlet 42 of the internal combustion engine 4.

[0059] According to a second operating mode, only the fuel cell 7 is running. The internal combustion engine 4 is then off. In this case, only the first compressor 30 is operating. The first inlet 93 of the first valve 91 can then be closed while the second inlet 94 is open. The first compressor 30 can then operate to reach a first level of air pressure in the cathode circuit of the fuel cell. This first pressure level allows the fuel cell to reach a first electrical power and a first temperature level. The electrical current produced by the fuel cell can either be used directly to drive the electric motor 3 or converted into chemical energy stored in the electrochemical battery 23.

[0060] According to a third operating mode, the internal combustion engine 4 and the fuel cell 7 operate simultaneously. Such an operating mode can occur when the need for mechanical torque to drive the vehicle's drive wheels is at its maximum. In this case, the second valve 44 is controlled so that its two outlets 97 and 98 are open. Part of the airflow generated by the second compressor 44 is directed to the second inlet 42 of the internal combustion engine 4, while the other part of the airflow is directed to the inlet 71 of the first compressor. The part of the airflow directed to the inlet 71 of the first compressor is then compressed a second time by the first compressor 30. The airflow exiting the first compressor then reaches a second air pressure level in the fuel cell's cathode circuit, higher than the first level.This second pressure level allows for a second electrical power output and a second temperature level in the fuel cell, respectively higher than the first electrical power output and the first temperature level. This provides maximum electrical power to supply the fuel cell. the electric motor 3 in addition to the torque supplied by the internal combustion engine. The drive torque of the vehicle's drive wheels is therefore maximized

[0061] As a side note, assuming that the second compressor 44 were an electric compressor, it would be possible to operate the second compressor 44 to increase the air pressure in the cathode circuit even when the internal combustion engine 4 is not running.

[0062] According to an alternative embodiment, the drive system 1 could include only one of the two valves, or even neither of these two valves. In this case, the hydraulic line 100 could be connected directly to the inlet 71 of the first compressor on the one hand and to the outlet 80 of the second compressor 81 on the other. The air pressure in the cathode circuit of the fuel cell would then be controlled solely by the operation of the first compressor 30 and the second compressor 44.

Claims

Demands

1. Powertrain system (1) for a motor vehicle, comprising: - a tank (5) for holding hydrogen, - a fuel cell (7) for producing an electric current by chemical reaction between hydrogen from the tank and oxygen, the fuel cell comprising an anodic circuit having a first inlet (11) for supplying hydrogen, a cathodic circuit having a second inlet (13) for supplying oxygen-rich air, - an internal combustion engine (4) for producing driving torque by chemical reaction between hydrogen from the tank and oxygen, the internal combustion engine comprising a first inlet (41) for supplying hydrogen, a second inlet (42) for supplying oxygen-rich air,- a first air compressor (30) comprising an inlet (71) configured to draw air from an environment external to the powertrain system, and an outlet (72) configured to supply the second inlet (13) of the fuel cell (7) with compressed air, - a second air compressor (44) comprising an inlet (79) configured to draw air from an environment external to the powertrain system, and an outlet (80) configured to supply the second inlet (42) of the internal combustion engine (4) and the second inlet (13) of the fuel cell (7) with compressed air.

2. Powertrain system according to the preceding claim, characterized in that it further comprises an electric motor (3) intended to produce a drive torque, the electric motor being intended to be powered directly or indirectly by an electric current produced by the fuel cell (7), in particular in that the powertrain system comprises an electrochemical battery (23) intended to be recharged by an electric current produced by the fuel cell and in that the electric motor is intended to be powered by an electric current from the electrochemical battery.

3. Powertrain system according to any one of the preceding claims, characterized in that it comprises: - a first valve (91) comprising a first inlet (93) hydraulically connected to an outlet of the second compressor (44), a second inlet (94) hydraulically connected to an environment external to the powertrain system, and an outlet (95) hydraulically connected to the second inlet (13) of the fuel cell (7), and / or - a second valve (92) comprising an inlet (96) hydraulically connected to the outlet (80) of the second compressor (44), a first outlet (97) hydraulically connected to the second inlet (42) of the internal combustion engine (4) and a second outlet (98) hydraulically connected to the second inlet (13) of the fuel cell (7).

4. Powertrain system according to any one of the preceding claims, characterized in that the outlet (80) of the second compressor (44) is hydraulically connected to the inlet (71) of the first compressor (30).

5. Powertrain system according to any one of the preceding claims, characterized in that the first compressor (30) is an electric air compressor, and / or in that the second compressor (44) is a turbocharger configured to be driven by exhaust gases from the internal combustion engine.

6. Powertrain system according to any one of the preceding claims, characterized in that it comprises a first cooler (31) including an inlet (77) hydraulically connected to the outlet (72) of the first compressor (30), the first cooler including an outlet (78) hydraulically connected to the second inlet (13) of the fuel cell (7), and / or in that it comprises a second cooler (32) including an inlet (86) hydraulically connected to the outlet (80) of the second compressor (44), the second cooler including an outlet (87) hydraulically connected to the second inlet (42) of the internal combustion engine (4).

7. A powertrain system according to any one of the preceding claims, characterized in that it comprises a first air filter (29) including an inlet (75) hydraulically connected to an environment external to the powertrain system, the first filter air including an outlet (76) hydraulically connected to the inlet of the first compressor, and / or including a second air filter (43) including an inlet (84) hydraulically connected to an environment external to the powertrain system, the second air filter including an outlet (85) hydraulically connected to the inlet of the second compressor (44).

8. Powertrain system according to any one of the preceding claims, characterized in that the fuel cell comprises a proton exchange membrane (17), the membrane comprising a hydrocarbon polymer.

9. A method of using a powertrain system according to any one of the preceding claims, wherein the first compressor (30) and the second compressor (44) operate simultaneously, the first compressor and the second compressor both contributing to increasing the air pressure at the second inlet of the fuel cell.

10. Motor vehicle comprising a powertrain system (1) according to any one of claims 1 to 8.

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