Hydrogen powertrain

Abstract

The invention relates to a powertrain (1, 100) operating with hydrogen, said powertrain (1, 100) comprising a hydrogen tank (2), an internal combustion engine (5) supplied with hydrogen by said hydrogen tank, and an electric motor (6) operating from a fuel cell (3) supplied with hydrogen from this hydrogen tank (2). According to the invention, the powertrain (100) comprises an air-circulation connection circuit (101) provided with an opening / closing means (102) and connecting an air outlet of the fuel cell (3) to an air inlet (103) of the internal combustion engine (5) to allow oxygen-depleted air from the fuel cell (3) to supply the internal combustion engine (3).

Description

Description Title of the invention: Hydrogen powertrain

[0001] The present invention relates to a hydrogen powertrain.

[0002] The invention therefore relates to hydrogen propulsion technology and the use of the best means of transforming this energy to propel a motor vehicle.

[0003] Current solutions include using a fuel cell system coupled with a battery, particularly for managing start-up and operating transients. Another possible solution involves burning hydrogen in an internal combustion engine. Both solutions obviously require storing hydrogen in the vehicle, for example, in pressurized cylinders.

[0004] The advantages of the "fuel cell" solution include, in particular, a very high efficiency on partial loads corresponding to low power levels, and the generation of usable electrical power in an electric motor to propel the vehicle without any regulated polluting emissions.

[0005] The advantages of the internal combustion engine solution include its ability to generate high power outputs with high efficiency, corresponding to high engine loads. However, the internal combustion engine produces regulated pollutants in small quantities.

[0006] To leverage the advantages of each of these solutions, they have been combined within a vehicle's powertrain. Thus, the powertrain combining these two solutions includes: -A hydrogen storage system including an interface for its filling and enabling the supply of hydrogen to the internal combustion engine and the fuel cell, -An internal combustion engine powered by hydrogen, connected to the drive shaft, propels the vehicle. The engine is supplied with hydrogen by the hydrogen storage system. -An electric motor linked to the transmission shaft allows the vehicle to move forward. The electric motor is powered by a buffer battery and by a fuel cell system powered by the hydrogen storage system.

[0007] Regarding the air supply requirements of this powertrain, it should be noted that both elements, the internal combustion engine and the fuel cell, must each be supplied with air during their operation.

[0008] One could then consider a first air supply system for the internal combustion engine, and a second air supply system for the fuel cell. The two systems are distinct and independent of each other. However, such a configuration proves cumbersome and requires the implementation of a large number of components, generating significant additional costs.

[0009] Application WO2015193111 Al relates to a hydrogen storage unit for supplying hydrogen to an internal combustion engine and a fuel cell. An air intake system is provided for both the internal combustion engine and the fuel cell. The fuel cell air supply system includes an air compressor coupled to an electric motor and a three-way valve. However, this document does not describe the following features: -a 3-way valve that directs the airflow from the fuel cell to a silencer at the fuel cell outlet or oxygen-depleted air to the air intake of the internal combustion engine, -an air supply system including an air filter for the fuel cell, and an air filter and silencer for the internal combustion engine.

[0010] A powertrain according to the invention combines a hydrogen-powered internal combustion engine and an electric motor powered by a fuel cell, and whose air supply to said internal combustion engine and fuel cell has been improved.

[0011] The invention relates to a hydrogen-powered powertrain, said powertrain comprising a hydrogen tank, an internal combustion engine supplied with hydrogen from said hydrogen tank and an electric motor operating from a fuel cell supplied with hydrogen from this hydrogen tank.

[0012] According to the invention, the powertrain comprises a first air circulation circuit opening into an air inlet of the fuel cell so as to supply air to said fuel cell, and an air circulation link circuit equipped with an opening / closing means and connecting an air outlet of the fuel cell to an air inlet of the internal combustion engine to allow oxygen-depleted air from the fuel cell to supply the internal combustion engine, the internal combustion engine being supplied with air by a second air circulation circuit. In this way, thanks to the judicious presence of the air circulation link circuit between the fuel cell and the internal combustion engine, said internal combustion engine can benefit from the oxygen-depleted air from the fuel cell.Indeed, the air exiting the fuel cell is depleted in oxygen because some of the oxygen present at the cell's inlet has been consumed in the production of electrical power. This oxygen-depleted air can be routed to the air intake of the internal combustion engine, allowing the internal combustion engine to operate on oxygen-depleted air. oxygen. This operation allows the internal combustion engine to be used with a 1:1 air-fuel ratio because there will no longer be oxygen at the engine outlet, while still benefiting from diluted intake air, the O2 / N2 ratio being reduced compared to that of the outside air. The opening / closing means, which can, for example, be a three-way valve, can be controlled independently, either to allow oxygen-depleted air from the fuel cell to be routed to an air intake of the internal combustion engine, or to interrupt the circulation of this oxygen-depleted air between said fuel cell and said internal combustion engine. A powertrain according to the invention can thus operate in three different ways: -either solely with the fuel cell, in which case the opening / closing mechanism of the connecting circuit is in a closed position, the fuel cell being supplied with air by the first circuit, -either solely with the combustion engine, in which case the opening / closing means of the connecting circuit is in a closed position, said internal combustion engine operating with air only from the second air circulation circuit -either by combining the operation of the fuel cell and the operation of the internal combustion engine to allow said internal combustion engine to benefit from the oxygen-depleted air coming from the fuel cell, and in this case, the means for opening / closing the air circulation link circuit is in an open position.

[0013] According to one possible feature of the invention, the first air circulation circuit comprises an air inlet, a first air filter, and a first air compressor, these three elements being arranged upstream of the fuel cell with respect to the direction of airflow in said first circuit to supply compressed air to said fuel cell. This first air circuit allows pressurized air from outside the vehicle to be injected into the fuel cell.

[0014] According to one possible feature of the invention, the first air compressor is associated with a first electric motor. The injection of pressurized air into the fuel cell is carried out autonomously and triggered by the activation of the first electric motor.

[0015] According to one possible feature of the invention, the opening / closing means is a three-way valve placed between the air outlet of the fuel cell and the air inlet of the internal combustion engine, said three-way valve occupying a first position in which it directs the airflow from the fuel cell towards the air inlet of the internal combustion engine, or a second position in which it directs the airflow from the fuel cell towards a si- This three-way valve allows either the oxygen-depleted air from the fuel cell to be routed to an air intake of the internal combustion engine, or this oxygen-depleted air to a silencer without supplying the internal combustion engine. The silencer is placed on a separate exhaust line for the oxygen-depleted gas from the fuel cell, distinct from the main exhaust circuit.

[0016] According to one possible feature of the invention, the air circulation linkage circuit includes a control valve located between the three-way valve and the air inlet of the internal combustion engine. This control valve occupies a first position in which it allows the circulation of oxygen-depleted air to the air inlet, or a second position in which it stops the circulation of this oxygen-depleted air. Thus, if the three-way valve were in an open position to allow oxygen-depleted air from the fuel cell to flow to the internal combustion engine, this control valve allows the circulation of this oxygen-depleted air from the three-way valve to be interrupted at any time. This control valve allows for finer adjustment of the conditions of the oxygen-depleted air flow, particularly to the internal combustion engine.This regulating valve is a valuable complement to the three-way valve.

[0017] According to one possible feature of the invention, the second air supply circuit comprises a second air inlet, a second air filter, a second air compressor, and a cooler. This second air circuit allows for the injection of cooled, pressurized air from outside the vehicle into the internal combustion engine.

[0018] According to one possible feature of the invention, the air inlet of the internal combustion engine into which the air circulation link circuit from the fuel cell opens, connects to the second air circulation circuit in a tube linking the second air filter and the second air compressor.

[0019] According to one possible feature of the invention, the powertrain includes an air exhaust circuit originating from an air outlet of the internal combustion engine, said air exhaust circuit comprising a turbine coupled to the second air compressor and supplied by the airflow exiting said internal combustion engine.

[0020] According to one possible feature of the invention, the exhaust system comprises a silencer inserted between the turbine and an air outlet of said exhaust system. The exhaust gases emitted by the internal combustion engine are discharged outside the vehicle via the silencer.

[0021] According to one possible feature of the invention, the powertrain includes a buffer battery intended to supplement the fuel cell to ensure the operation of the electric motor.

[0022] A powertrain according to the invention has the advantage of being able to operate in three different modes, namely, fuel cell alone, internal combustion engine alone, or a combination of said fuel cell and said engine, thanks to a judicious implementation of an air circulation link between the fuel cell and the internal combustion engine. In this way, the mode combining the fuel cell and the internal combustion engine allows said engine to operate with oxygen-depleted air from said fuel cell and provides a gain in: -The post-processing architecture compared to a post-processing architecture for a thermal engine operating at a 1:1 air-fuel ratio or a lean mixture, -Engine efficiency is improved because it operates with a diluted mixture. This allows the benefits of dilution on engine efficiency to be achieved without the drawbacks of lean-mixture aftertreatment systems.

[0023] A detailed description of a preferred embodiment of a powertrain according to the invention is given below, with reference to the following figures:

[0024] [Fig. 1] Fig. 1 is a simplified schematic view of a powertrain according to the prior art.

[0025] [Fig.2] Fig.2 is a simplified diagram of a powertrain according to the invention.

[0026] Referring to [Fig. 1], a powertrain 1 according to the prior art comprises a hydrogen tank 2, a fuel cell 3, a buffer battery 4, a hydrogen-powered internal combustion engine 5, and an electric motor 6. The hydrogen tank 2 can, for example, be represented by at least one pressurized hydrogen cylinder. A first pipe 7 connects the hydrogen tank 2 to the fuel cell 3 to allow hydrogen from the tank 2 to supply the fuel cell 3. A second pipe 8 originates from the first pipe 7 upstream of the fuel cell 3 and extends to the internal combustion engine 5, said second pipe 8 allowing hydrogen from the tank 2 to be delivered to said internal combustion engine 5. The internal combustion engine 5 conventionally comprises combustion chambers 9.The fuel cell 3, complemented by the buffer battery 4, ensures the operation of the electric motor 6. The internal combustion engine 5, which runs on hydrogen, and the electric motor 4 are both connected to a transmission shaft 10 of the vehicle, which can be rotated by at least one of said two motors 4, 5 to propel the vehicle.

[0027] The fuel cell 3 is supplied with air from outside the vehicle via a first air circulation circuit 11. This first air circulation circuit 11 comprises, in order, a first air inlet 12, a first air filter 13, and a first air compressor 14 powered by a self-contained electric motor 15. The first filter 13 cleans the air coming from the first inlet 12 before it is compressed by the first compressor 14 and then injected into the fuel cell 3. This first air circulation circuit 11 allows pressurized air to be injected into the fuel cell 3 to ensure its operation. This air is then discharged through an outlet pipe 16 originating on the fuel cell 3 and terminating in a silencer 30.

[0028] The internal combustion engine 5 is supplied with air from outside the vehicle via a second air circulation circuit 17. This second circuit 17 comprises, in order, a second air inlet 18, a second air filter 19, a second compressor 20, and a cooler 21 located just before the internal combustion engine 5. The second filter 19 cleans the air coming from the second inlet 18 before it is compressed by the second compressor 20 and then cooled by the cooler 21. The compressed and cooled air from the cooler 21 is then injected into the combustion chambers 9 of the internal combustion engine 5.The exhaust gases are then evacuated from the combustion chambers 9 by means of an exhaust circuit 22 comprising a turbine 23 which is coupled to the second compressor 20, a silencer 24 and an air outlet 25, said silencer 24 being placed between said turbine 23 and said air outlet 25.

[0029] For such a powertrain configuration 1, the internal combustion engine 5 and the electric motor 4 via the fuel cell 3, operate simultaneously, both being supplied with air from outside the vehicle in which the powertrain would be mounted.

[0030] Referring to [Fig. 2], a powertrain 100 according to the invention differs from the powertrain 1 of the prior art described above in that the outlet pipe 16 of the fuel cell 3 no longer terminates with the silencer 30, but is extended to the internal combustion engine 5, to form a connecting pipe 101 for air circulation between said internal combustion engine 5 and said fuel cell 3. This connecting pipe 101 includes a three-way valve 102 that can occupy a first position in which it directs the airflow from the fuel cell 3 towards an air inlet 103 of the internal combustion engine 5, and a second position in which it directs the airflow from the fuel cell 3 towards an oxygen-depleted air exhaust branch equipped with a silencer 104. The air inlet 103 of the engine to The internal combustion engine 5 is located on an air circulation pipe 106 connecting the second air filter 19 and the second compressor 20 of the second air circulation circuit 17. In other words, the connecting air circulation pipe 101 connecting the fuel cell 3 and the internal combustion engine 5 opens into the air circulation pipe 106 connecting the second air filter 19 and the second compressor 20 of the second air circulation circuit 17. A control valve 107 is inserted on the connecting pipe 101 between the three-way valve 102 and the air inlet 103 of the internal combustion engine 5, said control valve 107 being able to occupy: - a first position in which it allows the oxygen-depleted air circulating in the connecting pipe 101 to flow towards the air inlet 103 of the internal combustion engine 5, or -a second position in which it stops said air circulation in the connecting tube 101, preventing oxygen-depleted air from entering said internal combustion engine 5.

[0031] The unique feature of a powertrain 100 according to the invention is that the hydrogen-powered internal combustion engine 5 can benefit, during certain phases of vehicle operation, from oxygen-depleted air supplied by the fuel cell 3. Indeed, the air exiting the fuel cell 3 is oxygen-depleted because some of the oxygen present at the inlet of said fuel cell 3 has been consumed in the production of electrical power. Thanks to this supply of oxygen-depleted air, the internal combustion engine 5 can operate at a richness level of 1, meaning that there will be no oxygen at the outlet of said engine 5, while still benefiting from diluted intake air, as the O2 / N2 ratio is reduced compared to that of the ambient outside air. This operating mode with oxygen-depleted air provides a gain in: - The post-processing architecture compared to a post-processing architecture for a thermal engine operating at a 1:1 air-fuel ratio or a lean mixture, -Engine efficiency is improved because it operates with a diluted mixture. This allows the benefits of dilution on engine efficiency to be achieved without the drawbacks of lean-mixture aftertreatment systems.

Claims

Claims

1. A powertrain (1, 100) operating on hydrogen, said powertrain (1, 100) comprising a hydrogen tank (2), an internal combustion engine (5) supplied with hydrogen by said hydrogen tank and an electric motor (6) operating from a fuel cell (3) supplied with hydrogen from this hydrogen tank (2), characterized in that it comprises a first air circulation circuit (11) opening into an air inlet of the fuel cell (3) so as to supply air to said fuel cell (3), and in that it comprises an air circulation connecting circuit (101) provided with an opening / closing means (102) and connecting an air outlet of the fuel cell (3) to an air inlet (103) of the internal combustion engine (5) to allow oxygen-depleted air from of the fuel cell (3) to power the internal combustion engine (3),the internal combustion engine (5) being supplied with air by a second air circulation circuit (17).,

2. Powertrain according to claim 1, characterized in that the first air circulation circuit (11) comprises an air inlet (12), a first air filter (13) and a first air compressor (14), and in that these three elements (12, 13, 14) are arranged upstream of the fuel cell (3) relative to the direction of movement of the air in said first circuit (11) to supply said cell (3) with compressed air.

3. Powertrain according to claim 2, characterized in that the first air compressor (14) is associated with a first electric motor (15)

4. Powertrain according to any one of the two claims 1 to 3, characterized in that the opening / closing means is a three-way valve (102) placed between the air outlet of the fuel cell (3) and the air inlet (103) of the internal combustion engine (5), and in that said three-way valve (102) occupies a first position for which it directs the air flow coming from the fuel cell (3) towards the air inlet (103) of the internal combustion engine (5), or a second position for which it directs the air flow coming from the fuel cell (3) towards a silencer (104).

5. Powertrain according to claim 4, characterized in that the air circulation connection circuit (101) comprises a re- regulation (107) placed between the three-way valve (102) and the air inlet (103) of the internal combustion engine (5), and in that said regulation valve (107) occupies a first position for which it allows the circulation of oxygen-depleted air towards said air inlet (103) or a second position for which it stops said circulation of depleted air.

6. Powertrain according to any one of claims 1 to 5, characterized in that the second air supply circuit (17) comprises a second air inlet (18), a second air filter (19), a second air compressor (20) and a cooler (21).

7. Powertrain according to claim 7, characterized in that the air inlet (103) of the internal combustion engine into which the connecting circuit (101) for circulating air from the fuel cell (3) opens, connects to the second air circulation circuit (17) in a pipe (106) connecting the second air filter (19) and the second air compressor (20).

8. A powertrain according to any one of claims 7 or 8, characterized in that it comprises an air exhaust circuit (22) originating at an air outlet of the internal combustion engine (5), and in that said air exhaust circuit (22) comprises a turbine (23) coupled to the second air compressor (20) and powered by the air flow leaving said internal combustion engine (5).

9. Powertrain according to claim 8, characterized in that the exhaust circuit (22) comprises a silencer (24) inserted between the turbine (23) and an air outlet (25) of said exhaust circuit (22).

10. A powertrain according to any one of claims 1 to 10. 9, characterized in that it comprises a buffer battery (4) intended to supplement the fuel cell (3) to ensure the operation of the electric motor (6).

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