Method for managing a hybrid powertrain for a hydrogen motor vehicle and associated powertrain

Abstract

The invention relates to a method for managing a hybrid powertrain of a hydrogen motor vehicle, which hybrid powertrain comprises an internal combustion engine (2), a fuel cell (3), a hydrogen storage tank (14) and a line C1 connecting an air outlet (10) of the fuel cell (3) to an air inlet (12) of the internal combustion engine (2), which line has a cutoff valve V1, the method comprising the steps of: a) controlling the shutdown of the fuel cell (3); b) stopping the internal combustion engine (2); c) when the fuel cell (3) and the internal combustion engine (2) are stopped, opening the cutoff valve V1; and d) running the internal combustion engine (2) without injecting hydrogen from the storage tank (14) in order to draw, via the line C1, the fluids present in the fuel cell (3) to the internal combustion engine (2).

Description

[0001] Method for managing a hybrid powertrain for a hydrogen-powered motor vehicle and associated powertrain

[0002] The present invention relates, in general, to motor vehicles using hydrogen as an energy source and, in particular, to hybrid motor vehicles incorporating an internal combustion engine and a fuel cell powered by hydrogen.

[0003] More specifically, the invention relates to a method for managing a hybrid powertrain for a hydrogen-powered motor vehicle comprising an internal combustion engine and a fuel cell, as well as to an associated powertrain.

[0004] With the aim of offering an alternative to fossil fuels, hydrogen technology has attracted great interest, particularly in the automotive sector.

[0005] There are now different architectures of motor vehicles using hydrogen as an energy source.

[0006] In one example, US 20140001033 describes a system using hydrogen as a secondary energy source. For this, water is drawn into a fuel cell that generates a mixture of hydrogen and oxygen. The resulting hydrogen is mixed with the fuel that powers the internal combustion engine.

[0007] Other vehicles use hydrogen as their sole energy source.

[0008] In particular, according to a reverse operation, a fuel cell can be coupled to an electric battery which it supplies with an electric current produced from hydrogen and oxygen. The electric battery can thus deliver electrical energy to an electric motor, particularly during a start-up phase or transient phases.

[0009] The advantages of the fuel cell include a very high efficiency on partial loads, i.e. when low power is required, and the generation of electrical power that can be used in an electric motor to move the vehicle forward without any regulated polluting emissions.

[0010] Other vehicles operate solely on the combustion of hydrogen in an internal combustion engine. The advantage of an internal combustion engine is that it can generate high power outputs with high efficiency under heavy loads. However, the internal combustion engine produces small quantities of regulated pollutants.

[0011] To take advantage of the benefits of both structures, some hydrogen hybrid vehicles incorporate an internal combustion engine and an electric motor coupled to a battery, itself powered by a fuel cell. Hydrogen is then used as the sole energy source by both the internal combustion engine and the fuel cell.

[0012] However, when the fuel cell is shut down, water may still be present within it. When shut down, the prolonged presence of water impacts its stability and lifespan.

[0013] In particular, when the outside temperature is negative, the water still present freezes, which disrupts its operation by preventing it from restarting.

[0014] The invention therefore aims to remedy these drawbacks and to propose a fuel cell shutdown strategy ensuring optimal restart, whatever the outside temperature, positive or negative, and intended to extend its lifespan and ensure its stability.

[0015] A method is therefore proposed for managing a hybrid powertrain of a hydrogen-powered motor vehicle comprising an internal combustion engine, a fuel cell, a hydrogen storage tank and a pipe C1 connecting an air outlet of the fuel cell to an air inlet of the internal combustion engine and comprising a cut-off valve VI, the method comprising the following steps: a) the fuel cell is stopped; b) the internal combustion engine is stopped; c) when the fuel cell and the internal combustion engine are stopped, the cut-off valve VI is opened; and d) when the cut-off valve VI is open, the internal combustion engine is driven without injecting hydrogen from the tank in order to suck, via the pipe C1, the fluids present in the fuel cell towards the internal combustion engine.

[0016] In one embodiment, the powertrain may comprise a line C2 connecting a hydrogen outlet of the fuel cell to the air inlet of the internal combustion engine and comprising a cut-off valve V2, step c) comprising the opening of the cut-off valve V2 in addition to the valve VI, in order to also suck in step d), via the line C2, the fluids present in the fuel cell towards the internal combustion engine.

[0017] According to one feature, the operation of the internal combustion engine in step d) can be maintained for a predetermined time interval.

[0018] According to another feature, the operation of the internal combustion engine in step d) can be maintained until the humidity level in the fuel cell is less than or equal to a predetermined threshold value.

[0019] The invention also relates to a hybrid powertrain for a hydrogen-powered motor vehicle comprising: an internal combustion engine; a fuel cell; a hydrogen storage tank; a pipe C1 connecting an air outlet of the fuel cell to an air inlet of the internal combustion engine and comprising a cut-off valve VI for the selective passage of fluids present in the fuel cell from said air outlet to the internal combustion engine; and a control device configured to control the opening of the cut-off valve VI when the fuel cell and the internal combustion engine are stopped, and to drive the internal combustion engine without injecting hydrogen from the storage tank in order to suck, via the pipe C1, the fluids present in the fuel cell to the internal combustion engine.

[0020] In one embodiment, the powertrain may comprise a line C2 connecting a hydrogen outlet of the fuel cell to the air inlet of the internal combustion engine and comprising a cut-off valve V2 for the selective passage of fluids present in the fuel cell from said hydrogen outlet to the internal combustion engine, the control device being configured to control the opening of the cut-off valve V2 in addition to the valve VI before starting the internal combustion engine without hydrogen injection, in order to also suck, via the line C2, the fluids present in the fuel cell to the internal combustion engine.

[0021] Advantageously, the powertrain may comprise a recirculation unit connected to the fuel cell for recirculating hydrogen from the hydrogen outlet to a hydrogen inlet of the fuel cell, the recirculation unit being connected to the line C2. Preferably, the line C2 is connected to the line C1 upstream of the air inlet of the internal combustion engine.

[0022] Preferably, the powertrain comprises at least one condenser positioned on line C1 and / or line C2.

[0023] Advantageously, the internal combustion engine can be coupled to a turbocharger positioned on the line C1, upstream of the air inlet of the internal combustion engine and downstream of the fuel cell.

[0024] The invention also relates to a motor vehicle comprising a powertrain as described above.

[0025] Other aims, advantages and characteristics will emerge from the description which follows, given purely for illustrative purposes and with reference to the attached drawings in which:

[0026] [Fig 1] illustrates a hybrid powertrain for a hydrogen-powered motor vehicle according to one embodiment of the invention.

[0027] [Fig 2] illustrates a hybrid powertrain for a hydrogen-powered motor vehicle according to another embodiment of the invention.

[0028] Furthermore, the expression "at least one" used in this description is equivalent to the expression "one or more".

[0029] In the present invention, the terms "upstream" and "downstream" refer to the direction of flow of fluids drawn by the internal combustion engine from the fuel cell.

[0030] Figure 1 illustrates a powertrain 1 for a motor vehicle.

[0031] In the example illustrated, hydrogen is the sole energy source for the motor vehicle.

[0032] Of course, it will be possible to provide for the powertrain to be incorporated into a motor vehicle using one or more energy sources other than hydrogen.

[0033] The powertrain 1 comprises an internal combustion engine 2, incorporating a combustion chamber, and a fuel cell 3 both using hydrogen as an energy source.

[0034] In the example illustrated, the powertrain 1 comprises an electric motor 4 coupled to a battery 5, itself coupled to the fuel cell 3.

[0035] The powertrain 1 is hybrid such that both the internal combustion engine 2 and the electric motor 4 of the hybrid powertrain 1 are rotatably coupled to a transmission shaft 6 to drive the motor vehicle.

[0036] The fuel cell 3 has a hydrogen inlet 7 and a hydrogen outlet 8, as well as an air inlet 9 and an air outlet 10.

[0037] The hydrogen inlet 7 and the hydrogen outlet 8 are advantageously, respectively, an anode hydrogen inlet 7 and an anode hydrogen outlet 8, positioned in contact with an anode of the fuel cell 3.

[0038] The air inlet 9 and the air outlet 10 are advantageously, respectively, a cathode air inlet 9 and a cathode air outlet 10, positioned in contact with a cathode of the fuel cell 3.

[0039] The fuel cell 3 generates an electric current and water from oxygen present in the air and hydrogen. The generated electric current powers the battery 5 which itself powers the electric motor 4.

[0040] Advantageously, the internal combustion engine 2 comprises a hydrogen inlet 11, an air inlet 12 and an exhaust gas outlet 13.

[0041] Preferably, the powertrain 1 comprises at least one storage tank 14 connected to the hydrogen inlet 7 of the fuel cell 3 and to the hydrogen inlet 11 of the internal combustion engine 2 to supply them with hydrogen.

[0042] In the example illustrated, a three-way valve V3 allows the selective passage of hydrogen from the storage tank 14 to the fuel cell 3 or the internal combustion engine 2.

[0043] The air admitted into the fuel cell 3 and into the internal combustion engine may, advantageously, be outside air collected when the vehicle is moving which, preferably, passes through an air filter, respectively 15 and 16, upstream of the fuel cell 3 and upstream of the internal combustion engine 2.

[0044] Preferably, a compressor 17 is arranged upstream of the air inlet 9 of the fuel cell 3.

[0045] Preferably, a turbocharger 18 is arranged upstream of the air inlet 12 of the internal combustion engine 2.

[0046] Furthermore, the powertrain comprises a conduit C l connecting the air outlet 10 of the fuel cell 3 to the air inlet 12 of the internal combustion engine 2. A cut-off valve VI is positioned on the conduit C l for the selective passage of fluids present in the fuel cell 3 from the air outlet 10 of the fuel cell 3 to the internal combustion engine 2.

[0047] Advantageously, an exhaust pipe E can be arranged on the pipe C1, upstream of the cut-off valve VI for the exhaust of air coming from the fuel cell 3.

[0048] In addition, a control device 19 is configured to control the opening of the cut-off valve VI when the fuel cell 3 and the internal combustion engine 2 are stopped.

[0049] The control device 19 is also configured to drive, using an electric motor such as the motor 4 for example, the internal combustion engine 2 without injecting hydrogen from the tank 14, in order to suck the fluids present in the fuel cell 3 towards the internal combustion engine 2.

[0050] As illustrated in Figure 1, the powertrain 1 may comprise a recirculation unit 20 connected to the hydrogen outlet 8 and the hydrogen inlet 7 of the fuel cell 3.

[0051] The recirculation unit 20 advantageously incorporates a pump and allows the recirculation of non-oxidized hydrogen by the fuel cell 3 from the hydrogen outlet 8 to the hydrogen inlet 7.

[0052] In the illustrated example, a line C2 connects the hydrogen outlet 8 of the fuel cell 3 to the air inlet 12 of the internal combustion engine 2.

[0053] In addition, a cut-off valve V2 is arranged on the line C2 and allows the selective passage of fluids present in the fuel cell 3 from the hydrogen outlet 8 of the fuel cell 3 to the internal combustion engine 2.

[0054] The control device 19 is preferably configured to control the opening of the cut-off valve V2, in addition to the valve VI, before driving the internal combustion engine 2 without hydrogen injection.

[0055] Suction of fluids via line C2 in addition to suction via line C1 makes it possible to increase the efficiency of water removal from the fluids present in the fuel cell 3.

[0056] In the example illustrated, the recirculation unit 20 is connected to the line C2.

[0057] The pipe C2 can be connected to the pipe C1, upstream of the air inlet 12 of the internal combustion engine 2, so that the pipes C1 and C2 form a common portion C3 which opens into the internal combustion engine 2 via the air inlet 12.

[0058] Preferably, the powertrain comprises at least one condenser 21 positioned on the line C1 and / or the line C2.

[0059] In the example illustrated, the condenser is positioned downstream of the connection of pipes C1 and C2, on the common portion C3.

[0060] The condenser 21 helps to evacuate the liquid water from the fluids sucked into the internal combustion engine 2.

[0061] The invention also relates to a method for managing a powertrain 1 as described previously, and comprising the following steps: a) the fuel cell 3 is stopped; b) the internal combustion engine 2 is stopped; c) when the fuel cell 3 and the internal combustion engine 2 are stopped, the cut-off valve VI is opened; and d) when the cut-off valve VI is open, the internal combustion engine 2 is driven without injecting hydrogen from the storage tank 14 in order to suck the fluids present in the fuel cell 3 towards the internal combustion engine 2.

[0062] The combustion engine 2 therefore operates empty, like a pump, sucking the fluids present in the fuel cell 3, in particular air and water, towards the combustion chamber of the internal combustion engine 2.

[0063] The management method according to the invention thus makes it possible to dry the fuel cell 3 after it has been stopped. This drying makes it possible, in particular, during restarting, and in particular when the outside temperature is negative, to avoid having a large quantity of frozen water in the fuel cell 3 which would prevent it from being restarted. By drying the fuel cell 3, restarting is therefore made easier and the service life of the fuel cell 3 is improved.

[0064] Steps a) and / or b) can be controlled by the control device 19, in response to an instruction to stop the motor vehicle by the driver.

[0065] Furthermore, steps a) and / or b) may be ordered simultaneously or successively. Step b) may be carried out before step a) or vice versa.

[0066] Preferably, the opening control of the valve VI is carried out by the control device 19.

[0067] In one embodiment, the powertrain 1 comprises a recirculation unit 20. Preferably, step c) comprises the opening of the cut-off valve V2, in addition to the valve VI, which can also be controlled by the control device 19.

[0068] According to another characteristic, the operation of the internal combustion engine 2 in step d) can be maintained until the humidity level in the fuel cell 3 is less than or equal to a predetermined threshold value.

[0069] The predetermined threshold value may advantageously be a humidity level value considered sufficiently low so as not to affect the operation of the fuel cell 3 upon restart and its lifetime.

[0070] Alternatively, the operation of the internal combustion engine 2 in step d) is maintained for a predetermined time interval. This avoids the costs associated with installing a humidity sensor for measuring the humidity level in the fuel cell 3.

[0071] The time interval is, for example, determined based on pre-established tests, or may correspond to an estimate of a time interval allowing the fuel cell 3 to be dried to a level considered sufficient.

[0072] As illustrated in Figure 2, the internal combustion engine 2 can be coupled to a turbocharger 18 positioned on the line C1. The turbocharger 18 is therefore arranged upstream of the air inlet 12 of the internal combustion engine 2 and downstream of the fuel cell 3.

[0073] In the example illustrated, the common portion C3 of the pipes C1 and C2 is connected upstream of an air inlet of the turbocharger 18.

[0074] It may be provided that in the absence of a common portion C3, each of the pipes C1 and C2 are connected independently upstream of the air inlet of the turbocharger 18.

[0075] In one embodiment, in addition to driving the internal combustion engine 2 in step d), the turbocharger 18 can be driven in order to provide more power to the suction of the fluids present in the fuel cell 3 towards the internal combustion engine 2.

[0076] In this regard, the control device 19 can be configured to control the drive of the turbocharger 18 in step d) or successively in step d).

Claims

CLAIMS 1. Method for managing a hybrid powertrain of a hydrogen-powered motor vehicle comprising an internal combustion engine (2), a fuel cell (3), a hydrogen storage tank (14) and a pipe C1 connecting an air outlet (10) of the fuel cell (3) to an air inlet (12) of the internal combustion engine (2) and comprising a cut-off valve VI, the method comprising the following steps: a) the fuel cell (3) is stopped; b) the internal combustion engine (2) is stopped; c) when the fuel cell (3) and the internal combustion engine (2) are stopped, the cut-off valve VI is opened; and d) when the cut-off valve VI is open, the internal combustion engine (2) is driven without injecting hydrogen from the storage tank (14) in order to suck, via the line C1, the fluids present in the fuel cell (3) towards the internal combustion engine (2).

2. Method according to claim 1, in which the powertrain (1) comprises a pipe C2 connecting a hydrogen outlet (8) of the fuel cell (3) to the air inlet (12) of the internal combustion engine (2) and comprising a cut-off valve V2, step c) comprising the opening of the cut-off valve V2 in addition to the valve VI, in order to also suck in step d), via the pipe C2, the fluids present in the fuel cell (3) towards the internal combustion engine (2).

3. Method according to claim 1 or 2, wherein the operation of the internal combustion engine (2) in step d) is maintained for a predetermined time interval.

4. Method according to claim 1 or 2, wherein the operation of the internal combustion engine (2) in step d) is maintained until the humidity level in the fuel cell (3) is less than or equal to a predetermined threshold value.

5. Hybrid powertrain for a hydrogen-powered motor vehicle comprising: an internal combustion engine (2); a fuel cell (3); > a hydrogen storage tank (14); a pipe C1 connecting an air outlet (10) of the fuel cell (3) to an air inlet (12) of the internal combustion engine (2) and comprising a cut-off valve VI for the selective passage of fluids present in the fuel cell (3) from said air outlet (10) to the internal combustion engine (2); and a control device (19) configured to control the opening of the cut-off valve VI when the fuel cell (3) and the internal combustion engine (2) are stopped, and to drive the internal combustion engine (2) without injecting hydrogen from the tank (14) in order to suck, via the pipe C1, the fluids present in the fuel cell (3) to the internal combustion engine (2).

6. Powertrain according to claim 5, comprising a line C2 connecting a hydrogen outlet (8) of the fuel cell (3) to the air inlet (12) of the internal combustion engine (2) and comprising a cut-off valve V2 for the selective passage of fluids present in the fuel cell (3) from said hydrogen outlet (8) to the internal combustion engine (2), the control device (19) being configured to control the opening of the cut-off valve V2 in addition to the valve VI before starting the internal combustion engine (2) without hydrogen injection, in order to also suck, via the line C2, the fluids present in the fuel cell (3) to the internal combustion engine (2).

7. Powertrain according to claim 6, wherein the powertrain (1) comprises a recirculation unit (20) connected to the fuel cell (3) for recirculating hydrogen from the hydrogen outlet (8) to a hydrogen inlet (7) of the fuel cell (3), the recirculation unit (20) being connected to the line C2.

8. Powertrain according to claim 6 or 7, in which the line C2 is connected to the line C1 upstream of the air inlet (12) of the internal combustion engine (2).

9. Powertrain according to any one of claims 5 to 8, comprising at least one condenser (21) positioned on the pipe C1 and / or the pipe C2.

10. Powertrain according to any one of claims 5 to 9, wherein the internal combustion engine (2) is coupled to a turbocharger (18) positioned on the line Cl, upstream of the air inlet (12) of the internal combustion engine (2) and downstream of the fuel cell (3).

11. Motor vehicle comprising a powertrain (1) according to any one of claims 5 to 10.

Images