Hybrid drive train for motor vehicle comprising fuel cell

Abstract

The invention relates to a motor vehicle power train (10) comprising:-a fuel cell (18) supplied with air by a supply circuit (32) comprising a first air filter, referred to as a fuel cell filter (40); -an internal combustion engine (14) supplied with air by an intake circuit (50) comprising a second air filter, referred to as an engine filter (58); characterised in that the control system comprises:-a bypass pipe (66) connecting the intake circuit (50) downstream of the engine filter (58) with the supply circuit (32) upstream of the fuel cell filter (18); and-controlled means for alternately directing an air flow from the intake circuit (50) to the combustion engine (14) or via the bypass to the supply circuit (32).

Description

Technical field

[0001] The present invention relates to a motor vehicle powertrain, which comprises:

[0002] - a fuel cell supplied with air by a supply circuit including a first air filter known as a fuel cell filter;

[0003] - an internal combustion engine supplied with air by an intake circuit including a second air filter known as an engine filter. Background art

[0004] Currently, it is necessary to store energy in a motor vehicle in a form such that carbon dioxide emissions can be avoided when the energy is used to move the motor vehicle.

[0005] Hydrogen is such a form of energy. For example, it involves storing hydrogen in the vehicle in the form of pressurized cylinders.

[0006] A currently known solution is to use a fuel cell in a motor vehicle equipped with an electric traction motor.

[0007] The fuel cell advantageously has a very high efficiency at partial load, i.e., at low power. In addition, the fuel cell makes it possible to generate electricity that can be used in the electric traction motor to move the vehicle without any regulated pollutant emissions.

[0008] In order for a motor vehicle to achieve optimal performance with good efficiency, it is advantageous to combine an internal combustion engine with an electric traction motor. Thus, the vehicle has a hybrid powertrain. Therefore, the internal combustion engine makes it possible to generate high power with significant efficiency in the case of high load on the internal combustion engine.

[0009] Advantageously, the internal combustion engine is designed to be supplied with a fuel that emits very few regulated pollutants. For example, the fuel is formed of hydrogen.

[0010] However, the present invention is also applicable to internal combustion engines powered by conventional fuels such as gasoline, natural gas or diesel.

[0011] For operation, the fuel cell must be supplied with hydrogen on the one hand and air on the other hand. Inside the fuel cell, electricity is generated by the chemical reaction between hydrogen and oxygen in the air.

[0012] It is known that air pollutants present in the air, such as particulate matter, carbon monoxide (CO), sulfur oxides (SOx) and other molecules, are pollutants for the fuel cell. Therefore, their presence has an impact on the performance and durability of the fuel cell.

[0013] Therefore, it is necessary to position the air filter upstream of the fuel cell air supply to prevent air pollutants from entering the fuel cell and damaging it.

[0014] For the cell, the air filter is a so-called combined filter, in other words, it includes at least a particulate filter element and an element for adsorbing target gaseous compounds.

[0015] This combined air filter is particularly expensive. However, this air filter has a maximum service life, for example corresponding to the number of hours of use of the fuel cell or the distance traveled by the vehicle. Once this maximum service life is exceeded, it is necessary to replace the air filter to keep it efficient in terms of performance and filtering capacity.

[0016] In addition, the particulate filter element becomes clogged when capturing new particles. This results in a pressure loss in the air flow circulating through the air filter. Therefore, it must also be ensured that the pressure loss is always compatible with the use of the entire system. If the performance deteriorates, the entire system will quickly degrade, leading to the failure of the fuel cell.

[0017] In addition, as is known, an internal combustion engine operates by burning fuel with an oxidant, which is usually air. Like fuel cells, the air supplied to the internal combustion engine must be filtered to remove most of the contaminant particles that are likely to reduce efficiency or even damage the internal combustion engine.

[0018] For the internal combustion engine, the filter only has a particulate filter element. This is because the internal combustion engine is much less sensitive to gaseous pollutants in the air.

[0019] As a result, replacing the air filter of the internal combustion engine is much cheaper than that of the fuel cell air filter. SUMMARY OF THE INVENTION

[0020] The present invention provides a motor vehicle powertrain, which includes:

[0021] - a fuel cell, which is supplied with air by a supply circuit including a first air filter called a fuel cell filter;

[0022] - an internal combustion engine, which is supplied with air by an intake circuit including a second air filter called an engine filter;

[0023] Characterized in that the control system includes:

[0024] - a bypass pipe, which connects the intake circuit downstream of the engine filter to the supply circuit upstream of the fuel cell filter; and

[0025] - A control device for alternately guiding an air flow from an intake circuit to a combustion engine or to a supply circuit via a bypass pipe.

[0026] According to another feature of the invention, the supply circuit includes a shut-off valve which is arranged upstream of the connection with the bypass pipe and is commanded to switch between at least an open state and a closed state.

[0027] According to another feature of the invention, the engine filter includes at least one particulate filter element.

[0028] According to another feature of the invention, the fuel cell filter includes at least one particulate filter element.

[0029] According to another feature of the invention, the fuel cell filter includes at least one adsorption element made of an adsorption material (such as activated carbon).

[0030] According to another feature of the invention, the particulate filter element and the adsorption element of the fuel cell filter are integrated in a common filter cartridge.

[0031] According to another feature of the invention, the control device for guiding the air flow includes a three-way valve which is arranged at the connection between the intake circuit and the bypass pipe.

[0032] According to another feature of the invention, the intake circuit includes an air compressor called an engine compressor which is arranged downstream of the connection with the bypass pipe.

[0033] According to another feature of the invention, the supply circuit includes an air compressor called a fuel cell compressor which is arranged downstream of the fuel cell filter.

[0034] According to another feature of the invention, the internal combustion engine is a hydrogen engine.

[0035] According to another feature of the invention, the fuel cell supplies electric power to an electric traction motor.

[0036] According to another feature of the invention, when the vehicle is driven only by the electric traction motor, the shut-off valve is commanded to switch to its closed state, and the control guiding device is commanded to switch to divert all the air entering the intake circuit to the bypass pipe.

[0037] According to another feature of the invention, when the internal combustion engine is used, the shut-off valve is commanded to switch to its open state, and the control guiding device is commanded to switch such that all the air entering the intake circuit is guided to the internal combustion engine. Description of the Drawings

[0038] Other features and advantages of the present invention will become apparent upon reading the following detailed description, and a clearer understanding thereof can be obtained by reference to a single attached Figure 1 which schematically depicts a hybrid powertrain produced in accordance with the teachings of the present invention. DETAILED DESCRIPTION

[0039] In the remainder of this specification, elements having the same structure or similar functions will be denoted by the same reference numerals.

[0040] In the remainder of the specification, the terms "upstream" and "downstream" will be used with reference to the direction of movement of the air flow in the duct.

[0041] Figure 1 shows a motor vehicle powertrain 10. This is a hybrid powertrain 10 which includes two separate motors 12, 14, thereby allowing the drive wheels of the vehicle to be driven to rotate simultaneously or alternately so as to move the vehicle.

[0042] Thus, the first motor 12 is an electric traction motor 12 which is intended to drive the drive wheels of the vehicle via a drive shaft 16, as indicated by the arrow "F".

[0043] The electric traction motor 12 is supplied with power by an electrical system including a fuel cell 18. The fuel cell 18 is connected to the electric traction motor 12 via a circuit 20 which in this case consists of two cables 20A, 20B.

[0044] In order to be able to convert the current generated by the fuel cell 18 into a voltage suitable for the operation of the electric traction motor 12, a first DC / DC transformer 22 is interposed in the circuit 20. A second DC / AC transformer 24 is also interposed in the circuit 20, between the first transformer 22 and the electric traction motor 12.

[0045] Furthermore, the electrical system also includes a high-voltage battery 26 which is connected in parallel with the fuel cell 18 to the electric traction motor 12. The battery 26 is more specifically connected to the circuit 20 between the first transformer 22 and the second transformer 24. The battery 26 is particularly used to manage the start-up phase and the transient operation phase of the electric traction motor 12, for which the fuel cell 18 alone cannot provide sufficient power.

[0046] The fuel cell 18 is supplied with hydrogen by a storage tank 28 via a hydrogen supply pipe 30.

[0047] ​In addition, the fuel cell 18 is also supplied with air by a supply circuit 32 including an air supply pipe 34. In this case, the supply pipe 34 has an air inlet 36 at its upstream end. In this case, it includes at least one downstream end 38 connected to the air inlet of the fuel cell 18. Thus, the supply pipe 34 allows a first air flow to circulate from the air inlet 36 to the fuel cell 18.

[0048] A first air filter, referred to as the fuel cell filter 40, is interposed in the supply pipe 34 of the fuel cell 18. The fuel cell filter 40 includes at least one particulate filter element 40A.

[0049] Regardless of the type of particulate filter element used, particulates remain trapped in the particulate filter element 40A. As a result, the particulate filter element 40A eventually becomes saturated with particulates.

[0050] In this case, the fuel cell filter 40 does not include any means for regenerating the particulate filter element 40A. This is because such means are very expensive and very difficult to implement. Therefore, it is simpler and cheaper to replace the fuel cell filter regularly before it becomes saturated.

[0051] As a non-limiting example, the particulate filter element 40A is made of a porous material in this case. The first air flow entering through the air inlet 36 passes through the particulate filter element 40A, passing through pores (not shown). Thus, the particulate filter element 40A enables the capture of particulates larger than the size of its pores. As the fuel cell filter 40 is used, the pores of the particulate filter element 40A eventually become clogged. This results in a pressure loss in the air flow passing through it.

[0052] As a non-limiting example, the porous material consists of a paper made of a synthetic fiber assembly or a non-woven fabric folded into a bellows-like structure to present a large channel surface area.

[0053] The fuel cell filter 40 includes at least one adsorption element 40B for adsorbing certain gases harmful to the fuel cell 18. The adsorption element 40B is made of an adsorption material. This adsorption element 40B is arranged downstream of the particulate filter element 40A to protect it from contaminated particulates. It is designed to neutralize certain contaminated gases contained in the air that may damage the fuel cell 18. The adsorption element 40B contains, for example, activated carbon.

[0054] In use, the adsorption material of the gas filter element 40A becomes saturated, and after a certain time, it can no longer adequately filter the contaminated gases. Therefore, it is necessary to change it.

[0055] Thus, the fuel cell air filter 40 forms a combined filter, in which the particulate filter element 40A and the adsorption element 40B are integrated in a common filter cartridge 42.

[0056] Furthermore, the supply circuit 32 includes an air compressor known as a fuel cell compressor 44, which is interposed in the supply pipe 34 downstream of the fuel cell air filter 40 to increase the pressure of the filtered air.

[0057] The supply circuit 32 also includes a heat exchanger 46, which is interposed in the supply pipe 34 downstream of the fuel cell compressor 44 to cool the air.

[0058] As is known, the internal combustion engine 14 includes a plurality of cylinders, and pistons defining combustion chambers 48 slide in each of these cylinders. As a non-limiting example, the combustion engine 14 includes three cylinders. The internal combustion engine 14 is intended to drive the drive wheels of the vehicle via a drive shaft 16, as indicated by the arrow "F".

[0059] Each combustion chamber 48 is supplied with a mixture of fuel and air, which is intended to release, by combustion of the mixture, the energy required to generate the drive torque of the drive shaft 16.

[0060] Thus, the internal combustion engine 14 is supplied with air by an intake circuit 50 including an intake pipe 52. In this case, the intake pipe 52 includes an air intake 54 at its upstream end. In this case, it includes at least one downstream end 56, which is connected to the air inlet of the internal combustion engine 14, which then distributes the air flow between the respective combustion chambers 48. The intake pipe 52 thus allows a second air flow to circulate from the air intake 54 to the internal combustion engine 14.

[0061] A second air filter, known as an engine filter 58, is interposed in the intake pipe 52. The engine filter 58 includes at least one particulate filter element 58A. Particulate matter is trapped in the particulate filter element 58A. Regardless of the type of particulate filter element used, particulate matter is trapped in the particulate filter element 58A. As a result, the particulate filter element 58A eventually becomes saturated with particulate matter.

[0062] In this case, the engine filter 58 does not include any means for regenerating the particulate filter element 58A. This is because such means are very expensive and very difficult to implement. Therefore, it is simpler and cheaper to be able to replace the engine filter regularly before the engine filter 58 becomes saturated.

[0063] As a non - limiting example, the particulate filter element 58A is made of a porous material in this case. A second air flow entering through the air inlet 54 passes through the particulate filter element 58A, passing through pores (not shown). Thus, the particulate filter element 58A enables particles larger than the size of its pores to be captured. Therefore, when the engine filter 58 is used, the pores of the particulate filter element 58A eventually become clogged, thereby clogging the particulate filter element 58A. This results in a pressure loss in the air flow passing through it.

[0064] As a non - limiting example, the porous material consists of a paper made of a synthetic fiber assembly or a non - woven fabric folded into a bellows - like structure to present a large channel surface area.

[0065] In this case, the engine filter 58 is merely a particulate filter including one or more particulate filter elements 58A. The engine filter 58 does not particularly include an adsorption element. The (multiple) particulate filter elements 58A are generally arranged in the same filter cartridge to allow for the replacement of the particulate filter element in a single operation.

[0066] Furthermore, the intake circuit 50 includes an air compressor known as the engine compressor 60, which is interposed in the intake pipe 52 downstream of the engine filter 58 to increase the pressure of the filtered air.

[0067] The intake circuit 50 also includes a heat exchanger 62, which is interposed in the intake pipe 52 downstream of the engine compressor 60 to cool the air.

[0068] The present invention is applicable to any type of internal combustion engine that requires air supply to enable fuel combustion. Thus, the internal combustion engine 14 can be designed to operate with conventional fuels such as gasoline, diesel, or natural gas.

[0069] By way of non - limiting example, the internal combustion engine 14 is advantageously a hydrogen engine, which is designed to operate with a fuel formed from hydrogen. Specifically, the combustion of hydrogen emits very few polluting gases. Furthermore, due to the presence of the fuel cell 18, a hydrogen storage tank 28 already exists on the motor vehicle. The same hydrogen storage tank can be used to supply the internal combustion engine 14 via a fuel supply pipe 64. The internal combustion engine 14 and the fuel cell 18 are thus powered by a common hydrogen source (constituted by the storage tank 28 in this case).

[0070] In addition, the combustion products of the fuel - air mixture are discharged from the combustion chamber 48 to the atmosphere through the exhaust pipe 65, and a muffler 67 is interposed in the exhaust pipe.

[0071] As described above, the fuel cell filter 40 is a combined filter, and it can be expensive to replace when the particulate filter element 40A or the adsorption element 40B becomes saturated. Generally, the particulate filter element 40A becomes saturated before the adsorption element 40B. Since the particulate filter element 40A and the adsorption element 40B are arranged in a common filter element, this means that they must be replaced simultaneously, even when the adsorption element 40B can still continue to perform its function for a long time.

[0072] Therefore, the present invention aims to extend the service life of the fuel cell filter 40 while maintaining simplicity in replacement and a minimum volume.

[0073] To this end, the powertrain 10 includes a bypass pipe 66 that connects the intake circuit downstream of the engine filter 58 to the supply circuit 32 upstream of the fuel cell filter 40.

[0074] More specifically, in this case, the upstream end of the bypass pipe 66 is connected to the intake pipe 52 at a connection portion 66A located downstream of the engine filter 58. The downstream end 66B of the bypass pipe 66 is connected to the supply pipe 34 upstream of the fuel cell filter 40.

[0075] In this case, the engine compressor 60 is arranged in the intake pipe 52, downstream of the connection portion 66A with the bypass pipe 66.

[0076] In this case, the supply circuit 32 is connected to the intake circuit 50 only via the bypass pipe 66.

[0077] In addition, the powertrain 10 further includes a control device for alternately guiding the air flow from the second supply circuit to the internal combustion engine 14 or the supply circuit 32 via the bypass pipe 66.

[0078] The control device for guiding the air flow advantageously includes a three-way valve 68 that is arranged at the connection portion 66A between the intake pipe 52 and the bypass pipe 66. Thus, the three-way valve 68 has an inlet connected to the outlet of the engine filter 58, and two outlets, one of which is connected to the internal combustion engine 14 and the other is connected to the bypass pipe 66. The three-way valve 68 is commanded to switch between a first state of guiding all the incoming air flow to the internal combustion engine 14 and a second state of guiding all the incoming air flow to the bypass pipe 66.

[0079] In a variant of the invention not shown, the controlled device for guiding the air flow includes a first two-way valve inserted in the intake pipe 52, downstream of the connection portion 66A with the bypass pipe 66, and a second two-way valve inserted in the bypass pipe 66. By closing one of the two two-way valves and opening the other, the same effect of guiding the air flow as using the three-way valve 68 is achieved.

[0080] In addition, the supply circuit 32 includes a two-way valve called a shut-off valve 70, which is inserted in the supply pipe 34, upstream of the connection portion 66B with the bypass pipe 66. The shut-off valve 70 is commanded to switch at least between an open state that allows the incoming air flow to circulate in the supply circuit 32 as far as the fuel cell, through the fuel cell filter 40, and a closed state that cuts off the incoming air flow and prevents it from entering the fuel cell filter 40.

[0081] When the vehicle is driven only by the electric traction motor 12, the internal combustion engine 14 is not supplied with air. However, the fuel cell 18 does have to be supplied with air. In this configuration, in order to allow an extended service life of the particulate filter element 40A of the fuel cell filter 40, it is advantageous to pre-filter the air flow supplied to the fuel cell 18 using the engine filter 58.

[0082] For this purpose, the shut-off valve 70 is commanded to switch to its closed state in order to prevent the unfiltered air entering through the air intake 36 from entering the fuel cell filter 40. At the same time, the controlled guiding device formed here by the three-way valve 68 is commanded to switch to a second state that guides all the air flow entering through the air intake 54 to the bypass pipe 66.

[0083] Thus, the air flow supplied to the fuel cell 18 enters through the air intake 54 of the intake pipe 52, then successively passes through the engine filter 58, where most of the particles remain trapped, then through the bypass pipe 66, and subsequently through the fuel cell filter 40. After being filtered by the fuel cell filter 40, the air flow is conveyed to the fuel cell via the supply pipe 32.

[0084] Since the air has been pre-filtered by the engine filter 58 beforehand, very few particles are trapped by the particulate filter element 40A of the fuel cell filter 40. As a result, the service life of this particulate filter element 40A of the fuel cell filter 40 is extended.

[0085] In addition, when the internal combustion engine 14 is used, air must be supplied to it again. As a result, the closing valve 70 is commanded to switch to its open state, and the controlled guiding device formed by the three-way valve 68 here is commanded to switch such that the air entering through the air inlet 54 of the intake air circuit 50 is completely guided to the internal combustion engine 14, passing only through the engine filter 58. If the fuel cell 18 is used simultaneously, the air required for its operation enters through the air inlet 36 of the supply pipe 32, and then is filtered only by the fuel cell filter 40, and then is guided by the supply pipe 34 to the fuel cell 18.

[0086] Therefore, the present invention advantageously makes it possible to extend the service life of the fuel cell filter 40.

[0087] In addition, by passing the air supplied to the fuel cell 18 through two filters 40, 58 in series, the quality of this air is further improved, which makes it possible to further extend the service life of the fuel cell 18.

Claims

1. A motor vehicle power train (10), comprising: - A fuel cell (18) supplied with air by a supply circuit (32) that includes a first air filter known as a fuel cell filter (40); - An internal combustion engine (14) supplied with air by an intake circuit (50) that includes a second air filter known as an engine filter (58); Characterized in that the control system includes: - A bypass pipe (66) that connects the intake circuit (50) downstream of the engine filter (58) to the supply circuit (32) upstream of the fuel cell filter (18); and - A controlled device for alternately directing the air flow from the intake circuit (50) to the combustion engine (14) or via the bypass pipe (66) to the supply circuit (32).

2. The power transmission system (10) according to claim 1, characterized in that, The supply circuit (32) includes a shut-off valve (70) arranged upstream of the connection portion (66B) with the bypass pipe (66) and commanded to switch between at least an open state and a closed state.

3. The powertrain (10) according to any one of the preceding claims, characterized in that, The engine filter (58) includes at least one particulate filter element (58A).

4. The powertrain (10) according to any one of the preceding claims, characterized in that, The fuel cell filter (40) includes at least one particulate filter element (40A).

5. The powertrain (10) according to any one of the preceding claims, characterized in that, The fuel cell filter (40) includes at least one adsorption element (40B) made of an adsorption material such as activated carbon.

6. The powertrain according to claim 4 in combination with claim 5, characterized in that, The particulate filter element (40A) and the adsorption element (40B) of the fuel cell filter (40) are integrated in a common filter element.

7. The powertrain (10) according to any one of the preceding claims, characterized in that, The controlled device for directing the air flow includes a three-way valve (68) arranged at the connection portion (66A) between the intake circuit (50) and the bypass pipe (66).

8. The powertrain (10) according to any one of the preceding claims, characterized in that, The intake circuit (50) includes an air compressor known as an engine compressor (60) arranged downstream of the connection portion (66A) with the bypass pipe (66).

9. The powertrain (10) according to any one of the preceding claims, characterized in that, The supply circuit (32) includes an air compressor known as a fuel cell compressor (44) arranged downstream of the fuel cell filter (40).

10. The power transmission system (10) according to any one of the preceding claims, characterized in that, The internal combustion engine (14) is a hydrogen engine.

11. The power transmission system (10) according to any one of the preceding claims, characterized in that, The fuel cell (18) supplies electric power to an electric traction motor (12).

12. The implementation method according to the previous claim, characterized in that, When the vehicle is driven only by the electric traction motor (12), the shut-off valve (70) is commanded to switch to its closed state, and the controlled guiding device is commanded to switch to divert all the air entering the intake circuit (50) to the bypass pipe (66).

13. The method according to the preceding claim, characterized in that, When the internal combustion engine (14) is in use, the shut-off valve (70) is commanded to switch to its open state, and the controlled guiding device is commanded to switch such that all the air entering the intake circuit (50) is directed to the internal combustion engine (14).

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