Gas tank arrangement for an internal combustion engine

Abstract

Gas tank arrangement (2) for an internal combustion engine (3), comprising at least a first tank (6) and a second tank (7) fluidically connected to it, wherein the second tank (7) is designed to be filled with gas (25) from the at least one first tank (6) and to supply gas (25) to an internal combustion engine (3), wherein the second tank (7) is designed to be at least partially filled with a liquid (24) and to supply the liquid (24) to the internal combustion engine (3).

Description

[0001] The present invention relates to a gas tank assembly for an internal combustion engine, in particular for an internal combustion engine for a motor vehicle. The invention also relates to a method for operating a gas tank assembly, an engine assembly, a method for operating an engine assembly, and a vehicle, in particular a motor vehicle.

[0002] Storing gaseous fuel typically requires relatively large storage tanks, which are filled at high pressure to achieve the required energy density. In the case of hydrogen-air combustion, the reaction products of combustion are water or water vapor and nitrogen. The condensed vapor can be stored and used as a coolant. This requires an additional tank.

[0003] In connection with gaseous fuel filling stations, pressure accumulators designed for a constant storage pressure are typically used. During a fuel dispensing phase, the pressure is kept constant by conveying a liquid from a liquid reservoir into the respective pressure accumulator. Examples of this are disclosed in documents DE 10 2017 204 746 A1, DE 10 2015 016 327 A1, and US Pat. No. 5,454,408 A. Documents WO 2008 / 074 075 A1 and WO 2018 / 144 328 A1 describe gas tank arrangements with multiple pressure vessels.

[0004] In connection with gas tanks arranged in a vehicle for operating an internal combustion engine, it is advantageous if they take up as little storage space as possible and can be operated at as constant a pressure as possible, in particular to avoid pressure fluctuations that place stress on the material.

[0005] Against this background, the object of the present invention is to provide an advantageous gas tank assembly for an internal combustion engine, in particular for an internal combustion engine for a motor vehicle, as well as a method for operating such a gas tank assembly. These objects are achieved by a gas tank assembly according to claim 1, a method for operating a gas tank assembly according to claim 8, an engine assembly according to claim 13, and a vehicle according to claim 14. The dependent claims contain further advantageous embodiments of the invention.

[0006] The gas tank arrangement according to the invention for an internal combustion engine comprises at least a first tank and a second tank fluidically connected thereto. The first and second tanks are preferably designed to store gas, in particular gaseous fuel, preferably hydrogen. The second tank is designed to be filled with a gas, for example hydrogen, from the at least one first tank and to deliver the gas to an internal combustion engine. For supplying gas to the first tank, the first tank can have a gas inlet valve. For delivering gas to an internal combustion engine, the second tank can have a gas outlet valve. The second tank is further designed to be at least partially filled with a liquid, for example water, and to deliver the liquid, for example water, to the internal combustion engine.In a preferred variant, the gas and liquid are stored in the same volume or cavity within the second tank. The gas and liquid thus come into direct contact with each other.

[0007] The gas tank arrangement according to the invention has the advantage that, by jointly storing gas, in particular gaseous fuel, and water, preferably condensate generated by the operation of the combustion engine or another device, pressure losses of the gas resulting from gas consumption by the combustion engine are compensated for by filling the second tank with water. At the same time, any resulting condensate is stored in a space-saving manner, can be efficiently pressurized by the gas in the second tank, and is thus available for injection into the combustion engine.

[0008] By adding water to the second tank, the volume available for the gas in the tank is reduced, thereby increasing the pressure in the second tank. In a conventional gas tank system, the pressure decreases as the gas is consumed according to the ideal gas law (p*V = m*R*T, with p-pressure, V-volume, m-mass, T-temperature, R-specific gas constant). In contrast, within the scope of the present invention, particularly when using hydrogen gas, the water produced during combustion can be returned to the tank, making it possible to efficiently maintain the tank at a desired pressure level. The liquid water collects at the bottom of the tank. This makes it possible to remove the gas, for example the hydrogen, from the top of the tank and to remove the stored water from the bottom of the tank.The solution according to the invention is suitable for any liquid and any gas in combination with each other, as long as the corresponding gas has a low solubility in the corresponding liquid.

[0009] As already mentioned, one advantage of the proposed solution is that the pressure in the tank does not decrease when gas is removed from it. Another advantage is that the liquid, especially water, is stored in the same volume as the gas, thereby reducing the overall required storage volume. Another advantage is that, compared to conventional gas tanks, the tank walls have to withstand a lower pressure gradient, as the pressure in the tank can be kept constant within a certain pressure range.

[0010] Conventional gas tanks typically have to withstand an internal pressure of 300 bar and an ambient pressure of 1 bar, i.e., a ratio of 300:1, when fully filled, or a pressure ratio of 150:1 when half empty, and a correspondingly lower ratio upon further emptying, for example, 50:1, etc. This significantly increases the stress and strain on the walls during use, requiring correspondingly thicker walls or a correspondingly resilient material. Within the scope of the present invention, the tank pressure can be kept nearly constant, which is why the second tank only needs to be designed for a constant pressure gradient, and the stress on the walls caused by the pressure gradient is applied evenly at all times.

[0011] In an advantageous variant, the first tank is designed for a maximum internal pressure between 350 bar and 750 bar. Additionally or alternatively, the second tank can be designed for a maximum internal pressure between 30 bar and 350 bar. Furthermore, the second tank is preferably designed to deliver gas to an internal combustion engine at a pressure between 7 bar and 30 bar (operating pressure). This has the advantage that the gas tank arrangement is suitable for an internal combustion engine powered by gaseous fuel, for example, hydrogen.

[0012] In a preferred variant, the second tank comprises a gas inlet with a gas inlet valve and a gas outlet with a gas outlet valve and a liquid inlet with a liquid inlet valve and a liquid outlet and a liquid outlet valve.

[0013] In a further variant, the second tank can be connected to a liquid storage device and / or a liquid return device and / or a liquid pump. The second tank can be connected, for example, to an exhaust system of an internal combustion engine, preferably an internal combustion engine. Additionally, the second tank can be connected to other devices whose operation generates condensation, such as an air conditioning system. In this way, condensation accumulating in various devices during operation can be stored and efficiently reused.

[0014] Furthermore, a turbine can be arranged fluidically between the first and second tanks. This allows energy to be generated from the pressure difference between the first and second tanks. For example, the pressure in the first tank can be 750 bar and the pressure in the second tank 30 bar. Accordingly, an energy-efficient use of this condition is possible using the turbine.

[0015] Within the scope of the inventive method for operating a previously described gas tank arrangement according to the invention, a gaseous fuel, for example hydrogen, is supplied to the first tank at a pressure of more than 15 bar, for example at a pressure between 350 bar and 750 bar. In other words, the first tank is filled with gaseous fuel and the gaseous fuel is subjected to high pressure. Furthermore, gaseous fuel is supplied to the second tank by means of the first tank at a pressure of at least 10 bar, for example at a pressure between 30 bar and 350 bar. In other words, the second tank is filled by means of the first tank, for example via a corresponding flow channel using, in particular, a corresponding valve.Subsequently, gaseous fuel is fed from the second tank to an internal combustion engine, for example an internal combustion engine, to operate it at an operating pressure within a specified pressure range. Liquid, for example water, which is at least partially recovered during operation of the internal combustion engine, for example a hydrogen-powered internal combustion engine, e.g. by condensation, is filled into the second tank. This is preferably done by means of a valve and / or a pump. The liquid from the second tank is fed to the internal combustion engine, for example the internal combustion engine. The liquid can be pressurized by means of the gaseous fuel in the second tank. This makes it possible to ensure the injection pressure required for feeding without the need for additional measures such as pumps or compressors.

[0016] The method according to the invention has the features and advantages already described above in connection with the gas tank arrangement according to the invention. The gaseous fuel is preferably hydrogen. The liquid is preferably water. When filling the second tank, a turbine arranged fluidically between the first tank and the second tank can be driven, for example to generate energy. The operating pressure or injection pressure for injecting the gaseous fuel into the combustion engine can be, for example, between 10 bar and 30 bar. The liquid, preferably the water, can be recovered during operation of the combustion engine or during operation of another device also operated in connection with the operation of the combustion engine, for example during operation of a cooling device or air conditioning system.

[0017] If the pressure in the second tank falls below a specified limit, fluid can be pumped into the second tank until a specified pressure is reached. This allows a constant pressure to be maintained in the second tank, thus reducing the stress on the tank walls. Fluid, such as water, can be pumped from a suitable fluid reservoir into the second tank using a pump.

[0018] The engine assembly according to the invention comprises an internal combustion engine designed to be operated with a gaseous fuel, for example, hydrogen. The engine assembly comprises a gas tank assembly according to the invention as described above. The engine assembly is additionally or alternatively designed to be operated according to a prescribed method according to the invention. The engine assembly according to the invention has the features and advantages already described. In particular, the engine assembly can be connected to an air conditioning system, and condensate water produced during operation of the air conditioning system can be returned to the second tank.

[0019] The vehicle according to the invention comprises an engine assembly according to the invention. The vehicle according to the invention can be a motor vehicle or a vessel, for example a passenger car, a truck, a bus, a motorcycle, a moped, etc.

[0020] In connection with internal combustion engines powered by gaseous fuel, in particular hydrogen, such as hydrogen internal combustion engines, the present invention has the further advantage that water can be efficiently supplied to the combustion process. This has the advantage that knocking noises can be easily and significantly reduced. Hydrogen, in particular, is considerably more sensitive to engine knocking during combustion than gasoline-powered internal combustion engines. Therefore, solutions that reduce the occurrence of engine knocking are required and can be implemented very efficiently within the scope of the present invention, since the water to be injected into the combustion chamber for this purpose is obtained from condensate. Furthermore, no additional water tank is required, since, as already described, the water is stored in the same tank as the gaseous fuel.

[0021] The invention will be explained in more detail below using exemplary embodiments with reference to the accompanying figures. Although the invention is illustrated and described in more detail by the preferred embodiments, the invention is not limited to the disclosed examples, and other variations may be derived therefrom by those skilled in the art without departing from the scope of the invention.

[0022] The figures are not necessarily detailed or to scale and may be enlarged or reduced to provide a better overview. Therefore, the functional details disclosed herein are not to be interpreted in a limiting sense, but merely as an illustrative basis for teaching one skilled in the art how to variously employ the present invention.

[0023] As used herein, the term "and / or," when used in a series of two or more elements, means that any of the listed elements may be used alone, or any combination of two or more of the listed elements may be used. For example, if a composition is described as containing components A, B, and / or C, the composition may contain A alone; B alone; C alone; A and B in combination; A and C in combination; B and C in combination; or A, B, and C in combination. Fig. 1 shows schematically a motor arrangement according to the invention. Fig. 2 shows schematically a vehicle according to the invention. Fig. 3 schematically shows a method according to the invention for operating a gas tank arrangement according to the invention and an engine arrangement in the form of a flow chart.

[0024] The Fig. 1 schematically shows an engine assembly 1 according to the invention. The engine assembly 1 comprises a gas tank assembly 2 according to the invention, an internal combustion engine 3, a condenser 4 and optionally an air conditioning condenser 5 connected to an air conditioning system (not shown). The gas tank assembly 2 comprises a first tank 6 and a second tank 7.

[0025] The first tank has a gas inlet with an inlet valve 11, which is preferably connected to a filler neck 12. The first tank 6 further has a gas outlet, which is fluidly connected to a gas inlet 13 of the second tank 7 via a flow channel 8. The first tank 6 and / or the flow channel 8 comprises a valve 9. Furthermore, the flow channel 8 is preferably connected to a gas turbine 10 for energy generation. The first tank 6 is designed to store a gas 25, preferably hydrogen, at a pressure between a maximum of 350 bar and a maximum of 750 bar.

[0026] The second tank 7 comprises a gas inlet 13 and a gas outlet 13 for filling gas into the tank and for discharging gas from the tank. The gas inlet and gas outlet 13 are arranged in the Fig. 1 as a single component. However, it can also be two components designed and arranged separately from one another. The gas inlet and / or the gas outlet 13 are preferably arranged in a vertically upper region of the second tank 7. The second tank 7 is preferably designed to store a gas, for example, hydrogen, at a maximum pressure between 30 bar and 350 bar.

[0027] The second tank 7 further comprises a liquid inlet and a liquid outlet 15, which in the variant shown are designed as a single component. In principle, a separate liquid inlet with an inlet valve and a liquid outlet with an outlet valve can also be provided. The liquid inlet and / or liquid outlet 15 is preferably arranged in a vertically lower region of the second tank 7. Advantageously, the gas inlet and / or gas outlet 13 is arranged vertically above the liquid inlet and / or liquid outlet 15. Fig. 1, gas stored in the second tank 7, preferably hydrogen, is designated by reference numeral 25, and liquid stored in the second tank 7, preferably water, is designated by reference numeral 24. The gas stored in the first tank 6 is also designated by reference numeral 25.

[0028] The liquid outlet 15 is connected to a flow channel 20, which includes a valve 19 and is fluidly connected to the internal combustion engine 3. For example, water is injected into the combustion chamber of the internal combustion engine 3 via the flow channel 20 in order to reduce, preferably completely eliminate, knocking noises during combustion. The pressure required for the water injection is preferably built up by means of the gas 25 stored in the second tank 7 and is provided in such a way that the water is supplied at a pressure above a specified minimum pressure.

[0029] Gaseous fuel, for example hydrogen, is also supplied to the internal combustion engine 3 via a flow channel 21, which fluidically connects the second tank 7 to the internal combustion engine 3 and which preferably comprises a valve 14. The gaseous fuel is preferably supplied to the internal combustion engine 3 at a pressure within a specified pressure range, for example, at an operating pressure between 10 bar and 30 bar.

[0030] The internal combustion engine 3 is connected to an exhaust system 23, through which the exhaust gas is discharged. The exhaust system 23 comprises a condenser 4, in which condensate is extracted from the exhaust gas. The water collected by the condenser 4 is fed to the second tank 7 via the liquid inlet 15 via a flow channel 26, which preferably comprises a valve 17. For this purpose, in the variant shown, a pump, preferably a water pump 16, is arranged between the condenser 4 and the liquid inlet 15. In the variant shown, the pump 16 is arranged downstream of the valve 17.

[0031] The Fig. The motor assembly 1 shown in Figure 1 is also fluidly connected to a condenser 5, which can be connected to an air conditioning system. A flow channel 22 with a valve 18 is arranged between the condenser 5 and the liquid inlet 15 of the second tank 7. Condensate collected in the condenser 5 is fed to the second tank 7 via the flow channel 22. The flow channel 22 is connected to the liquid pump 16.

[0032] The Fig. Figure 2 shows schematically a vehicle according to the invention, for example a motor vehicle 27. The motor vehicle according to the invention comprises a Fig. 1 and an air conditioning system 28 with a condenser 5. The condenser 5, as shown in the Fig. 1, is fluidly connected to the second tank 7 of the engine assembly 1. Instead of or in addition to the air conditioning system 28, the vehicle 27 can also include other or additional components whose operation generates condensation. These components can be fluidly connected to the engine assembly 1 in a manner analogous to the air conditioning system 28 shown, such that the resulting condensation is or can be fed to the second tank 7.

[0033] The Fig. Figure 3 schematically shows a method according to the invention for operating a gas tank assembly 2 according to the invention and an engine assembly 1 in the form of a flowchart. In a first step 31, the first tank 6 is filled with a gaseous fuel, for example, hydrogen. This preferably takes place via the filler neck 12 and the valve 11.

[0034] In a next step 32, gaseous fuel 25 is supplied to the second tank 7 by means of the first tank 6, i.e., from the first tank 6. The second tank 7 is preferably filled with gaseous fuel, for example, hydrogen, at a pressure of at least 10 bar, for example, between 30 bar and 350 bar. The second tank 7 is filled via the flow channel 8 and the valve 9 via the gas inlet 13. The pressure difference between the first tank 6 and the second tank 7 is advantageously used to generate energy by means of the gas turbine 10.

[0035] In a third step 33, gaseous fuel is supplied from the second tank 7 to an internal combustion engine, for example, a hydrogen-powered internal combustion engine 3. The liquid fuel, for example, hydrogen, is supplied to the internal combustion engine at a specified operating pressure within a specified pressure range, for example, at a pressure between 10 bar and 3 bar.

[0036] In step 34, liquid, for example water, which is at least partially recovered during operation of the combustion engine 3, for example by condensation, is filled into the second tank 7. This is preferably carried out as in the Fig. 1, via the condenser 4, the flow channel 26 and the pump 16. In addition, liquid, for example condensate water, can be drawn from other components, for example a condenser of an air conditioning system 5, as shown in the Fig. 1, are fed to the second tank 7.

[0037] In a next step 35, liquid, preferably water, is supplied from the second tank 7 to the combustion engine 3. For this purpose, the gaseous fuel 25 located in the second tank 7 can be used to pressurize the liquid 24, preferably water, also located in the tank. Preferably, the pressure is at least high enough to reach the minimum pressure required for injecting the liquid into the combustion engine 3. List of reference symbols: 1 Motor arrangement 2 Gas tank arrangement 3 combustion engine 4 Capacitor 5 Air conditioning condenser 6 first tank 7 second tank 8 connecting line 9 Valve 10 gas turbines 11 Valve 12 filler necks 13 Gas inlet, gas outlet 14 Valve 15 Liquid inlet, liquid outlet 16 Liquid pump 17 Valve 18 Valve 19 Valve 20 flow channel 21 Flow channel 22 flow channel 23 Exhaust system 24 Liquid, Water 25 Gas, Hydrogen 26 flow channel 27 vehicles 28 Air conditioning 31 Filling the first tank 32 Filling the second tank 33 Fuel from the second tank to the combustion engine 34 Fill the second tank with liquid 35 Liquid from the second tank to the combustion engine

Claims

[1] Gas tank arrangement (2) for an internal combustion engine (3), which comprises at least a first tank (6) and a second tank (7) fluidically connected thereto, wherein the second tank (7) is designed to be filled with gas (25) from the at least one first tank (6) and to deliver gas (25) to an internal combustion engine (3), wherein the second tank (7) is designed to be at least partially filled with a liquid (24) and to deliver the liquid (24) to the internal combustion engine (3). [2] Gas tank arrangement (2) according to claim 1, characterized by that within the second tank (7) gas (25) and liquid (24) are stored in the same cavity. [3] Gas tank arrangement (2) according to claim 1 or claim 2, characterized by that the first tank (6) is designed for a maximum internal pressure between 350 bar and 750 bar and / or the second tank (7) is designed for a maximum internal pressure between 30 bar and 350 bar [4] Gas tank arrangement (2) according to one of claims 1 to 3, characterized by that the second tank (7) is designed to deliver gas (25) at a pressure between 10 bar and 30 bar to an internal combustion engine (3). [5] Gas tank arrangement (2) according to one of claims 1 to 4, characterized by that the second tank (7) comprises a gas inlet (13) with a gas inlet valve (9) and a gas outlet (13) with a gas outlet valve (14) and a liquid inlet (15) with a liquid inlet valve (17, 18) and a liquid outlet (15) with a liquid outlet valve (19). [6] Gas tank arrangement (2) according to one of claims 1 to 5, characterized by that the second tank (7) is connected to a liquid storage device (4) and / or a liquid return device (4) and / or a liquid pump (16). [7] Gas tank arrangement (2) according to one of claims 1 to 6, characterized bythat a turbine (10) is arranged fluidically between the first tank (6) and the second tank (7). [8] Method for operating a gas tank arrangement (2) according to one of claims 1 to 7, characterized by , that - gaseous fuel is supplied to the first tank at a pressure of more than 15 bar (31), - gaseous fuel is supplied to the second tank by means of the first tank at a pressure of at least 10 bar (32), - gaseous fuel is supplied from the second tank to an internal combustion engine for operating the engine at an operating pressure within a specified pressure range (33), - liquid (water), which is at least partially recovered during operation of the combustion engine, is filled into the second tank (34), - the liquid from the second tank is fed to the combustion engine (35). [9] Method according to claim 8, characterized bythat the liquid (24) from the second tank (7) is pressurized by means of the gaseous fuel (25) located in the second tank (7). [10] Method according to claim 8 or claim 9, characterized by that the gaseous fuel (25) is hydrogen and / or the liquid (24) is water. [11] Method according to one of claims 8 to 10, characterized by that when the second tank (7) is filled, a turbine (10) arranged fluidically between the first tank (6) and the second tank (7) is driven. [12] Method according to one of claims 8 to 11, characterized by that if the pressure in the second tank (7) is below a predetermined limit, liquid (24) is pumped into the second tank (7) until a predetermined pressure is reached. [13] Engine arrangement (1) comprising a gaseous fuel-operated internal combustion engine (3), characterized by that the engine arrangement (1) comprises a gas tank arrangement (2) according to one of claims 1 to 7 and / or is designed to be operated according to a method according to one of claims 8 to 12. [14] Vehicle (27) comprising an engine assembly (1) according to claim 13.

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