Hydrogen supply system for an internal combustion engine

Abstract

The invention relates to a hydrogen supply system for an internal combustion engine with an inlet-side high-pressure region (A), with an outlet-side low-pressure region (C) and with a medium-pressure region (B) which is arranged fluidically between the high-pressure region (A) and the low-pressure region (C), wherein a mechanical pressure-reducing device (15) is provided to lower a high pressure in the high-pressure region (A) to a medium pressure in the medium-pressure region (B), and wherein an electrically actuable pressure-reducing device (23) is provided to lower the medium pressure in the medium-pressure region (B) to a low pressure in the low-pressure region (C). It is provided here that a pressure-limiting valve (17) and, downstream of the latter, a shut-off valve (22) are arranged in the medium-pressure region (B) and / or in the low-pressure region (C). The hydrogen supply system according to the invention can comprise, in particular, a single hydrogen supply unit ("one-box solution").

Description

[0001] Description

[0002] title

[0003] Hydrogen supply system for an internal combustion engine

[0004] State of the art

[0005] From DE 10 2016 205 713 A1 of the applicant, a pressure control system for gas-powered internal combustion engines is already known, comprising a gas line for supplying a gas valve with gaseous fuel, wherein a pressure regulator for setting a constant gas pressure is arranged in the gas line, and comprising a shut-off valve which is located between the pressure regulator and a tank container in which gas is located under high pressure.

[0006] Disclosure of the invention

[0007] The invention is based on the inventors' desire to provide the simplest possible hydrogen supply system for an internal combustion engine.

[0008] According to the invention, the hydrogen supply system is provided with a high-pressure region on the inlet side, a low-pressure region on the outlet side, and a medium-pressure region fluidly arranged between the high-pressure region and the low-pressure region, wherein a mechanical pressure reducing device is provided for reducing a high pressure in the high-pressure region to a medium pressure in the medium-pressure region, and wherein an electrically controllable pressure reducing device is provided for reducing the medium pressure in the medium-pressure region to a low pressure in the low-pressure region. The high pressure can, for example, be a pressure in the range of 200 to 700 bar, corresponding to a pressure in a hydrogen tank of the hydrogen supply system or a hydrogen tank to which the hydrogen supply system is connected on the high-pressure side.The intermediate pressure can be, for example, a pressure in the range between 35 bar and 200 bar, for example, a pressure of 40 bar. The low pressure can be, for example, a pressure that can dynamically fluctuate between 15 bar and 35 bar depending on the operating state of the internal combustion engine and is intended for injecting hydrogen into a combustion chamber of the internal combustion engine.

[0009] For safety reasons, the provision of at least one shut-off valve in such a hydrogen supply system is mandatory in order to be able to completely shut off fluidically at least the part of the low-pressure area located in the flow direction from the high-pressure area.

[0010] The shut-off valve can be designed, in particular, as an electrically controlled, normally closed switching valve. This is a valve that has only two switching states: open and closed, but, due to its design, cannot remain in intermediate states. In this respect, it differs from proportional valves, which, due to their design, can remain in intermediate states when electrically controlled accordingly. Proportional valves are therefore not shut-off valves within the meaning of the invention.

[0011] The shut-off valve of the hydrogen supply system or hydrogen supply unit (see below) may differ from a proportional valve also included in the hydrogen supply system or hydrogen supply unit in that the shut-off valve has a larger fluid cross-section than the proportional valve.

[0012] In order to be able to provide the simplest possible hydrogen supply system for an internal combustion engine under these boundary conditions, the invention further provides for a shut-off valve to be arranged in the medium-pressure range or in the low-pressure range.

[0013] By locating the shut-off valve in the medium-pressure or low-pressure range, it is essentially possible to significantly simplify the technical design of the shut-off valve, as it only needs to be capable of shutting off medium or low pressure, but not high pressure. It can therefore be used as a medium-pressure shut-off valve or a low-pressure shut-off valve.

[0014] A low-pressure shut-off valve may be provided and a high-pressure shut-off valve in the hydrogen supply system may be dispensable.

[0015] Subsequently, however, the problem was recognized that mechanical pressure reducing devices have a leakage that cannot be ruled out, so that in the case in which the shut-off valve shuts off in the medium-pressure range or in the low-pressure range, a pressure could gradually build up in the medium-pressure range or in the low-pressure range due to this leakage, which corresponds to the high pressure and for which the medium-pressure shut-off valve or low-pressure shut-off valve is not designed.

[0016] Because the invention further provides that a pressure limiting valve is provided in the medium-pressure range or low-pressure range, the pressure in the medium-pressure range or low-pressure range can be limited by this to the medium pressure or low pressure, even if the shut-off valve in the medium-pressure range or low-pressure range is closed and at the same time the mechanical pressure reducing device has a non-negligible leakage.

[0017] The pressure relief valve can, for example, be designed as a release valve through which hydrogen can be released into the environment of the hydrogen supply system when a pressure in the medium-pressure or low-pressure range exceeds the medium-pressure or low-pressure range. It can, for example, be a spring-loaded check valve.

[0018] In a further development of the invention, the possibility of simplifying the hydrogen supply system can be realized by designing it with a hydrogen tank, and the high-pressure region extending fluidically from the hydrogen tank to the mechanical pressure reducing device without the interposition of a shut-off valve, and optionally also the medium-pressure region extending fluidically from the mechanical pressure reducing device to the electrically controllable pressure reducing device without the interposition of a shut-off valve. In other words, the hydrogen supply system is thus implemented without a high-pressure shut-off valve and optionally even without a medium-pressure shut-off valve. This represents a significant technical simplification because the technical complexity of shut-off valves decreases from high-pressure shut-off valves to medium-pressure shut-off valves to low-pressure shut-off valves.

[0019] In a further development of the invention, a fuel distributor and several injectors fluidically connected to it can also be provided in the low-pressure region, through which hydrogen can be injected into the combustion chambers of the internal combustion engine.

[0020] On the other hand, the hydrogen supply system can also be a hydrogen supply unit having a housing in the interior of which a fluid channel is arranged in which the mechanical pressure reducing device, the electrically controllable pressure reducing device, the pressure relief valve and the shut-off valve are arranged.

[0021] The housing may in particular be a one-piece housing, which is manufactured, for example, as a cast body or by machining, for example from aluminum or steel.

[0022] Alternatively, the housing can also consist of two or more sub-housings that are connected to one another, particularly in a non-detachable manner. The sub-housings can, for example, be made as cast bodies or by machining, for example, from aluminum or steel.

[0023] On the high-pressure side of such a hydrogen supply unit, a high-pressure connection piece communicating with the fluid channel can be provided for connection to a high-pressure line. This connection piece can, for example, be a piece for detachably connecting, e.g., screwing on, a high-pressure line.

[0024] On the low-pressure side of such a hydrogen supply unit, a low-pressure connection piece communicating with the fluid channel can be provided for connection to a low-pressure line. This connection piece can, for example, be a piece for detachably connecting, e.g., screwing on, a low-pressure line.

[0025] The hydrogen supply unit can in particular be a compact component which extends in length, width and height to a maximum of 40 cm, in particular a maximum of 30 cm or even only a maximum of 25 cm.

[0026] The hydrogen supply unit can in particular be part of a comprehensive hydrogen supply system, which further comprises the components tank, high-pressure line, low-pressure line, fuel distributor and / or injectors already described above.

[0027] The hydrogen supply unit or the hydrogen supply system or the comprehensive hydrogen supply system can have a pressure sensor and / or a filter device in the high-pressure range, the medium-pressure range and / or the low-pressure range.

[0028] Exemplary embodiments of the invention are explained below with reference to the drawing. In the drawing:

[0029] Figure 1 shows a first embodiment of the invention.

[0030] Figure 2 shows a second embodiment of the invention.

[0031] Figure 1 shows a first embodiment of the invention. A hydrogen supply system 10 for an internal combustion engine comprises a hydrogen tank 12 in which hydrogen is stored under high pressure (e.g., 700 bar) and which is detachably connected via a high-pressure line 13 to a first pressure reducing unit 14 via its high-pressure nozzle 141.

[0032] The first pressure reducing unit 14 is implemented as a one-piece unit and further comprises a mechanical pressure reducing device 15 for reducing the high pressure to an intermediate pressure, for example, to 40 bar. The first pressure reducing unit 14 further comprises a particle filter 16 on the inlet side and, downstream of the mechanical pressure reducing device 15, a pressure relief valve 17 designed as a check valve, which opens as soon as it is subjected to a pressure on the inlet side that is greater than the intermediate pressure and then releases hydrogen from the hydrogen supply system 10 through a discharge opening 18. The pressure relief valve 17 can therefore also be referred to as a discharge valve. Downstream of the mechanical pressure reducing device 15, a intermediate pressure sensor 19 is also provided in the first pressure reducing unit 14.

[0033] The first pressure reducing unit 14 is detachably connected downstream via its medium-pressure nozzle 142 to a medium-pressure line 20, which in turn is detachably connected downstream to the inlet nozzle 211 of a second pressure reducing unit 21.

[0034] The second pressure reducing unit 21 is implemented as a single unit. In the order of flow direction, the second pressure reducing unit 21 further comprises, connected in series, a shut-off valve 22, another medium-pressure sensor 19, a particulate filter 16, and an electrically controllable pressure reducing device 23, which in this example is designed as a proportional valve. It serves to reduce the medium pressure to a low pressure.

[0035] Via its low-pressure nozzle 212, the second pressure reducing unit 21 is detachably connected to a low-pressure line 25, which is further connected to a fuel distributor 26, which supplies hydrogen to a plurality of injectors 27 fluidly connected to it.

[0036] In this example, shut-off valve 22 is a medium-pressure shut-off valve, meaning it is designed to shut off hydrogen at a medium pressure, for example, 40 bar. However, it is not a high-pressure shut-off valve and therefore is not designed to shut off hydrogen at a high pressure, for example, 250 bar or 700 bar. The shut-off valve 22 can therefore be a relatively simple component.

[0037] Because the pressure relief valve 17 is connected upstream of the shut-off valve 22 in the example, the occurrence of a pressure greater than the mean pressure at the shut-off valve 22 is always reliably excluded, even in the case of shut-off and if a certain leakage occurs at the mechanical pressure reducing device 15.

[0038] According to the first embodiment (Figure 1), the first pressure reducing unit 14 and the second pressure reducing unit 21 are realized as two separate units, each having its own housing (“two-box solution”).

[0039] Figure 2 shows a second embodiment of the invention. A hydrogen supply system 10 for an internal combustion engine comprises a hydrogen tank 12 in which hydrogen is stored under high pressure (e.g., 700 bar) and which is detachably connected via a high-pressure line 13 to a hydrogen supply unit 30 via its high-pressure nozzle 301. On the opposite side, the hydrogen supply unit 30 is detachably connected via its low-pressure nozzle 302 to a low-pressure line 25, which is further connected to a fuel distributor 26 that supplies hydrogen to a plurality of injectors 27 fluidly connected to it.

[0040] The hydrogen supply unit 30 has a one-piece housing 303, which is made, for example, by casting or machining from aluminum or steel. Inside the housing 303 of the hydrogen supply unit 30, a fluid channel 304 extends from the high-pressure region A through the medium-pressure region B to the low-pressure region C, i.e., from nozzle 301 to nozzle 302.

[0041] In the fluid channel 304, in the order of the flow direction, a high-pressure sensor 31, a mechanical pressure reducing device 15 for reducing the high pressure to a medium pressure, for example to 40 bar, an electrically controllable pressure reducing device 23 for dynamically variable reduction of the medium pressure to a low pressure, for example 15 bar to 35 bar, a pressure relief valve 17 and a shut-off valve 22 are provided.

[0042] The electrically controllable pressure reducing device 23 is designed as a proportional valve in the example. The pressure relief valve 17 is designed as a check valve that opens as soon as it is subjected to a pressure on the inlet side that is greater than the highest expected low pressure or the medium pressure, and then releases hydrogen from the hydrogen supply system 10 through a discharge opening 18. The pressure relief valve 17 can therefore also be referred to as a discharge valve.

[0043] In the example, shut-off valve 22 is a low-pressure shut-off valve, meaning it is designed to shut off hydrogen at the highest expected low pressure, for example, 35 bar, or the medium pressure, for example, 40 bar. However, it is not a high-pressure shut-off valve and therefore is not designed to shut off hydrogen at a high pressure, for example, 250 bar or 700 bar. The shut-off valve 22 can therefore be a comparatively simple component.

[0044] Because the pressure relief valve 17 is connected upstream of the shut-off valve 22 in the example, the occurrence of a pressure that is greater than the highest low pressure to be expected or than the medium pressure is always reliably excluded at the shut-off valve 22, even in the case of shut-off and if a certain leakage occurs at the mechanical pressure reducing device 15 and at the electrically controllable pressure reducing device 23.

[0045] According to the second embodiment (Figure 2), a hydrogen supply unit 30 is realized as a single unit which reduces a pressure of the hydrogen in two stages from high pressure via medium pressure to low pressure and has a single housing (“one-box solution”).

Claims

Claims 1. Hydrogen supply system for an internal combustion engine with a high-pressure region (A) on the inlet side, with a low-pressure region (C) on the outlet side and with a medium-pressure region (B) arranged fluidly between the high-pressure region (A) and the low-pressure region (C), wherein a mechanical pressure reducing device (15) is provided for reducing a high pressure in the high-pressure region (A) to a medium pressure in the medium-pressure region (B) and wherein an electrically controllable pressure reducing device (23) is provided for reducing the medium pressure in the medium-pressure region (B) to a low pressure in the low-pressure region (C), wherein a pressure-limiting valve (17) and a shut-off valve (22) are arranged downstream of this in the medium-pressure region (B) and / or in the low-pressure region (C).

2. Hydrogen supply system according to claim 1, further comprising a hydrogen tank (12), wherein the high-pressure region (A) extends fluidically from the hydrogen tank (12) to the mechanical pressure reducing device (15) without the interposition of a shut-off valve (22).

3. Hydrogen supply system according to claim 1 or 2, wherein the medium-pressure region (B) extends fluidically from the mechanical pressure reducing device (15) to the electrically controllable pressure reducing device (23) without the interposition of a shut-off valve (22).

4. Hydrogen supply system according to one of the preceding claims, in the low-pressure region (C) further comprising a fuel distributor (26) and at least one injector (27) fluidly connected thereto.

5. Hydrogen supply system according to one of the preceding claims, designed as a hydrogen supply unit (30) with a housing (303), in the interior of which a fluid channel (304) is arranged, in which the mechanical pressure reducing device (15), the electrically controllable pressure reducing device (23), the pressure limiting valve (17) and the shut-off valve (22) are arranged.

6. Hydrogen supply system according to claim 5, wherein on the high-pressure side of the housing (303) a high-pressure connection piece (301) communicating with the fluid channel (304) is provided for connection to a high-pressure line (13) and on the low-pressure side of the housing (303) a low-pressure connection piece (302) communicating with the fluid channel (304) is provided for connection to a low-pressure line (25).

7. Hydrogen supply system according to one of the preceding claims, wherein the pressure limiting valve (17) is designed as a discharge valve through which hydrogen can be diverted into the environment of the hydrogen supply system (10) when a pressure in the medium pressure region (B) or in the low pressure region (C) exceeds the medium pressure.

8. Hydrogen supply system according to one of the preceding claims, wherein a pressure sensor (19, 31) and / or a filter device (16) are provided in the high-pressure region (A), the medium-pressure region (B) and / or the low-pressure region (C).

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