FUEL GAS SUPPLY DEVICE FOR PROVIDING A FUEL GAS, AND AN INTERNAL COMBUSTION ENGINE

Abstract

A fuel gas supply device for providing a fuel gas to a fuel gas supply point, including: a fuel gas reservoir that is configured to store liquid fuel gas, the fuel gas reservoir being fluidically connected to a first supply path and a second supply path, the first supply path and second supply path each including a heat exchanger configured to evaporate liquid fuel gas; and a valve device configured alternately to connect the first supply path to the fuel gas supply point and simultaneously block the second supply path or connect it to the fuel gas reservoir, and to connect the second supply path to the fuel gas supply point and simultaneously block the first supply path or connect it to the fuel gas reservoir.

Claims

1-9. (canceled)

10. A fuel gas supply device for providing a fuel gas to a fuel gas supply point, comprising: a first supply path; a second supply path; a fuel gas reservoir set up for storing liquid fuel gas, wherein the fuel gas reservoir is fluidically connected to the first supply path and to the second supply path; a first heat exchanger arranged in the first supply path to evaporate liquid fuel gas; a second heat exchanger arranged in the second supply path to evaporate liquid fuel gas; and a valve device operatively arranged to alternately a) connect the first supply path to the fuel gas supply point, and simultaneously block the second supply path or connect it to the fuel gas reservoir, and b) connect the second supply path to the fuel gas supply point, and simultaneously block the first supply path or connect it to the fuel gas reservoir.

11. The fuel gas supply device according to claim 10, wherein the fuel gas reservoir has a first storage volume for liquid fuel gas, and has a second storage volume for gaseous fuel gas as a pressure cushion for the first storage volume, wherein the valve device is configured so that, when one of the supply paths is connected to the fuel gas supply point, the other supply path: a) is connectable to the second storage volume, b) is connectable to the first storage volume, and c) is blocked.

12. The fuel gas supply device according to claim 10, wherein the valve device includes for each supply path a first switching valve in a first fluidic connection between the first storage volume and the heat exchanger, and a second switching valve in a second fluidic connection between the heat exchanger and the fuel gas supply point.

13. The fuel gas supply device according to claim 12, wherein the valve device includes for each supply path a third switching valve in a third supply path between the heat exchanger and the second storage volume.

14. The fuel gas supply device according to claim 10, wherein the fuel gas supply point, the first supply path and/or the second supply path is/are assigned a buffer container.

15. The fuel gas supply device according to claim 14, wherein the valve device is switchable dependent on a pressure in the buffer container assigned to the fuel gas supply point.

16. The fuel gas supply device according to claim 10, wherein the heat exchanger of a supply path is activated when the supply path is blocked, and the heat exchanger is otherwise deactivated.

17. The fuel gas supply device according to claim 13, wherein at least one cooling device is arranged in the third supply path.

18. An internal combustion engine, comprising a fuel gas supply device according to claim 10.

Description

[0036] The invention is discussed in more detail below on the basis of the drawing, in which:

[0037] FIG. 1 shows a schematic illustration of an exemplary embodiment of an internal combustion engine having a fuel gas supply device, and

[0038] FIG. 2 shows a schematic, diagrammatic illustration of the operating principle for the fuel gas supply device.

[0039] FIG. 1 shows a schematic illustration of an internal combustion engine 1 having a fuel gas supply device 3 which is set up for providing a fuel gas to a fuel gas supply point 5 above a first pressure level. Connected to the fuel gas supply point 5 is a gas regulating section 7 to which, in turn, an engine block 9 is connected. Fuel gas provided by the fuel gas supply device 3 can be supplied to the engine block 9 via the gas regulating section 7. Here, the fuel gas is provided by way of the fuel gas supply device 3 for the gas regulating section 7 to the fuel gas supply point 5 at a pressure above the first pressure level, wherein the gas regulating section 7 serves for reducing the pressure, in a regulated manner, to a predetermined inlet pressure for the engine block 9.

[0040] The combustive force supply device 3 has a fuel gas reservoir 11 which is set up for storing liquid fuel gas, in particular for storing cryogenic, liquid fuel gas, in particular liquefied natural gas (LNG).

[0041] The fuel gas reservoir 11 is fluidically connected to a first supply path 13 and to a second supply path 15. The first supply path 13 has a first heat exchanger 17, and the second supply path 15 has a second heat exchanger 19. The heat exchangers 17, 19 are set up for evaporating liquid fuel gas.

[0042] There is provided a valve device 21 which is set up to alternately connect the first supply path 13 to the fuel gas supply point 5, and at the same time block the second supply path 15 or connect it to the fuel gas reservoir 11, and connect the second supply path 15 to the fuel gas supply point 5, and at the same time block the first supply path 13 or connect it to the fuel gas reservoir 11.

[0043] The fuel gas reservoir 11 has a first storage volume 23 for liquid fuel gas, and has a second storage volume 25 for gaseous fuel gas in particular as a pressure cushion for the first storage volume 23. In the fuel gas reservoir 11, the first storage volume 23 and the second storage volume 25 are preferably separated only by the phase boundary between the liquid fuel gas (liquid phase) and the gaseous fuel gas (gas phase).

[0044] The valve device 21 is set up such that, when one of the supply paths 13, 15 is connected to the fuel gas supply path 5, the other supply path 15, 13 is connected by the device to the second storage volume 25, then connected by the device to the first storage volume 23, and subsequently blocked by the device.

[0045] For this purpose, the valve device 21 has a first switching valve in each supply path, specifically a first switching valve A.13 in the first supply path 13 and a first switching valve A.15 in the second supply path 15. The first switching valves A.13, A.15 are each arranged in first fluid paths 27.13, 27.15 which are assigned to the supply paths 13, 15 and which each connect the first storage volume 23 to in each case one inlet of the heat exchanger 17, 19.

[0046] Furthermore, the valve device 21 has a second switching valve B.13, B.15 in each of the supply paths 13, 15, wherein these two switching valves B.13, B.15 are each arranged in second fluid paths 29.13, 29.15 which each connect an outlet of the heat exchangers 17, 19 to the fuel gas supply point 5.

[0047] The valve device 21 furthermore has for each of the supply paths 13, 15 a third switching valve C.13, C.15 which is arranged in each case in a third fluid path 31.13, 31.15, wherein the third fluid paths 31.13, 31.15 extend in each case to the second storage volume 25 from in each case one mouth into the second fluid paths 29.13, 29.15. In this case, the third fluid paths 31.13, 31.15 open into the second fluid paths 29.13, 29.15 in each case downstream of the outlets of the heat exchangers 17, 19 and upstream of the second switching valves B.13, B.15. The third fluid paths 31.13, 31.15 are merged into a common line section 33 through which they run together, wherein the common line section 33 opens into the second storage volume 25. There is arranged in the common line section 33 a cooling device 35 for cooling the fuel gas flowing through the common line section 33.

[0048] The first supply path 13 is assigned a first buffer container 37 in which a first pressure p1 prevails. The second supply path 15 is assigned a second buffer container 39 in which a second pressure p2 prevails. The buffer containers 37, 39 are arranged in the supply paths 13, 15 in each case downstream of the outlets of the heat exchangers 17, 19 and preferably upstream of the mouths of the third fluid paths 31.13, 31.15.

[0049] The fuel gas supply point 5 is assigned a third buffer container 41 in which a third pressure p3 prevails.

[0050] The pressures p1, p2, p3 vary with respect to time. Preferably, at least the third buffer container 41 is assigned a pressure sensor, which monitors the pressure in the third buffer container 41. It is additionally possible that at least one of the first and second buffer containers 37, 39, particularly preferably both buffer containers 37, 39, is in each case assigned a pressure sensor.

[0051] The valve device 21 is preferably switched in a manner dependent on the pressure p3 in the third buffer container 41, wherein, in particular, a prediction about the later development of the pressure p3 is factored into the switching behavior of the valve device 21.

[0052] The valve device 21 preferably has a control device (not illustrated) which is operatively connected both to the pressure sensor and to the switching valves such that the switching valves are able to be switched, by means of the control device, in a manner dependent on the pressure detected by the pressure sensor.

[0053] FIG. 2 shows a diagrammatic operating principle of the combustive force supply device 3. In this case, the pressures p1, p2 and p3 are plotted against time t here in three diagrams illustrated one below the other.

[0054] During a time interval denoted by T1, the valve device 21 is in a first switching state in which, in the first supply path 13, the first switching valve A.13 is open, the second switching valve B.13 is closed, and the third switching valve C.13 is closed. In the second supply path, the first switching valve A.15 is closed, the second switching valve B.15 is open, and the third switching valve C.15 is closed. In this case, liquid fuel gas flows from the first storage volume 23 into the first heat exchanger 17, and at the same time the fuel gas supply point 5 and thus also the gas regulating section 7 are supplied with gaseous fuel gas from the second supply path 15. The first pressure p1 is in this case at the level of the pressure p in the fuel gas reservoir 11, and so liquid fuel gas is able to flow in in particular by way of the action of gravity. The pressures p2, p3 in the second supply path 15 and at the fuel gas supply point 5 are identical and decrease over time t because fuel gas is discharged into the gas regulating section 7. In this case, a prediction as to when the pressure p3 is expected to reach a first, predetermined pressure level p.sub.n is preferably made on the basis of the rate at which the pressures p2, p3in particular the pressure p3decrease over time t. The valve device 21 is switched into a second switching state, which prevails during a second time interval T2, in good time beforehand.

[0055] In said second switching state, all switching valves A.13, B.13, C.13 of the first supply path 13 are closed, and, in the second supply path, again the second switching valve B.15 only is open, and all the other switching valves are closed. The fuel gas supply point 5 and thus the gas regulating section 7 therefore continue to be provided with a supply from the second supply path 15, this also being recognizable from the constantly decreasing pressures p2, p3.

[0056] The first heat exchanger 17 is activated in the first supply path, as a result of which liquid fuel gas is evaporated and a build-up of pressure occurs.

[0057] Shortly before the third pressure p3 reaches the first pressure level p.sub.n, the valve device 21 is switched into a third switching state T3. In this third switching state, in the first supply path 13, the first switching valve A.13 is closed, the second switching valve B.13 is open, and the third switching valve C.13 is closed. In the second supply path, the first switching valve A.15 and the second switching valve B.15 are closed, and the third switching valve C.15 is open. The fuel gas supply point 5 is now fed from the first supply path, which is why the pressure p3 suddenly increases to the pressure level of the first pressure p1 when switching into the third switching state T3, with both pressures then decreasing together and synchronously due to the supply of fuel gas to the gas regulating section 7. By contrast, the second supply path 15 is relieved of pressure toward the second storage volume 25 via the third fluid path 31.15 and the third switching valve C.15 such that the pressure here decreases to the pressure level of the fuel gas reservoir 11 p.sub.R.

[0058] Once said pressure level p.sub.R is reached, the valve device 21 is switched into a fourth switching state T4. In said state, in the first supply path 13, again the first switching valve A.13 is closed, the second switching valve B.13 is open, and the third switching valve C.13 is closed, and so the fuel gas supply point 5 continues to be provided with a supply from the first supply path 13. In the second supply path 15, the first switching valve A.15 is now open, while the second switching valve B.15 and the third switching valve C.15 are closed. Thus, liquid fuel gas flows from the fuel gas reservoir 11, specifically from the first storage volume 23, into the second heat exchanger 19, wherein this is possible in particular by way of the action of gravity because the fuel gas reservoir 11 and the second supply path 15 have the same pressure level p.sub.R.

[0059] The valve device 21 is switched into a fifth switching state T5, again in good time, before the third pressure p3 reaches the predetermined first pressure level p.sub.n. In said fifth switching state, in the first supply path 13, the first switching valve A.13 is closed, the second switching valve B.13 is open, and the third switching valve C.13 is closed, and so the fuel gas supply point 5 continues to be provided with a supply from the first supply path 13. In the second supply path 15, all switching valves A.15, B.15, C.15 are now closed, and the second heat exchanger 19 is activated, with the result that a build-up of pressure occurs in the second supply path 15.

[0060] Shortly before the pressure p3 reaches the predetermined, first pressure level p.sub.n, the valve device 21 is switched into a sixth switching state T6. In said state, in the first supply path 13, the first switching valve A.13 and the second switching valve B.13 are closed, and the third switching valve C.13 is open. The first supply path 13 is therefore now relieved of pressure toward the pressure cushion 25 via the third fluid path 31.13 and the third switching valve C.13, as a result of which the pressure decreases to the pressure level p.sub.R of the fuel gas reservoir 11. At the same time, the fuel gas supply point 5 is again fed from the second supply path 15 in which the first switching valve A.15 is closed, the second switching valve B.15 is open, and the third switching valve C.15 is closed.

[0061] The first switching state T1 then follows the sixth switching state T6 again, and a cyclic sequence of the six switching states described here is the overall result.

[0062] In this way, it is possible to keep the pressure p3 in the fuel gas supply point 5, and in particular in the buffer container 41 assigned thereto, above the first, predetermined pressure level p.sub.n, and in particular above the pressure level p.sub.R of the fuel gas reservoir 11, at all times.

[0063] This is possible without a pump, with the pressure increase beyond the pressure level p.sub.R of the fuel gas reservoir resulting rather as a consequence exclusively of the alternate switching of the supply paths 13, 15 and the supply of thermal energy in the heat exchangers 17, 19.

[0064] It is thus possible to keep the fuel gas reservoir 11 at a pressure level p.sub.R which is lower than that which is necessary for the supply of fuel gas to a consumer, here the gas regulating section 7 or the engine block 9.

[0065] Thus, overall, by means of the fuel gas supply device 3 and the internal combustion engine 1, the result is reduced costs for the fuel gas reservoir 11 and a reduction in the weight of the fuel gas reservoir 11. It is possible to dispense with a cryopump, and protection against a pressure drop in the case of sloshing in a tank is afforded, and so here the proposed fuel gas supply device 3 is particularly suitable for marine applications.