POWER GENERATING ASSEMBLY, VEHICLE COMPRISING A POWER GENERATING ASSEMBLY, AND METHOD FOR ADJUSTING AN INERT GAS PRESSURE

Abstract

A power generating assembly including an internal combustion engine and a combustion gas supply connected to the internal combustion engine in order to supply combustion gas. The combustion gas supply has an at least double-walled line at least in the region of the internal combustion engine, the line having an inner line volume for combustion gas and an outer line volume. The outer line volume is fluidically connected to an inert gas supply. The power generating assembly also includes a combustion gas pressure adjusting device that adjusts a combustion gas pressure in the inner line volume, and an inert gas pressure adjusting device that adjusts an inert gas pressure in the outer line volume. The combustion gas pressure adjusting device and the inert gas pressure adjusting device select the inert gas pressure and the combustion gas pressure such that the inert gas pressure is higher than the combustion gas pressure.

Claims

1-10. (canceled)

11. A power generating assembly, comprising: an internal combustion engine; an inert gas supply; a combustion gas supply connected to the internal combustion engine to supply combustion gas, wherein the combustion gas supply includes, at least in a region of the internal combustion engine, an at least double-walled line that has an inner line volume for combustion gas, and an outer line volume, wherein the outer line volume is fluidically connected to the inert gas supply; a combustion gas pressure adjusting device configured to adjust a combustion gas pressure in the inner line volume; and an inert gas pressure adjusting device configured to adjust an inert gas pressure in the outer line volume, wherein the combustion gas pressure adjusting device and the inert gas pressure adjusting device are configured to select the inert gas pressure and the combustion gas pressure so that the inert gas pressure is higher than the combustion gas pressure.

12. The power generating assembly according to claim 10, wherein the inert gas supply includes a supply vessel fluidically connected to the outer line volume via a first switching valve.

13. The power generating assembly according to claim 12, wherein the inert gas supply includes an inert gas reservoir and/or an inert gas generating device, and a second switching valve that fluidically connects the supply vessel to the inert gas reservoir and/or to the inert gas generating device.

14. The power generating assembly according to claim 13, wherein the inert gas supply includes an inert gas venting line and a third switching valve that fluidically connects the supply vessel to the inert gas venting line.

15. The power generating assembly according to claim 11, further comprising a pressure sensor for sensing the inert gas pressure in the outer line volume and operatively connected to the inert gas pressure adjusting device.

16. The power generating assembly according to claim 14, wherein the inert gas pressure adjusting device is configured to adjust the inert gas pressure in the outer line volume by cyclically actuating the first switching valve, on the one hand, and the second switching valve or the third switching valve, on the other.

17. The power generating assembly according to claim 14, wherein the inert gas pressure adjusting device is configured to actuate at least two of the switching valves with a switching frequency as a function of a pressure variable of the inert gas pressure in the outer line volume.

18. The power generating assembly according to claim 11, wherein the inert gas pressure adjusting device is configured to determine a leakage rate from the outer line volume based on an instantaneous switching frequency and a pressure variable of the inert gas pressure in the outer line volume.

19. A vehicle comprising a power generating assembly according to claim 11.

20. A method for adjusting an inert gas pressure in an outer line volume of an at least partially double-walled combustion gas supply, comprising the step of selecting the inert gas pressure to be higher in an outer line volume of the combustion gas supply than a combustion gas pressure in an inner line volume of the combustion gas supply.

Description

[0043] The invention will be explained in more detail below with reference to the drawing, in which:

[0044] FIG. 1 shows a schematic illustration of an exemplary embodiment of a power generating assembly, and

[0045] FIG. 2 shows a schematic illustration of the method of functioning of the power generating assembly.

[0046] FIG. 1 shows a schematic illustration of an exemplary embodiment of a vehicle 100 with a power generating assembly 1 which has an internal combustion engine 3 and a combustion gas supply 5 which is connected to the internal combustion engine 3 in order to supply combustion gas. The combustion gas supply 5 is embodied in a double-walled fashion at least in the region of the internal combustion engine 3, here in particular within a machine room 7, that is to say has a double-walled line 9, wherein the internal combustion engine 3 has two cylinder banks A, B here, wherein each cylinder bank is assigned a separate double-walled line 9.A, 9.B.

[0047] The double-walled lines 9 each have an inner line volume 11 in which combustion gas flows during the operation of the internal combustion engine 3, and an outer line volume 13 which surrounds the inner line volume 11 and in which an inert gas is arranged in any case during the operation of the internal combustion engine 3.

[0048] The outer line volume 11 is fluidically connected to an inert gas supply 15.

[0049] A combustion gas pressure adjusting device 17 is provided which is configured to adjust the combustion gas pressure in the inner line volume 11, wherein the combustion gas pressure adjusting device is embodied here, in particular, as a gas control system and is configured to perform closed-loop control of the combustion gas pressure in the inner line volume 11.

[0050] An inert gas pressure adjusting device 19 is provided which is configured to adjust an inert gas pressure, in particular to perform closed-loop control thereof, in the outer line volume 13.

[0051] The combustion gas pressure adjusting device 17 and the inert gas pressure adjusting device 19 are arranged here in a separate pressure adjusting space 21 which is separated off from the machine room.

[0052] The combustion gas pressure adjusting device 17 and the inert gas pressure adjusting device 19 are configured to select the inert gas pressure and the combustion gas pressure in such a way that the inert gas pressure in the outer line volume 13 is higher than the combustion gas pressure in the inner line volume 11.

[0053] The inert gas supply 19 has a supply vessel 23 which is fluidically connected to the outer line volume 13 via a first switching valve 25. In this context, the cylinder banks A, B are each assigned a first switching valve 25.A, 25.B, wherein in the text which follows only the method of functioning of a first switching valve 25 is described in conjunction with a cylinder bank A, B, wherein the method of functioning for the other cylinder bank B, A is completely analogous. It is possible that the internal combustion engine 3 has only one cylinder bank, wherein only one outer volume 13 and only one first switching valve 25 are then also provided. However, the concept can be extended to any desired number of cylinder banks A, B by assigning each cylinder bank a separate outer volume 13, and wherein a dedicated first switching valve 25 is assigned to each separate outer line volume 13.

[0054] Everything which is stated generally below about a first switching valve 25 then applies here specifically to both first switching valves 25.A, 25.B.

[0055] The inert gas supply 25 also has an inert gas reservoir 27 and here additionally also an inert gas generating device 29. Inert gas can be generated by means of the inert gas generating device 29, which is preferably embodied as a nitrogen generator, and said inert gas can then be stored in the inert gas reservoir 27. The supply vessel 23 is fluidically connected here, in particular, to the inert gas reservoir 27 via a second switching valve 31. Viewed from the outer line volume 13, the first switching valve 25 and the second switching valve 31 are arranged in series. The supply vessel 23 is fluidically arranged here between the second switching valve 31 and the first switching valve 25.

[0056] The supply vessel 23 is fluidically connected to an inert gas venting line 35 via a third switching valve 33. The inert gas venting line 35 can be integrated, for example, in a vent mast of a marine vessel which has the power generating assembly 1.

[0057] Viewed from the outer line volume 13 again, the third switching valve 33 is arranged in series with the first switching valve 25 and in parallel with the second switching valve 31.

[0058] A pressure sensor 37 is provided which is configured and arranged so as to sense the inert gas pressure in the outer line volume 13. The pressure sensor is preferably operatively connected to the inert gas pressure adjusting device 19. The latter preferably has a control unit (not illustrated here) which is operatively connected to the switching valves 31, 33, 35 and to the pressure sensor 37.

[0059] Each cylinder bank A, B is preferably assigned a dedicated pressure sensor, wherein for the sake of simpler illustration only one pressure sensor 37, which is assigned to the cylinder bank A, is illustrated here.

[0060] FIG. 1 also illustrates a non-return valve 39 which is embodied as an overpressure safety valve and which is configured to vent the inert gas reservoir 27 to the inert gas venting line 35 when there is an unacceptable rise in pressure upstream of the second switching valve 31.

[0061] FIG. 2 shows a schematic illustration of the method of functioning of the power generating assembly 1 and, in particular, of the inert gas pressure adjusting device 19. In this context, the time t is plotted on the horizontal axis and pressure p in the outer line volume 13 is plotted on a first, left-hand vertical axis, said pressure p being preferably sensed by means of the pressure sensor 37, wherein a switching frequency f for the switching valves 25, 31, 33 is plotted on a second, right-hand vertical axis. In this context, in the text which follows only an actuation of the first switching valve 25 and an actuation of the second switching valve 31 are described because the illustration which is provided in this respect is limited to the behavior of the inert gas pressure adjusting device in the case of a leakage, consequently a drop in pressure. However, it is readily comprehensible that when there is an unacceptable rise in pressure the first switching valve 25 and the third switching valve 33 could be actuated in an analogous fashion in order to relieve the pressure of the outer line volume 13 to the inert gas venting line 35 via the supply vessel 23. Such an unacceptable rise in pressure can occur, for example, for thermal reasons, in particular in the case of a rise in temperature in the machine room 7.

[0062] A setpoint pressure p.sub.s and a pressure band between a minimum pressure p.sub.min and a maximum pressure p.sub.max are indicated in the diagram in FIG. 2, in said pressure band the pressure in the outer line volume 13 can differ from the setpoint pressure p.sub.s, wherein such a pressure difference is tolerated without a further measure of the inert gas pressure adjusting device 19.

[0063] A first curve K1, which is illustrated here in a continuous form, shows the profile of the actual pressure in the outer line volume 13 with the time t, and a second curve K2, which is illustrated here in a dashed form, shows a switching frequency for the switching valves 25, 31 as a function of the time t.

[0064] If the pressure profile of the first curve K1 starting from the left-hand vertical axis of the diagram is considered, it becomes apparent that the actual pressure drops starting from the setpoint pressure p.sub.s with the time t with a certain rate, for example because a certain leakage, in particular an unavoidable residual leakage, is already present. If the actual pressure reaches the minimum pressure p.sub.min, the second switching valve 31 and the first switching valve 25 are actuated alternately with a first switching frequency f.sub.1, as a result of which the pressure in the outer line volume 13 is increased incrementally. If the second switching valve 31 is closed and the first switching valve 25 is opened, inert gas flows from the supply vessel 23 into the outer line volume 13 if the pressure in the supply vessel 23 is higher than the pressure in the outer line volume 13. This is typically the case when there is a leakage in the outer line volume 13, wherein, in particular, the pressure in the inert gas reservoir 27 or in the inert gas generating device 29 is preferably higher than the setpoint pressure p.sub.s. This then applies correspondingly also to the pressure in the supply vessel 23 after it has been filled from the inert gas reservoir 27. If the first switching valve 25 is closed and the second switching valve 31 is opened, inert gas flows from the inert gas reservoir 27 into the supply vessel 23. This occurs, as already stated, in an alternating fashion, wherein the pressure in the outer line volume 13 is increased incrementally.

[0065] If the pressure reaches the pressure setpoint value p.sub.s again, the actuation of the switching valves 25, 31 is ended. The actual pressure then drops with the rate already described above, which rate can correspond, in particular, to an unavoidable residual leakage rate.

[0066] At a specific time, which is characterized here by a first leakage event L1, an increase in the leakage occurs, or a leakage which is not provided occurs for the first time beyond the unavoidable residual leakage. It is therefore possible that a leakage which occurs for the first time or that a leakage which is already present becomes larger. As a result, the leakage rate becomes larger, and the actual pressure drops more quickly than before to the minimum pressure p.sub.min. Subsequently, the switching valves 25, 31 are actuated with a second, relatively high switching frequency f2, and the pressure is in turn increased incrementally, this time with a relatively short sequence owing to the relatively short switching frequency, until said pressure reaches the setpoint pressure p.sub.s again. Subsequently, the actuation of the switching valves 25, 31 stops.

[0067] The pressure then drops with the second, relatively large leakage rate until its pressure reaches the minimum pressure p.sub.min again, wherein the switching valves are then again actuated with the second switching frequency f2 until the pressure reaches the setpoint pressure p.sub.s.

[0068] At a second time, characterized by a second leakage event L2, a critical increase in the leakage occurs, with the result that the leakage rate increases once more and the pressure drops more quickly to the minimum pressure p.sub.min. The switching valves 25, 31 are then actuated with a third, maximum switching frequency f.sub.3, wherein the profile of the first curve K1 shows that with this maximum switching frequency and the present leakage rate it is just still possible to keep the inert gas pressure in the outer line volume 13 to the minimum pressure level p.sub.min.

[0069] The switching frequency for the switching valves 25, 31 is preferably selected as a function of a pressure variable, in particular the actual pressure, a derivative of the actual pressure over time and/or integration of the actual pressure over a specific time period. A leakage rate is preferably calculated as a function of the switching frequency and the pressure variable. In this context it is monitored whether the leakage rate exceeds a first threshold value. In the present example, this is not the case until after the second leakage event L2. The preceding leakage is accordingly tolerated. However, after the second leakage event L2 the leakage rate exceeds the predetermined, first threshold value, with the result that a first alarm signal A1 is output.

[0070] At a third leakage event L3, the leakage rate increases once more, with the result that despite continued actuation of the switching valves 25, 31 with the maximum switching frequency f.sub.3 it is no longer possible to maintain the pressure in the outer line volume 13. The latter therefore drops further. The leakage rate preferably exceeds a second threshold value here, with the result that a second alarm A2 is output.

[0071] A third threshold value for the leakage rate is also preferably provided, wherein the internal combustion engine 3 is switched off if the leakage rate exceeds this third threshold value.

[0072] In addition, it is also explained that an excess pressure which occurs in the outer line volume 13, for example for thermal reasons, in particular when the maximum pressure p.sub.max is reached, can be reduced incrementally by alternately actuating the third switching valve 33 and the first switching valve 25, wherein the procedure is selected here in a way which is precisely analogous to the procedure for increasing the pressure in the outer line volume 13.

[0073] Overall it becomes apparent that the power generating assembly 1, the vehicle and the method permit very safe operation of internal combustion engines with combustion gas, in particular for marine applications. In this context, there is no need for any additional measuring devices, in particular no volume flow measuring device, in order to detect a leakage rate. Double shutting off with respect to separation of the combustion gas from the inert gas takes place. Furthermore, the power generating assembly and, in particular, the inert gas pressure adjusting device have a simple design, wherein, in particular, there is no need for pressure control by means of a pressure control valve.