Method for operating an energy converter, and device therefor

Abstract

The present invention relates to a method for shutting down a gas-operated energy converter (1), in particular an internal combustion engine or a fuel cell, comprising a gas tank (2), a gas line (3) leading away from the gas tank (2), a tank valve (4) between the gas tank (2) and an injection device (5) for injecting the gas into the energy converter, wherein, after a stop command to stop the energy converter, the tank valve (4) is closed and the energy converter (1) continues to be operated for a predetermined period of time in order to reduce a gas pressure in the gas line (3) until the gas pressure in the gas line (3) has reached a first predetermined pressure level.

Description

[0001] Description

[0002] title

[0003] Method for operating a and device for this purpose

[0004] State of the art

[0005] The present invention relates to a method for operating a gas-powered energy converter during a shutdown process of the energy converter and to a device for carrying out the method.

[0006] In particular, the invention relates to a method for operating an internal combustion engine or a fuel cell with hydrogen.

[0007] In gas-powered energy converters such as internal combustion engines or fuel cells, the gas, e.g., hydrogen, is trapped in a piping system when the energy converter is shut down. As a result, the gas in the piping system remains under a relatively high pressure, which is greater than the ambient pressure. This can lead to the problem of gas escaping into the internal combustion engine through, for example, incompletely gas-tight injection valves. There, it may either form a flammable mixture in the crankcase or enter the engine's exhaust system. This poses the risk of the gas mixture igniting, with uncontrollable consequences.

[0008] Disclosure of the invention

[0009] The inventive method for operating an energy converter when the energy converter is shut down, with the features of claim 1, has the advantage that the pressure in a line system designed to supply gas, in particular hydrogen, from a tank to the energy converter can be reduced. This reduces the risk of the gas entering areas of the energy converter in an uncontrolled manner, where an ignitable mixture can form and ignite. The inventive method is very simple and cost-effective to implement.This is achieved according to the invention in that the method for shutting down the gas-operated energy converter, which has a gas tank, a gas line leading from the gas tank to the energy converter, and a tank valve between the gas tank and an injection device, is operated in such a way that first, after a stop command to shut down the energy converter, the tank valve is closed. The energy converter then continues to operate for a predetermined period of time in order to reduce the gas pressure in the gas line through gas consumption in the energy converter. The energy converter continues to operate until a first predetermined pressure level is reached in the gas line. This reduces the pressure and the amount of combustible gas present in the gas line between the gas tank and the injection device. When the predetermined pressure level in the gas line is reached, the energy converter is shut down.The pressure in the gas line is preferably still greater than the ambient pressure, but due to the significantly reduced gas quantity in the gas line, the risk of a flammable mixture forming in areas of the energy converter due to leaks in the gas system, in particular leaks in the injection device, is significantly reduced.

[0010] The subclaims show preferred developments of the invention.

[0011] The gas system preferably comprises at least one line valve located in the gas line between the tank valve and the injection device. During the shutoff process, the tank valve is closed before the line valve. This ensures that the gas tank is disconnected from the gas line first, and then the gas in the gas line can be at least partially removed from the gas line in a safe manner.

[0012] Preferably, the line valve is closed when the gas pressure in the gas line has dropped below a second predetermined pressure level. As a result, the line length to the injection device, in which gas is present, is reduced by closing the line valve, while gas can continue to be removed from the gas line in the remaining line length between the line valve and the injection device.

[0013] The energy converter will preferably continue operating after the stop command. This causes gas to continue to be consumed from the gas line, which is separated from the gas tank by the closed tank valve, thus reducing the gas pressure and gas flow in the gas line.

[0014] Preferably, the energy converter is operated in a mode that results in higher consumption than during normal operation. This allows the pressure in the gas line and the gas flow in the gas line to be reduced more quickly.

[0015] Particularly preferably, the injection duration is extended by the injection device of the energy converter. Alternatively or additionally, if the energy converter is an internal combustion engine, the speed is increased. Alternatively or additionally, efficiency-enhancing measures are reduced or completely eliminated during energy conversion.

[0016] Preferably, at least two line valves, in particular a first and a second line valve, are arranged in series in the gas line, extending from the tank valve to the injection device. According to a preferred method according to the invention, during shutdown, the first and second line valves are closed at different times. This makes it possible, in particular, to subdivide the gas line into different gas line sections, wherein different gas line sections can have different pressure levels. The pressure levels can be subdivided, for example, depending on the risk of gas escaping, into sections in which an ignitable mixture could develop.

[0017] Preferably, if there are several line valves in the gas line, the line valve that is closest to the tank valve is closed first.

[0018] Further preferably, if several line valves are present, the line valves are closed one after the other in series, starting with the line valve located closest to the tank valve. The line valve closest to the injection device is preferably closed last.

[0019] The gas used to power the energy converter is preferably hydrogen or natural gas or CNG or LPG or methane.

[0020] The energy converter is preferably a gas-powered internal combustion engine or a gas-powered fuel cell.

[0021] Furthermore, the present invention relates to a device, in particular an internal combustion engine arrangement or a fuel cell arrangement, designed to carry out the method according to the invention.

[0022] drawing

[0023] A preferred embodiment of the invention will be described in detail below with reference to the accompanying drawings. In the drawing:

[0024] Figure 1 is a schematic representation of a device for

[0025] Implementation of the method according to the invention according to a preferred embodiment of the invention.

[0026] Preferred embodiments of the invention

[0027] A method for shutting down a gas-powered energy converter and a device for carrying out the method are described in detail below with reference to Figure 1.

[0028] The energy converter 1, shown schematically in Figure 1, is a gas-powered internal combustion engine. The internal combustion engine is preferably powered by hydrogen, but can also be powered by another gaseous fuel.

[0029] A gas tank 2 is arranged to supply the energy converter 1. The gas tank 2 is connected to the energy converter 1 via a gas line 3. The gas line 3 opens into a rail 14, which is connected to several combustion chambers 8 to supply the combustion chambers with fuel gas.

[0030] At least one injection device 5, preferably an injection valve, is arranged on each combustion chamber 8.

[0031] A tank valve 4 is located at the outlet of the gas tank 2 to the gas line 3. The tank valve 4 can open and close a connection between the gas tank 2 and the gas line 3.

[0032] A pressure regulator 7 is also arranged in the gas line 3. The pressure regulator 7 is designed to regulate the gas pressure in the gas line to a predetermined pressure level before it reaches the energy converter 1. A first pressure sensor 11 is arranged in the gas line upstream of the pressure regulator 7, and a second pressure sensor 12 is arranged in the gas line downstream of the pressure regulator 7. The pressure regulator 7 and the pressure sensors 11, 12 are connected to a control unit 10.

[0033] A third pressure sensor 13 is arranged in the rail 14.

[0034] The pressure regulator 7 is designed to regulate a gas pressure in the gas line upstream of the injection devices 5 to a predetermined pressure level.

[0035] Furthermore, a line valve arrangement 6 with a first line valve 6.1 and a second line valve 6.2 is arranged in the gas line 3. The two line valves 6.1 and 6.2 are arranged in series in the gas line 3 between the tank valve 4 and the injection device 5.

[0036] More precisely, the two injection valves 6.1 and 6.2 are arranged between the pressure regulator 7 and the injection device 5.

[0037] The tank valve 4, the injection devices 5, the line valves 6.1 and 6.2 and the internal combustion engine are connected to the control unit 10.

[0038] During normal operation of the energy converter 1, the tank valve 4 and the

[0039] Line valves 6.1 and 6.2 are opened so that gas from the gas tank 2 can reach the rail 14 via the pressure regulator 7 and can be blown into the combustion chambers 8 via the injection devices 5.

[0040] In the method according to the invention for shutting down the energy converter 1, when a shutdown request is made, the tank valve 4 is closed by the control unit 10, which has received a stop command to shut down the energy converter 1. This interrupts the connection between the gas tank 2 and the gas line 3.

[0041] However, the stop command for the energy converter 1 does not immediately result in the energy converter 1 being switched off, but the energy converter continues to operate for a predetermined period of time in order to reduce a gas pressure in the gas line 3 by gas consumption in the internal combustion engine until a predetermined pressure level in the gas line 3 is reached.

[0042] Due to the continued operation of the energy converter 1, gas continues to be blown into the combustion chambers 8 and consumed, so that a gas pressure in the gas line 3 continuously decreases, since the connection to the gas tank 2 is interrupted by the closed tank valve 4.

[0043] If, after the stop command and continued operation of the energy converter 1, the gas pressure in the gas line 3 has dropped to a predetermined pressure level, the first line valve 6.1, which is located closer to the tank valve 4 in the gas line than the second line valve 6.2, is closed. The energy converter 1 continues to operate. If the pressure level in the gas line 3 between the first line valve 6.1 and the injection devices 5 has then dropped further and reached a second predetermined pressure level, the second line valve 6.2 is also closed. The second pressure level is also preferably the pressure level at which the injection by the injection devices 5 is terminated and the energy converter 1 is completely shut down.

[0044] The second pressure level in the gas line 3 is selected such that any outflow of gas from the gas line 3, for example via leaks at the injection devices 5, is minimal or does not occur. The maximum possible leakage of gas from the gas line 3 is preferably selected such that, as far as possible, no ignitable mixture can occur in the combustion chamber 8 or a crankcase or at other locations in the vehicle.

[0045] Thus, by the method and device according to the invention, gas still present in the gas line 3 after a stop command is combusted by continued operation of the energy converter 1. This maintains a pressure gradient emanating from the gas tank 2 and the successively shut-off gas line sections of the gas line 3, which additionally ensures improved tightness, since the tank valve 4, in particular, only achieves technical tightness when a defined pressure gradient prevails across the tank valve 4 in a de-energized state.

[0046] When the energy converter 1 continues to operate after the stop command, the consumption of the energy converter 1 is set as high as possible in order to stop the energy converter 1 as quickly as possible, for example by increasing the speed of an internal combustion engine or by reducing or interrupting efficiency measures of the energy converter 1 which are actually intended to increase the efficiency of the energy converter 1.

[0047] It should also be noted that if there are several injection devices 5, as in the embodiment shown, a gradual shutdown of the plurality of injection devices 5 is also possible here via the control unit 10.

[0048] Thus, by the inventive idea, a gas present in the gas line 3 after a stop command can continue to be used and burned in the energy converter 1 in order to reduce the pressure in the gas line 3, whereby leakages of gas from the gas line 3 after receiving the stop command can be minimized.

[0049] By sequentially shutting off tank valve 4 and line valves 6.1 and 6.2, an optimization can be achieved during a stop command between safety provided by the existing system seal and energy efficiency. The run-on time of energy converter 1 after the stop command is kept as short as possible to prevent the user of energy converter 1 from having the unwanted impression that energy converter 1 will not shut down immediately after the stop command.

Claims

Claims 1 . Method for shutting down a gas-operated energy converter (1), in particular an internal combustion engine or a fuel cell, comprising a gas tank (2), a gas line (3) leading away from the gas tank (2), a tank valve (4) between the gas tank (2) and an injection device (5) for injecting the gas into the energy converter (1), wherein after a stop command to stop the energy converter (1), the tank valve (4) is closed and the energy converter (1) continues to operate for a predetermined period of time in order to reduce a gas pressure in the gas line (3) until the gas pressure in the gas line (3) has reached a first predetermined pressure level 2. Method according to claim 1, wherein the energy converter (1) further comprises at least one line valve (6.1, 6.2), wherein the line valve (6.1, 6.2) is arranged in the gas line (3) between the tank valve (4) and the injection device (5), wherein the tank valve (4) is closed before the line valve (6.1, 6.2).

3. The method according to claim 2, wherein the line valve (6.1, 6.2) is closed when a gas pressure in the gas line (3) has dropped below a second predetermined pressure level which is greater than the first predetermined pressure level.

4. Method according to one of the preceding claims, wherein the energy converter (1) continues to operate after the stop command in such a way that the energy converter (1) is operated in an operating mode with a higher consumption than a technically possible minimum consumption.

5. The method according to claim 4, wherein after the stop command, an injection duration of the energy converter (1) is extended and / or a speed of an internal combustion engine is increased and / or efficiency-enhancing combustion measures are reduced or switched off.

6. Method according to one of the preceding claims, wherein at least a first and a second line valve (6.1, 6.2) are arranged in series in the gas line (3), starting from the tank valve (4) to the injection device (5), wherein the first line valve (6.1) is closed at a different time than the second line valve (6.2).

7. The method according to claim 6, wherein the line valve which is arranged in the gas line (3) closest to the tank valve (4) is closed first.

8. The method according to claim 7, wherein the first and second line valves (6.1, 6.2) are closed one after the other in series, starting with the line valve closest to the tank valve (4) and the line valve closest to the injection device (5) is closed last.

9. A process according to any one of the preceding claims, wherein hydrogen is used as the gas.

10. Device arranged to carry out a method according to one of the preceding claims.

Images