Method and device for operating internal combustion engine

Abstract

The invention relates to a method for operating an internal combustion engine (100) having at least one combustion chamber (102) and an intake system (103) and an exhaust system (110) for the at least one combustion chamber (102), in which a combustible gas, in particular hydrogen, is used as a fuel, and in which the at least one combustion chamber (102) is closed by means of the intake system (103) and the exhaust system (110). In order to reduce the concentration of the combustible gas, air drawn in from the intake system (103) is additionally blown into the exhaust system (110) in accordance with the operating state of the internal combustion engine (100) and / or in accordance with the concentration of the combustible gas detected in the intake system (103) and / or the exhaust system (110) that exceeds a threshold value.

Description

Field of the Invention

[0001] The present invention relates to a method and a device for operating an internal combustion engine, in which a combustible gas, in particular hydrogen, is used as fuel. The method or device according to the invention is characterized by particularly high operating safety during the operation of the internal combustion engine. Furthermore, the present invention also relates to a computer program product and an internal combustion engine, which are configured to utilize or implement the method according to the invention. Background Art

[0002] A method for operating an internal combustion engine is known from the published patent application DE102021210001A1 of the applicant, in which a combustible gas, in particular hydrogen or natural gas, is used as fuel. In order to improve the efficiency of an exhaust gas turbocharger arranged in the exhaust gas mechanism, the known method can additionally blow unburned gas into the exhaust gas mechanism before the exhaust gas turbocharger.

[0003] Furthermore, in connection with the so-called secondary air injection technique (source: https: / / de.wikipedia.org / wiki / Sekund%C3%A4rluftsystem), it is known to blow air into the exhaust gas manifold. Thereby, the air meets the unburned fuel, so that the fuel burns in the exhaust gas mechanism. The secondary air injection is used to reduce hydrocarbons and nitrogen oxides in the exhaust gas. Summary of the Invention

[0004] The method according to the invention for operating an internal combustion engine having the features of claim 1 has the following advantages: The method avoids the concentration of the combustible gas in the exhaust gas mechanism exceeding the boundary value, and thus in particular avoids damage to the internal combustion engine components due to the uncontrolled combustion of the unburned fuel in the exhaust gas mechanism. Furthermore, by using the method according to the invention, it is also possible to avoid the (unburned) gaseous substances in the exhaust gas mechanism exceeding the legally required boundary values. The present invention also enables the possible excessive concentration of the gaseous fuel in the intake mechanism to be reduced by sucking away the fuel from the area near the combustion chamber inlet and sucking in fresh air. The idea underlying the present invention is to reduce the concentration of the unburned combustible gas to a level below the boundary value by specifically blowing air into the exhaust gas mechanism, and to reduce the situation where the concentration of the gaseous fuel in the exhaust gas mechanism exceeds the boundary value.

[0005] Therefore, in this context, a method for operating an internal combustion engine according to the invention having the features of claim 1 is provided, wherein the internal combustion engine has at least one combustion chamber and an intake mechanism and an exhaust gas mechanism for the at least one combustion chamber, wherein a combustible gas, in particular hydrogen, is used as fuel, and wherein, depending on the operating state of the internal combustion engine and / or depending on the concentration of the combustible gas detected in the exhaust gas mechanism exceeding a limit value and / or depending on the operating state of the internal combustion engine potentially causing an increase in the concentration of the combustible gas, air drawn in from the intake mechanism is additionally blown into the exhaust gas mechanism to reduce the concentration of the combustible gas; in the case where the concentration of the gaseous fuel in the intake mechanism exceeds the limit value, the concentration of the gaseous fuel in the intake mechanism is reduced by sucking it away from the intake mechanism and blowing it into the exhaust gas mechanism.

[0006] Advantageous developments of the method for operating an internal combustion engine according to the invention are specified in the dependent claims.

[0007] In principle, the method can be advantageously applied to different operating states of the internal combustion engine, in which there is a potential risk of an excessively high concentration of unburned fuel in the exhaust gas mechanism or in the intake mechanism. In this context, the method according to the invention thus includes the following operating states, which include the motor starting and / or warm-up phase of the internal combustion engine, wherein, at the latest at the time of motor starting, air is blown into the exhaust gas mechanism if necessary even before motor starting. This is done in the following context: during motor starting, especially when the temperature of the internal combustion engine is low, a relatively large amount of combustible gas is blown into the combustion chamber of the internal combustion engine. If an ignition failure occurs during the starting process, for example if the ignition device is defective, a small amount of unburned charge is sufficient to generate a critical amount of unburned gas in the exhaust gas mechanism.

[0008] It can also be considered that if a functional disturbance that may cause an increase in the concentration of unburned gas in the exhaust gas mechanism is detected during the regulated operation, the relevant operating state of the internal combustion engine is this regulated operation of the internal combustion engine.

[0009] Finally, it can also be considered that this operating state is the motor shutdown of the internal combustion engine, wherein air is blown into the exhaust gas mechanism within a pre-given time period after motor shutdown.

[0010] To optimize the method according to the invention, it is also provided that the amount of air blown into the exhaust gas mechanism per unit time can be varied or adjusted depending on the operating state, environmental conditions (such as temperature) or other conditions.

[0011] For further optimization of the method, it is provided that, depending on the detected operating state, air is sucked either from the region of the intake mechanism close to the air filter or from the region close to the cylinder.

[0012] Furthermore, it is preferably to blow air into the area of the exhaust gas mechanism close to the cylinder. This enables a good mixing or reduction of the gas concentration in the exhaust gas mechanism.

[0013] The invention also includes a device for performing the above method according to the invention. The device has at least one sensor configured to detect the concentration of combustible gas in the intake mechanism or the exhaust gas mechanism of the internal combustion engine; a first device for taking air out of the intake mechanism; a second device for blowing the air taken out of the intake mechanism into the exhaust gas mechanism; and a controller configured to control the first device and the second device according to the detected concentration of combustible gas in the intake mechanism or the exhaust gas mechanism and / or according to the operating state of the internal combustion engine that potentially causes an increase in the concentration of combustible gas.

[0014] In a preferred expansion solution of the device, the first device includes: two extraction sites for air arranged at different parts of the intake mechanism, and a switching device controllable by the controller for extracting air from different extraction sites.

[0015] Furthermore, a preferred structural configuration is one in which the first device includes an inhalation device for air controllable by the controller, and the second device includes a valve device controllable by the controller.

[0016] The invention also includes a computer program product, in particular a data program or a data carrier, or a data program stored in a control device. The computer program product includes an algorithm configured to implement at least one step of the method according to the invention.

[0017] Finally, the invention also includes an internal combustion engine configured to perform the method according to the invention or having the device according to the invention.

[0018] Other advantages, features and details of the invention result from the following description of the preferred embodiments of the invention and the drawings. Description of the Drawings

[0019] In the sole Figure 1 figure, a schematic illustration shows an internal combustion engine for operating with gaseous fuel. Detailed Description of the Invention

[0020] In Figure 1In [the figure], an internal combustion engine 100 is shown in a very simplified manner, which is operated by means of a combustible gas, in particular by means of hydrogen. For this purpose, in this embodiment, the internal combustion engine 100 includes four cylinders 101 arranged in a row, which cylinders have combustion chambers 102 not shown in detail, and these combustion chambers are connected to an intake mechanism 103. The intake mechanism 103 includes an intake pipe 104, which sucks in ambient air through an air filter 105. An intake manifold 106 leads from the intake pipe 104 to each of these cylinders 101 or to each of the combustion chambers.

[0021] Furthermore, the internal combustion engine 100 includes an exhaust gas mechanism 110, which has an exhaust gas manifold 112 for each cylinder 101 or combustion chamber 102. The exhaust gas mechanism 110 discharges the exhaust gas into the environment through a catalytic converter 114.

[0022] The formation of the mixture in the combustion chambers 102 of the cylinders 101, i.e., the delivery and mixing of ambient air and the combustible gas (in particular hydrogen), can be carried out in different, and thus not shown in detail, and in itself known ways. Thus, the gas can, for example, either be introduced or blown into the intake pipe 104, or directly introduced or blown into each combustion chamber 102 of the cylinder 101 by means of a gas valve provided therefor and known from the prior art.

[0023] Furthermore, it should be mentioned that, for example, an exhaust gas turbocharger can also be arranged or present in the exhaust gas mechanism 110. For this, reference is made to the applicant's application document DE102021210001A1 mentioned at the beginning.

[0024] Furthermore, the internal combustion engine 100 includes a device 10, which is configured to reduce an excessive concentration of unburned combustible gas that may be present in the exhaust gas mechanism 110 by diluting or mixing the combustible gas with ambient air (hereinafter only referred to as "air"). For this purpose, the device 10 has a sensor 12, which is preferably arranged in the exhaust gas mechanism 110 close to the catalytic converter 114. The signal of the sensor 12 can be transmitted as an input parameter to a controller 15. Alternatively or additionally, it can also be considered that the sensor 12 is arranged in the intake mechanism 103 close to the air filter 105 as indicated by the dashed line.

[0025] Furthermore, the device 10 includes a first device 16 configured to extract air from the intake mechanism 103. For this purpose, two variants can be considered. Thus, the first device 16 can have first extraction sites 18, which are respectively arranged in the region of the cylinders 101, preferably in the region of the respective intake manifolds 106. The air extracted from the first extraction sites 18 is conveyed through the suction line 21 via a secondary air pump 20 serving as an intake device and, with a check valve 22 and a changeover valve 24 controllable by the controller 15 interposed therebetween, is fed to the exhaust mechanism 112 through a second device 25 having at least one valve device 26 in the form of a secondary air valve. Blow-in sites 28 branched off from the blow-in line 27 are used for this purpose, and these blow-in sites are preferably arranged in the immediate outlet region of each cylinder 101 or combustion chamber 102 in the region of the exhaust manifold 112. The secondary air pump 20 and the valve device 28 can both be controlled by the controller 15 here.

[0026] However, preferably, the first device 16 has (only) a single second extraction site 34 that extracts air from the region of the air filter 115 and conveys it through a second suction line 31 to the changeover valve 24. This means that, in addition to the second extraction site 34, the above-mentioned first extraction sites 18 can also be provided. In the case where only the second extraction site 34 is provided, the changeover valve 24 (and the check valve 22) can of course be omitted, so that the second suction line 31 is directly connected to the secondary air pump 20.

[0027] Furthermore, at least one rotational speed sensor 30 is provided for detecting the engine speed of the internal combustion engine 100, and the signal of this rotational speed sensor is transmitted to the controller 15 as an input parameter. Other sensors not shown, such as temperature sensors, knock sensors, etc., can be used to detect critical ambient conditions or operating states of the internal combustion engine 100 in particular, and these ambient conditions or operating states may potentially cause an increase in the concentration of unburned gases in the exhaust mechanism 110. The measurement parameters detected by the mentioned sensors are also transmitted to the controller 15 as input parameters. The controller 15 has an algorithm 35 for appropriately controlling the secondary air pump 20, the valve device 26, and the changeover valve 24.

[0028] When the internal combustion engine 100 is started and warmed up, the air inhaled through the first device 16 can be continuously blown in to mitigate the potentially incomplete combustion caused by the motor starting effect (rich mixture, ignition failure, long starting time in the case of low motor temperature, etc.). Alternatively or additionally, when an interference is detected during normal motor operation (for example, an ignition failure is found, etc., which may cause an unburned gas (hydrogen) to potentially form a critical concentration in the exhaust gas mechanism 110), air can be blown into the exhaust gas mechanism 110. Alternatively or additionally, air can also be blown into the exhaust gas mechanism 110 when the motor is shut down. This can especially also be kept active for a pre-given period of time after the motor is shut down to support the combustible gas (hydrogen) during so-called purging. During purging, the pressure of the combustible gas in the injection system (such as the rail, supply line, or gas injector) is reduced to reduce the amount of combustible gas contained in the injection system.

[0029] When the motor is stationary, the blowing-in of air into the exhaust gas mechanism 110 can also be activated in order to flush the exhaust gas mechanism 110 or the intake mechanism 103 (as well as other possible components of the internal combustion engine 100) with ambient air in certain special cases (such as an internal leak of the gas injector), thereby avoiding a dangerously high concentration of combustible gas.

[0030] Preferably, air is taken out through the second extraction site 34 near the air filter 105. In certain special cases, such as when the motor is shut down or during motor stationary periods, the extraction of air through the first extraction site 18 can be utilized. Here, in particular, the potentially excessive concentration of combustible gas in the intake mechanism 103 can be reduced when taking out air in the area of the first extraction site 18. Through the changeover valve 24 controlled by the control device 15, the corresponding activation can be carried out.

[0031] The control or activation of the secondary air pump 26 is also carried out by the control device 15. Here, the amount of air blown in or inhaled per unit time is selected according to the operation.

[0032] Additionally, in the operating point of the internal combustion engine 100 without air excess, blowing air into the exhaust gas mechanism 110 can contribute to the combustion of the gas and thus potentially reduce nitrogen oxide emissions.

[0033] If the internal combustion engine 100 is started, especially when the temperature of the internal combustion engine 100 is very low, a relatively large amount of combustible gas is blown into the combustion chamber 102 of the cylinder 101 of the internal combustion engine 100. If an ignition failure occurs during the starting process, for example if the ignition device is faulty, a small amount of unburned charge is sufficient to produce a critical amount of unburned gas in the exhaust gas mechanism 110. Therefore, blowing air into the exhaust gas mechanism 110 can be carried out before the motor is started, that is, before the starter is activated. This also has the advantage that it can be checked by the controller 15 or the motor control device whether the device 10 is operating properly. If the device 10 is faulty, the motor control device can decide whether to allow the motor to start. In addition, the combustible gas that may have accumulated in the exhaust gas mechanism 110 due to internal leakage from the blowing system during the motor standstill can be flushed out of the exhaust gas mechanism 110.

[0034] During (normal) motor operation, the concentration of combustible gas in the exhaust gas is detected by means of the sensor 12. When the threshold value or boundary value is exceeded, the controller 15 activates the blowing of air into the exhaust gas mechanism 110. In particular, the algorithm 35 of the controller 15 identifies combustion faults, for example by diagnosing ignition, diagnosing the motor speed curve, etc. When conditions exist for a long time from which it can be inferred that the combustion in the combustion chamber 102 of the cylinder 101 may be disturbed, the controller 15 activates the blowing of air into the exhaust gas mechanism 110. This alternative can also be implemented especially in the case where there is no sensor 12 in the exhaust gas mechanism 110.

[0035] Operation of the internal combustion engine 100 can be achieved by diluting or reducing the concentration of combustible gas (hydrogen) in the exhaust gas mechanism 110 by means of air blowing, even if the internal combustion engine 100 repeatedly experiences ignition failures. Therefore, the internal combustion engine 100 can continue to operate for a certain period of time with the activated air blowing without shutting down the internal combustion engine. This can contribute to traffic safety because in this way the vehicle can move away from the danger zone.

[0036] The method or device 10 described so far can be modified or changed in various ways without departing from the concept of the present invention. Therefore, it should be particularly mentioned that the method should not be limited to the use of the internal combustion engine 100 provided for road vehicles. Instead, stationary motors or hybrid motors, railway drives or combined heat and power units can also be equipped with the corresponding device 10 or operated according to the method according to the present invention described so far.

Claims

1. A method for operating an internal combustion engine (100), which internal combustion engine has at least one combustion chamber (102), an intake mechanism (103) for the at least one combustion chamber (102) and an exhaust gas mechanism (110), wherein, Using a combustible gas, in particular hydrogen, as fuel, and additionally blowing air sucked in from the intake mechanism (103) into the exhaust mechanism (110) according to the operating state of the internal combustion engine (100) and / or according to the concentration of the combustible gas detected in the exhaust mechanism (110) that exceeds a boundary value, in order to reduce the concentration of the combustible gas, or, in the case where the concentration of the gaseous fuel in the intake mechanism (103) exceeds the boundary value, reducing the concentration of the gaseous fuel in the intake mechanism (103) by sucking it out from the intake mechanism (103) and blowing it into the exhaust mechanism (100).

2. The method according to claim 1, wherein The operating state of the internal combustion engine (100) is the motor starting or warm-up phase of the internal combustion engine (100), and air is blown into the exhaust mechanism (110) before the motor starts or at the time point when the motor starts.

3. The method according to claim 1 or 2, characterized in that, If a functional disturbance that may cause an increase in the concentration of unburned gas in the exhaust mechanism (110) is detected during the regulated operation, the operating state of the internal combustion engine (100) is the regulated operation of the internal combustion engine.

4. The method according to any one of claims 1 to 3, characterized in that The operating state of the internal combustion engine (100) is the motor shutdown of the internal combustion engine (100), and air is blown into the exhaust mechanism (110) within a pre-given time period after the motor shutdown.

5. The method according to any one of claims 1 to 4, characterized in that, The amount of air blown into the exhaust mechanism (110) per unit time is adjusted according to the operating state of the internal combustion engine (100), environmental conditions, or other conditions.

6. The method according to any one of claims 1 to 5, characterized in that, According to the detected operating state of the internal combustion engine (100), air is sucked in from the intake mechanism (103) either from the area near the air filter (105) or from the area near the combustion chamber (102).

7. The method according to any one of claims 1 to 6, characterized in that Air is blown into the exhaust mechanism (110) in the area near the combustion chamber (102).

8. An apparatus (10) for performing the method according to one of claims 1 to 7, the apparatus having: at least one sensor (12) configured to detect the concentration of a combustible gas in the intake mechanism (103) or the exhaust mechanism (110) of the internal combustion engine (100); a first device (16) for taking air out of the intake mechanism (103); and a second device (25) for blowing the air taken out from the intake mechanism (103) into the exhaust mechanism (110); and a controller (15) configured to control the first device (16) and the second device (25) according to the detected concentration of the combustible gas in the intake mechanism (103) or the exhaust mechanism (110) and / or according to the operating state of the internal combustion engine (100) that may cause an increase in the concentration of the gas.

9. The device according to claim 8, characterized in that The first device (16) includes: two extraction sites (18, 34) for air, which are arranged at different parts of the intake mechanism (103); and a switching device (24) that can be controlled by the controller (15), and the switching device is used to extract air from different extraction sites (18, 34).

10. The device according to claim 8 or 9, characterized in that, The first device (16) includes an air suction device (20) that can be controlled by the controller (15), and the second device (25) includes a valve device (26) that can be controlled by the controller (15).

11. A computer program product, in particular a data carrier or a data program stored in a controller (15), the computer program product includes an algorithm (35), and the algorithm is configured to implement at least one step of the method according to one of claims 1 to 7.

12. An internal combustion engine (100), which is configured to execute the method according to one of claims 1 to 7 and / or has a device (10) according to one of claims 8 to 10.

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