DE-102021128973-B4 - Control unit for controlling the amount of hydrogen injected into an internal combustion engine

Abstract

Control unit (1) for a powertrain (2) comprising an internal combustion engine (3), wherein the internal combustion engine (3) is designed as a hydrogen engine and wherein the control unit (1) is designed and configured to perform the following steps: - Determining a required air ratio (S11, λ erf ) based on a load requirement and a current air mass flow, - Determining a target combustion center (S12), - Determining a minimum air-fuel ratio (S13, λ min ) at the determined target combustion center of gravity (S12) taking into account NOx emissions and/or a ratio of H2/NOx emissions, - Comparing (S20) the required air ratio (S11, λ erf ) and the minimum air ratio (S13, λ min ), - Determining a shift of the combustion center of gravity (S30) if comparison (S20) shows that the required air ratio (S11, λ erf ) is smaller than the minimum air ratio (S13, λ min ), and - Control (S40) of an injection quantity of hydrogen based on the required air ratio (S11, λ erf ) or the determined shift of the combustion center of gravity (S30).

Inventors

• Joschka Schaub
• Carole QUEREL
• Lukas Virnich
• Aleksandar Boberic
• Volker Müller

Assignees

• FEV Group GmbH

Dates

Publication Date

20260513

Application Date

20211108

Priority Date

20201114

Claims (9)

1. Control unit (1) for a powertrain (2) comprising an internal combustion engine (3), wherein the internal combustion engine (3) is configured as a hydrogen engine and wherein the control unit (1) is designed and configured to perform the following steps: - Determining a required air-fuel ratio (S11, λ _erf) based on a load request and a current air mass flow rate, - Determining a target combustion center of gravity (S12), - Determining a minimum air-fuel ratio (S13, λ_min ) at the determined target combustion center of gravity (S12), taking into account NOx emissions and/or a ratio of H2/NOx emissions, - Comparing (S20) the required air-fuel ratio (S11, λ_erf) and the minimum air-fuel ratio (S13, λ_min), - Determining a shift of the combustion center of gravity (S30) if the comparison (S20) shows that the required air-fuel ratio (S11, λ _erf) is smaller than the minimum air-fuel ratio (S13, λ_min). air ratio (S13, λ min ) is, and - control (S40) of an injection quantity of hydrogen based on the required air ratio (S11, λ erf ) or the determined shift of the combustion center of gravity (S30).
2. Control unit (1) after Claim 1 , wherein the control unit (1) is designed and configured to take into account NOx emissions and/or H2/NOx emission ratios when determining the displacement of the combustion center of gravity (S30).
3. Control unit (1) after Claim 1 or 2 , wherein the control unit (1) is designed and configured to take into account a limitation of the specific displacement of the combustion center of gravity (S30) and wherein the limitation depends on combustion stability and/or exhaust gas temperature.
4. Control unit (1) after Claim 3 , wherein the control unit (1) is designed and configured to take into account, when controlling (S40) the injection quantity, a limitation of the injection quantity based on the limitation of the specific displacement of the combustion center of gravity (S30).
5. Control unit (1) according to one of the preceding claims, wherein the control unit (1) is designed and configured to take combustion stability into account when determining the target combustion center of gravity (S12).
6. Control unit (1) according to one of the preceding claims, wherein the powertrain (2) comprises an exhaust aftertreatment system (4) and wherein the control unit (1) is designed and configured to determine the minimum air ratio (S13, λ min ) based on a state of the exhaust aftertreatment system (4), based on a combustion mode, based on a change in NOx emissions and/or based on a change in the ratio of H2/NOx emissions.
7. Control unit (1) according to one of the preceding claims, wherein the control unit (1) is designed and configured to execute a model for determining NOx and/or H2 emissions and to perform the determination of the minimum air ratio (S13, λ min ) and/or the determination of the displacement of the combustion center of gravity (S30) based on a result of the model.
8. Control unit (1) according to one of the preceding claims, wherein the internal combustion engine (3) comprises an ignition device (40) and wherein the control unit (1) is designed and configured to determine an ignition timing based on the determined displacement of the combustion center of gravity (S30) and to actuate the ignition device (40) based on the determined ignition timing.
9. Control unit (1) according to one of the preceding claims, wherein the control unit (1) is designed and configured to control (S40) the To adjust the injection quantity.

Description

The invention relates to a control unit for a powertrain comprising an internal combustion engine, for controlling an injection quantity of hydrogen. From the DE 43 44 715 A1 is a system for controlling an air-fuel ratio for an engine powered by a gaseous fuel. The WO 2007 / 085 897 A1 discloses a gas engine and a method for controlling it, wherein it is provided to control the gas engine depending on the load range in which it is located, whereby operating modes with different air ratios and combustion types are selected. The invention is based on the objective of providing an improved control unit for a powertrain with a hydrogen combustion engine, which limits pollutant emissions such as NOx in transient operating ranges of the engine, taking into account fuel consumption, engine power output and/or the integrity of components integrated into or downstream of the powertrain. This objective is achieved by the control unit according to the invention. The control unit according to the invention for a powertrain comprising an internal combustion engine, wherein the internal combustion engine is designed as a hydrogen engine, is designed and configured to perform the following steps: - Determining a required air-fuel ratio based on a load requirement and a current air mass flow rate, - Determining a target combustion focus, - Determining a minimum air-fuel ratio at the determined target combustion center of gravity, taking into account NOx emissions and/or a ratio of H2/NOx emissions, - Comparing the required air-fuel ratio and the minimum air-fuel ratio, - Determining a shift in the combustion center of gravity if comparison shows that the required air-fuel ratio is smaller than the minimum air-fuel ratio at the determined target combustion center of gravity and - Controlling the amount of hydrogen injected based on the required air-fuel ratio or the specific shift of the combustion center of gravity. By controlling the amount of hydrogen injected based on the required air-fuel ratio or a specific shift in the combustion center of gravity, the invention enables the injection quantity to be adjusted taking into account NOx emissions and/or the H2/NOx emission ratio. This has the advantage that the control unit can weigh the load requirement, an efficiency change resulting from the specific shift in the combustion center of gravity, and the NOx emissions and/or the H2/NOx emission ratio when controlling the injection quantity. The target combustion center of gravity is understood as a combustion center of gravity that enables efficient operation of the internal combustion engine. This depends on the current combustion mode. In efficiency-controlled operation, for example, the target combustion center of gravity is defined to achieve the highest possible efficiency. In heating operation, however, it might be defined to provide an advantageous exhaust gas temperature. The minimum air-fuel ratio at the determined target combustion center is understood here as an air-fuel ratio for which, at the determined target combustion center, NOx emissions are lower than the target NOx emissions and/or the ratio of H2/NOx emissions is higher than the target H2/NOx ratio. NOx emission, as used here, refers to raw NOx emissions, i.e., NOx emissions upstream of an exhaust aftertreatment system of the combustion engine. Similarly, the ratio of H2/NOx emissions is understood here as the ratio of raw emissions of H2 and NOx. The NOx target emission is defined here in such a way that legal requirements regarding NOx emissions downstream of an exhaust aftertreatment system of the powertrain can be met. The NOx target emission can be defined depending on the operating state of the powertrain. The target H2/NOx ratio is defined here such that a specific hydrogen content is present in the exhaust gas. This hydrogen can then be used, for example, for NOx reduction in the exhaust gas by an H2-SCR catalyst, so that an H2 injector is not needed in the exhaust system of the powertrain, or at least less H2 needs to be introduced into the exhaust system. Here, "taxes" refers to both taxes with an open or temporarily closed course of action and regulations with a closed course of action. To determine the required air-fuel ratio, the control unit preferably calculates the necessary amount of hydrogen to be injected based on the load demand. The load demand results, for example, from the position of the accelerator pedal in the powertrain. To calculate the required amount of injection, the control unit particularly preferably uses an efficiency model of the internal combustion engine, taking a combustion mode into account. A combustion mode can be, for example, efficiency-controlled operation, NOx-controlled operation, or heating operation of the internal combustion engine. Furthermore, to determine the required air-fuel ratio, the control unit measures the current air mass flow in the intake manifold of the combustion engine. Based on the measu