CN-122003542-A - Method of operating a gaseous fuel engine

Abstract

A method of operating a hydrogen-powered internal combustion engine includes executing a torque estimation routine, wherein an actual torque T actual of an engine cycle is calculated by estimating cylinder pressure based on intake air pressure and temperature, and using a lambda value lambda des determined from a map based on an engine operating state.

Inventors

• M. Shubula
• KISSEL JUTTA

Assignees

• 菲尼亚德尔福卢森堡有限公司

Dates

Publication Date

20260508

Application Date

20241010

Priority Date

20231017

Claims (18)

1. 1. A method of operating a hydrogen-powered internal combustion engine, the method comprising executing a torque estimation routine wherein an actual torque T actual of an engine cycle is calculated by estimating cylinder pressure based on intake air pressure and temperature, and using a lambda value lambda des determined from a map based on engine operating conditions.
2. 2. The method according to claim 1, wherein the actual torque (τ actual ) is calculated based on the following formula: Where P manifold is manifold pressure, H is fuel low heating value, T manifold is manifold temperature, R mix is mixture constant, AFR stochio is stoichiometric air-fuel ratio, eff vol is volumetric efficiency, eff therm is thermal efficiency, eff spark is firing efficiency, n active cylinder is the number of active cylinders in a given engine cycle, n cylinder is the total number of cylinders in the engine, disp eng is engine displacement.
3. 3. A method according to any preceding claim, wherein the engine operating state is defined by an engine coolant temperature.
4. 4. A method according to claim 3, wherein lambda des decreases as the engine coolant temperature increases.
5. 5. A method according to any preceding claim, wherein the engine operating state is defined by engine speed.
6. 6. A method according to any preceding claim, wherein the engine operating state is defined by a torque parameter representing the allowable torque at the current engine load or the actual torque of a previous engine cycle.
7. 7. The method of any preceding claim, wherein the cylinder pressure is further estimated using a gas constant R mix mapped according to lambda des .
8. 8. The method of claim 7, wherein the gas constant R mix decreases with increasing lambda des .
9. 9. A method according to any one of the preceding claims, wherein lambda des is limited to between 1.0 and 5.0, preferably between 1.6 and 4.0.
10. 10. A method according to any one of the preceding claims, wherein the intake pressure, i.e. the manifold pressure, and the intake temperature, i.e. the manifold temperature, are measured.
11. 11. A method according to any one of the preceding claims, wherein the actual torque is calculated periodically at a frequency of 20 Hz or higher, preferably 25 Hz or higher.
12. 12. A method according to any one of the preceding claims, wherein the actual torque is compared with an allowable torque.
13. 13. The method of claim 12, comprising operating the engine in a safe mode if the actual torque is greater than the allowable torque.
14. 14. The method of claim 13, wherein operating the engine in a safe mode includes limiting a torque output of the engine.
15. 15. A method according to claims 12 to 14, comprising triggering a flag indicating a fault if the actual torque is greater than the allowed torque.
16. 16. A method according to claims 12 to 15, wherein the allowable torque is calculated based on torque demand and/or input from a driver, preferably including a pedal position of the driver.
17. 17. A computer program comprising instructions which, when executed by a computer, cause the computer to perform the method of any preceding claim.
18. 18. A processing unit configured to perform the method of any one of claims 1 to 16.

Description

Method of operating a gaseous fuel engine Technical Field The present invention relates generally to a method of operating a gaseous-fuelled internal combustion engine and, more particularly, to a method of estimating torque in such an engine. The present invention proposes a strategy for estimating the torque produced by a hydrogen engine, which is particularly suitable for implementation in an ECU for safety diagnostics. Background The transition to cleaner and more sustainable energy sources has prompted a great deal of interest in hydrogen as a potential alternative fuel for internal combustion engines. Hydrogen internal combustion engines (H2-ICE) offer the prospect of significantly reducing greenhouse gas emissions and contributing to a more environmentally friendly transportation and industry paradigm. With the increasing interest in hydrogen as a viable fuel, accurate monitoring and control of torque in hydrogen internal combustion engines has become a key factor in achieving optimal performance, efficiency, and emissions reduction. Conventional torque monitoring techniques designed for conventional internal combustion engines may have shortcomings in accurately measuring and managing torque in the particular context of hydrogen combustion. The characteristics of hydrogen fuel, including its rapid burn rate and unique combustion characteristics, require specialized monitoring solutions to ensure safe and efficient engine operation. Thus, there is clearly a need for an innovative torque monitoring method tailored to hydrogen internal combustion engines that can provide real-time insight, enhanced accuracy, and adaptability to unique challenges presented by hydrogen-based combustion processes. This torque monitoring capability is particularly desirable in the context of ECU safety monitoring, a safety function that the ECU operates to estimate the actual torque and compare it to the expected/reference torque. Technical problem It is an object of the present invention to provide a method of operating a gaseous fuel engine that employs a torque estimation strategy suitable for H2-ICE. This object is achieved by a method as claimed in claim 1. Disclosure of Invention To achieve this object, the present invention proposes a method of operating a hydrogen-powered internal combustion engine, the method comprising executing a torque estimation routine, wherein an actual torque T actual of an engine cycle is calculated by estimating cylinder pressure based on intake air pressure and temperature, and using a lambda value lambda des determined from a map based on an engine operating state. An advantage of the present invention is that it provides a torque estimation method suitable for hydrogen-powered internal combustion engine characteristics that operates at various lambda values, as opposed to conventional methods that assume lambda to be stoichiometric. For this purpose, a map that correlates lambda with engine operating conditions is used. The proposed method estimates cylinder pressure caused by combustion in each cylinder in a given engine cycle based on measured intake air parameters such as pressure and temperature. Lambda value lambda des is derived from a map calibrated based on a predetermined engine operating condition. One relevant parameter of the engine operating state is the engine coolant temperature. In an embodiment, the map may be calibrated such that lambda des decreases as the engine coolant temperature increases. In this mapping, lambda des may be limited to between 1.0 and 5.0, in particular between 1.6 and 4.0. That is, the map of λ des defines different values of λ des depending on the operating conditions. Inside the ECU, access to the lambda des map is advantageously limited to the torque estimation procedure, i.e. not used by other functions/modules, for safety/integrity reasons. The use of a dedicated lambda des map also reduces the chance of computational failure. Other relevant parameters of the engine operating state are engine speed and torque parameters. In the context of lambda des map, the term torque parameter may represent the allowable torque of an engine cycle (threshold for maximum torque) or the actual torque of a previous engine cycle (i.e. determined by the same torque estimation procedure). Advantageously, the estimation of the cylinder pressure involves estimating the air mass using the ideal gas law, wherein the gas constant is modified to take into account the volume occupied by the hydrogen, called Rmix. Rmix advantageously depends on the amount of hydrogen and can therefore be mapped according to lambda des. In particular, the gas constant R mix may decrease as lambda des increases. In fuel cut (accelerator pedal released) or pure air conditions, rmix is preferably equal to R. One skilled in the art may employ different methods to estimate the average cylinder pressure due to combustion (average pressure for all cylinders in a combustion cycle). In particular