Internal combustion engine control device
By optimizing fuel injection quantity using catalyst temperature and air-fuel ratio signals, the problems of large NOx concentration variations and reduced output torque controllability in hydrogen fuel cell internal combustion engines were solved, achieving stable operation of the internal combustion engine and improved exhaust characteristics.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- TOYOTA JIDOSHA KK
- Filing Date
- 2025-11-27
- Publication Date
- 2026-06-12
AI Technical Summary
In internal combustion engines that use hydrogen as fuel, the accuracy of the air-fuel ratio sensor readings is easily reduced, and the NOx concentration in the exhaust fluctuates greatly, leading to a decrease in exhaust characteristics and output torque controllability.
The catalyst temperature is obtained by the control device, and the upper limit protection of the fuel injection quantity of the fuel injection valve is set to ensure that the fuel injection quantity does not exceed the upper limit. Combined with the catalyst temperature and air-fuel ratio sensor signals, the fuel injection quantity is optimized to improve NOx reduction capacity and output torque controllability.
It balances the exhaust characteristics and output torque control of the internal combustion engine, suppresses the decrease in output torque, improves the NOx reduction capacity of the catalyst, and ensures the stable operation of the internal combustion engine.
Smart Images
Figure CN122190923A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to an internal combustion engine control device suitable for internal combustion engines using hydrogen as fuel. Background Technology
[0002] The internal combustion engine disclosed in Patent Document 1 includes: a catalyst disposed in an exhaust passage; and an air-fuel ratio sensor that detects the air-fuel ratio of the exhaust gas flowing in the exhaust passage.
[0003] Patent Document 1: Japanese Patent Application Publication No. 2005-220833 Summary of the Invention
[0004] In recent years, internal combustion engines using hydrogen as fuel have been under development. In such engines, the accuracy of correcting fuel injection based on air-fuel ratio sensor readings tends to decrease, and the NOx concentration in the exhaust fluctuates significantly with changes in the air-fuel ratio. In other words, in hydrogen-fueled internal combustion engines, changes in the air-fuel ratio towards a richer state have a substantial impact on exhaust characteristics.
[0005] An internal combustion engine control device for solving the above-mentioned problems is applicable to an internal combustion engine using hydrogen as fuel, the internal combustion engine comprising: a cylinder; a fuel injection valve for injecting the fuel supplied into the cylinder; an exhaust passage for supplying exhaust gas discharged from the cylinder; and a catalyst disposed in the exhaust passage. The internal combustion engine control device comprises: a processing circuit for controlling the fuel injection quantity of the fuel injection valve. The processing circuit performs the following processes: a temperature acquisition process for acquiring a catalyst temperature, which is the temperature of the catalyst; a protection setting process for setting an upper limit protection such that the higher the catalyst temperature, the greater the upper limit protection of the fuel injection quantity of the fuel injection valve; and an injection process for operating the fuel injection valve such that the fuel injection quantity of the fuel injection valve does not exceed the upper limit protection.
[0006] Invention Effects
[0007] The advantage of this invention is that it simultaneously mitigates the decrease in the controllability of the output torque of the internal combustion engine and improves the exhaust characteristics of the internal combustion engine. Attached Figure Description
[0008] Figure 1 This is a schematic diagram showing a control device as one embodiment of an internal combustion engine control device and a schematic structural diagram of an internal combustion engine controlled by the control device.
[0009] Figure 2 It means Figure 1 A block diagram of multiple processes performed by the processing circuitry of the control device.
[0010] Figure 3 It means Figure 2 A detailed block diagram of the protection settings processing. Detailed Implementation
[0011] according to Figures 1 to 3 An embodiment of the internal combustion engine control device will be described.
[0012] Figure 1 The diagram illustrates an internal combustion engine 10 and a control device 60 adapted to the internal combustion engine 10. The control device 60 corresponds to "internal combustion engine control device".
[0013] <Structure of Internal Combustion Engine 10>
[0014] The internal combustion engine 10 is a hydrogen engine that uses hydrogen as fuel. The internal combustion engine 10 has multiple cylinders 11, an intake passage 12, multiple fuel injection valves 13, and an exhaust passage 14. Figure 1 Only one of the multiple cylinders 11 is shown in the diagram. Each of the multiple cylinders 11 houses a piston 15. The reciprocating motion of the piston 15 within the multiple cylinders 11 rotates the crankshaft, which serves as the output shaft of the internal combustion engine 10.
[0015] The intake passage 12 is connected to multiple cylinders 11. The intake passage 12 is a passage for airflow into the multiple cylinders 11. A throttle valve 18 is provided in the intake passage 12 to regulate the amount of air introduced into the multiple cylinders 11.
[0016] Multiple fuel injection valves 13 inject fuel (i.e., hydrogen) supplied to their corresponding cylinders 11. Figure 1 In the example shown, fuel injection valve 13 is illustrated as an in-cylinder injection valve that directly injects fuel into cylinder 11. The internal combustion engine 10 may also have an intake manifold injection valve as fuel injection valve 13, which injects hydrogen in the portion of the intake passage 12 that is further downstream of throttle valve 18.
[0017] Within multiple cylinders 11, a mixture of air and fuel is combusted by a spark discharge from a spark plug. This causes the piston 15 to reciprocate within the cylinders 11, thus rotating the crankshaft. Exhaust gas is generated within the cylinders 11 due to the combustion of the mixture. This exhaust gas is discharged from the cylinders 11 into an exhaust passage 14, where it flows.
[0018] A catalyst 19 is provided in the exhaust passage 14. When the catalyst 19 is activated, it can reduce NOx contained in the exhaust gas. When the catalyst 19 is activated, the higher the temperature of the catalyst 19, the higher the degree of activation of the catalyst 19. Moreover, the higher the temperature and the higher the degree of activation of the catalyst 19, the higher the NOx reduction capacity of the catalyst 19.
[0019] The internal combustion engine 10 includes an exhaust-driven turbocharger 40. The turbocharger 40 has a turbine 41 disposed in an exhaust passage 14 and a compressor 42 disposed in an intake passage 12. The turbine 41 operates based on the flow rate of exhaust gas flowing in the exhaust passage 14. The compressor 42 is disposed in the intake passage 12 upstream of the throttle valve 18. The compressor 42 pressurizes the air flowing in the intake passage 12 by operating synchronously with the turbine 41.
[0020] <Sensors for Internal Combustion Engine 10>
[0021] The internal combustion engine 10 includes multiple sensors that output signals corresponding to the detection results to the control device 60. These sensors include an air flow meter 51, a crankshaft angle sensor 52, an air-fuel ratio sensor 53, and a catalyst temperature sensor 54. The air flow meter 51 is located upstream of the compressor 42 in the intake passage 12. It detects the flow rate of air flowing in the intake passage 12. The crankshaft angle sensor 52 detects the rotation angle of the crankshaft of the internal combustion engine 10 and outputs a signal corresponding to the crankshaft's rotational speed. The air-fuel ratio sensor 53 is located upstream of the catalyst 19 in the exhaust passage 14. It detects the air-fuel ratio of the air-fuel mixture burned in the multiple cylinders 11. The catalyst temperature sensor 54 detects the temperature of the catalyst 19.
[0022] Hereinafter, the air flow rate based on the detection signal from the air flow meter 51 will be recorded as "Intake Air Quantity GA". The crankshaft speed based on the detection signal from the crankshaft angle sensor 52 will be recorded as "Internal Combustion Engine Speed NE". The air-fuel ratio based on the detection signal from the air-fuel ratio sensor 53 will be recorded as "Air-fuel Ratio AF". The catalyst temperature based on the detection signal from the catalyst temperature sensor 54 will be recorded as "Catalyst Temperature TPc".
[0023] <Control Device 60>
[0024] The control device 60 includes a processing circuit 61 for controlling the operation of the internal combustion engine 10. One example of the processing circuit 61 is an electronic control device. In this case, the processing circuit 61 has a CPU 62 and a memory 63. The memory 63 stores various control programs executed by the CPU 62. By executing the control programs in the memory 63, the processing circuit 61 can control the fuel injection quantity of multiple fuel injection valves 13 and the opening degree of the throttle valve 18.
[0025] <Various processes performed in processing circuit 61>
[0026] refer to Figure 2 and Figure 3The following describes several processes performed by the processing circuit 61 to control the fuel injection quantity of multiple fuel injection valves 13. These processes include a request torque calculation process M11, a basic injection quantity calculation process M12, a temperature acquisition process M13, an internal combustion engine load rate calculation process M14, a protection setting process M15, a target injection quantity setting process M16, and an injection process M17.
[0027] The requested torque calculation process M11 is a process that calculates the requested torque TqR, which is the requested value of the internal combustion engine torque as the output torque of the internal combustion engine 10. When the driver operates the throttle, in the requested torque calculation process M11, the processing circuit 61 calculates, for example, the value corresponding to the amount of throttle operation as the requested torque TqR.
[0028] The basic injection quantity calculation process M12 is a process for calculating the basic injection quantity QfB, which serves as the base value for the fuel injection quantity of the fuel injection valve 13. In the basic injection quantity calculation process M12, the processing circuit 61 calculates the basic injection quantity QfB so that the larger the requested torque TqR, the larger the value.
[0029] Temperature acquisition processing M13 is a process for acquiring the temperature of catalyst 19. In temperature acquisition processing M13, processing circuit 61 acquires, for example, the catalyst temperature TPc based on the detection signal of catalyst temperature sensor 54.
[0030] The internal combustion engine load rate calculation process M14 is a process for calculating the internal combustion engine load rate KL, which is the load rate of the internal combustion engine 10. In the internal combustion engine load rate calculation process M14, the processing circuit 61 calculates the internal combustion engine load rate KL based on the internal combustion engine speed NE and the intake air volume GA. The internal combustion engine load rate KL represents the ratio of the current cylinder inflow air volume to the cylinder inflow air volume that allows the internal combustion engine 10 to operate stably under full load. In addition, the cylinder inflow air volume is the amount of air that flows into each of the plurality of cylinders 11 during the intake stroke.
[0031] Protection setting process M15 is the process for setting the upper limit protection QL of the fuel injection quantity of fuel injection valve 13. In protection setting process M15, processing circuit 61 sets the upper limit protection QL based on internal combustion engine load rate KL, intake air quantity GA, catalyst temperature TPc, and air-fuel ratio AF. That is, when catalyst 19 is activated, processing circuit 61 sets the upper limit protection QL to be larger as the catalyst temperature TPc is higher.
[0032] refer to Figure 3 This section provides a detailed explanation of an example of the protection setting process M15.
[0033] The protection setting process M15 includes the spectrum selection process M151 and the upper limit protection calculation process M152.
[0034] In the spectrum selection process M151, the processing circuit 61 starts from... Figure 3 Among the multiple mappings MP1, MP2, MP3, ... shown, select the mapping corresponding to the catalyst temperature TPc. Hereinafter, the mapping selected in the spectrum selection process M151 will be recorded as "Selection Mapping MPc".
[0035] Multiple mappings MP1, MP2, MP3, ... represent the relationship between the excess air coefficient λ and the internal combustion engine load rate KL, and are used when setting the upper limit protection QL. The excess air coefficient λ is the value obtained by dividing the air-fuel ratio by the stoichiometric air-fuel ratio. When the air-fuel ratio is the same as the stoichiometric air-fuel ratio, the excess air coefficient λ is 1. When the excess air coefficient λ is greater than 1, it indicates that the air-fuel ratio is leaner than the stoichiometric air-fuel ratio.
[0036] Here, the hydrogen engine operates with an excess air coefficient λ greater than 1. Even with an excess air coefficient λ greater than 1, the NOx concentration in the exhaust gas discharged from multiple cylinders 11 to the exhaust passage 14 is relatively high when the excess air coefficient λ is relatively small. That is, if the excess air coefficient λ is gradually increased from 1, the NOx concentration gradually increases. After the excess air coefficient λ reaches a certain value, the NOx concentration gradually decreases as the excess air coefficient λ increases.
[0037] By making the excess air coefficient λ leaner, the NOx concentration can be sufficiently reduced. However, if the fuel supply to the cylinders 11 is insufficient, even if the NOx concentration in the exhaust gas from the cylinders 11 to the exhaust passage 14 is sufficiently reduced, the responsiveness of the hydrogen engine's output torque may decrease.
[0038] As described above, the NOx reduction capacity of the activated catalyst 19 depends to some extent on the temperature of the catalyst 19. Specifically, the higher the temperature, the higher the NOx reduction capacity based on the catalyst 19. Therefore, when the temperature of the catalyst 19 is high, compared with the case of low temperature, even if the NOx concentration of the exhaust gas discharged from the multiple cylinders 11 to the exhaust passage 14 is high, the catalyst 19 can fully reduce NOx.
[0039] Therefore, the control device 60 is equipped with multiple mappings MP1, MP2, MP3, ... corresponding to the catalyst temperature TPc, i.e., the degree of activation of the catalyst 19. Among the multiple mappings MP1, MP2, MP3, ..., mapping MP1 is the mapping with the largest excess air coefficient λ corresponding to the same internal combustion engine load rate KL. Mapping MP2 is the mapping with the second largest excess air coefficient λ corresponding to the same internal combustion engine load rate KL. Mapping MP3 is the mapping with the third largest excess air coefficient λ corresponding to the same internal combustion engine load rate KL.
[0040] Furthermore, among the multiple mappings MP1, MP2, MP3, ..., mapping MP1 represents the relationship between the excess air coefficient λ and the internal combustion engine load rate KL when the catalyst temperature TPc is the first temperature TP1. Mapping MP2 represents the relationship between the excess air coefficient λ and the internal combustion engine load rate KL when the catalyst temperature TPc is the second temperature TP2. The second temperature TP2 is a temperature higher than the first temperature TP1. Mapping MP3 represents the relationship between the excess air coefficient λ and the internal combustion engine load rate KL when the catalyst temperature TPc is the third temperature TP3. The third temperature TP3 is a temperature higher than the second temperature TP2.
[0041] Therefore, for example, when the catalyst temperature TPc is below the first temperature TP1, the processing circuit 61 selects mapping MP1 as the selected mapping MPc. For example, when the catalyst temperature TPc is above the first temperature TP1 and below the third temperature TP3, the processing circuit 61 selects mapping MP2 as the selected mapping MPc. For example, when the catalyst temperature TPc is above the third temperature TP3, the processing circuit 61 selects mapping MP3 as the selected mapping MPc.
[0042] In the upper limit protection calculation process M152, the processing circuit 61 calculates the upper limit protection QL using the selection mapping MPC. Specifically, the processing circuit 61 obtains the excess air coefficient λ corresponding to the current internal combustion engine load rate KL based on the selection mapping MPC. Furthermore, the processing circuit 61 calculates the upper limit protection QL based on the intake air quantity GA and the excess air coefficient λ. For example, the processing circuit 61 calculates the fuel injection quantity that can make the actual excess air coefficient equal to the excess air coefficient λ based on the intake air quantity GA. The fuel injection quantity as a result of this calculation is the upper limit protection QL.
[0043] return Figure 2 The target injection quantity setting process M16 sets the target injection quantity QfTr as the target value of the fuel injection quantity of the fuel injection valve 13. In the target injection quantity setting process M16, the processing circuit 61 sets the smaller of the basic injection quantity QfB and the upper limit protection QL as the target injection quantity QfTr.
[0044] Injection processing M17 is a process that controls the fuel injection of multiple fuel injection valves 13 by adjusting the energization to the multiple fuel injection valves 13. In injection processing M17, processing circuit 61 operates multiple fuel injection valves 13 according to a target injection quantity QfTr. Thus, processing circuit 61 can operate the fuel injection valves 13 to ensure that the fuel injection quantity of the fuel injection valves 13 does not exceed the upper limit protection QL.
[0045] <Function and Effects of This Implementation Method>
[0046] (1) As described above, when the catalyst 19 is activated, the higher the catalyst temperature TPc, the higher the NOx reduction capacity based on the catalyst 19. Therefore, when the catalyst temperature TPc is relatively high, even if the NOx concentration of the exhaust gas discharged from multiple cylinders 11 to the exhaust passage 14 is high, NOx can be appropriately reduced by the catalyst 19.
[0047] Therefore, in the control device 60, the processing circuit 61 sets an upper limit protection QL when the catalyst 19 is activated, with the value increasing as the catalyst temperature TPc increases. That is, the processing circuit 61 sets the upper limit protection QL based on the NOx reduction capacity of the catalyst 19. Thus, the processing circuit 61 can prevent setting an excessively small value as the upper limit protection QL. Furthermore, the processing circuit 61 activates the fuel injection valve 13 to ensure that the fuel injection quantity of the fuel injection valve 13 does not exceed the upper limit protection QL. As a result, the output torque of the internal combustion engine 10 is prevented from falling significantly below the requested torque TqR.
[0048] Therefore, the control device 60 can simultaneously suppress the reduction in the output torque of the internal combustion engine 10 and improve the exhaust characteristics of the internal combustion engine 10.
[0049] (2) If the turbocharger 40 starts to pressurize the internal combustion engine 10 during operation, the boost pressure will begin to rise. At this time, sometimes due to the response delay of the boost pressure rise, a deviation occurs between the target value of the internal combustion engine load rate KL and the actual internal combustion engine load rate KL. If the deviation between the target value of the internal combustion engine load rate KL and the internal combustion engine load rate KL is large, the fuel injection quantity becomes excessive relative to the intake air quantity GA, and the excess air coefficient λ changes towards the rich side.
[0050] In the control device 60, the processing circuit 61 sets an upper limit protection QL. At this time, when the NOx reduction capacity based on the catalyst 19 is relatively high, a larger value is set as the upper limit protection QL. Moreover, the processing circuit 61 sets the smaller of the basic injection quantity QfB based on the requested torque TqR and the upper limit protection QL as the target injection quantity QfTr. Then, the processing circuit 61 activates the fuel injection valve 13 according to this target injection quantity QfTr.
[0051] Therefore, the control device 60 can suppress the output torque of the internal combustion engine 10 from deviating from the requested torque TqR, while improving the exhaust characteristics of the internal combustion engine 10.
[0052] <Example of Change>
[0053] The above-described embodiments can be implemented with the following modifications. The above-described embodiments and the following modifications can be combined with each other to implement them within the scope of technical inconsistency.
[0054] • The internal combustion engine suitable for the control device 60 can be an internal combustion engine without a turbocharger 40.
[0055] • The internal combustion engine suitable for the control device 60 can be a structure having at least one cylinder 11.
[0056] • The processing circuit 61 is not limited to a processing circuit that has a CPU and ROM and performs software processing. That is, the processing circuit 61 can be any of the following structures (a), (b) and (c).
[0057] (a) The processing circuit 61 includes one or more processors that perform various processes according to a computer program. The processor includes a CPU and memories such as RAM and ROM. The memories store program code or instructions configured for processing by the CPU. Memory, or computer-readable medium, includes any available medium that is accessible to a computer, whether general or special purpose.
[0058] (b) The processing circuit 61 has one or more dedicated hardware circuits for performing various processes. Examples of dedicated hardware circuits include application-specific integrated circuits (ASICs) or FPGAs. ASIC stands for "Application Specific Integrated Circuit," and FPGA stands for "Field Programmable Gate Array."
[0059] (c) The processing circuit 61 has one or more processors that execute a portion of various processes according to a computer program and one or more dedicated hardware circuits that execute the remaining processes in the various processes.
[0060] Furthermore, the term "at least one" as used in this specification indicates "more than one" of the desired options. For example, when there are two options, "at least one" means "only one option" or "both options". As another example, when there are three or more options, "at least one" means "only one option" or "any combination of two or more options".
[0061] Symbol Explanation
[0062] 10-Internal combustion engine, 11-Cylinder, 13-Fuel injection valve, 14-Exhaust passage, 19-Catalyst, 40-Turbocharger, 60-Control device, 61-Processing circuit.
Claims
1. An internal combustion engine control device suitable for an internal combustion engine using hydrogen as fuel, the internal combustion engine comprising: a cylinder; a fuel injection valve for injecting fuel supplied into the cylinder; an exhaust passage for supplying exhaust gas flow from the cylinder; and a catalyst disposed in the exhaust passage, the internal combustion engine control device being characterized in that it comprises: The processing circuit controls the amount of fuel injected by the fuel injection valve. The processing circuit performs the following processing: Temperature acquisition process, which acquires the catalyst temperature as the temperature of the catalyst; The protection setting process sets the upper limit protection in such a way that the higher the catalyst temperature, the greater the upper limit protection of the fuel injection quantity of the fuel injection valve; and The fuel injection valve is operated in such a way that the amount of fuel injected by the fuel injection valve does not exceed the upper limit protection.
2. The internal combustion engine control device according to claim 1, characterized in that, The internal combustion engine is equipped with a turbocharger. The processing circuit performs the following processing: The basic injection quantity calculation process calculates the basic value of the fuel injection quantity of the fuel injection valve based on the requested value of the internal combustion engine torque; and The target injection quantity setting process sets the smaller of the base value of the fuel injection quantity and the upper limit protection value as the target value of the fuel injection quantity of the fuel injection valve. In the injection process, the fuel injection valve is activated based on the target value of the fuel injection quantity.