Vehicle control device and vehicle control method

Abstract

A vehicle control device and a vehicle control method are provided. The control device controls a vehicle that includes an engine having an injector that supplies hydrogen as a fuel into a cylinder, and a VN turbocharger that adjusts a boost pressure by changing a VN opening degree that is an opening degree of nozzle vanes. The control device includes a processing circuit. The processing circuit determines a target value of an air-fuel ratio of a mixture that is combusted in the cylinder, which is a target air-fuel ratio, and a target value of the boost pressure, which is a target boost pressure, based on a required torque. The processing circuit changes the VN opening degree based on the target air-fuel ratio and the target boost pressure, such that the smaller the target air-fuel ratio, the larger a clearance between the nozzle vanes.

Description

Technical Field

[0001] This disclosure relates to vehicle control devices and vehicle control methods. Background Technology

[0002] Japanese Patent Application Publication No. 2021-099036 discloses an engine assembly including an engine, a turbocharger, and a control device. When upstream purging is performed while the turbocharger is operating, fuel vapors are introduced into the intake system, thus decreasing the air-fuel ratio (the ratio of air to fuel mass). Therefore, in this engine assembly, when upstream purging is performed while the turbocharger is operating, the throttle is controlled to increase the throttle opening compared to when upstream purging is not performed. This prevents insufficient airflow through the throttle relative to the engine's required airflow. Summary of the Invention

[0003] The problem that the invention aims to solve

[0004] Compared to fuels like gasoline and light oil, hydrogen has a higher calorific value per unit mass. Therefore, hydrogen engines, which use hydrogen as fuel, experience greater variations in exhaust temperature due to changes in the air-fuel ratio. The lower the air-fuel ratio of the mixture, the higher the exhaust temperature.

[0005] A variable-capacity turbocharger with a variable nozzle mechanism is known. The variable-capacity turbocharger adjusts the boost pressure by varying the nozzle blade opening. In a hydrogen engine with a variable-capacity turbocharger, even with the same nozzle blade opening, the boost pressure may become excessively high if the air-fuel ratio decreases.

[0006] Methods for solving problems

[0007] In one aspect of this disclosure, a vehicle control device for controlling a vehicle is provided. The vehicle includes: an internal combustion engine having a fuel injection device for supplying hydrogen as fuel into cylinders; and a variable-capacity turbocharger that adjusts the boost pressure by changing the opening of the nozzle blades. The vehicle control device includes a processing circuit. The processing circuit is configured to determine a target air-fuel ratio and a target boost pressure based on a required torque, wherein the target air-fuel ratio is a target value for the air-fuel ratio of the mixture burned in the cylinder, and the target boost pressure is a target value for the boost pressure. The processing circuit is configured to change the opening based on the target air-fuel ratio and the target boost pressure such that the smaller the target air-fuel ratio, the larger the gap between the nozzle blades.

[0008] In one of the two aspects of this disclosure, a vehicle control method for controlling a vehicle is provided. The vehicle includes: an internal combustion engine having a fuel injection device for supplying hydrogen as fuel into a cylinder; and a variable-capacity turbocharger that adjusts the boost pressure by changing the opening of the nozzle blades. The vehicle control method includes: determining a target air-fuel ratio and a target boost pressure based on a required torque, wherein the target air-fuel ratio is a target value of the air-fuel ratio of the mixture burned in the cylinder, and the target boost pressure is a target value of the boost pressure; and changing the opening based on the target air-fuel ratio and the target boost pressure such that the smaller the target air-fuel ratio, the larger the gap between the nozzle blades. Attached Figure Description

[0009] Figure 1 This is a schematic diagram showing the structure of a vehicle equipped with a control device.

[0010] Figure 2 It means Figure 1 The flowchart shows the process of changing the VN opening in the VN turbocharger, executed by the processing circuit of the control device.

[0011] Figure 3 yes Figure 1 The block diagram shows the process performed by the control device's processing circuit to obtain the reference VN opening degree by referring to the two-dimensional opening degree mapping.

[0012] Figure 4 It means stored in Figure 1 A coordinate graph showing the relationship between the λ ratio and the correction coefficient in the λ correction mapping of a storage device.

[0013] Figure 5 This is a flowchart illustrating the process of changing the VN opening degree in the VN turbocharger, executed by the processing circuit of the control device in the second embodiment.

[0014] Figure 6 This is a block diagram of the process performed by the processing circuit of the control device in the second embodiment to obtain the VN opening indication value by referring to the three-dimensional opening mapping. Detailed Implementation

[0015] <First Implementation Method>

[0016] The following is for reference Figures 1-4 A first embodiment of the control device 11, which is one embodiment of the vehicle control device, will be described.

[0017] <Structure of Vehicle 10>

[0018] Figure 1 This is a schematic diagram showing the structure of vehicle 10. (For example...) Figure 1As shown, vehicle 10 includes a control unit 11, an engine 20, a VN turbocharger 40, and multiple sensors. "VN" in VN turbocharger 40 stands for Variable Nozzle. The aforementioned multiple sensors include five sensors: an accelerometer opening sensor 71, a wheel speed sensor 72, a crankshaft angle sensor 73, an air flow meter 74, and a boost pressure sensor 75.

[0019] like Figure 1 As shown, the control device 11 includes a processing circuit 12 and a storage device 13. The processing circuit 12 is a processing device having a CPU that executes processing according to a program and a ROM that stores the program. The storage device 13 is a non-volatile memory that stores data related to the vehicle 10.

[0020] The control device 11 controls the vehicle 10 and its components, such as the engine 20 and VN turbocharger 40, based on data obtained from multiple sensors mounted on the vehicle 10. The control device 11 is, for example, an engine ECU (Electronic Control Unit).

[0021] Engine 20 is an internal combustion engine with multiple cylinders 21B. The fuel for engine 20 is hydrogen. Each cylinder 21B constitutes a combustion chamber for burning a mixture of hydrogen and air.

[0022] The engine 20 includes a crankcase 21A, cylinders 21B, cylinder head 21C, intake passage, and exhaust passage. The intake passage consists of a first intake passage 41, a second intake passage 42, a third intake passage 43, and a fourth intake passage 44. The exhaust passage consists of a first exhaust passage 51, a second exhaust passage 52, and a third exhaust passage 53.

[0023] Pistons 22 and connecting rods 23 are housed inside each cylinder 21B. Connecting rods 23 are connected to crankshafts 24 housed in crankcases 21A.

[0024] A cylinder head 21C is mounted on the upper part of each cylinder 21B. Each cylinder 21B and cylinder head 21C constitutes the combustion chamber of each cylinder 21B. The cylinder head 21C has an intake valve 25, an exhaust valve 27, an injector 29, and an ignition device 30. The engine 20 is a direct-injection hydrogen engine that directly injects hydrogen into each cylinder 21B. The injector 29 is a fuel injection device that supplies hydrogen to each cylinder 21B. A fourth intake passage 44 and a first exhaust passage 51, communicating with each combustion chamber, are respectively connected to the cylinder head 21C.

[0025] The intake passage is a passage that introduces external intake air into each combustion chamber. The external intake air flows into each combustion chamber in the order of first intake passage 41, second intake passage 42, third intake passage 43, and fourth intake passage 44. An intercooler 45 is installed between the second intake passage 42 and the third intake passage 43. A throttle valve 46 is installed between the third intake passage 43 and the fourth intake passage 44. The throttle valve 46 changes the airflow area by varying the valve opening, thereby regulating the flow rate of intake air into each cylinder 21B. The downstream end of the fourth intake passage 44 communicates with each combustion chamber. An intake valve 25 is installed at this end.

[0026] The exhaust passage is a passage that guides exhaust gas from each cylinder 21B to the exhaust system components. Exhaust gas from each cylinder 21B flows outward through the exhaust passage in the order of first exhaust passage 51, second exhaust passage 52, and third exhaust passage 53. The upstream end of the first exhaust passage 51 communicates with each combustion chamber. An exhaust valve 27 is provided at this end. A catalyst device 54 for removing harmful substances from the exhaust gas is provided between the second exhaust passage 52 and the third exhaust passage 53.

[0027] A VN turbocharger 40 is disposed in the intake and exhaust passages of the engine 20. The VN turbocharger 40 is a turbocharger having a compressor 40C and a turbine 40T. The compressor 40C and the turbine 40T are connected via a bearing portion 40B. A turbine shaft 40S is inserted inside the bearing portion 40B, and a turbine impeller 40W housed inside the turbine 40T and a compressor impeller 40I housed inside the compressor 40C are fixed to the turbine shaft 40S. The compressor 40C is connected to a first intake passage 41 and a second intake passage 42. The turbine 40T is connected to a first exhaust passage 51 and a second exhaust passage 52.

[0028] When the exhaust gas flowing into the turbine 40T from the first exhaust passage 51 causes the turbine impeller 40W to rotate, the turbine shaft 40S and the compressor impeller 40I rotate as a unit with the turbine impeller 40W. When the compressor impeller 40I rotates, the intake air flowing into the compressor 40C from the first intake passage 41 is compressed and sent to the second intake passage 42.

[0029] The VN turbocharger 40 is a variable capacity turbocharger. The VN turbocharger 40 has multiple nozzle blades 40N and a variable nozzle mechanism 40V. The nozzle blades 40N are disposed inside the turbine 40T around the turbine impeller 40W. The nozzle blades 40N are partitions that guide exhaust gas flowing into the turbine 40T from the first exhaust passage 51 toward the turbine impeller 40W. The nozzle blades 40N are arranged circumferentially toward the turbine impeller 40W. Exhaust gas flowing into the turbine 40T flows toward the turbine impeller 40W through the gaps between adjacent nozzle blades 40N.

[0030] A variable nozzle mechanism 40V, located on the turbine 40T, changes the angle of the nozzle blades 40N via a linkage mechanism. This linkage mechanism is driven by an actuator located on the variable nozzle mechanism 40V. As the angle of the nozzle blades 40N changes, the gap between them also changes. The angle of the nozzle blades 40N is referred to as the opening degree of the nozzle blades 40N. Hereinafter, the opening degree of the nozzle blades 40N will be denoted as VN opening degree OP.

[0031] When the nozzle blades 40N have an angle that decreases the gap between them, the VN opening OP is large. When the nozzle blades 40N have an angle that increases the gap between them, the VN opening OP is small. When the gap between the nozzle blades 40N is small, the exhaust velocity flowing through this gap to the turbine impeller 40W increases, thus increasing the rotational speed of the turbine impeller 40W. Therefore, with the same exhaust energy flowing into the turbine 40T, a larger VN opening OP results in a higher boost pressure in the engine 20. On the other hand, when the gap between the nozzle blades 40N is large, the exhaust velocity flowing through this gap to the turbine impeller 40W decreases. Therefore, with the same exhaust energy flowing into the turbine 40T, a smaller VN opening OP results in a lower boost pressure in the engine 20. Therefore, the VN turbocharger 40 adjusts the boost pressure in the engine 20 by changing the VN opening OP. The VN opening mentioned here is defined as the increase in opening when the flow rate is increased, that is, when the flow velocity is increased by reducing the gap between the nozzle blades by 40N.

[0032] The control unit 11 controls the engine 20 and the VN turbocharger 40 based on data obtained from sensors mounted on the vehicle 10. For example, the accelerator pedal opening sensor 71 senses the driver's accelerator operation. The accelerator pedal opening sensor 71 senses the amount of accelerator operation by the driver and inputs this information as the accelerator pedal opening to the control unit 11. The wheel speed sensor 72 measures the wheel speed of each wheel of the vehicle 10 and inputs this data to the control unit 11. The control unit 11 calculates the vehicle speed of the vehicle 10 based on the wheel speed data.

[0033] The crank angle sensor 73 measures the amount of change in the crank angle per unit time, and inputs the data to the control device 11. The control device 11 calculates the engine speed of the engine 20 based on the amount of change in the crank angle per unit time. The air flow meter 74 measures the flow rate of air flowing in the first intake passage 41, and inputs the data to the control device 11. The flow rate of intake air in the engine 20 is the flow rate of air measured by the air flow meter 74. The boost pressure sensor 75 measures the pressure of intake air in the third intake passage 43, and inputs the data to the control device 11. The pressure of intake air measured by the boost pressure sensor 75 is the boost pressure in the engine 20.

[0034] The control device 11 is connected to the injector 29, the ignition device 30, the throttle valve 46, and the variable nozzle mechanism 40V, respectively. The control device 11 controls the injector 29 to adjust the injection amount of hydrogen injected into each cylinder 21B. The control device 11 controls the ignition device 30 to change the ignition timing in each cylinder 21B. The control device 11 controls the throttle valve 46 to adjust the amount of air introduced into each cylinder 21B. The control device 11 controls the variable nozzle mechanism 40V to change the VN opening degree OP.

[0035] <Change of VN Opening Degree OP>

[0036] Figure 2 shows the processing executed by the processing circuit 12 of the control device 11 when changing the VN opening degree OP. The processing circuit 12 repeatedly executes, for example, at a cycle shorter than the interval of fuel injection in each cylinder 21B Figure 2 the series of processing shown in the figure. Figure 2 The letter "S" shown in the figure is an abbreviation for "Step" in the series of processing.

[0037] First, in S100, the processing circuit 12 calculates the required torque DT. The required torque DT is determined based on information such as the accelerator opening degree, vehicle speed, engine speed, and gear ratio. The magnitude of the required torque DT varies according to the driver's accelerator operation, the traveling state of the vehicle 10, and the like.

[0038] In S110, the processing circuit 12 determines the fuel injection quantity QF and the target air-fuel ratio λE based on the required torque DT calculated in S100. The fuel injection quantity QF is the amount of hydrogen fuel injected from the injector 29 into the cylinder 21B. The target air-fuel ratio λE is the target value of the air-fuel ratio λ of the mixture burned in the cylinder 21B. When hydrogen is used as fuel, the air-fuel ratio λ is the ratio of the mass of air to the mass of hydrogen in the mixture. Therefore, the smaller the air-fuel ratio λ, the greater the proportion of hydrogen fuel in the mixture. The processing circuit 12 calculates the fuel injection quantity QF and the target air-fuel ratio λE required to meet the required torque DT. Generally, the larger the required torque DT, the larger the fuel injection quantity QF of the processing circuit 12. For example, the larger the required torque DT, the smaller the target air-fuel ratio λE of the processing circuit 12.

[0039] In S120, the processing circuit 12 calculates the required air quantity QA based on the fuel injection quantity QF and the target air-fuel ratio λE. The required air quantity QA is the product of the amount of hydrogen fuel corresponding to the amount of fuel injection quantity QF determined in S110 and the target air-fuel ratio λE, which is the amount of air required for combustion in cylinder 21B.

[0040] In S130, the processing circuit 12 calculates the target intake flow rate QI based on the required air volume QA. The target intake flow rate QI is a target value for the flow rate of intake air introduced into the VN turbocharger 40, specifically, it is the required intake flow rate to introduce the amount of air corresponding to the required air volume QA into the cylinder 21B.

[0041] In S140, the processing circuit 12 calculates the target boost pressure PB. The target boost pressure PB is the target value of the boost pressure, specifically, it is the boost pressure required to introduce an amount of air corresponding to the required air volume QA into the cylinder 21B by boosting the intake air introduced with the target intake flow rate QI.

[0042] In S110 to S140, the processing circuit 12 determines the target air-fuel ratio λE, the target intake air flow rate QI, and the target boost pressure PB based on the required torque DT.

[0043] In S150, the processing circuit 12 obtains the reference VN opening OS by referring to the two-dimensional opening mapping. Figure 3 This is a block diagram of the processing circuit 12 obtaining the reference VN opening OS by referring to a two-dimensional opening mapping. The two-dimensional opening mapping is stored in the storage device 13 of the control device 11. Alternatively, the two-dimensional opening mapping can also be stored in the ROM of the processing circuit 12.

[0044] The VN turbocharger 40 changes the boost pressure by altering the VN opening OP. The VN turbocharger 40 adjusts the VN opening OP to an optimal opening relative to the target intake air flow rate QI, thereby achieving the target boost pressure PB. In the two-dimensional opening mapping, for each combination of the target intake air flow rate QI and the target boost pressure PB, the optimal VN opening OP value for achieving the target boost pressure PB at the target intake air flow rate QI is defined. The two-dimensional opening mapping is created with the air-fuel ratio λ fixed at a reference air-fuel ratio λS. The reference air-fuel ratio λS is defined as a reference in the engine 20. For example, the reference air-fuel ratio λS is set to the maximum value among the target air-fuel ratio λE values ​​that can be set in the engine 20. Under the condition that the air-fuel ratio λ is the reference air-fuel ratio λS, the value of the VN opening OP most suitable for achieving the target boost pressure PB relative to the target intake air flow rate QI is the reference VN opening OS (reference opening).

[0045] like Figure 3 As shown, the processing circuit 12 refers to the two-dimensional opening mapping to obtain the reference VN opening OS corresponding to the combination of the target intake flow rate QI calculated in S130 and the target boost pressure PB calculated in S140.

[0046] In S160, processing circuit 12 determines whether vehicle 10 is accelerating. If processing circuit 12 determines that vehicle 10 is not accelerating (S160; No), processing proceeds to S170. If processing circuit 12 determines that vehicle 10 is accelerating (S160; Yes), processing proceeds to S210. For example, processing circuit 12 determines that vehicle 10 is accelerating when the accelerator opening is above a predetermined value.

[0047] In S170, the processing circuit 12 calculates the λ ratio. The λ ratio is the ratio of the reference air-fuel ratio λS calculated according to the following mathematical formula 1 to the target air-fuel ratio λE.

[0048]

[0049] As shown in Equation 1 above, the smaller the target air-fuel ratio λE, the larger the λ ratio. When the λ ratio is calculated according to Equation 1 above, the processing circuit 12 initiates the processing step S180.

[0050] In S180, the processing circuit 12 obtains the correction coefficient L by referring to the λ correction mapping. Figure 4 This is a coordinate graph showing the relationship between the λ ratio and the correction coefficient L in the λ correction mapping. The λ correction mapping is stored in storage device 13. Alternatively, the λ correction mapping can also be stored in the ROM of processing circuit 12. Figure 4As shown, in the λ-correction mapping, the value of the correction coefficient L is specified such that the larger the value of the λ ratio, the smaller the value of the correction coefficient L. The correction coefficient L is specified such that when the value of the λ ratio is "1", the value of the correction coefficient L is "1".

[0051] Processing circuit 12 refers to the λ correction mapping to obtain the correction coefficient L corresponding to the λ ratio calculated in S170. For example, when the value of the λ ratio is "B", processing circuit 12 obtains "LB" as the value of the correction coefficient L by referring to the λ correction mapping.

[0052] In S190, the processing circuit 12 uses the value of the correction coefficient L obtained in S180 to correct the reference VN opening degree OS. The processing circuit 12 obtains the corrected VN opening degree OR by correcting the reference VN opening degree OS according to the following mathematical formula 2.

[0053]

[0054] The smaller the value of the correction coefficient L, the smaller the value of the corrected VN opening OR calculated according to the above mathematical formula 2. Therefore, the smaller the target air-fuel ratio λE, the smaller the value of the corrected VN opening OR. That is, the processing circuit 12 corrects the reference VN opening OS in such a way that the smaller the target air-fuel ratio λE, the smaller the value of the VN opening OP.

[0055] In S200, the processing circuit 12 substitutes the corrected VN opening degree OR into the VN opening degree indication value OC. The VN opening degree indication value OC is a signal value sent to the variable nozzle mechanism 40V as the value of the opening degree to be changed when the processing circuit 12 controls the variable nozzle mechanism 40V to change the VN opening degree OP.

[0056] In S160, if it is determined that vehicle 10 is accelerating, in S210, processing circuit 12 substitutes the reference VN opening degree OS into the VN opening degree indication value OC. That is, if processing circuit 12 determines that vehicle 10 is accelerating, it does not perform correction using the correction coefficient L shown in S170, S180 and S190.

[0057] In S220, the processing circuit 12 sends a control signal containing the VN opening indication value OC to the variable nozzle mechanism 40V, changing the VN opening OP to the VN opening indication value OC. Thus, the processing circuit 12 changes the VN opening OP to the VN opening OP determined based on the required torque DT. When the processing in S220 is executed, the processing circuit 12 terminates the aforementioned series of processes.

[0058] <The Role of the First Implementation Method>

[0059] With the same VN opening OP, the smaller the air-fuel ratio λ of the mixture, the greater the increase in exhaust energy with the increase in fuel composition. This results in higher turbocharger driving force and higher boost pressure. When the target air-fuel ratio λE is small, the control device 11 changes the VN opening OP, increasing the clearance between the nozzle blades 40N of the VN turbocharger 40. The control device 11 suppresses the increase in boost pressure caused by the decrease in air-fuel ratio λ by changing the VN opening OP in accordance with the change in the target air-fuel ratio λE.

[0060] <Effects of the First Implementation Method>

[0061] (1-1) According to the control device 11, when the air-fuel ratio λ decreases, it is possible to prevent the boost pressure from becoming too large compared to the target boost pressure.

[0062] (1-2) Based on the required torque DT, processing circuit 12 determines the target value of the intake air flow rate introduced into VN turbocharger 40, i.e., the target intake air flow rate QI. Processing circuit 12 refers to a two-dimensional opening mapping that corresponds to the combination of target boost pressure PB and target intake air flow rate QI under the condition that the air-fuel ratio λ is the reference air-fuel ratio λS. Processing circuit 12 refers to the two-dimensional opening mapping to obtain the reference VN opening rate OS corresponding to the target boost pressure PB and target intake air flow rate QI. Processing circuit 12 uses a correction coefficient L based on the λ ratio to correct the reference VN opening rate OS in such a way that the larger the λ ratio, the larger the gap between the nozzle blades 40N. Then, processing circuit 12 changes the VN opening rate OP to the corrected opening rate, i.e., the corrected VN opening rate OR.

[0063] In the two-dimensional opening mapping, there is a predetermined reference VN opening degree OS corresponding to the two parameters of target boost pressure PB and target intake air flow rate QI. The reference VN opening degree OS is defined as follows: when the air-fuel ratio λ is the reference air-fuel ratio λS, the VN opening degree OP becomes the appropriate opening degree relative to the target boost pressure PB and target intake air flow rate QI.

[0064] Control device 11 obtains a VN opening OP, i.e., a reference VN opening OS, suitable when the air-fuel ratio λ is the reference air-fuel ratio λS, by referring to a two-dimensional opening mapping. Control device 11 uses a correction coefficient L to correct the reference VN opening OS. When the target air-fuel ratio λE is less than the reference air-fuel ratio λS, control device 11 corrects the VN opening OP towards the side that suppresses the rise in boost pressure. According to control device 11, by using a simple correction process of the ratio of air-fuel ratios λ, i.e., the λ ratio, a VN opening OP suitable for the target air-fuel ratio λE can be achieved.

[0065] (1-3) The reference air-fuel ratio λS is the maximum value among the target air-fuel ratio λE values ​​that can be set in the engine 20. When the vehicle 10 is accelerating, the processing circuit 12 does not perform correction on the reference VN opening OS using the correction coefficient L, but changes the VN opening OP to the reference VN opening OS corresponding to the target boost pressure PB and the target intake air flow rate QI.

[0066] When the reference air-fuel ratio λS is the maximum value among the target air-fuel ratio λE that can be set, the reference air-fuel ratio λS is the largest air-fuel ratio λ among the air-fuel ratios λ of the mixture burned in the engine 20. Therefore, when the VN opening OP is changed to the reference VN opening OS, the boost pressure is more likely to rise compared to the case where the VN opening OP is changed according to the target boost pressure PB.

[0067] When the vehicle accelerates to 10, there is a delay in the rise of boost pressure, resulting in insufficient intake air relative to the hydrogen injected into cylinder 21B and a smaller target air-fuel ratio λE. If the gap between the nozzle blades 40N is increased accordingly to the decrease in air-fuel ratio λ, the rise of boost pressure is suppressed, thereby causing further intake insufficiency.

[0068] When the vehicle 10 accelerates, the control device 11 does not perform corrections corresponding to the target air-fuel ratio λE, but instead fixes the VN opening OP to the reference VN opening OS, making it easier for the boost pressure to rise. According to the control device 11, the boost pressure is promoted to rise during acceleration, making it easier to utilize the output of the engine 20.

[0069] <Second Implementation Method>

[0070] Next, refer to Figure 5 and Figure 6 A second embodiment of the control device 11 will be described. In the following description, the differences from the first embodiment will be mainly explained. Details of the parts identical to the first embodiment will be omitted. The difference between the second and first embodiments is that the processing circuit 12 obtains the VN opening indication value OC by referring to a three-dimensional opening mapping. The storage device 13 stores the three-dimensional opening mapping instead of the two-dimensional opening mapping and the λ correction mapping.

[0071] Figure 5 This describes the processing performed by the processing circuit 12 in the second embodiment when the VN opening degree OP is changed. The processing circuit 12, like in the first embodiment, repeatedly executes the process, for example, at a cycle shorter than the fuel injection interval in each cylinder 21B. Figure 5 The series of processes shown. Figure 5 The letter "S" shown is an abbreviation for "step" in a series of processes.

[0072] In S500, processing circuit 12 calculates the required torque DT. In S510, processing circuit 12 determines the fuel injection quantity QF and the target air-fuel ratio λE. In S520, processing circuit 12 calculates the required air quantity QA. In S530, processing circuit 12 calculates the target intake air flow rate QI. In S540, processing circuit 12 calculates the target boost pressure PB. The processes performed by processing circuit 12 in S500 to S540 are respectively related to... Figure 2 The processing in S100~S140 is the same.

[0073] In S550, the processing circuit 12 determines whether the vehicle 10 is accelerating, similar to the first embodiment. If the processing circuit 12 determines that the vehicle 10 is not accelerating (S550; No), the processing proceeds to S560. If the processing circuit 12 determines that the vehicle 10 is accelerating (S550; Yes), the processing proceeds to S570.

[0074] In S560, in the processing after S580, the processing circuit 12 decides to use the target air-fuel ratio λE determined in S510 as the target air-fuel ratio λE.

[0075] On the other hand, in S570, the processing circuit 12 determines, in the processing after S580, to use the maximum air-fuel ratio λM as the target air-fuel ratio λE. The maximum air-fuel ratio λM is the maximum value of the target air-fuel ratio λE that can be set in the engine 20.

[0076] Then, in S580, the processing circuit 12 obtains the VN opening indication value OC by referring to the three-dimensional opening mapping. The VN opening indication value OC is the same as in the first embodiment, which is the signal value sent by the processing circuit 12 to the variable nozzle mechanism 40V as the value of the opening that should be changed for the VN opening OP.

[0077] Figure 6 This is a block diagram of the processing circuit 12 obtaining the VN opening indication value OC by referring to a three-dimensional opening mapping. The three-dimensional opening mapping is stored in the storage device 13 of the control device 11. Alternatively, the three-dimensional opening mapping can also be stored in the ROM of the processing circuit 12. In the three-dimensional opening mapping, for each combination of the values ​​of the target intake air flow rate QI, the target boost pressure PB, and the target air-fuel ratio λE, the VN opening value OP that is most suitable for achieving the target boost pressure PB is defined in the target air-fuel ratio λE and the target intake air flow rate QI.

[0078] like Figure 6As shown, the processing circuit 12, referring to a three-dimensional opening mapping, obtains the VN opening indication value OC as the VN opening OP corresponding to the target intake air flow rate QI, the target boost pressure PB, and the target air-fuel ratio λE. Specifically, the processing circuit 12, referring to the three-dimensional opening mapping, obtains the VN opening indication value OC corresponding to the combination of the target air-fuel ratio λE determined in S510, the target intake air flow rate QI determined in S530, and the target boost pressure PB determined in S540. Furthermore, if it is determined in S550 that the vehicle 10 is accelerating, the processing circuit 12 uses the maximum air-fuel ratio λM as the target air-fuel ratio λE for processing in S580.

[0079] In S590, the processing circuit 12 sends a control signal containing the VN opening indication value OC to the variable nozzle mechanism 40V, changing the VN opening OP to the VN opening indication value OC. Thus, the processing circuit 12 changes the VN opening OP to the VN opening OP determined based on the required torque DT. When the processing in S590 is executed, the processing circuit 12 terminates the aforementioned series of processes.

[0080] <Function of the Second Implementation Method>

[0081] In the three-dimensional opening mapping, there are predetermined VN opening indication values ​​OC corresponding to three parameters: target air-fuel ratio λE, target boost pressure PB, and target intake air flow rate QI. The VN opening indication value OC is defined as the VN opening OP being an appropriate opening relative to the target air-fuel ratio λE, target boost pressure PB, and target intake air flow rate QI. The control device 11 obtains VN opening indication values ​​OC suitable for the target air-fuel ratio λE, target boost pressure PB, and target intake air flow rate QI respectively by referring to the three-dimensional opening mapping. The VN opening indication value OC is also optimized relative to the target air-fuel ratio λE.

[0082] <Effects of the Second Implementation>

[0083] In addition to the effects of the first embodiment (1-1), the second embodiment also has the following effects.

[0084] (2-1) Based on the required torque DT, the processing circuit 12 determines the target value of the intake air flow rate, i.e., the target intake air flow rate QI, introduced into the VN turbocharger 40. The processing circuit 12 refers to a pre-defined three-dimensional opening mapping corresponding to the VN opening OP of the combination of the target air-fuel ratio λE, the target boost pressure PB, and the target intake air flow rate QI, and obtains a VN opening indication value OC corresponding to the target air-fuel ratio λE, the target boost pressure PB, and the target intake air flow rate QI. The processing circuit 12 changes the VN opening OP to the obtained VN opening indication value OC. According to the control device 11, by referring to the three-dimensional opening mapping, a VN opening OP suitable for the target air-fuel ratio λE can be achieved.

[0085] (2-2) When the vehicle 10 is accelerating, the processing circuit 12 uses the maximum value of the target air-fuel ratio λE that can be set in the engine 20, namely the maximum air-fuel ratio λM, as the target air-fuel ratio λE value when referring to the three-dimensional opening mapping. The processing circuit 12 refers to the three-dimensional opening mapping, obtains the VN opening indication value OC corresponding to the maximum air-fuel ratio λM, the target boost pressure PB, and the target intake air flow rate QI, and changes the VN opening OP to the obtained VN opening indication value OC.

[0086] The maximum air-fuel ratio λM is the largest air-fuel ratio λ among the air-fuel ratios λ of the mixture burned in the engine 20. Therefore, when the maximum air-fuel ratio λM is set as the target air-fuel ratio λE and the VN opening OP is changed with reference to the three-dimensional opening mapping, the boost pressure tends to rise more easily compared to the case where the VN opening OP is changed based on the target air-fuel ratio λE determined by the required torque DT.

[0087] When the vehicle accelerates to 10, there is a delay in the rise of boost pressure, resulting in insufficient intake air relative to the hydrogen injected into cylinder 21B and a smaller target air-fuel ratio λE. If the gap between the nozzle blades 40N is increased accordingly to the decrease in air-fuel ratio λ, the rise of boost pressure is suppressed, thereby causing further intake insufficiency.

[0088] When the vehicle 10 accelerates, the control device 11 fixes the VN opening OP to the VN opening OP when the target air-fuel ratio λE is the maximum air-fuel ratio λM, making it easier for the boost pressure to rise. According to the control device 11, the boost pressure is promoted to rise during acceleration, making it easier to utilize the output of the engine 20.

[0089] <Example of Change>

[0090] Furthermore, the following elements are common to the modifications made in the above embodiments. The following modifications can be combined and implemented within a technically compatible framework.

[0091] The processing circuit 12 determines whether the vehicle 10 is accelerating in S160 and S550. The processing circuit 12 can also determine whether the engine 20 is being boosted in S160 and S550. For example, if the processing circuit 12 determines in S160 that the engine 20 is being boosted, it proceeds to S170; conversely, if it determines in S160 that the engine 20 is not being boosted, it proceeds to S210. Therefore, when the engine 20 is operating in a naturally aspirated state without boosting, correction using the correction factor L can be avoided. In the modified control device 11, when the engine 20 is not being boosted, the process of changing the VN opening OP can be simplified.

[0092] The processing circuit 12 can also change the VN opening degree OP based on the target air-fuel ratio λE and the target boost pressure PB. For example, the processing circuit 12 can also change the VN opening degree OP for each combination of the target air-fuel ratio λE and the target boost pressure PB by referring to a two-dimensional mapping that specifies the optimal VN opening degree OP value for achieving the target boost pressure PB at the target air-fuel ratio λE. In this two-dimensional mapping, the value of VN opening degree OP is specified according to the relationship that the smaller the target air-fuel ratio λE, the smaller the VN opening degree OP.

Claims

1. A vehicle control device for controlling a vehicle, wherein, The vehicle has the following features: An internal combustion engine having a fuel injection device that supplies hydrogen as fuel into the cylinder; and Variable capacity intensifiers adjust the boost pressure by changing the opening of the nozzle blades. The vehicle control device includes processing circuitry. The processing circuit determines the target air-fuel ratio and target boost pressure based on the required torque. The target air-fuel ratio is a target value for the air-fuel ratio of the mixture burned in the cylinder, and the target boost pressure is a target value for the boost pressure. The processing circuit is configured to change the opening degree based on the target air-fuel ratio and the target boost pressure, so that the smaller the target air-fuel ratio, the larger the gap between the nozzle blades.

2. The vehicle control device according to claim 1, wherein, The processing circuit is configured as follows: The target intake flow rate is determined based on the required torque; the target intake flow rate is a target value for the flow rate of intake air introduced into the turbocharger. The reference opening degree, corresponding to the target boost pressure and the target intake air flow rate, is obtained by referring to a predefined two-dimensional mapping of the reference opening degree. The reference opening degree is the opening degree corresponding to the combination of the target boost pressure and the target intake air flow rate when the air-fuel ratio is a reference air-fuel ratio defined as a reference in the internal combustion engine. The reference opening is corrected using a correction factor defined based on the ratio of the reference air-fuel ratio to the target air-fuel ratio, such that a larger ratio of the reference air-fuel ratio to the target air-fuel ratio results in a larger gap between the nozzle blades. Change the opening degree to the corrected opening degree.

3. The vehicle control device according to claim 2, wherein, The reference air-fuel ratio is the maximum value among the target air-fuel ratio values ​​that can be set in the internal combustion engine. The processing circuit is configured to, when the vehicle is accelerating, not perform correction on the reference opening using the correction coefficient, but change the opening to the reference opening corresponding to the target boost pressure and the target intake air flow.

4. The vehicle control device according to claim 1, wherein, The processing circuit is configured as follows: The target intake flow rate is determined based on the required torque; the target intake flow rate is a target value for the flow rate of intake air introduced into the turbocharger. The opening degree corresponding to the target air-fuel ratio, target boost pressure, and target intake flow rate is obtained by referring to a three-dimensional mapping that predefines the combination of the target air-fuel ratio, target boost pressure, and target intake flow rate. Change the opening degree to the obtained opening degree.

5. The vehicle control device according to claim 4, wherein, The processing circuit is configured as follows: When the vehicle is accelerating, and referring to the three-dimensional mapping, the maximum value among the target air-fuel ratio values ​​that can be set in the internal combustion engine is used as the target air-fuel ratio value. Referring to the aforementioned three-dimensional mapping, the opening degree corresponding to the maximum value of the target air-fuel ratio, the target boost pressure, and the target intake flow rate is obtained. Change the opening degree to the obtained opening degree.

6. A vehicle control method for controlling a vehicle, wherein, The vehicle has the following features: An internal combustion engine has a fuel injection device that supplies hydrogen as fuel into the cylinder; and Variable capacity intensifiers adjust the boost pressure by changing the opening of the nozzle blades. The vehicle control method includes: The target air-fuel ratio and target boost pressure are determined based on the required torque. The target air-fuel ratio is a target value for the air-fuel ratio of the mixture burned in the cylinder, and the target boost pressure is a target value for the boost pressure. and The opening is adjusted based on the target air-fuel ratio and the target boost pressure, such that the smaller the target air-fuel ratio, the larger the gap between the nozzle blades.

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