Control system for hybrid vehicles

Abstract

This invention provides a technology for a hybrid vehicle control system that adjusts the fuel injection amount to enable the hybrid vehicle to operate with NOx emissions below a threshold level. [Solution] A control device for a hybrid vehicle, comprising: an information collection unit that collects state information including the current injection amount; a torque calculation unit that determines a suitable injection amount and calculates a suitable engine torque using the state information; and a setting unit that sets the suitable engine torque. The torque calculation unit determines the current injection amount as the suitable injection amount if the current estimated amount estimated based on the state information is less than a threshold amount, and if the current estimated amount is greater than the threshold amount, it estimates a first estimated amount which is an estimated amount of NOx emissions when fuel is injected at the first injection amount, and then determines the suitable injection amount based on a regression analysis model created using the current injection amount and the current estimated amount, and the first injection amount and the first estimated amount.

Description

[Technical Field]

[0001] The present invention relates to a control device for a hybrid vehicle. [Background Art]

[0002] Conventionally, hybrid vehicles using an engine and a motor generator as drive sources are known. In such a hybrid vehicle, as disclosed in Patent Document 1, the engine and the motor generator each share the load to meet the required torque demanded during acceleration. [Prior Art Documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Unexamined Patent Publication No. 2015-77897 [Summary of the Invention] [Problem to be Solved by the Invention]

[0004] One of the parameters that determines the amount of NOx discharged to the outside of a hybrid vehicle is the fuel injection amount into the engine. The NOx emission amount tends to increase as the fuel injection amount increases. However, in a hybrid vehicle like that disclosed in Patent Document 1, sufficient consideration has not been given to adjusting the fuel injection amount so that the NOx emission amount is less than a threshold amount.

[0005] The present invention has been made to solve at least part of the above-described problems, and an object of the present invention is to provide a technique in a control device for a hybrid vehicle that can allow the hybrid vehicle to travel with a NOx emission amount less than a threshold amount by adjusting the fuel injection amount. [Means for Solving the Problem]

[0006] The present invention has been made to solve at least part of the above-described problems, and can be implemented as the following aspects.

[0007] (1) According to one embodiment of the present invention, a control device for a hybrid vehicle is provided. This control device includes an information collection unit that collects state information indicating the current operating state of the engine, which includes at least the current injection amount currently being injected as the fuel injection amount in the engine; a torque calculation unit that uses the state information to determine a suitable injection amount, which is the injection amount at which NOx emissions are less than a threshold amount, and calculates a suitable engine torque, which is the engine torque when the fuel is injected with the suitable injection amount; and a torque calculation unit that sets the suitable engine torque as the engine torque to be output by the engine, and according to the difference between the suitable engine torque and the required torque required for the hybrid vehicle, The torque calculation unit includes a setting unit for setting the motor generator torque to be output by the motor generator, and if the current estimated amount, which is an estimated amount of the current NOx emissions estimated based on the state information, is less than the threshold amount, the torque calculation unit determines the current injection amount as the preferred injection amount, and if the current estimated amount is greater than the threshold amount, it estimates a first estimated amount, which is an estimated amount of NOx emissions when the fuel is injected with a first injection amount less than the current injection amount, and then determines the preferred injection amount based on a regression analysis model created using the current injection amount and the current estimated amount, and the first injection amount and the first estimated amount.

[0008] This configuration allows for the accurate creation of a regression analysis model that estimates NOx emissions based on the fuel injection amount. Since fuel is injected into the engine at an adjusted amount determined by this highly accurate regression analysis model, the hybrid vehicle can be driven with NOx emissions below the threshold. Furthermore, when fuel is injected into the engine at an adjusted amount that results in NOx emissions close to the threshold, it is possible to maximize the amount of engine torque that meets the required torque while keeping NOx emissions below the threshold.

[0009] (2) In the control device of the above form, if the current estimated amount is greater than the threshold amount and the first estimated amount is greater than the threshold amount, the torque calculation unit estimates a second estimated amount which is an estimated amount of NOx emissions when the fuel is injected with a second injection amount which is less than the first injection amount, and the current injection amount and the current estimated amount, the first injection amount and the first estimated amount, and the second injection amount and the second estimated amount may be used to create the regression analysis model. In this configuration, the NOx emission estimates used to create the regression analysis model include three different estimates (current estimate, first estimate, and second estimate). Therefore, based on the regression analysis model created using these three injection rates, the optimal injection rate can be determined with high accuracy.

[0010] (3) In the control device of the above form, if the current estimated amount is greater than the threshold amount and the first estimated amount is greater than the threshold amount, the torque calculation unit searches for a combination of a second injection amount less than the first injection amount and a second estimated amount which is an estimated amount of NOx emissions when the fuel is injected with the second injection amount and is less than the threshold amount. The current injection amount and the current estimated amount, the first injection amount and the first estimated amount, and the second injection amount and the second estimated amount may be used to create the regression analysis model. According to this configuration, the NOx emission estimates used to create the regression analysis model include estimates of NOx emissions above the threshold (current estimate and first estimate) and estimates of NOx emissions below the threshold (second estimate). Therefore, based on a regression analysis model created using these three injection rates, the optimal injection rate can be determined with high accuracy.

[0011] (4) In the control device of the above form, if the current estimated amount is greater than the threshold amount and the first estimated amount is less than the threshold amount, the torque calculation unit estimates a third estimated amount which is an estimated amount of NOx emissions when the fuel is injected with a third injection amount that is greater than the first injection amount and less than the current injection amount, and the current injection amount and the current estimated amount, the first injection amount and the first estimated amount, and the third injection amount and the third estimated amount may be used to create the regression analysis model. According to this configuration, the NOx emission estimates used to create the regression analysis model include a current estimate that is greater than the threshold, a first estimate that is less than the threshold, and a third estimate that is greater than the first estimate. Therefore, based on a regression analysis model created using these three injection rates, the optimal injection rate can be determined with high accuracy.

[0012] (5) In the control device of the above form, the torque calculation unit may determine the preferred injection amount using a corrected threshold amount, which is a threshold amount corrected according to the purification rate of the catalyst that purifies the exhaust gas from the engine. With this configuration, the optimal injection amount can be determined using a corrected threshold amount adjusted according to the catalyst's purification rate. Since the corrected threshold amount is a value adjusted according to the catalyst's purification rate, even if fuel is injected with the optimal injection amount determined based on the corrected threshold amount, the NOx emissions can be reduced below the threshold amount due to catalyst purification. Therefore, it is possible to maximize the amount of engine torque that satisfies the required torque while keeping NOx emissions below the threshold amount, according to the catalyst's purification rate.

[0013] (6) In the control device of the above form, if the amount of charge stored in the secondary battery that supplies power to the motor generator and stores the power generated by the motor generator is greater than a preset set amount of charge, the setting unit may set the preferred engine torque by decreasing it and the motor generator torque by increasing it. With this configuration, if the amount of charge stored in the secondary battery is greater than a preset storage amount, the amount of torque that is satisfied by the motor-generator torque can be increased while reducing the amount that is satisfied by the suitable engine torque relative to the required torque. As a result, NOx emissions can be reduced.

[0014] (7) In the control device of the above form, in the engine, multi-stage injection of the fuel is performed in one combustion process, and when the sum of the injection amounts of each injection in the multi-stage injection is called the total injection amount, the current injection amount represents the current total injection amount, the preferred injection amount represents the total injection amount at which the NOx emission amount is less than the threshold amount, and the first injection amount may represent the total injection amount that is less than the current injection amount. In this configuration, the current injection amount, preferred injection amount, and first injection amount are all parameters related to the total injection amount, and the preferred engine torque is calculated based on these parameters related to the total injection amount. Therefore, the preferred engine torque can be determined with high accuracy.

[0015] (8) In the control device of the above form, the engine may perform multi-stage injection of the fuel in one combustion process, and when the fuel is injected at the preferred injection amount, the injection amount and injection timing of each injection which are suitable for the multi-stage injection may be derived, and the engine may be operated with said injection amount and injection timing. With this configuration, EG torque can be obtained with multi-stage injection amounts and injection amounts that match the optimal injection amount, thus enabling operation with reduced engine noise.

[0016] (9) In the control device of the above form, in the engine, multi-stage injection of the fuel is performed in one combustion process, and when the injection amount at the time of the injection with the largest injection amount among the multi-stage injections is defined as the main injection amount, the current injection amount may represent the current main injection amount, the preferred injection amount may represent the main injection amount at which the NOx emission amount is less than the threshold amount, and the first injection amount may represent the main injection amount that is less than the current injection amount. According to this configuration, the load required for calculating the optimal injection amount can be reduced compared to the case where the current injection amount, the optimal injection amount, and the first injection amount are all parameters related to the total injection amount.

[0017] Note that the present invention can be implemented in various aspects, for example, in the form of a hybrid vehicle equipped with the control device, a control method for a hybrid vehicle, and the like. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] [Figure 1] It is an explanatory diagram illustrating the configuration of the control device according to the first embodiment. [Figure 2] It is a flowchart showing the procedure of torque setting processing executed by the control device. [Figure 3] It is an explanatory diagram illustrating a regression analysis model. [Figure 4] It is an explanatory diagram showing NOx emissions in the control device according to the first embodiment. [Figure 5] It is an explanatory diagram showing NOx emissions in the control device of a comparative example. [Figure 6] It is an explanatory diagram illustrating the configuration of the control device according to the second embodiment. [Figure 7] It is an explanatory diagram comparing calculation times required until calculation of optimal EG torque. [Figure 8] It is an explanatory diagram illustrating the configuration of the control device according to the third embodiment. MODE FOR CARRYING OUT THE INVENTION

[0019] <First Embodiment> FIG. 1 is an explanatory diagram illustrating the configuration of a hybrid vehicle 1 including a control device 20 (details will be described later) according to the first embodiment. In addition to the control device 20, the hybrid vehicle 1 includes an engine 11, a clutch C attached to the engine 11, a transmission 12, a propeller shaft 13, a differential gear 14, a drive shaft 15, tires 16, a motor generator 17, and a secondary battery 18.

[0020] In the hybrid vehicle 1, the engine torque (hereinafter referred to as EG torque) output from the engine 11 is transmitted to the propeller shaft 13 as axle torque. During powering, the motor-generator torque (hereinafter referred to as MG torque) output from the motor-generator 17 using power supplied from the secondary battery 18 is also transmitted to the propeller shaft 13 as axle torque. The axle torque is transmitted to the tires 16 as driving torque via the differential gear 14 and the drive shaft 15. Thus, the hybrid vehicle 1 uses the engine 11 and the motor-generator 17 as power sources. In this embodiment, the engine 11 performs multi-stage fuel injection in a single combustion cycle.

[0021] On the other hand, during regeneration, the axle torque is transmitted to the motor generator 17 as MG torque. This MG torque is used to generate electricity with the motor generator 17. At this time, the engine 11 and the transmission 12 are disconnected by the clutch C. The electricity generated by the motor generator 17 is used to charge the secondary battery 18. In this way, the secondary battery 18 supplies power to the motor generator 17 during powering and stores the electricity generated by the motor generator 17 during regeneration.

[0022] The control device 20 includes a setting unit 21, an EG drive control unit 23, an MG drive control unit 25, and a torque calculation unit 27. The setting unit 21 sets the EG torque and MG torque according to the requested torque requested by the hybrid vehicle 1. In this embodiment, the requested torque is calculated by the setting unit 21, which detects the amount the accelerator pedal (not shown) of the hybrid vehicle 1 is pressed. When calculating the requested torque, the setting unit 21 refers to a map showing the correspondence between the amount the accelerator pedal is pressed and the requested torque.

[0023] The EG drive control unit 23 drives the engine 11 according to the EG torque set by the setting unit 21. The EG drive control unit 23 also acts as an information collection unit, collecting state information that indicates the current operating state of the engine 11. The state information includes at least the current injection amount CJ (not shown in Figure 1), which is the amount of fuel currently being injected into the engine 11. In this embodiment, when the total injection amount is defined as the sum of the injection amounts of each injection in the multi-stage injection of the engine 11, the current injection amount CJ represents the current total injection amount. In addition to the current injection amount CJ, the state information includes the injection amount and timing of each injection in the multi-stage injection, rotational speed, EGR rate, oxygen concentration, A / F ratio, coolant temperature, intake air volume, intake air temperature, boost pressure, fuel temperature, etc. The injection amount and timing of each injection among the state information are appropriately set by the EG drive control unit 23 according to the EG torque set in the setting unit 21. The EG drive control unit 23 periodically collects status information while the hybrid vehicle 1 is in operation and transmits signals indicating this information to the torque calculation unit 27, which will be described later.

[0024] The MG drive control unit 25 drives the motor generator 17 according to the MG torque set by the setting unit 21. The torque calculation unit 27 uses the state information collected by the EG drive control unit 23 to calculate a suitable engine torque (hereinafter referred to as the suitable EG torque) that the setting unit 21 refers to when setting the EG torque. Details of the suitable EG torque and its calculation method will be described later.

[0025] Figure 2 is a flowchart showing the procedure for the torque setting process performed by the control device 20. The torque setting process is the process of setting the EG torque and MG torque according to the requested torque. The torque setting process is performed periodically while the hybrid vehicle 1 is running. When the torque setting process is started, the setting unit 21 first calculates the requested torque (step S11).

[0026] Next, the EG drive control unit 23 acquires state information (step S12) and then transmits that state information to the torque calculation unit 27. Based on the received state information, the torque calculation unit 27 estimates the current estimated amount CE, which is the estimated amount of NOx emissions currently emitted to the outside of the hybrid vehicle 1 (step S13). The torque calculation unit 27 stores a map showing the correspondence between state information and estimated NOx emissions. The torque calculation unit 27 estimates the current estimated amount CE by applying the state information to this map. It should be noted that the current estimated amount CE can also be said to be the estimated amount of NOx emissions when fuel is injected at the current injection amount CJ.

[0027] Next, the torque calculation unit 27 determines whether the current estimated amount CE is greater than the threshold amount TE (step S14). The threshold amount TE is the NOx emission amount set considering exhaust emission regulations, etc. If the current estimated amount CE is less than the threshold amount TE (step S14: NO), the torque calculation unit 27 determines the current injection amount CJ as the preferred injection amount (step S15). The preferred injection amount is the injection amount at which the NOx emission amount is less than the threshold amount TE. In this embodiment, the preferred injection amount represents the total injection amount at which the NOx emission amount is less than the threshold amount TE.

[0028] On the other hand, if the current estimated amount CE is greater than the threshold amount TE (step S14: YES), the torque calculation unit 27 estimates a first estimated amount 1E, which is the estimated amount of NOx emissions when fuel is injected with a first injection amount 1J that is less than the current injection amount CJ (step S16). In this embodiment, the first injection amount 1J corresponds to half the injection amount of the current injection amount CJ, and also represents a total injection amount that is less than the current injection amount CJ. Specifically, in step S16, the torque calculation unit 27 estimates the first estimated amount 1E by applying updated state information, obtained by updating only the current injection amount CJ to the first injection amount 1J from the state information used to estimate the current estimated amount CE in step S13, to a map showing the correspondence between state information and estimated NOx emissions.

[0029] Next, the torque calculation unit 27 determines whether the first estimated amount 1E is greater than the threshold amount TE (step S17). If the first estimated amount 1E is greater than the threshold amount TE (step S17: YES), the torque calculation unit 27 estimates the second estimated amount 2E, which is the estimated amount of NOx emissions when fuel is injected with a second injection amount 2J that is less than the first injection amount 1J (step S18). In this embodiment, the second injection amount 2J corresponds to an injection amount that is 1 / 4 of the current injection amount CJ, and represents a total injection amount that is less than the current injection amount CJ. Specifically, in step S18, the torque calculation unit 27 estimates the second estimated amount 2E by applying the updated state information, which is obtained by updating only the current injection amount CJ to the second injection amount 2J from the state information used to estimate the current estimated amount CE in step S13, to a map showing the correspondence between state information and estimated NOx emissions.

[0030] On the other hand, if the first injection amount 1J is less than the threshold amount TE (step S17: NO), the torque calculation unit 27 estimates a third estimated amount 3E, which is an estimated amount of NOx emissions when fuel is injected with a third injection amount 3J that is more than the first injection amount 1J and less than the current injection amount CJ (step S19). In this embodiment, the third injection amount 3J corresponds to 3 / 4 of the current injection amount CJ and represents a total injection amount that is less than the current injection amount CJ. Specifically, in step S19, the torque calculation unit 27 estimates the third estimated amount 3E by applying updated state information, obtained by updating only the current injection amount CJ to the third injection amount 3J from the state information used to estimate the current estimated amount CE in step S13, to a map showing the correspondence between state information and estimated NOx emissions. Thus, the torque calculation unit 27 can be considered a predictive device for predicting NOx emissions, as it estimates the first estimated amount 1E to the third estimated amount 3E, which are estimated amounts of NOx emissions, based on state information.

[0031] After estimating the second estimator 2E (step S18) or the third estimator 3E (step S19), the torque calculation unit 27 creates a regression analysis model (step S20). The regression analysis model is a function with fuel injection amount (total injection amount in this embodiment) as the explanatory variable and NOx emissions as the dependent variable. If the second estimator 2E was estimated (step S18), the current injection amount CJ and current estimator CE, the first injection amount 1J and first estimator 1E, and the second injection amount 2J and second estimator 2E are used to create the regression analysis model. If the third estimator 3E was estimated (step S19), the current injection amount CJ and current estimator CE, the first injection amount 1J and first estimator 1E, and the third injection amount 3J and third estimator 3E are used to create the regression analysis model.

[0032] Figure 3 is an explanatory diagram illustrating a regression analysis model. In Figure 3, the regression equation representing the correspondence between fuel injection amount (total injection amount in this embodiment) and NOx emissions is shown as a solid line SL, as an example of a regression analysis model. Points P1 to P3 represent various data used to create the regression analysis model. For example, if the second estimator 2E was estimated (step S18), point P1 represents the data for the combination of the current injection amount CJ and the current estimator CE, point P2 represents the data for the combination of the first injection amount 1J and the first estimator 1E, and point P3 represents the data for the combination of the second injection amount 2J and the second estimator 2E. If the third estimator 3E was estimated (step S19), point P1 represents the data for the combination of the current injection amount CJ and the current estimator CE, point P2 represents the data for the combination of the third injection amount 3J and the third estimator 3E, and point P3 represents the data for the combination of the first injection amount 1J and the first estimator 1E.

[0033] After creating a regression analysis model as shown in Figure 3 (step S20), the torque calculation unit 27 determines the optimal injection amount (the injection amount at which NOx emissions are less than the threshold amount TE) based on this regression analysis model (step S21). Using Figure 3, the torque calculation unit 27 finds the intersection IS between the threshold amount TE (shown by the dashed line) and the solid line SL, and determines the injection amount at or below the injection amount IJ at that intersection IS as the optimal injection amount OJ. Through the series of processes from steps S13 to S21 described above, the torque calculation unit 27 determines the optimal injection amount using state information. State information is used, for example, in the processes of steps S13, 16, 18, and 19.

[0034] After determining the optimal injection amount based on a regression analysis model (step S21) or after determining the currently estimated amount CE as the optimal injection amount (step S15), the torque calculation unit 27 calculates the optimal EG torque, which is the engine torque when fuel is injected at the optimal injection amount (step S22). In this embodiment, the optimal EG torque is calculated as the EG torque when fuel is injected at the maximum injection amount (shown as injection amount IJ in Figure 3) among the optimal injection amounts OJ (see Figure 3). Specifically, in step S22, the torque calculation unit 27 calculates the optimal EG torque by applying the optimal injection amount to a map showing the correspondence between the fuel injection amount and EG torque in the engine 11. Such a map is pre-stored in the torque calculation unit 27. Information indicating the optimal EG torque calculated by the torque calculation unit 27 is transmitted to the setting unit 21.

[0035] Upon receiving information indicating the optimal EG torque, the setting unit 21 determines the distribution of the required torque (step S23). The engine 11 and the motor generator 17 (see Figure 1) are responsible for responding to the required torque. Specifically, in step S23, the setting unit 21 sets the optimal EG torque as the EG torque to be output by the engine 11, and sets the MG torque to be output by the motor generator 17 according to the difference between the optimal EG torque and the required torque requested by the hybrid vehicle 1. If the required torque is greater than the optimal EG torque, the setting unit 21 sets the torque corresponding to the difference between the required torque and the optimal EG torque as the MG torque. On the other hand, if the required torque can be met with the optimal EG torque alone, the MG torque is either not set or set to 0. After executing the process in step S23, the torque setting process executed by the control device 20 is completed.

[0036] Figure 4 is an explanatory diagram showing NOx emissions from a hybrid vehicle equipped with the control device of the comparative example. Figure 5 is an explanatory diagram showing NOx emissions from a hybrid vehicle 1 equipped with the control device 20 of the first embodiment. The horizontal axis in Figures 4 and 5 represents the elapsed time during driving, and the vertical axis in Figures 4 and 5 represents NOx emissions. In addition, the threshold amount TE is shown as a dashed line in both Figures 4 and 5. As shown in Figure 4, with the control device of the comparative example, which does not perform fuel injection control at the optimal injection amount OJ, NOx emissions may momentarily exceed the threshold amount TE. On the other hand, as shown in Figure 5, with the control device 20 of the first embodiment, NOx emissions are always maintained at an amount lower than the threshold amount TE.

[0037] According to the control device 20 of the first embodiment described above, a regression analysis model that estimates NOx emissions based on the fuel injection amount can be accurately created. Since fuel is injected into the engine 11 at an injection amount adjusted to a suitable injection amount OJ determined based on such a highly accurate regression analysis model, the hybrid vehicle can be driven with NOx emissions lower than the threshold amount TE. In addition, in this embodiment, since fuel is injected into the engine 11 at the maximum injection amount within the suitable injection amount OJ (see Figure 3), it is possible to maximize the portion of the required torque that is satisfied by the engine torque while keeping NOx emissions below the threshold amount TE. Note that fuel may be injected into the engine 11 at any injection amount as long as it is less than or equal to the suitable injection amount OJ. Furthermore, with such a regression analysis model, NOx emissions can be estimated based on the fuel injection amount even under unusual environmental conditions such as low temperature environments.

[0038] Furthermore, in the control device 20 of the first embodiment, when the first estimator 1E is greater than the threshold amount TE (step S17: YES), the NOx emission estimate used to create the regression analysis model includes three different estimators (current estimator CE, first estimator 1E, and second estimator 2E). Therefore, based on the regression analysis model created using these three injection amounts, the preferred injection amount OJ can be determined with high accuracy.

[0039] Furthermore, in this embodiment, since the second injection amount 2J corresponds to 1 / 4 of the current injection amount CJ, there is a high probability that the second estimated amount 2E will be less than the threshold amount TE. When the second estimated amount 2E is less than the threshold amount TE, the current estimated amount CE and the first estimated amount 1E, which are greater than the threshold amount TE, and the second estimated amount 2E, which is less than the threshold amount TE, will be used to create the regression analysis model. Therefore, based on the regression analysis model created using these three injection amounts, the optimal injection amount OJ can be determined with high accuracy.

[0040] Furthermore, in the control device 20 of the first embodiment, when the first estimator 1E is less than the threshold amount TE, the NOx emission estimate used to create the regression analysis model includes the current estimate CE, which is greater than the threshold amount TE; the first estimator 1E, which is less than the threshold amount TE; and the third estimator 3E, which is greater than the first estimator 1E. Therefore, based on the regression analysis model created using these three injection amounts, the optimal injection amount OJ can be determined with high accuracy.

[0041] Furthermore, in this embodiment, since the third injection amount 3J corresponds to 3 / 4 of the current injection amount CJ, there is a high probability that the third estimated amount 3E will be greater than the threshold amount TE. When the third estimated amount 3E is greater than the threshold amount TE, the current estimated amount CE and the third estimated amount 3E, which are greater than the threshold amount TE, and the first estimated amount 1E, which is less than the threshold amount TE, will be used to create the regression analysis model. Therefore, based on the regression analysis model created using these three injection amounts, the optimal injection amount OJ can be determined with high accuracy.

[0042] Furthermore, in the control device 20 of the first embodiment, the current injection amount CJ, the preferred injection amount OJ, and the first injection amounts 1J to the third injection amounts 3J are all parameters related to the total injection amount. The preferred EG torque is then calculated based on these parameters related to the total injection amount. Therefore, the preferred EG torque can be determined with high accuracy.

[0043] <Second Embodiment> Figure 6 is an explanatory diagram illustrating the configuration of a hybrid vehicle 1a equipped with the control device 20a of the second embodiment (details of which will be described later). The control device 20a differs from the control device 20 of the first embodiment in that it does not have a torque calculation unit 27 and has an EG drive control unit 23a instead of an EG drive control unit 23.

[0044] The EG drive control unit 23a also functions as a torque calculation unit 27. That is, the series of processes from step S13 to step S22, which were handled by the torque calculation unit 27 in the torque setting process of the first embodiment (see Figure 2), are handled by the EG drive control unit 23 in the torque setting process of the second embodiment. In the second embodiment, when the injection amount at the time of the injection with the largest injection amount among the multi-stage injections in the engine 11 is defined as the main injection amount, the current injection amount CJ represents the current main injection amount. The preferred injection amount represents the main injection amount at which the NOx emission amount is less than the threshold amount TE. The first injection amount 1J to the third injection amount 3J represent main injection amounts less than the current injection amount CJ. Therefore, the torque setting process of the second embodiment consists of a series of processes from step S11 to step S23, similar to the torque setting process of the first embodiment, but differs from the torque setting process of the first embodiment in that the current injection amount CJ, preferred injection amount OJ, and first injection amount 1J to third injection amount 3J in each process are all parameters related to the main injection amount. Furthermore, when calculating the current estimated amount CE, preferred engine torque, and the first estimated amounts 1E to 3rd estimated amounts 3E, a map is used that shows the correspondence between these calculation targets and parameters related to the main injection amount (current injection amount CJ, preferred injection amount OJ, and first injection amount 1J to 3rd injection amount 3J).

[0045] Figure 7 is an explanatory diagram comparing the calculation time required to calculate the optimal EG torque. In Figure 7, "First Embodiment" shows that the current injection amount CJ, optimal injection amount OJ, and first injection amounts 1J to third injection amounts 3J are all parameters related to the total injection amount, and it shows the calculation time required to calculate the optimal EG torque (a series of processes from step S11 to step S22 of the torque setting process) using the EG drive control unit 23 and torque calculation unit 27 of the first embodiment. In Figure 7, "Second Embodiment" shows that the current injection amount CJ, optimal injection amount OJ, and first injection amounts 1J to third injection amounts 3J are all parameters related to the main injection amount, and it shows the calculation time required to calculate the optimal EG torque using the EG drive control unit 23a of the second embodiment. In Figure 7, "Modified Embodiment" shows that the current injection amount CJ, optimal injection amount OJ, and first injection amounts 1J to third injection amounts 3J are all parameters related to the total injection amount, and it shows the calculation time required to calculate the optimal EG torque using the EG drive control unit 23a of the second embodiment.

[0046] In both the "First Embodiment" and the "Modified Embodiment," the current injection amount CJ, preferred injection amount OJ, and first injection amount 1J to third injection amount 3J in each process are all parameters related to the total injection amount. On the other hand, in the "First Embodiment," the processing units used to calculate the preferred EG torque are the EG drive control unit 23 and the torque calculation unit 27, while in the "Modified Embodiment," the processing unit used to calculate the preferred EG torque is the EG drive control unit 23a. For this reason, the calculation time in the "Modified Embodiment," which performs the calculation with one processing unit, is longer than in the "First Embodiment," which performs the calculation with two processing units.

[0047] The calculation time in the "second embodiment," in which calculation is performed by one processing unit, is equivalent to the calculation time in the "first modified form," in which calculation is performed by two processing units. The reason for this is explained below. When the optimal EG torque is calculated by two processing units (EG drive control unit 23 and torque calculation unit 27), as in the "first modified form," even if the current injection amount CJ, optimal injection amount OJ, and first injection amount 1J to third injection amount 3J in each process are all parameters related to the total injection amount, calculation is possible in a short calculation time. On the other hand, in the "second embodiment," since the current injection amount CJ, optimal injection amount OJ, and first injection amount 1J to third injection amount 3J in each process are all parameters related to the main injection amount, the load required to calculate the optimal EG torque is lighter compared to when the optimal EG torque is calculated based on parameters related to the total injection amount. Therefore, even with a single processing unit (EG drive control unit 23a), the calculation time required to calculate the optimal EG torque does not become prolonged. For this reason, it is considered that the calculation time in the "second embodiment" and the calculation time in the "first modified form" are equivalent in Figure 7.

[0048] In the control device 20a of the second embodiment described above, similar to the first embodiment, the hybrid vehicle 1a can be driven with NOx emissions lower than the threshold amount TE. Furthermore, in the control device 20a of the second embodiment, the current injection amount CJ, the preferred injection amount OJ, and the first to third injection amounts 1J to 3J are all parameters related to the main injection amount. Therefore, compared to the case where the current injection amount CJ, preferred injection amount OJ, and the first to third injection amounts 1J to 3J are all parameters related to the total injection amount, the load required to calculate the preferred injection amount can be reduced. Since the main injection amount is the injection amount at the time of the injection with the largest injection amount among the multi-stage injections, the preferred EG torque can be calculated while reducing the load by handling parameters related to the main injection amount in each process of the torque setting process (see Figure 2).

[0049] <Third Embodiment> Figure 8 is an explanatory diagram illustrating the configuration of a hybrid vehicle 1b equipped with the control device 20b of the third embodiment. The control device 20b of the third embodiment differs from the control device 20 of the first embodiment in that it includes a torque calculation unit 27b which is different from the torque calculation unit 27 of the first embodiment. The hybrid vehicle 1b further differs from the hybrid vehicle 1 of the first embodiment in that it includes an exhaust pipe 19p and a catalytic converter 19c.

[0050] The exhaust pipe 19p connects the engine 11 to the catalytic converter 19c and is a pipe that sends exhaust gas from the engine 11 to the catalytic converter 19c. The catalytic converter 19c houses a catalyst (NOx catalyst) that purifies the exhaust gas from the engine 11. The exhaust gas sent from the exhaust pipe 19p passes through the catalyst inside the catalytic converter 19c and is then discharged to the outside of the hybrid vehicle 1b.

[0051] The status information transmitted from the EG drive control unit 23 to the torque calculation unit 27b includes the floor temperature of the catalyst housed in the catalyst section 19c and the flow rate of exhaust gas flowing into the catalyst section 19c. The floor temperature of the catalyst may be detected by a temperature sensor capable of directly detecting the temperature of the catalyst, or it may be detected indirectly by a temperature sensor capable of detecting the temperature near the catalyst. The flow rate of exhaust gas may be detected by a flow sensor capable of directly detecting the flow rate of exhaust gas flowing inside the exhaust pipe 19p, or it may be detected indirectly by a flow sensor capable of detecting the flow rate of gas drawn into the engine 11.

[0052] The torque calculation unit 27b calculates the catalyst purification rate using the catalyst floor temperature and the flow rate of exhaust gas flowing into the catalyst unit 19c, which are included in the state information. More specifically, the torque calculation unit 27b calculates the catalyst purification rate by referring to a map that shows the correspondence between the catalyst floor temperature, the flow rate of exhaust gas flowing into the catalyst unit 19c, and the catalyst purification rate. This map may be stored in the torque calculation unit 27b, or it may be stored in an external device or server that can communicate with the torque calculation unit 27b. The calculated purification rate is used to correct the threshold amount TE.

[0053] In the control device 20b of the third embodiment, the torque setting process (see Figure 2) is performed in the same manner as in the first and second embodiments. On the other hand, in the torque setting process of the third embodiment, before determining whether the currently estimated amount CE is greater than the threshold amount TE (step S14), the torque calculation unit 27b corrects the threshold amount TE. When the corrected threshold amount TE is taken as the corrected threshold amount TF, the torque calculation unit 27b corrects the threshold amount TE to the corrected threshold amount TF using the following equation (1), which expresses the relationship between the threshold amount TE, the catalyst purification rate a (0-100%), and the corrected threshold amount TF. TF = 100TE / (100-a) ... (1)

[0054] In the torque setting process of the third embodiment, the torque calculation unit 27b, in step S14, uses a corrected threshold amount TF instead of a threshold amount TE to compare with the current estimated amount CE. In other words, in step S14, the torque calculation unit 27b determines whether the current estimated amount CE is greater than the corrected threshold amount TF (step S14). Similarly, in step S17, the torque calculation unit 27b determines whether the first estimated amount 1E is greater than the corrected threshold amount TF (step S17). In this way, the torque calculation unit 27b determines the optimal injection amount (step S15 or step S21) through steps S14 and S17, which use the corrected threshold amount TF instead of the threshold amount TE. That is, the torque calculation unit 27b determines the optimal injection amount using a corrected threshold amount TF that has been corrected according to the purification rate of the catalyst that purifies the exhaust gas from the engine 11. Note that in the torque setting process of the third embodiment, the processing in steps other than steps S14 and S17 is the same as in the torque setting process of the first embodiment.

[0055] In the control device 20b of the third embodiment described above, similar to the first embodiment, the hybrid vehicle 1b can be driven with NOx emissions lower than the threshold amount TE. Furthermore, in the control device 20b of the third embodiment, the preferred injection amount is determined using the corrected threshold amount TF. Since the corrected threshold amount TF is a value corrected according to the catalyst purification rate a, even if fuel is injected with the preferred injection amount determined based on the corrected threshold amount TF, the NOx emissions can be reduced to below the threshold amount TE due to catalyst purification. Therefore, while keeping NOx emissions below the threshold amount TE, the amount that satisfies the required torque with EG torque can be maximized according to the catalyst purification rate a.

[0056] <Fourth Embodiment> The control device of the fourth embodiment differs from the control device 20 of the first embodiment in that it adjusts the EG torque setting and the MG torque setting according to the amount of charge stored in the secondary battery 18.

[0057] In the fourth embodiment, when setting the preferred EG torque and MG torque in step S23, the setting unit 21 sets the preferred EG torque and MG torque corrected according to the amount of charge stored in the secondary battery 18. Specifically, in step S23, if the amount of charge stored in the secondary battery 18 is greater than a preset set amount, the setting unit 21 sets the preferred EG torque with a decrease correction and sets the MG torque with an increase correction. More specifically, the setting unit 21 sets the preferred EG torque calculated in step S22 with a decrease correction and sets the MG torque with an increase correction according to the difference between the preferred EG torque and the required torque. On the other hand, in step S23, if the amount of charge stored in the secondary battery 18 is less than or equal to the set amount, the setting unit 21 sets the preferred EG torque and MG torque without performing a decrease correction on the preferred EG torque or an increase correction on the MG torque. Note that in the torque setting process in the fourth embodiment, the processing in steps other than step S23 is the same as in the torque setting process in the first embodiment.

[0058] In the control device of the fourth embodiment described above, similar to the first embodiment, the hybrid vehicle 1b can be driven with NOx emissions lower than the threshold amount TE. Furthermore, in the control device of the fourth embodiment, the preferred EG torque and MG torque are corrected according to the amount of charge stored in the secondary battery 18. Therefore, when the amount of charge stored in the secondary battery 18 is greater than the set amount of charge stored, the amount of the required torque that is satisfied by the preferred EG torque is reduced while the amount that is satisfied by the MG torque is increased. As a result, NOx emissions can be reduced.

[0059] <Fifth Embodiment> The control device of the fifth embodiment is the same as the control device 20 of the first embodiment, except that the process performed in step S18 of the torque setting process (see Figure 2) is different from that of the control device 20 of the first embodiment.

[0060] In the torque setting process of the first embodiment, if the first estimated amount 1E is greater than the threshold amount TE (step S17: YES), the torque calculation unit 27 estimates a second estimated amount 2E, which is the estimated amount of NOx emissions when fuel is injected with a second injection amount 2J (an injection amount that is 1 / 4 of the current injection amount CJ), which is less than the first injection amount 1J (step S18). On the other hand, in the torque setting process of the fifth embodiment, if the first estimated amount 1E is greater than the threshold amount TE (step S17: YES), the torque calculation unit 27 searches for a combination of a second injection amount 2J, which is less than the first injection amount 1J, and a second estimated amount 2E, which is the estimated amount of NOx emissions when fuel is injected with a second injection amount 2J, and is also less than the threshold amount TE (step S18). That is, the torque calculation unit 27 searches for a second injection amount 2J as an injection amount that results in an estimated amount of NOx emissions less than the threshold amount TE. Then, after searching for such combinations of the second injection amount 2J and the second estimated amount 2E (step S18), the torque calculation unit 27 creates a regression analysis model (step S20). Similar to the first embodiment, the current injection amount CJ and current estimated amount CE, the first injection amount 1J and first estimated amount 1E, and the second injection amount 2J and second estimated amount 2E are used to create the regression analysis model. In other words, in the torque setting process in the fifth embodiment, the processing in steps other than step S18 is the same as in the torque setting process in the first embodiment.

[0061] In the control device of the fifth embodiment described above, similar to the first embodiment, the hybrid vehicle 1b can be driven with NOx emissions lower than the threshold amount TE. Furthermore, in the control device of the fifth embodiment, when the first estimator 1E is greater than the threshold amount TE (step S17: YES), the NOx emission estimates used to create the regression analysis model include an estimate of NOx emissions greater than the threshold amount TE (current estimate CE and first estimate 1E) and an estimate of NOx emissions less than the threshold amount (second estimate 2E). Therefore, based on the regression analysis model created using these three injection amounts, the optimal injection amount can be determined with high accuracy.

[0062] <Sixth Embodiment> The control device of the sixth embodiment is the same as the control device 20 of the first embodiment, except that the process performed in step S21 of the torque setting process (see Figure 2) is different.

[0063] In the first embodiment, if the currently estimated amount CE is greater than the threshold amount TE (step S14: YES), the process from S16 to S20 is followed by the determination of the optimal injection amount in step S21 (step S21). On the other hand, in the sixth embodiment, in step S21, in addition to determining the optimal injection amount, an injection pattern for the optimal injection amount is also derived. Specifically, in step S21, after the optimal injection amount is determined, the EG drive control unit 23 uses the setting logic for the injection amount and injection timing of each injection in multi-stage injection, which is installed in the EG drive control unit 23, to derive the injection amount and injection timing for each injection that is optimal for multi-stage injection when performing multi-stage injection with the optimal injection amount. In the torque setting process in the sixth embodiment, the processing in steps other than step S21 is the same as in the torque setting process in the first embodiment. Then, when the EG drive control unit 23 injects fuel with the optimal injection amount, it injects fuel at the derived injection amount and injection timing.

[0064] In the control device of the sixth embodiment described above, similar to the first embodiment, the hybrid vehicle 1b can be driven with NOx emissions lower than the threshold amount TE. Furthermore, in the control device of the sixth embodiment, since EG torque can be obtained with multi-stage injection amounts and injection amounts that match the optimal injection amount, operation with reduced engine noise can be achieved.

[0065] <Modified form of this embodiment> The present invention is not limited to the embodiments described above, and can be implemented in various forms without departing from its spirit, for example, the following modifications are also possible.

[0066] In the embodiments described above, the control device 20, etc., performed torque setting processing for an engine 11 in which multi-stage fuel injection is performed in a single combustion stroke, but it is not limited to this. The control device 20, etc., may also perform torque setting processing for an engine 11 in which single-stage fuel injection is performed in a single combustion stroke.

[0067] In the embodiments described above, when estimating the current estimator CE and the first to third estimators 1E to 3E, a map showing the correspondence between state information and the estimated NOx emissions was used, but the invention is not limited to this. When estimating the current estimator CE and the first to third estimators 1E to 3E, a regression equation showing the correspondence between state information and the estimated NOx emissions, or a neural network that has learned this correspondence, may be used. Similarly, when calculating the required torque, a regression equation showing the correspondence between the accelerator pedal depression amount and the required torque, or a neural network that has learned this correspondence, may be used. Similarly, when calculating the preferred EG torque, a regression equation showing the correspondence between the fuel injection amount in the engine 11 and the EG torque, or a neural network that has learned this correspondence, may be used.

[0068] In the embodiments described above, a regression equation representing the relationship between fuel injection amount and NOx emissions was used as an example of a regression analysis model (see Figure 3), but the model is not limited to this. The regression analysis model may be a map representing the relationship, or a neural network that has learned the relationship.

[0069] In the embodiment described above, the first estimated quantity 1E estimated in step S16 of the torque setting process (see Figure 2) was an estimate of NOx emissions when fuel was injected at an injection amount of 1 / 2 of the current injection amount CJ, with the first injection amount 1J being used as the first injection amount 1J. In other words, one first estimated quantity 1E was estimated using one first injection amount 1J, but this is not limited to this. Multiple first estimated quantities 1E may be estimated using multiple first injection amounts 1J in step S16 of the torque setting process. For example, multiple first estimated quantities 1E may be estimated based on each of the first injection amounts 1J, with each of the injection amounts being 1 / 2 of the current injection amount CJ, 1 / 4 of the current injection amount CJ, and 3 / 4 of the current injection amount CJ being used as the first injection amount 1J. In such a case, after executing step S16 in the torque setting process, a regression analysis model can be created by executing step S20 without executing steps S17 to S19. In this case, the current injection volume CJ and current estimator CE, along with three types of first injection volumes 1J and three types of first estimators 1E, are used to create the regression analysis model. Alternatively, four or more first estimators may be estimated based on four or more types of first injection volumes 1J, and then the regression analysis model may be created using these first injection volumes 1J and first estimators 1E, along with the current injection volume CJ and current estimator CE.

[0070] In the embodiment described above, the first injection amount 1J was defined as half of the current injection amount CJ, the second injection amount 2J was defined as one-quarter of the current injection amount CJ, and the third injection amount 3J was defined as three-quarters of the current injection amount CJ. However, the embodiment is not limited to this. The first injection amount 1J may be any injection amount as long as it is less than the current injection amount CJ. The second injection amount 2J may be any injection amount as long as it is less than the first injection amount 1J. The third injection amount 3J may be any injection amount as long as it is greater than the first injection amount 1J and less than the current injection amount CJ.

[0071] In the first embodiment described above, when the first injection amount 1J is less than the threshold amount TE (step S17:NO), the torque calculation unit 27 estimated a third estimated amount 3E, which is an estimated amount of NOx emissions when fuel is injected with a third injection amount 3J that is greater than the first injection amount 1J and less than the current injection amount CJ (step S19). However, it is not limited to this. When the first injection amount 1J is less than the threshold amount TE (step S17:NO), the torque calculation unit 27 may, as an alternative to step S19, search for a combination of a third injection amount 3J that is greater than the first injection amount 1J and less than the current injection amount CJ, and a third estimated amount 3E, which is an estimated amount of NOx emissions when fuel is injected with a third injection amount 3J and is greater than the threshold amount TE. That is, the torque calculation unit 27 may search for a third injection amount 3J as an injection amount that results in an estimated amount of NOx emissions greater than the threshold amount TE.

[0072] In the third embodiment described above, when calculating the catalyst purification rate, the torque calculation unit 27b referred to a map showing the correspondence between the catalyst floor temperature, the flow rate of exhaust gas flowing into the catalyst unit 19c, and the catalyst purification rate, but is not limited to this. It may also refer to a regression equation showing the correspondence between the catalyst floor temperature, the flow rate of exhaust gas flowing into the catalyst unit 19c, and the catalyst purification rate, or a neural network that has learned said correspondence.

[0073] In the third embodiment described above, the catalyst section 19c contained a NOx catalyst as a catalyst for purifying exhaust gas from the engine 11, but it is not limited to this. The catalyst section 19c may also contain an ammonia SCR (selective catalytic reduction) as a catalyst for purifying exhaust gas from the engine 11. In such a case, the torque calculation unit 27 calculates the catalyst's purification rate by referring to a map or the like that shows the correspondence between the amount of ammonia adsorbed by the catalyst, the amount of ammonia added to the catalyst, and the catalyst's purification rate.

[0074] The embodiments of this specification have been described above based on the embodiments and modifications described above. The embodiments described above are for the purpose of facilitating understanding of this specification and do not limit it. This specification may be modified and improved without departing from its spirit and the scope of the claims, and equivalents thereof are included in this specification. Furthermore, any technical features that are not described as essential in this specification may be deleted as appropriate.

[0075] The present invention can also be realized in the following forms. [Application Example 1] A control device for a hybrid vehicle that uses an engine and a motor generator as power sources, An information gathering unit collects state information indicating the current operating state of the engine, which includes at least the currently injected fuel amount as the fuel injection amount of the engine. A torque calculation unit determines a suitable injection amount, which is the injection amount at which NOx emissions are less than a threshold amount, using the aforementioned state information, and calculates a suitable engine torque, which is the engine torque when the fuel is injected at the suitable injection amount. The system includes a setting unit that sets the preferred engine torque as the engine torque to be output by the engine, and sets the motor-generator torque to be output by the motor-generator according to the difference between the preferred engine torque and the required torque required by the hybrid vehicle, The torque calculation unit, If the current estimated amount, which is the estimated amount of current NOx emissions estimated based on the state information, is less than the threshold amount, the current injection amount is determined as the preferred injection amount. A control device for a hybrid vehicle, which, when the current estimated amount is greater than the threshold amount, first estimates a first estimated amount which is the estimated amount of NOx emissions when the fuel is injected with a first injection amount less than the current injection amount, and then determines the preferred injection amount based on a regression analysis model created using the current injection amount and the current estimated amount, and the first injection amount and the first estimated amount. [Application Example 2] A control device for a hybrid vehicle as described in Application Example 1, The torque calculation unit, when the current estimated amount is greater than the threshold amount and the first estimated amount is greater than the threshold amount, estimates a second estimated amount, which is the estimated amount of NOx emissions when the fuel is injected with a second injection amount that is less than the first injection amount. A control device for a hybrid vehicle, wherein the current injection amount and the current estimated amount, the first injection amount and the first estimated amount, and the second injection amount and the second estimated amount are used to create the regression analysis model. [Application Example 3] A control device for a hybrid vehicle as described in Application Example 1, The torque calculation unit searches for a combination of a second injection amount less than the first injection amount and a second estimated amount less than the threshold amount, which is an estimated amount of NOx emissions when the fuel is injected with the second injection amount. A control device for a hybrid vehicle, wherein the current injection amount and the current estimated amount, the first injection amount and the first estimated amount, and the second injection amount and the second estimated amount are used to create the regression analysis model. [Application Example 4] A control device for a hybrid vehicle as described in any of Application Examples 1 to 3, The torque calculation unit, when the current estimated amount is greater than the threshold amount and the first estimated amount is less than the threshold amount, estimates a third estimated amount, which is the estimated amount of NOx emissions when the fuel is injected at a third injection amount that is greater than the first injection amount and less than the current injection amount. A control device for a hybrid vehicle, wherein the current injection amount and the current estimated amount, the first injection amount and the first estimated amount, and the third injection amount and the third estimated amount are used to create the regression analysis model. [Application Example 5] A control device for a hybrid vehicle described in any of Application Examples 1 to 4, A control device for a hybrid vehicle, wherein the torque calculation unit determines the preferred injection amount using a corrected threshold amount, which is a threshold amount corrected according to the purification rate of a catalyst that purifies exhaust gas from the engine. [Application Example 6] A control device for a hybrid vehicle described in any of Application Examples 1 to 5, The setting unit is a control device for a hybrid vehicle, which, when the amount of charge stored in the secondary battery that supplies power to the motor generator and stores the power generated by the motor generator is greater than a preset set amount of charge, sets the preferred engine torque by decreasing it and sets the motor generator torque by increasing it. [Application Example 7] A control device for a hybrid vehicle described in any of Application Examples 1 to 6, In the aforementioned engine, multi-stage injection of the fuel is performed in a single combustion cycle. When the total injection amount of each injection in the multi-stage injection is defined as the total injection amount, The current injection amount represents the current total injection amount. The preferred injection amount represents the total injection amount at which the NOx emission amount is less than the threshold amount. A control device for a hybrid vehicle, wherein the first injection amount represents the total injection amount which is less than the current injection amount. [Application Example 8] A control device for a hybrid vehicle described in any of Application Examples 1 to 7, further comprising: The engine drive control unit drives the engine according to the preferred engine torque set by the setting unit, In the aforementioned engine, multi-stage injection of the fuel is performed in a single combustion cycle. A control device for a hybrid vehicle, characterized in that the engine drive control unit derives the injection amount and injection timing of the fuel for each injection which are suitable for the multi-stage injection, and when injecting the fuel at the suitable injection amount, it injects the fuel at the derived injection amount and injection timing. [Application Example 9] A control device for a hybrid vehicle described in any of Application Examples 1 to 6, In the aforementioned engine, multi-stage injection of the fuel is performed in a single combustion cycle. When the injection amount during the injection with the largest injection amount among the multi-stage injections is defined as the main injection amount, The current injection amount refers to the current main injection amount. The preferred injection amount represents the main injection amount at which the NOx emission amount is less than the threshold amount. A control device for a hybrid vehicle, wherein the first injection amount represents the main injection amount which is less than the current injection amount. [Explanation of symbols]

[0076] 1, 1a, 1b... Hybrid vehicles 11… Engine 12... Transmission 13…Propeller shaft 14…Differential gear 15…Drive shaft 16... Tires 17…Motor Generator 18…Secondary battery 19c...Catalyst section 19p... Exhaust pipe 20, 20a, 20b… Control devices 21...Settings section 23,23a...EG drive control unit 25...MG drive control unit 27,27b... Torque calculation unit

Claims

1. A control device for a hybrid vehicle that uses an engine and a motor generator as power sources, An information gathering unit collects state information indicating the current operating state of the engine, which includes at least the currently injected fuel amount as the fuel injection amount of the engine. A torque calculation unit determines a suitable injection amount, which is the injection amount at which NOx emissions fall below a threshold amount, using the aforementioned state information, and calculates a suitable engine torque, which is the engine torque when the fuel is injected at the suitable injection amount. The system includes a setting unit that sets the preferred engine torque as the engine torque to be output by the engine, and sets the motor-generator torque to be output by the motor-generator according to the difference between the preferred engine torque and the required torque required by the hybrid vehicle, The torque calculation unit, If the current estimated amount, which is the estimated amount of current NOx emissions estimated based on the state information, is less than the threshold amount, the current injection amount is determined as the preferred injection amount. A control device for a hybrid vehicle, which, when the current estimated amount is greater than the threshold amount, first estimates a first estimated amount which is the estimated amount of NOx emissions when the fuel is injected with a first injection amount less than the current injection amount, and then determines the preferred injection amount based on a regression analysis model created using the current injection amount and the current estimated amount, and the first injection amount and the first estimated amount.

2. A control device for a hybrid vehicle according to claim 1, The torque calculation unit, when the current estimated amount is greater than the threshold amount and the first estimated amount is greater than the threshold amount, estimates a second estimated amount, which is the estimated amount of NOx emissions when the fuel is injected with a second injection amount that is less than the first injection amount. A control device for a hybrid vehicle, wherein the current injection amount and the current estimated amount, the first injection amount and the first estimated amount, and the second injection amount and the second estimated amount are used to create the regression analysis model.

3. A control device for a hybrid vehicle according to claim 1, The torque calculation unit searches for a combination of a second injection amount less than the first injection amount and a second estimated amount less than the threshold amount, which is an estimated amount of NOx emissions when the fuel is injected with the second injection amount. A control device for a hybrid vehicle, wherein the current injection amount and the current estimated amount, the first injection amount and the first estimated amount, and the second injection amount and the second estimated amount are used to create the regression analysis model.

4. A control device for a hybrid vehicle according to any one of claims 1 to 3, The torque calculation unit, when the current estimated amount is greater than the threshold amount and the first estimated amount is less than the threshold amount, estimates a third estimated amount, which is the estimated amount of NOx emissions when the fuel is injected at a third injection amount that is greater than the first injection amount and less than the current injection amount. A control device for a hybrid vehicle, wherein the current injection amount and the current estimated amount, the first injection amount and the first estimated amount, and the third injection amount and the third estimated amount are used to create the regression analysis model.

5. A control device for a hybrid vehicle according to claim 1, A control device for a hybrid vehicle, wherein the torque calculation unit determines the preferred injection amount using a corrected threshold amount, which is a threshold amount corrected according to the purification rate of a catalyst that purifies exhaust gas from the engine.

6. A control device for a hybrid vehicle according to claim 1, The setting unit is a control device for a hybrid vehicle, which, when the amount of charge stored in the secondary battery that supplies power to the motor generator and stores the power generated by the motor generator is greater than a preset set amount of charge, sets the preferred engine torque by decreasing it and sets the motor generator torque by increasing it.

7. A control device for a hybrid vehicle according to claim 1, In the aforementioned engine, multi-stage injection of the fuel is performed in a single combustion cycle. When the total injection amount of each injection in the multi-stage injection is defined as the total injection amount, The current injection amount represents the current total injection amount. The preferred injection amount represents the total injection amount at which the NOx emission amount is less than the threshold amount. A control device for a hybrid vehicle, wherein the first injection amount represents the total injection amount which is less than the current injection amount.

8. A control device for a hybrid vehicle according to claim 1, further, The engine drive control unit drives the engine according to the preferred engine torque set by the setting unit, In the aforementioned engine, multi-stage injection of the fuel is performed in a single combustion cycle. A control device for a hybrid vehicle, characterized in that the engine drive control unit derives the injection amount and injection timing of the fuel for each injection which are suitable for the multi-stage injection, and when injecting the fuel at the suitable injection amount, it injects the fuel at the derived injection amount and injection timing.

9. A control device for a hybrid vehicle according to claim 1, In the aforementioned engine, multi-stage injection of the fuel is performed in a single combustion cycle. When the injection amount during the injection with the largest injection amount among the multi-stage injections is defined as the main injection amount, The current injection amount refers to the current main injection amount. The preferred injection amount represents the main injection amount at which the NOx emission amount is less than the threshold amount. A control device for a hybrid vehicle, wherein the first injection amount represents the main injection amount which is less than the current injection amount.

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