Hybrid vehicles

Abstract

To provide a hybrid vehicle whose control device can efficiently perform, when warming up a catalyst to purify NOx through exhaust gas from an internal combustion engine, catalyst warming-up with a low NOx discharge amount in a simple control than ever.SOLUTION: A hybrid vehicle includes: a catalyst which purifies NOx; and a controller. The controller includes: a user request torque calculation unit which calculates a user request torque based on an operation state and an accelerator pedal stepping amount; a target warming-up torque calculation unit which calculates a target warming-up torque based on the operation state; and a catalyst warming-up processing unit which controls, when a catalyst warming-up condition is satisfied and the target warming-up torque is larger than the user request torque, an internal combustion engine to output the target warming-up torque, and controls a motor generator to consume a surplus torque obtained by subtracting the user request torque from the target warming-up torque in an electric power generation. The target warming-up torque is set to be a first target torque where a value of exhaust heat quantity / NOx discharge quantity regarding the operation state becomes an almost maximum value.SELECTED DRAWING: Figure 8

Description

Technical Field

[0001] The present invention relates to a hybrid vehicle having an internal combustion engine and a motor generator.

Background Art

[0002] Conventionally, in a hybrid vehicle having an internal combustion engine and a motor generator (having the functions of an electric motor (motor) and a generator (generator)), for example, in Patent Document 1, a control device for a hybrid vehicle is disclosed that can suppress the number of starts of the internal combustion engine while ensuring catalyst warm-up and improve fuel efficiency.

[0003] The control device for a hybrid vehicle described in Patent Document 1 includes a road information acquisition unit that acquires road information, a speed prediction unit that predicts the traveling speed on the planned travel route based on the road information, an engine operation prediction unit that predicts the engine operation state on the planned travel route based on the predicted traveling speed, a catalyst temperature prediction unit that predicts the catalyst temperature on the planned travel route based on the predicted traveling speed, and an engine control unit that changes the engine operation conditions during the previous engine drive to a higher load side than the normal operation conditions when it is predicted that the catalyst temperature will fall below the lower limit temperature during engine stop.

[0004] And, the control device for a hybrid vehicle described in Patent Document 1 sets the total increased load when changing the engine operation conditions to a higher load side than the normal operation conditions based on the predicted value (energy) of the catalyst temperature drop during the engine stop period including when it is predicted that the predicted catalyst temperature will fall below the lower limit temperature. And, it is set based on the predicted average traveling speed during the engine stop period when it is predicted that the catalyst temperature will fall below the lower limit temperature and the length of the engine stop period.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

[0006] The method for setting the total increased load in a control device for a hybrid vehicle described in Patent Document 1 states that the catalyst temperature can be kept above the lower limit temperature with the total increased load. However, since the priority is on improving fuel efficiency, this is undesirable because it may result in excessively high NOx emissions in relation to the increased engine load. Furthermore, the control is complex and involves many predictions, which is undesirable because predictions may be wrong and it may be difficult to obtain the expected effect.

[0007] This invention was conceived in view of the above points, and aims to provide a hybrid vehicle that can efficiently warm up a catalyst that purifies NOx using exhaust gas from an internal combustion engine with simpler control and lower NOx emissions. [Means for solving the problem]

[0008] To solve the above problems, the first invention is a hybrid vehicle having an internal combustion engine and a motor generator. The exhaust path of the internal combustion engine is provided with a catalyst for purifying NOx contained in the exhaust gas, and the vehicle has a control device for controlling the internal combustion engine and the motor generator. The control device has a user-requested torque calculation unit that determines the user-requested torque based on the operating state of the internal combustion engine and the amount the accelerator pedal is depressed, a target warm-up torque calculation unit that determines the target warm-up torque based on the operating state, and a catalyst warm-up processing unit that controls the internal combustion engine to output the target warm-up torque when catalyst warm-up conditions requiring the warm-up of the catalyst are met and the target warm-up torque is greater than the user-requested torque, and controls the motor generator to consume the surplus torque obtained by subtracting the user-requested torque from the target warm-up torque for power generation. The target warm-up torque is set based on NOx emission characteristics, which are the characteristics of NOx emissions corresponding to the operating state and the internal combustion engine torque, and exhaust heat characteristics, which are the characteristics of exhaust heat amount corresponding to the operating state and the internal combustion engine torque. The target warm-up torque is set to a first target torque corresponding to each operating state, where the value of exhaust heat amount / NOx emissions for that operating state is approximately the maximum value among torques that are greater than or equal to the driving torque required for the hybrid vehicle to run in that operating state.

[0009] Next, the second invention is a hybrid vehicle according to the first invention, wherein the control device stores an integrated NOx emission value calculated by accumulating NOx emissions based on the driving state, and an integrated mileage value calculated by accumulating the driving distance of the hybrid vehicle. Furthermore, the target warm-up torque is set to include the first target torque and a second target torque set based on the NOx emission characteristics, corresponding to each driving state, which is a torque greater than or equal to the driving torque for that driving state and results in approximately the minimum value of NOx emissions for that driving state. The control device then calculates the target warm-up torque using the target warm-up torque calculation unit, and if the integrated NOx emission value / integrated mileage value is less than or equal to a predetermined threshold, it calculates the first target torque as the target warm-up torque, and if the integrated NOx emission value / integrated mileage value is greater than the predetermined threshold, it calculates the second target torque as the target warm-up torque. [Effects of the Invention]

[0010] In the first invention, the target warm-up torque is set so that the exhaust heat output is higher with lower NOx emissions. When the catalyst warm-up conditions are met and the target warm-up torque is greater than the user-requested torque, the internal combustion engine is controlled to output the target warm-up torque. At this time, the surplus torque obtained by subtracting the user warm-up torque from the target warm-up torque is consumed by the motor generator, thereby transmitting the user-requested torque to the drive wheels and eliminating any discomfort for the user. The surplus torque is then converted into electricity and stored in the battery, so there is no waste. As a result, when warming up the catalyst that purifies NOx using the exhaust of the internal combustion engine, the catalyst can be warmed up efficiently and in a short time with simpler control and lower NOx emissions. Furthermore, according to the first invention, the target warm-up torque for efficient warm-up with lower NOx emissions can be appropriately set.

[0011] According to the second invention, a target warm-up torque can be appropriately set to efficiently warm up the engine with less NOx emissions, depending on the value of the combined NOx emission value / combined mileage value. [Brief explanation of the drawing]

[0012] [Figure 1] This is a schematic diagram of the hybrid vehicle according to the present invention. [Figure 2] Figure 1 is a schematic diagram of the internal combustion engine system installed in the hybrid vehicle shown. [Figure 3] This diagram illustrates an example of a user-requested torque characteristic, showing the relationship between accelerator pedal depression amount, internal combustion engine speed (N1~N5), and user-requested torque. [Figure 4] This diagram illustrates an example of NOx emission characteristics, showing NOx emissions in relation to the operating conditions of an internal combustion engine (in this example, engine speed) and the torque of the internal combustion engine. [Figure 5] This diagram illustrates an example of exhaust heat quantity characteristics, showing the amount of exhaust heat quantity corresponding to the operating state of an internal combustion engine (in this example, the engine speed) and the torque of the internal combustion engine. [Figure 6] This figure illustrates the exhaust heat quantity / NOx emission characteristics created based on the NOx emission characteristics shown in Figure 4 and the exhaust heat quantity characteristics shown in Figure 5, as well as an example of g(x), which represents the value of the exhaust heat quantity / NOx emission that is approximately the maximum for each operating state (each internal combustion engine speed in this example) within the range of driving torque. [Figure 7] This figure illustrates an example of the target warm-up torque characteristic (1), which was created based on the exhaust heat quantity / NOx emission characteristics and g(x) shown in Figure 6. [Figure 8] This is a flowchart illustrating an example of the processing procedure of the control device in the first embodiment. [Figure 9] Figure 4 illustrates the NOx emission characteristics and provides examples of h(x), which represents the value of the NOx emission that is approximately the minimum for each operating condition (in this example, each internal combustion engine speed) within the range of driving torque. [Figure 10] This figure illustrates an example of the target warm-up torque characteristics (2) created based on the NOx emission characteristics and h(x) shown in Figure 9. [Figure 11] This is a flowchart illustrating an example of the processing procedure of the control device in the second embodiment.

Best Mode for Carrying Out the Invention

[0013] Embodiments of the present invention will be described with reference to the drawings. The same reference numbers in the description mean the same elements having the same functions without redundant description. The control device 40 for a hybrid vehicle according to the present embodiment is applied to the hybrid vehicle 1 shown in FIG. 1. The hybrid vehicle 1 includes an internal combustion engine 2, a motor generator 3, a control device 40, front wheels 11a to 11b, rear wheels 12a to 12b, clutches 13a to 13b, a transmission 14, a differential gear 15, a transmission shaft 16, a propeller shaft 17, a drive shaft 18, an inverter 31, and a battery 32.

[0014] <Configuration of Hybrid Vehicle 1 (FIG. 1)> The internal combustion engine 2 and the motor generator 3 are mounted on the hybrid vehicle 1 as drive sources. The internal combustion engine 2 generates torque for rotating the crankshaft 2a. The internal combustion engine system including the internal combustion engine 2 will be described later with reference to FIG. 2.

[0015] The motor generator 3 is a well-known three-phase synchronous motor / generator that can function as either an electric motor (motor) or a generator (generator). When the motor generator 3 operates as an electric motor, it generates torque for rotating the motor shaft 3a. In this case, the inverter 31 converts the DC power supplied from the battery 32 into three-phase AC according to an instruction from the control device 40 and supplies it to the motor generator 3.

[0016] When the motor generator 3 operates as a generator, it converts the torque for rotating the motor shaft 3a into electric power. In this case, the inverter 31 converts the three-phase AC power supplied from the motor generator 3 into DC power according to an instruction from the control device 40 and supplies it to the battery 32. The battery 32 is a secondary battery (e.g., a lithium-ion battery) capable of charging and discharging.

[0017] The clutches 13a and 13b are switched between a connected state and a disconnected state in accordance with an instruction from the control device 40. When the clutch 13a is in the connected state, the crankshaft 2a and the motor shaft 3a are connected to each other so as to be torque-transmittable. When the clutch 13b is in the connected state, the motor shaft 3a and the transmission shaft 16 are connected to each other so as to be torque-transmittable.

[0018] The transmission 14 is a transmission that can switch the gear ratio (specifically, the ratio of the rotational speed of the transmission shaft 16 (input-side rotational speed) to the rotational speed of the propeller shaft 17 (output-side rotational speed)) in multiple steps or continuously in accordance with an instruction from the control device 40.

[0019] The propeller shaft 17 and the drive shaft 18 are connected to each other so as to be torque-transmittable via the differential gear 15. The rear wheels 12a and 12b are drive wheels of the hybrid vehicle 1 and rotate together with the rotation of the drive shaft 18.

[0020] The control device 40 is an electronic control unit (Electronic Control Unit, so-called ECU) including a CPU 41, a RAM 42, a ROM 43, a timer 44, an EEPROM 45, etc. The CPU 41 reads data, performs numerical calculations, outputs calculation results, etc. by sequentially executing a predetermined program. The ROM 43 corresponds to a storage device that stores programs and maps (look-up tables) executed by the CPU 41. The RAM 42 temporarily stores data referred to by the CPU 41. The timer 44 is used for measuring the interval time of the rotation sensor of the internal combustion engine, the fuel injection output from the injector, etc. The EEPROM 45 stores data referred to by the CPU 41 and further holds the stored data even when the control device 40 stops operating. Note that the CPU 41 has a user required torque calculation unit 41a, a target warm-up torque calculation unit 41b, a catalyst warm-up processing unit etc., and details thereof will be described later.

[0021] <Configuration of the internal combustion engine system installed in hybrid vehicle 1 (Figure 2)> As shown in Figure 2, the internal combustion engine 2, together with the supercharger 5, intake system 6, exhaust system 7, and EGR system 8, constitutes an internal combustion engine system. The internal combustion engine 2 includes a plurality of fuel injectors 21. Each of the fuel injectors 21 injects high-pressure fuel supplied from the accumulator chamber of a common rail system (not shown) into the cylinder (combustion chamber) in response to instructions from the control device 40.

[0022] The supercharger 5 includes a turbine 51, a variable nozzle mechanism 52, a nozzle actuator 52a, and a compressor 53. The turbine 51 is operated (rotates) by the pressure of the exhaust gas (combustion gas) discharged from each cylinder of the internal combustion engine 2. The variable nozzle mechanism 52 is equipped with nozzle vanes, which are a throttling mechanism for the exhaust gas flowing into the turbine 51 (a mechanism that adjusts the flow velocity of the exhaust gas that hits the turbine).

[0023] Specifically, the degree of closure of the exhaust passage in the turbine 51 (i.e., the degree to which the exhaust passage is narrowed) changes according to the nozzle closure degree Vn, which is the state of the nozzle vane. The nozzle actuator 52a changes the nozzle closure degree Vn between a predetermined fully open position (fully open state) and a fully closed position (fully closed state) in response to instructions from the control device 40. The compressor 53 operates (rotates) in conjunction with the turbine 51 and pressurizes the air (intake) drawn into each cylinder of the internal combustion engine 2.

[0024] The intake system 6 includes intake pipes 61a-61b, which are intake passages, an intake manifold 62, an intercooler 63, a throttle valve 64, and a throttle actuator 64a. Intake pipe 61a introduces intake air (fresh air) drawn in from the outside (outside the vehicle) to the compressor 53. Intake pipe 61b introduces intake air discharged from the compressor 53 to the intake manifold 62. The intake manifold 62 introduces intake air to each cylinder of the internal combustion engine 2.

[0025] The intercooler 63 is installed (interposed) in the intake manifold 61b. The intercooler 63 cools the intake air, which has been pressurized by the compressor 53 and whose temperature has risen. The throttle valve 64 is located downstream of the intercooler 63 in the intake manifold 61b. The throttle valve 64 adjusts the opening of the intake manifold 61b according to its rotational position. The throttle actuator 64a adjusts the rotational position of the throttle valve 64 according to instructions from the control device 40.

[0026] The exhaust system 7 includes an exhaust manifold 71, exhaust pipes 72a to 72b which constitute the exhaust passage (exhaust path), and an exhaust gas purification device 73. The exhaust manifold 71 introduces exhaust gas (combustion gas) discharged from each cylinder of the internal combustion engine 2 into the exhaust pipe 72a. The exhaust pipe 72a introduces the exhaust gas to the turbine 51. The exhaust pipe 72b discharges the exhaust gas discharged from the turbine 51 to the outside (outside the vehicle). The exhaust gas purification device 73 is installed in the exhaust pipe 72b. The exhaust gas purification device 73 includes a well-known oxidation catalyst, DPF (Diesel Particulate Filter), and SCR (Selective Catalytic Reduction), etc., to purify the exhaust gas. The SCR is equipped with a catalyst 73a that purifies NOx in the exhaust gas.

[0027] The EGR system 8 includes an EGR pipe 81, an EGR cooler 82, and an EGR valve 83. The EGR pipe 81 is an EGR path connecting the exhaust pipe 72a and the intake pipe 61b. The EGR cooler 82 is installed in the EGR pipe 81. The EGR cooler 82 cools the high-temperature exhaust gas (i.e., EGR gas) flowing in from the exhaust pipe 72a. The EGR valve 83 changes the opening degree of the EGR pipe 81 between a predetermined fully open state and a fully closed state in response to instructions from the control device 40. The EGR valve 83 adjusts the amount of EGR gas that flows back from the exhaust pipe 72a to the intake pipe 61b (specifically, the EGR rate, which is the concentration of EGR gas in the air drawn into the cylinders of the internal combustion engine 2).

[0028] The control device 40 is connected to a crank angle sensor 91, a cam position sensor 92, an airflow sensor 93, a nozzle closure sensor 94, pressure sensors 95a to 95c, intake air temperature sensors 96a to 96b, an accelerator opening sensor 97, a vehicle speed sensor 98, a coolant temperature sensor 99w, an exhaust temperature sensor 99h, and the like.

[0029] The crank angle sensor 91 outputs a pulse signal to the control device 40 each time the crankshaft 2a of the internal combustion engine 2 rotates by a predetermined angle. The camshaft position sensor 92 outputs a signal to the control device 40 corresponding to the rotational position of the camshaft (not shown) of the internal combustion engine 2. The control device 40 acquires the engine speed NE of the internal combustion engine 2 based on the signal input from the crank angle sensor 91. The control device 40 acquires the crank angle CA of a specific cylinder of the internal combustion engine 2 based on the signals input from the crank angle sensor 91 and the camshaft position sensor 92.

[0030] The airflow sensor 93 detects the intake air volume Ga, which is the amount of intake air flowing through the intake pipe 61a (specifically, the mass per unit time), and outputs a signal representing the intake air volume Ga to the control device 40. The nozzle closure sensor 94 detects the nozzle closure Vn and outputs a signal representing the nozzle closure Vn to the control device 40. The pressure sensor 95a is located downstream of the airflow sensor 93 in the intake pipe 61a. The pressure sensor 95a detects the atmospheric pressure Po, which is the pressure of the intake air flowing into the compressor 53, and outputs a signal representing the atmospheric pressure Po to the control device 40.

[0031] The pressure sensor 95b is located in the intake manifold 61b between the compressor 53 and the intercooler 63. The pressure sensor 95b detects the boost pressure Pbt, which is the pressure of the intake air flowing out of the compressor 53, and outputs a signal representing the boost pressure Pbt to the control device 40. The pressure sensor 95c is located in the intake manifold 62. The pressure sensor 95c detects the intake manifold pressure Pm, which is the pressure of the intake air flowing into the cylinders of the internal combustion engine 2, and outputs a signal representing the intake manifold pressure Pm to the control device 40.

[0032] The intake air temperature sensor 96a is located near the airflow sensor 93 in the intake manifold 61a. The intake air temperature sensor 96a detects the intake air temperature Ti, which is the temperature of the intake air flowing through the intake manifold 61a, and outputs a signal representing the intake air temperature Ti to the control device 40. The intake air temperature sensor 96b is located in the intake manifold 62. The intake air temperature sensor 96b detects the intake manifold intake air temperature Tm, which is the temperature of the intake air flowing into the cylinders of the internal combustion engine 2, and outputs a signal representing the intake manifold intake air temperature Tm to the control device 40.

[0033] The accelerator pedal position sensor 97 detects the accelerator pedal depression amount, which is the degree to which the driver (user) operates the accelerator pedal to control the speed of the hybrid vehicle 1, and outputs a signal representing the accelerator pedal depression amount to the control device 40. For example, the accelerator pedal depression amount is represented by a value from 0% to 100%. The vehicle speed sensor 98 detects the vehicle speed Vs, which is the driving speed of the hybrid vehicle 1, and outputs a signal representing the vehicle speed Vs to the control device 40.

[0034] The coolant temperature sensor 99w outputs a signal to the control device 40 corresponding to the temperature of the coolant (cooling water) used to cool the internal combustion engine 2. The exhaust temperature sensor 99h is located near the catalyst 73a and outputs a signal to the control device 40 corresponding to the temperature of the exhaust gas near the catalyst (catalyst bed temperature).

[0035] The catalyst 73a, which purifies NOx in exhaust gas, experiences reduced purification efficiency when its temperature is below its activation temperature. For this reason, the control device 40 controls the internal combustion engine 2, for example, immediately after starting the engine, to keep the engine speed relatively high, thereby raising the catalyst bed temperature to above the activation temperature as quickly as possible (warming up the catalyst 73a). However, since the engine speed of the internal combustion engine 2 is relatively high during the warming up of the catalyst 73a, there is a possibility that the amount of NOx generated may increase. Therefore, in the processing procedures of the first and second embodiments described below, the catalyst is warmed up efficiently with less NOx generation.

[0036] <<First Embodiment (Figures 3-8)>> Next, an example of the processing procedure of the control device 40 in the first embodiment will be described using Figures 3 to 8. First, the characteristics used in the processing of the control device 40 will be described.

[0037] <Examples of user-requested torque characteristics (Figure 3), NOx emission characteristics (Figure 4), exhaust heat quantity characteristics (Figure 5), exhaust heat quantity characteristics / NOx emission characteristics (Figure 6), and target warm-up torque characteristics (1) (Figure 7)> The user-requested torque characteristic shown in Figure 3 is set according to the amount the user depresses the accelerator pedal. N1 to N5 represent the rotational speed of each internal combustion engine. For example, if the internal combustion engine rotational speed is N3 and the accelerator pedal depression amount is Xa, the control device 40 calculates the user-requested torque as Ta. The user-requested torque characteristic is stored in the control device 40's memory device (ROM 43). Note that the user-requested torque is a torque set for convenience by the control device 40 to calculate the required torque of the internal combustion engine 2 and the required torque of the motor generator 3, and instead of the above calculation method, it may be calculated from the accelerator pedal depression amount and the current vehicle speed. In addition, the user-requested torque increases according to the accelerator pedal depression amount, but it does not have to be a linear characteristic with respect to the accelerator pedal depression amount.

[0038] The NOx emission characteristics shown in Figure 4 represent the results of measurements taken from actual vehicles and simulations, showing NOx emissions in relation to internal combustion engine speed (operating state of the internal combustion engine) and internal combustion engine torque (load of the internal combustion engine). In the NOx emission characteristics shown in Figure 4, darker colors represent higher NOx emissions.

[0039] The exhaust heat characteristics shown in Figure 5 represent the exhaust heat quantity measured in actual vehicles and simulations, corresponding to the internal combustion engine speed (operating state of the internal combustion engine) and the internal combustion engine torque (load of the internal combustion engine). In the exhaust heat characteristics shown in Figure 5, a larger exhaust heat quantity is represented by a darker color.

[0040] The exhaust heat quantity / NOx emission characteristics shown in Figure 6 were created using the NOx emission characteristics shown in Figure 4 and the exhaust heat quantity characteristics shown in Figure 5. They show the exhaust heat quantity / NOx emission in relation to the internal combustion engine speed (operating state of the internal combustion engine) and the internal combustion engine torque (load of the internal combustion engine). In the exhaust heat quantity / NOx emission characteristics shown in Figure 6, a larger value for the exhaust heat quantity / NOx emission is represented by a darker color. A darker color indicates a larger exhaust heat quantity relative to the NOx emission (i.e., a larger exhaust heat quantity can be obtained with a smaller NOx emission).

[0041] In Figure 6, the dotted line representing "driving torque" indicates the torque required for hybrid vehicle 1 to run at each internal combustion engine speed (operating state of the internal combustion engine). In actual control, it is necessary to control the internal combustion engine so that the internal combustion engine torque is greater than or equal to this "driving torque".

[0042] Furthermore, the solid line "g(x)" in Figure 6 represents a characteristic obtained by connecting the points where the exhaust heat quantity / NOx emission value for each internal combustion engine speed (each operating state) is approximately maximum among internal combustion engine torques that are equal to or greater than the driving torque for that internal combustion engine speed (each operating state). For example, when the internal combustion engine speed = Na, on the straight line Sa corresponding to internal combustion engine speed = Na, the point where the exhaust heat quantity / NOx is approximately maximum (the position of the darkest color) among internal combustion engine torques that are equal to or greater than the driving torque is internal combustion engine torque = Ta. Similarly, when the internal combustion engine speed = Nb, on the straight line Sb corresponding to internal combustion engine speed = Nb, the point where the exhaust heat quantity / NOx is approximately maximum (the position of the darkest color) among internal combustion engine torques that are equal to or greater than the driving torque is internal combustion engine torque = Tb. In this way, g(x) can be obtained by extracting the points with approximately maximum values ​​for each internal combustion engine speed and connecting these points.

[0043] The target warm-up torque characteristic (1) shown in Figure 7 is obtained by extracting the horizontal axis, vertical axis, and g(x) from the exhaust heat amount / NOx emission characteristic shown in Figure 6. The target warm-up torque characteristic (1) represents the internal combustion engine torque that maximizes the exhaust heat amount relative to NOx emissions (and is a torque greater than or equal to the driving torque, corresponding to the "first target torque") for each internal combustion engine rotation speed (each operating state). The target warm-up torque characteristic (1) is stored in the memory device (ROM 43) of the control device 40.

[0044] <Processing procedure of control device 40 (Figure 8)> Next, an example of the processing procedure of the control device 40 in the first embodiment will be described using Figure 8. The control device 40 starts the processing shown in Figure 8 at predetermined time intervals (for example, intervals of several tens of milliseconds) and proceeds to step S010.

[0045] In step S010, the control device 40 detects the operating state of the internal combustion engine 2 and proceeds to step S020. For example, the control device 40 acquires the accelerator pedal depression amount, internal combustion engine speed, catalyst floor temperature, etc.

[0046] In step S020, the control device 40 calculates the user-requested torque based on the accelerator pedal depression amount, the internal combustion engine rotation speed (operating state of the internal combustion engine), and the user-requested torque characteristics stored in the memory device, stores it in the user-requested torque (Te), and proceeds to step S030.

[0047] In step S030, the control device 40 determines whether the catalyst warm-up conditions are met. If they are met (Yes), the process proceeds to step S040; otherwise, the process proceeds to step S090. For example, the control device 40 determines that the catalyst warm-up conditions are met if the catalyst bed temperature detected using the exhaust temperature sensor 99h is below the catalyst activation temperature.

[0048] If the process proceeds to step S040, the control device 40 calculates the target warm-up torque (Td) (corresponding to the "first target torque") based on the internal combustion engine rotation speed (operating state of the internal combustion engine) and the target warm-up torque characteristics (1) stored in the memory device, stores it in the target warm-up torque (Td), and proceeds to step S050.

[0049] In step S050, the control device 40 determines whether the target warm-up torque (Td) is greater than the user-requested torque (Te). If the target warm-up torque (Td) is greater than the user-requested torque (Te) (Yes), the control device 40 proceeds to step S060; otherwise, it proceeds to step S090.

[0050] If the process proceeds to step S060, the control device 40 calculates the surplus torque (target warm-up torque - user-requested torque), and based on this surplus torque and the rotational speed of the motor generator 3, calculates the MG power generation related amount, which is the power generation related amount of the motor generator 3, and proceeds to step S070.

[0051] In step S070, the control device 40 controls the internal combustion engine 2 to output the target warm-up torque (Td), and also controls the motor generator 3 to generate power (consume surplus torque) based on the MG power generation related amount, thereby completing the process shown in Figure 8. The power generated by the motor generator 3 is stored in the battery 32 via the inverter 31, so the surplus torque is not wasted.

[0052] If the process proceeds to step S090, the control device 40 controls the internal combustion engine 2 and the motor generator 3 to output the user-requested torque (Te). Since step S090 is an existing process, a detailed explanation is omitted.

[0053] The control device 40 (CPU 41) that executes the process of step S020 corresponds to a user required torque calculation unit 41a (see FIGS. 1 and 2) that obtains a user required torque based on the operating state of the internal combustion engine, the accelerator pedal depression amount, and the user required torque characteristics.

[0054] The control device 40 (CPU 41) that executes the process of step S040 corresponds to a target warm-up torque calculation unit 41b (see FIGS. 1 and 2) that obtains a target warm-up torque based on the operating state of the internal combustion engine and the target warm-up torque characteristics.

[0055] When the control device 40 (CPU 41) that executes the processes of steps S030, S050, S060, and S070 satisfies the catalyst warm-up condition that the catalyst 73a needs to be warmed up and the target warm-up torque is greater than the user required torque, it controls the internal combustion engine 2 to output the target warm-up torque and controls the motor generator 3 to consume the surplus torque obtained by subtracting the user required torque from the target warm-up torque for power generation, which corresponds to a catalyst warm-up processing unit 41c (see FIGS. 1 and 2).

[0056] <<Second Embodiment (FIGS. 9 to 11)>> Next, an example of the processing procedure of the control device 40 in the second embodiment will be described with reference to FIGS. 9 to 11. Regarding the second embodiment, the differences from the first embodiment will be mainly described. In the second embodiment, in addition to the target warm-up torque characteristics (1) (see FIG. 7) used in the first embodiment, the target warm-up torque characteristics (2) shown in FIG. 10 are also used.

[0057] <Examples of NOx emission characteristics (FIG. 9), target warm-up torque characteristics (2) (FIG. 10)> The NOx emission characteristics shown in Figure 9, which represent NOx emissions in relation to internal combustion engine speed (operating state of the internal combustion engine) and internal combustion engine torque (internal combustion engine load) using the intensity of the colors, are identical to the NOx emission characteristics shown in Figure 4, with darker colors indicating higher NOx emissions. However, Figure 9 differs from Figure 4 in that it includes "driving torque" shown as a dotted line and "h(x)" shown as a solid line.

[0058] The "driving torque" shown by the dotted line in Figure 9 is the same as the "driving torque" shown by the dotted line in Figure 6. "Driving torque" indicates the torque required for hybrid vehicle 1 to run at each internal combustion engine speed (operating state of the internal combustion engine). In actual control, it is necessary to control the internal combustion engine so that the internal combustion engine torque is greater than or equal to this "driving torque".

[0059] In Figure 9, the solid line "h(x)" represents a characteristic obtained by connecting the points where the NOx emission value for each internal combustion engine speed (each operating state) is approximately the minimum among internal combustion engine torques that are greater than or equal to the driving torque for that internal combustion engine speed (each operating state). For example, when the internal combustion engine speed is Nn, on the straight line Sn corresponding to the internal combustion engine speed of Nn, the point where the NOx emission value is approximately the minimum (the position of the lightest color) among internal combustion engine torques that are greater than or equal to the driving torque is internal combustion engine torque = Tn. Similarly, when the internal combustion engine speed is Nm, on the straight line Sm corresponding to the internal combustion engine speed of Nm, the point where the NOx emission value is approximately the minimum (the position of the lightest color) among internal combustion engine torques that are greater than or equal to the driving torque is internal combustion engine torque = Tm. In this way, h(x) can be obtained by extracting the points with approximately the minimum value for each internal combustion engine speed and connecting these points.

[0060] The target warm-up torque characteristics (2) shown in Figure 10 are obtained by extracting the horizontal axis, vertical axis, and h(x) from the NOx emission characteristics shown in Figure 9. The target warm-up torque characteristics (2) represent the internal combustion engine torque that minimizes NOx emissions (and is greater than or equal to the driving torque, corresponding to the "second target torque") for each internal combustion engine speed (each operating state). The target warm-up torque characteristics (2) are stored in the memory device (ROM 43) of the control device 40. The NOx emission characteristics shown in Figure 4 are also stored in the memory device (ROM 43) of the control device 40.

[0061] <Processing procedure of control device 40 (Figure 11)> Next, an example of the processing procedure of the control device 40 in the second embodiment will be described using Figure 11. The flowchart of the second embodiment shown in Figure 11 differs from the flowchart of the first embodiment shown in Figure 8 in that steps S015, S035, and S045 have been added. The following will mainly explain these differences. Note that in the flowchart shown in Figure 11 (second embodiment), the processing of the same step numbers as in the flowchart shown in Figure 8 (first embodiment) is the same as in the first embodiment.

[0062] The control device 40, similar to the first embodiment, activates the process shown in Figure 11 at predetermined time intervals (for example, intervals of several tens of milliseconds) and proceeds to step S010.

[0063] The process in step S010 is the same as in the first embodiment (Figure 8), so its explanation is omitted. The control device 40 then proceeds to step S015.

[0064] In step S015, the control device 40 calculates the NOx emissions and mileage within the time interval of the process. Based on the internal combustion engine speed (operating state), internal combustion engine torque (internal combustion engine load), NOx emission characteristics, and the predetermined time interval of the process, the control device 40 calculates the NOx emissions at a predetermined time interval and adds the calculated NOx emissions to the NOx emission total value. The control device 40 also calculates the mileage at a predetermined time interval based on the predetermined time interval of the process and the vehicle speed detected using the vehicle speed sensor 98, and adds the calculated mileage to the mileage total value. For example, the NOx emission total value and the mileage total value are stored in non-volatile memory and are reset each time the mileage total value reaches a predetermined distance (e.g., 1000 [km]) or each time refueling is detected (flowchart diagram omitted). The control device 40 then proceeds to step S020.

[0065] The process in step S020 is the same as in the first embodiment (Figure 8), so its explanation is omitted. The control device 40 then proceeds to step S030.

[0066] In step S030, the control device 40 determines whether the catalyst warm-up conditions are met, similar to the first embodiment (Figure 8). If the conditions are met (Yes), the process proceeds to step S035; otherwise, the process proceeds to step S090. For example, the control device 40 determines that the catalyst warm-up conditions are met if the catalyst bed temperature detected using the exhaust temperature sensor 99h is below the catalyst activation temperature.

[0067] If the process proceeds to step S035, the control device 40 determines whether the NOx emission value / mileage value is below a predetermined threshold. If the NOx emission value / mileage value is below the predetermined threshold (Yes), the control device 40 proceeds to step S040. If the NOx emission value / mileage value is greater than the predetermined threshold (No), the control device 40 proceeds to step S045. The control device 40 also proceeds to step S040 if the mileage value is zero or below a predetermined distance.

[0068] If the process proceeds to step S040, the control device 40 calculates the target warm-up torque (Td) (corresponding to the "first target torque") based on the internal combustion engine rotation speed (operating state of the internal combustion engine) and the target warm-up torque characteristics (1) stored in the memory device, similar to the first embodiment (Figure 8), stores it in the target warm-up torque (Td), and proceeds to step S050.

[0069] If the process proceeds to step S045, the control device 40 calculates the target warm-up torque (Td) (corresponding to the "second target torque") based on the internal combustion engine rotation speed (operating state of the internal combustion engine) and the target warm-up torque characteristics (2) stored in the memory device, stores it in the target warm-up torque (Td), and proceeds to step S050.

[0070] The following steps S050, S060, S070, and S090 are the same as in the first embodiment (Figure 8), so their explanation will be omitted.

[0071] In the second embodiment, if the cumulative NOx emission value relative to the cumulative mileage is below a predetermined threshold, the catalyst is warmed up efficiently and quickly, similar to the first embodiment. If the cumulative NOx emission value relative to the cumulative mileage is greater than the predetermined threshold, the catalyst is warmed up in a way that minimizes NOx emissions.

[0072] The hybrid vehicle of the present invention is not limited to the configuration, processing procedures, etc., described in this embodiment, and various modifications, additions, and deletions are possible without altering the essence of the present invention. For example, the configuration of the hybrid vehicle is not limited to the configuration shown in Figure 1, and the configuration of the internal combustion engine system is not limited to the configuration shown in Figure 2.

[0073] Alternatively, the NOx emission characteristics shown in Figure 4, the exhaust heat quantity characteristics shown in Figure 5, and the exhaust heat quantity / NOx emission characteristics shown in Figure 6 may be prepared for each intake air temperature and coolant temperature (cooling water temperature), and a target warm-up torque characteristic (1) shown in Figure 7 may be created for each intake air temperature and coolant temperature and stored in a memory device. In this case, when determining the target warm-up torque (Td) in step S040 of the flowchart shown in Figures 8 and 11, the target warm-up torque characteristic (1) corresponding to the intake air temperature and coolant temperature may be used. Similarly, the NOx emission characteristics shown in Figure 9 may be prepared for each intake air temperature and coolant temperature, and a target warm-up torque characteristic (2) shown in Figure 10 may be created for each intake air temperature and coolant temperature and stored in a memory device. In this case, when determining the target warm-up torque (Td) in step S045 of the flowchart shown in Figure 11, the target warm-up torque characteristic (2) corresponding to the intake air temperature and coolant temperature may be used.

[0074] Furthermore, the numerical values ​​used in the description of this embodiment are merely examples and are not limited to these values. Also, terms such as greater than or equal to (≧), less than or equal to (≦), greater than (>), less than (<), etc., may or may not include the equals sign. [Explanation of Symbols]

[0075] 1. Hybrid vehicle 2 Internal Combustion Engine 2a Crankshaft 3 Motor Generator 3a Electric motor shaft 5. Supercharger 6. Intake System 7 Exhaust System 8 EGR system 11a, 11b front wheel 12a, 12b rear wheel 13a, 13b Clutch 14 Transmission 15 Differential Gear 16 Transmission shaft 17 Propeller Shaft 18 Drive shaft 21 Fuel Injector 31 Inverter 32 batteries 40 Control device 41 CPU 41a User-requested torque calculation unit 41b Target warm-up torque calculation unit 41c Catalytic converter warm-up section 51 Turbine 52 Variable nozzle mechanism 52a Nozzle Actuator 53 Compressor 61a, 61b Intake pipe 62 Intake Manifold 63 Intercooler 64 Throttle valve 64a Throttle Actuator 71 Exhaust Manifold 72a, 72b exhaust pipes 73 Exhaust gas purification device 73a Catalyst 81 EGR tube 82 EGR cooler 83 EGR valve 91 Crank Angle Sensor 92 Cam position sensor 93 Airflow Sensor 94 Nozzle Closure Sensor 95a~95c Pressure Sensor 96a, 96b Intake air temperature sensor 97 Accelerator position sensor 98 Vehicle speed sensor 99h Exhaust Temperature Sensor 99W Coolant Temperature Sensor

Claims

1. A hybrid vehicle having an internal combustion engine and a motor generator, The exhaust path of the aforementioned internal combustion engine is equipped with a catalyst that purifies NOx contained in the exhaust gas. The system includes a control device that controls the internal combustion engine and the motor generator, The control device is A user-requested torque calculation unit determines the user-requested torque based on the operating state of the internal combustion engine and the amount the accelerator pedal is depressed, A target warm-up torque calculation unit determines the target warm-up torque based on the aforementioned operating conditions, When catalyst warm-up conditions requiring the warm-up of the catalyst are met, and the target warm-up torque is greater than the user-requested torque, the catalyst warm-up processing unit controls the internal combustion engine to output the target warm-up torque, and controls the motor generator to consume the surplus torque obtained by subtracting the user-requested torque from the target warm-up torque for power generation. It has, The aforementioned target warm-up torque is, Based on the NOx emission characteristics, which are the characteristics of NOx emissions corresponding to the operating state and the internal combustion engine torque, and the exhaust heat quantity characteristics, which are the characteristics of exhaust heat quantity corresponding to the operating state and the internal combustion engine torque, In accordance with each driving state, a first target torque is set such that, among torques greater than or equal to the driving torque required for the hybrid vehicle to run in that driving state, the value of the exhaust heat amount / NOx emissions for that driving state is approximately the maximum value. Hybrid vehicle.

2. A hybrid vehicle according to claim 1, The control device stores, based on the operating state, an integrated NOx emission value calculated by accumulating NOx emissions and an integrated mileage value calculated by accumulating the mileage of the hybrid vehicle. As the aforementioned target warm-up torque, The above-mentioned first target torque and, Based on the NOx emission characteristics, a second target torque is set corresponding to each operating state, such that among torques greater than or equal to the aforementioned driving torque, the value of the NOx emission for that operating state is approximately the minimum value. It is set, The control device is When the target warm-up torque is determined by the target warm-up torque calculation unit, If the NOx emission value / mileage value is less than or equal to a predetermined threshold, the first target torque is determined as the target warm-up torque. If the NOx emission value / mileage value is greater than a predetermined threshold, the second target torque is determined as the target warm-up torque. Hybrid vehicle.

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