Control system for hybrid vehicles

Abstract

The aim is to ensure the required power output in hybrid vehicles while improving emissions. [Solution] A control device for a hybrid vehicle, which has an exhaust pipe equipped with a catalyst connected to it, an engine for driving the vehicle, and a rotating electric motor powered by battery power for driving the vehicle, and which can switch between an HV driving mode in which the vehicle is driven by the engine and the rotating electric motor, and an EV driving mode in which the engine is stopped and the vehicle is driven by the rotating electric motor, and which, when the EV driving mode is selected, determines that the catalyst is not warmed up and catalyst warm-up control of the engine is necessary, has a first control unit that generates catalyst warm-up control notification information to execute catalyst warm-up control when the engine is started. The first control unit notifies the second control unit, which issues an engine start command and a catalyst warm-up control execution command in conjunction with switching from EV driving mode to HV driving mode, of the catalyst warm-up control notification information prior to the engine start.

Description

Technical Field

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

Background Art

[0002] Conventionally, in a vehicle including an engine, a first rotating electric machine capable of generating electricity mechanically connected to the output shaft of the engine, and a second rotating electric machine for traveling, a proposal has been made to warm up a catalyst that purifies the exhaust gas of the engine (for example, see Patent Document 1). Patent Document 1 discloses that rapid catalyst warm-up is performed when the engine is in an idle-off state.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in a hybrid vehicle, a hybrid driving mode (HV driving mode) and an electric driving mode (EV driving mode) are selected. The HV driving mode is a mode in which the vehicle is driven by an engine and a rotating electric machine. On the other hand, the EV driving mode is a mode in which the engine is stopped and the vehicle is driven only by the rotating electric machine. In the EV driving mode, since the engine is stopped, the catalyst cannot be warmed up. When there is a high-power request for a hybrid vehicle in the EV driving mode, it may switch to the HV driving mode. If the catalyst warm-up is not completed at this time, the emissions may deteriorate.

[0005] Patent Document 1 proposes performing catalyst warm-up while the engine is idle-off. Therefore, control related to catalyst warm-up is initiated only after the engine is running. Furthermore, Patent Document 1 does not consider the state of the battery that drives the rotating electric machine. As a result, when the vehicle switches from EV driving mode to HV driving mode based on the battery state in order to secure the required output, it is likely that the catalyst warm-up will not be completed. Thus, Patent Document 1 had room for improvement in terms of securing the required output and emissions.

[0006] Therefore, the control device for hybrid vehicles disclosed herein aims to ensure the required output and improve emissions in hybrid vehicles. [Means for solving the problem]

[0007] The above problem is solved by a control device for a hybrid vehicle, which includes an engine that serves as a first drive source for vehicle driving, connected to an exhaust pipe equipped with a catalyst, and a rotating electric machine that is driven by battery power and serves as a second drive source for vehicle driving, and which can switch between a hybrid driving mode in which the vehicle is driven by the engine and the rotating electric machine, and an electric driving mode in which the vehicle is driven by the engine and the rotating electric machine, wherein the driving mode can be switched between a hybrid driving mode in which the vehicle is driven by the engine and the rotating electric machine, and an electric driving mode in which the vehicle is driven by the engine, and the control device for a hybrid vehicle, which includes a first control unit that, when the electric driving mode is selected, determines that the catalyst is not warmed up and catalyst warm-up control of the engine is necessary, generates catalyst warm-up control notification information that causes the catalyst warm-up control to be executed when the engine is started, and the first control unit notifies the second control unit, which issues the engine start command and the catalyst warm-up control execution command in conjunction with the switching of the driving mode from the electric driving mode to the hybrid driving mode, of the catalyst warm-up control notification information prior to the engine start.

[0008] In the control device for the hybrid vehicle having the above configuration, the control device may include the second control unit, and the second control unit may issue an engine start command and a catalyst warm-up control execution command to the first control unit when it detects signs of battery polarization occurring in the battery that supplies power to the rotating electric machine and has received catalyst warm-up control warning information.

[0009] Furthermore, in the control device for the hybrid vehicle with the above configuration, the second control unit may be configured to determine that an indication of battery polarization has been detected when the amount of voltage drop per unit time exceeds a predetermined threshold, based on the relationship between the current duration and voltage in the battery. [Effects of the Invention]

[0010] The control device for hybrid vehicles disclosed herein can ensure the required output and improve emissions in hybrid vehicles. [Brief explanation of the drawing]

[0011] [Figure 1] Figure 1 is a schematic diagram showing the general configuration of a hybrid vehicle equipped with a control device for a hybrid vehicle according to an embodiment. [Figure 2] Figure 2 is a schematic diagram showing the general configuration of the engine in a hybrid vehicle according to an embodiment. [Figure 3] Figure 3 is a flowchart illustrating an example of control performed by the engine ECU included in the control system of the hybrid vehicle of this embodiment. [Figure 4] Figure 4 is a flowchart showing an example of control performed by the HVECU included in the control unit of the hybrid vehicle of the embodiment. [Figure 5] Figure 5 is a graph showing an example of the battery status. [Modes for carrying out the invention]

[0012] Embodiments of the present invention will be described below with reference to the accompanying drawings. However, the dimensions and proportions of each part in the drawings may not be shown to be exactly the same as those of the actual parts. Also, some details may be omitted in the drawings.

[0013] (Embodiment) [Configuration of the Hybrid Vehicle] First, with reference to Figure 1, the hybrid electric vehicle (hereinafter simply referred to as "vehicle") 100 of the embodiment will be described. Figure 1 is a schematic diagram illustrating vehicle 100. Vehicle 100 includes an engine 1, a first motor generator (hereinafter referred to as the first MG) 61, a second motor generator (hereinafter referred to as the second MG) 62, a planetary gear mechanism 63, a transmission mechanism 64, and drive wheels 70. Vehicle 100 also includes an HVECU (Hybrid Vehicle Electronic Control Unit) 30, a PCU (Power Control Unit) 40, an engine ECU (Electronic Control Unit) 50, a battery 80, and a battery ECU 81. Furthermore, vehicle 100 includes a vehicle speed sensor 92, an accelerator pedal position sensor 93, a current sensor 94, and a voltage sensor 95. The current sensor 94 is attached to the output terminal of the battery 80 and measures the current of the battery 80. The voltage sensor 95 is attached between the terminals of the battery 80 and measures the voltage of the battery 80.

[0014] HVECU30 corresponds to the second control unit. Engine ECU50 corresponds to the first control unit. HVECU30 switches between EV driving mode and HV driving mode. For this purpose, HVECU30 issues an engine start command to Engine ECU50. HVECU30 also issues a command to execute catalyst warm-up control in engine 1. Engine ECU50 controls the intake air volume and ignition timing in conjunction with the operation of engine 1. Catalyst warm-up control is performed by Engine ECU50. HVECU30 and Engine ECU50 exchange information with each other in order to cooperate in controlling the vehicle 100. HVECU30 and Engine ECU50 will be described in more detail later.

[0015] Referring to Figure 2, Engine 1 is the first power source for vehicle propulsion. Engine 1 comprises a cylinder block with multiple cylinders 2 (only one cylinder 2 is shown in Figure 2). A piston 3 is slidably housed within each cylinder 2. The piston 3 forms a combustion chamber 2a between itself and the cylinder head located above the cylinder block. The piston 3 is connected to the crankshaft 5 via a connecting rod 4. The combustion chamber 2a is equipped with an injector 6 for injecting fuel into the cylinder and a spark plug 7. The fuel injected from the injector 6 becomes a fuel-air mixture in the combustion chamber 2a and is ignited by the spark plug 7. When the ignited fuel-air mixture burns and explodes, the piston 3 is pushed down. The pushed-down piston 3 transmits its explosive force to the crankshaft 5 via the connecting rod 4, causing the crankshaft 5 to rotate. Engine 1 is equipped with a crank angle sensor 15 for detecting the crank angle. Engine 1 is a gasoline engine, but is not limited to this and may be a diesel engine.

[0016] Engine 1 is equipped with an intake port 8 and an exhaust port 9 facing the combustion chamber 2a. An intake pipe 10 is connected to the intake port 8. An exhaust pipe 11 is connected to the exhaust port 9.

[0017] The intake manifold 10 is equipped with an air cleaner 12, an air flow meter 13, a throttle valve 17, and an intake manifold 18, in that order from the upstream side of the intake airflow. The air flow meter 13 detects the amount of air flowing through the intake manifold 10. The throttle valve 17 adjusts the amount of air supplied to the combustion chamber 2a. The intake manifold 10 is branched by the intake manifold 18 and connected to the intake port 8 of each cylinder.

[0018] The exhaust pipe 11 is equipped with an exhaust manifold 20 and a catalytic converter 21, in that order from the upstream side of the exhaust flow. The catalytic converter 21 performs exhaust purification.

[0019] The engine 1 includes an intake valve 23 that opens and closes an intake port 8 and an exhaust valve 24 that opens and closes an exhaust port 9. The intake valve 23 is opened and closed by a valve operating mechanism 25. The exhaust valve 24 is opened and closed by a valve operating mechanism 26.

[0020] The engine ECU 50 includes a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), a storage device, etc. The engine ECU 50 controls the engine 1 by executing programs stored in the ROM and the storage device. Programs and maps used for control are stored in the storage device. The engine ECU 50 functions as a catalyst warming control unit 50a for warming up the catalyst 21 by executing a program. The catalyst warming control unit 50a includes a catalyst warming preparation unit 50a1 and a catalyst warming execution unit 50a2. Also, a catalyst temperature estimation unit 51 is provided in the catalyst warming control unit 50a. The catalyst temperature estimation unit 51 estimates the temperature of the catalyst 21 based on information such as the intake air amount. Further, a coolant temperature sensor 52 that detects the temperature of the coolant circulating in the engine 1 is electrically connected to the catalyst warming control unit 50a. Note that instead of the catalyst temperature estimation unit 51, a catalyst temperature sensor may be provided and the temperature of the catalyst 21 may be detected by the catalyst temperature sensor.

[0021] The catalyst warming preparation unit 50a1 determines whether or not the catalyst 21 is not warmed up in a state where the ignition is on and the engine 1 is stopped and in the EV driving mode. Whether or not the catalyst 21 is not warmed up is determined based on an estimated value estimated by the catalyst temperature estimation unit 51. Specifically, when the estimated catalyst temperature is lower than a preset catalyst warming completion threshold value, it is determined that the catalyst 21 is not warmed up. The method for determining whether or not the catalyst 21 is not warmed up is not limited to this, and various conventionally known methods can be adopted.

[0022] The catalyst warm-up preparation unit 50a1 determines that the catalyst 21 is not warmed up and, when the catalyst warm-up execution conditions are met, determines that catalyst warm-up control is necessary. In this case, the catalyst warm-up preparation unit 50a1 generates catalyst warm-up control notification information. The generated catalyst warm-up control notification information is passed to the HVEDU 30 prior to the start of the engine 1. In this embodiment, when catalyst warm-up control notification information is generated, the catalyst warm-up control notification flag is turned on. Therefore, in this embodiment, prior to the start of the engine 1, the fact that the catalyst warm-up control notification flag is turned on is notified to the HVECU 30. In this way, the catalyst warm-up preparation unit 50a1 keeps the catalyst warm-up control in a ready state so that catalyst warm-up control is started immediately when the engine 1 starts.

[0023] Here, we will explain the conditions for performing catalyst warm-up. One of the conditions for performing catalyst warm-up is that the coolant temperature detected by the water temperature sensor 52 exceeds the lower limit of the water temperature preset for performing catalyst warm-up control. This condition is in place because performing catalyst warm-up control when the coolant temperature is too low may actually worsen emissions, and this is to avoid that. In addition, not being in engine check mode is also included as a condition for performing catalyst warm-up. Furthermore, the functioning of each part of the engine 1 is normal, for example, no abnormalities are detected in the OBD (On-Board Diagnostics) diagnosis is also included as a condition for performing catalyst warm-up. This is because if these conditions are not met, it is assumed that catalyst warm-up cannot be performed properly. In the following explanation, these conditions will be collectively referred to as catalyst warm-up conditions.

[0024] The catalyst warm-up execution unit 50a2 actually performs catalyst warm-up control. In this embodiment, it performs ignition timing retardation control. Ignition timing retardation control is accompanied by a limit on the output of the engine 1. Note that the content of catalyst warm-up control is not limited to ignition timing retardation control. Conventional known catalyst warm-up control can be employed. For example, the throttle valve 17 may be controlled to adjust the intake air volume, or the fuel injection pattern from the injector 6 may be controlled. Also, the content of catalyst warm-up control may be conventional known rapid catalyst warm-up control, or other control methods. When catalyst warm-up control is performed, it is usually accompanied by a limit on engine output.

[0025] The engine ECU 50 is electrically connected to the air flow meter 13 and the crank angle sensor 15. The engine ECU 50 calculates the output of the engine 1 based on the values ​​detected by the air flow meter 13 and the crank angle sensor 15.

[0026] The first MG61 and the second MG62 are rotating electric machines, each connected to the battery 80 via the PCU40, HVECU30, and battery ECU81. The first MG61 and the second MG62 function as motors that generate vehicle driving force in response to power supplied from the battery 80. Furthermore, the first MG61 and the second MG62 also function as generators that generate regenerative power to charge the battery 80 in response to power transmission from the engine 1 and the drive wheels 70. The power exchanged between the first MG61 and the second MG62 and the battery 80 is regulated by the PCU40. The second MG62 is a second power source for vehicle propulsion. The first MG61 also functions as a starter when starting the engine 1.

[0027] PCU40 is a power control device configured to control the input and output of power between the first MG61 and the second MG62 and the battery 80. Although not shown in the diagram, PCU40 includes an inverter, a boost converter, an SMR (System Main Relay), a motor ECU, and the like.

[0028] The planetary gear mechanism 63 mechanically connects the crankshaft 5 of engine 1, the rotating shaft of the first MG 61, the rotating shaft of the second MG 62, and the output shaft of the planetary gear mechanism 63. The planetary gear mechanism 63 includes a sun gear that rotates on its own axis, a ring gear that rotates coaxially with the sun gear, a pinion gear interposed between the sun gear and the ring gear and revolving around the sun gear, and a carrier that rotates coaxially with the sun gear in accordance with the revolution of the pinion gear. The carrier is connected to the crankshaft 5 of engine 1. The sun gear is connected to the rotating shaft of the first MG 61. The ring gear is linked to the rotating shaft of the second MG 62. The driving forces of engine 1, the first MG 61, and the second MG 62 are transmitted to the drive wheels 70 via the transmission mechanism 64.

[0029] The HVECU30, like the engine ECU50, is equipped with a CPU, RAM, ROM, and storage device. The HVECU30 controls the entire system of the vehicle 100 by executing programs stored in the ROM and storage device. The HVECU30 is electrically connected to the vehicle speed sensor 92, accelerator pedal position sensor 93, current sensor 94, and voltage sensor 95.

[0030] The HVECU30 switches the driving mode of the vehicle 100 between EV driving mode and HV driving mode. In EV driving mode, the vehicle is driven using the second MG62 as the power source with the engine 1 stopped. In HV driving mode, the vehicle is driven using the engine 1 as the power source. The case in which at least one of the first MG61 and the second MG62 is used in combination with the engine 1 is also included in HV driving mode.

[0031] The driving mode is switched based on the required torque to the vehicle 100, which is determined from the vehicle speed and accelerator pedal position. For example, if the required torque is less than the starting threshold for starting engine 1, the EV driving mode is selected, in which engine 1 is stopped to improve fuel efficiency. If the required torque is equal to or greater than the starting threshold for starting engine 1, the HV driving mode is selected, in which engine 1 is started.

[0032] HVECU30 includes parts that function as a battery polarization prediction unit (hereinafter simply referred to as the "prediction unit") 31 and a battery polarization determination unit (hereinafter simply referred to as the "determination unit") 32. Battery polarization is the difference between the theoretical electromotive force and the actual operating voltage. It is a phenomenon in which the surface SOC (State of Charge) of the active material decreases and the actual electromotive force decreases when current flows continuously to the discharge side for a long period of time. When battery polarization occurs, a phenomenon occurs in which the output of the battery 80 drops sharply. The prediction unit 31 determines that there is a precursor to battery polarization when it predicts a sharp drop in the output of the battery 80. The determination unit 32 determines that battery polarization is actually occurring when it detects a predetermined drop in the output of the battery 80. The determination of whether there is a precursor to battery polarization and whether battery polarization is actually occurring can be determined, for example, based on the relationship between the battery current duration and voltage, as shown in Figure 5. Battery polarization prediction and battery polarization determination will be explained in detail later.

[0033] [Catalytic Converter Warm-Up Control] Next, an example of control in this embodiment will be explained with reference to the flowcharts shown in Figures 3 and 4. The flowchart in Figure 3 is an example of control performed by the engine ECU 50. The flowchart in Figure 4 is an example of control performed by the HVECU 30. The control of both is performed in parallel. In addition, the HVECU 30 and the engine ECU 50 exchange information with each other, and the information generated and commands transmitted by the control of one are used in the control of the other. In this embodiment, the HVECU 30 and the engine ECU 50 are separate, but they may be integrated into a single control device.

[0034] First, we will explain the control performed by the engine ECU 50, referring to Figure 3. When information generated by the HVECU 30 is used, or when operations are performed based on commands issued by the HVECU 30, refer to Figure 4 as appropriate.

[0035] In step S1, the catalytic converter warm-up preparation unit 50a1 included in the engine ECU 50 determines whether the ignition is on or off. If the determination in step S1 is positive (Yes), the process proceeds to step S2. On the other hand, if the determination in step S1 is negative (No), the process in step S1 is repeated.

[0036] In step S2, the catalyst warm-up preparation unit 50a1 determines whether the catalyst 21 is not warmed up. Whether the catalyst 21 is not warmed up is determined based on the estimated value estimated by the catalyst temperature estimation unit 51. If the estimated value by the catalyst temperature estimation unit 51 is lower than a preset threshold, the catalyst 21 is considered to be not warmed up. If the determination in step S2 is Yes, the process proceeds to step S3. On the other hand, if the determination in step S2 is No, the engine ECU 50 terminates the process.

[0037] In step S3, the catalyst warm-up preparation unit 50a1 determines whether the catalyst warm-up execution conditions described above are met. If the determination in step S3 is Yes, the process proceeds to step S4. On the other hand, if the determination in step S3 is No, the process from step S2 is repeated.

[0038] In step S4, the catalyst warm-up preparation unit 50a1 generates catalyst warm-up control warning information and notifies the HVECU 30 of it. In this embodiment, a flag indicating that catalyst warm-up control warning information has been generated is turned on, and the fact that the flag has been turned on is notified to the HVECU 30. After the processing in step S4, the engine ECU 50 proceeds to step S5.

[0039] In step S5, the engine ECU 50 determines whether or not an engine start command has been received. Here, the engine start command includes both the command given in step S24 and the command given in step S26 in the flowchart shown in Figure 4. In other words, if either the engine start command given in step S24 or the engine start command given in step S26 has been received, a Yes determination is made in step S5. Steps S24 and S26 will be explained later. If a Yes determination is made in step S5, the process proceeds to step S6. On the other hand, if a No determination is made in step S5, the process of step S5 is repeated.

[0040] In step S6, the engine ECU 50 starts engine 1. After the processing in step S6, the engine ECU 50 proceeds to step S7.

[0041] In step S7, the engine ECU 50 determines whether or not a command to execute catalyst warm-up control has been issued. Here, the command to execute catalyst warm-up control is the command issued in step S24 in the flowchart shown in Figure 4. In other words, in step S6, if engine 1 is started based on the engine start command in step S24, a Yes determination is made. On the other hand, in step S6, if engine 1 is started based on the engine start command in step S26, a No determination is made. In step S7, if a Yes determination is made, the process proceeds to step S8. On the other hand, in step S7, if a No determination is made, the engine ECU 50 terminates the process.

[0042] In step S8, the catalyst warm-up execution unit 50a2 included in the engine ECU 50 performs the catalyst warm-up described above. In this embodiment, ignition timing retardation control is performed. This warms up the catalyst and improves emissions.

[0043] Next, the control performed by the HVECU30 will be explained with reference to Figure 4. When information generated by the engine ECU50 is used, refer to Figure 3 as appropriate.

[0044] In step S21, the HVECU 30 determines whether the vehicle 100 is in EV driving mode. That is, it determines whether the engine 1 is stopped. If the determination in step S21 is Yes, the process proceeds to step S22. On the other hand, if the determination in step S21 is No, the HVECU 30 terminates the process.

[0045] In step S22, the predictive detection unit 31 included in the HVECU 30 determines whether or not there is a precursor to battery polarization. Here, the precursor to battery polarization will be explained with reference to the graph shown in Figure 5. Figure 5 shows the relationship between battery current duration and voltage. In Figure 5, the relationship when the current is 50A and the ambient temperature is T1 degrees is shown by a thick solid line. The relationship when the current is 50A and the ambient temperature is T2 is shown by a thick dotted line. Furthermore, the relationship when the current is 100A and the ambient temperature is T1 degrees is shown by a thin solid line. The relationship when the current is 100A and the ambient temperature is T2 is shown by a thin dotted line. Here, T1 > T2.

[0046] Battery polarization warnings can be determined by whether the voltage drop per unit time, i.e., the voltage drop rate ΔV / Δt, exceeds a predetermined value in an environment where discharge is ongoing. The predetermined value can be set according to the current value and ambient temperature. Depending on the current value and ambient temperature, thresholds a1, b1, c1, and d1 can be set, for example, as shown in Figure 5. In other words, when threshold a1, etc., is detected according to the current value and ambient temperature, it is determined that there are signs of battery polarization, and a "Yes" decision is made in step S22. Ambient temperature can be detected by an ambient temperature sensor, etc. (not shown).

[0047] Here, we will explain the setting policy for threshold a1, etc. Threshold a1, etc. is set to a value that allows the second MG62 to exert a predetermined output if high output is required in vehicle 100 at this stage. Specifically, even if the output of engine 1 is limited by performing catalyst warm-up, the value is set to a value that allows the second MG62 to secure enough power to meet the output required by vehicle 100. If signs of battery polarization are detected, the battery power can be secured. Therefore, in this state, if engine 1 is started and catalyst warm-up is completed, the required output in vehicle 100 can be secured and emissions can be improved. The current value can be detected by the current sensor 94, and the voltage value can be detected by the voltage sensor 95.

[0048] If the result in step S22 is "Yes," the process proceeds to step S23. On the other hand, if the result in step S22 is "No," the process proceeds to step S27. In step S27, the EV driving mode is continued. After the processing in step S27, the process ends.

[0049] In step S23, the HVECU 30 determines whether or not the catalyst warm-up control warning flag is present. In other words, it determines whether or not the engine ECU 50 is performing the process in step S4 of the flowchart shown in Figure 3. If the result in step S23 is Yes, the process proceeds to step S24. On the other hand, if the result in step S23 is No, the process proceeds to step S25.

[0050] In step S24, the HVECU 30 issues an engine start command and a catalyst warm-up control execution command to the engine ECU 50. As a result, the engine ECU 50 makes a Yes determination in step S5 of the flowchart shown in Figure 3, and starts engine 1 in step S6. With engine 1 starting in step S6, vehicle 100 transitions from EV driving mode to HV driving mode. In other words, engine 1 and the second MG62 are used as the power source for vehicle 100. At this time, although there are signs of battery polarization, the battery 80 can supply enough power to drive the second MG62. Therefore, even if the output of engine 1 is limited, the required output for vehicle 100 can be secured. After the processing in step S24, the process ends.

[0051] In step S25, the determination unit 32 included in the HVECU 30 determines whether or not battery polarization is occurring. Referring to Figure 5, a voltage threshold is set. The determination unit 32 determines that battery polarization has occurred when the voltage falls below the voltage threshold. If the determination in step S25 is Yes, the process proceeds to step S26. On the other hand, if the determination in step S25 is No, the process proceeds to step S27. The process in step S27 is the same as when the determination in step S22 was No, so a detailed explanation is omitted here.

[0052] In step S26, the HVECU 30 sends an engine start command to the engine ECU 50. However, unlike in step S24, the engine start command in step S26 does not include a command to execute catalyst warm-up control. This is because the engine 1 is being started while battery polarization is occurring. When battery polarization occurs, it is difficult to secure output by driving the second MG 62. Therefore, in this case, the engine 1 is operated without limiting its output to prioritize securing the output requested by the vehicle 100. After the processing in step S26, the catalyst warm-up control in this embodiment is completed.

[0053] [effect] According to this embodiment, when the engine 1 is stopped and it is determined that the catalyst 21 is not warmed up and catalyst warm-up control is necessary, a catalyst warm-up control warning flag is turned on prior to the engine 1 is started, to execute catalyst warm-up control when the engine 1 is started. Therefore, catalyst warm-up control can be executed immediately when the engine 1 is started. This improves emissions.

[0054] Furthermore, when the catalyst warm-up control warning flag is on and signs of battery polarization are detected in the battery 80 that supplies power to the second MG62, the engine 1 is immediately started and catalyst warm-up control is performed. This makes it possible to improve emissions while ensuring the required output of the vehicle 100.

[0055] The embodiments described above are merely examples for carrying out the present invention, and the present invention is not limited thereto. Various modifications of these embodiments are within the scope of the present invention, and it is obvious from the above description that various other embodiments are possible within the scope of the present invention. [Explanation of Symbols]

[0056] 1...Engine, 2...Cylinder, 3...Piston, 4...Connecting rod, 5...Crankshaft, 6...Injector, 7...Spark plug, 10...Intake pipe, 11...Exhaust pipe, 12...Air cleaner, 13...Air flow meter, 15...Crank angle sensor, 17...Throttle valve, 21...Catalytic converter, 30...HVECU, 31...Battery polarization prediction unit, 32...Battery polarization determination unit, 40...PCU, 50...Engine EC U, 50a...Catalyst warm-up control unit, 50a1...Catalyst warm-up preparation unit, 50a2...Catalyst warm-up execution unit, 51...Catalyst temperature estimation unit, 52...Water temperature sensor, 61...First MG, 62...Second MG, 63...Planetary gear mechanism, 64...Transmission mechanism, 70...Drive wheel, 80...Battery, 81...Battery ECU, 92...Vehicle speed sensor, 93...Accelerator opening sensor, 94...Current sensor, 95...Voltage sensor, 100...Hybrid vehicle,

Claims

1. A control device for a hybrid vehicle comprising an engine that serves as a first drive source for vehicle propulsion and is connected to an exhaust pipe equipped with a catalyst, and a rotating electric machine that is driven by battery power and serves as a second drive source for vehicle propulsion, wherein the control device switches between a hybrid driving mode in which the vehicle is propelled by the engine and the rotating electric machine, and an electric driving mode in which the engine is stopped and the vehicle is propelled by the rotating electric machine, When the electric driving mode is selected, and it is determined that the catalyst is not warmed up and catalyst warm-up control of the engine is necessary, the system includes a first control unit that generates catalyst warm-up control notification information to execute the catalyst warm-up control when the engine is started. The first control unit notifies the second control unit, which issues the engine start command and the catalyst warm-up control execution command in conjunction with the switching of the driving mode from the electric driving mode to the hybrid driving mode, of the catalyst warm-up control advance prior to the engine start. Control system for hybrid vehicles.

2. The control device includes the second control unit, The second control unit, upon detecting signs of battery polarization in the battery supplying power to the rotating electric machine and receiving catalyst warm-up control warning information, issues an engine start command and a catalyst warm-up control execution command to the first control unit. A control device for a hybrid vehicle according to claim 1.

3. The second control unit determines, based on the relationship between the current duration and voltage in the battery, that an indication of battery polarization has been detected when the amount of voltage drop per unit time exceeds a predetermined threshold. A control device for a hybrid vehicle according to claim 2.

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