JP2013112101A - Hybrid vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make warmup of a catalyst compatible with suppression of misfire during lean imbalancing.SOLUTION: When a traveling mode is an electric traveling preferential mode (CD mode), an engine is started for the first time after system startup, a cooling water temperature Tw is lower than a threshold value Twref, further, it is under lean imbalancing and a catalyst predictive floor temperature Tcat is less than a threshold value Tcref, operation stop of the engine is prohibited (S160) till catalyst warmup is completed. By continuing the operation of the engine which is not catalyst warmup control, a little emission deterioration caused by no completion of catalyst warmup occurs but partial cylinder misfiring that may be incurred by executing catalyst warmup control during lean imbalancing can be suppressed and emission deterioration can be suppressed. Moreover, since catalyst warmup can be finished promptly, emission deterioration in engine start after the next time can be suppressed.

Description

  The present invention relates to a hybrid vehicle, and more specifically, a plurality of cylinders in which an exhaust gas purification apparatus having a motor that outputs driving power, a battery that can supply power to the motor, and a catalyst that purifies exhaust gas is attached to an exhaust system. If the engine coolant temperature is lower than the required warm-up temperature for the exhaust purification system when the engine is started, the engine ignition timing is increased to promote the warm-up of the catalyst. Control means for executing catalyst warm-up control that is later than the ignition timing after the completion of the engine, and a first mode in which priority is given to electric travel that travels with the power from the motor in a state where the operation of the engine is stopped; A second mode in which the engine is operated as necessary so as to maintain the charged amount of the battery within a predetermined range and travels using the power from the engine and the power from the motor. It relates to a hybrid vehicle traveling with any of the modes.

  Conventionally, as this type of technology, an engine, a first motor generator, a drive shaft coupled to an axle, a crankshaft of the engine, and a rotation shaft of the first motor generator are connected to a ring gear, a carrier, and a sun gear, respectively. A planetary gear mechanism, a second motor generator attached to the drive shaft, and a battery that exchanges electric power via the first motor generator, the second motor generator, and the inverter, and maintains the electric power of the battery Necessary for giving priority to maintaining the CD mode running with the power from the second motor generator and consuming the battery power in principle with the engine stopped in order to give priority to consumption Depending on the operation of the engine and the second motor generator In a hybrid vehicle that travels using any one of the CS mode that travels by force, while the engine is intermittently controlled by the CD mode and travels while the engine water temperature is low, the battery It has been proposed to limit the required discharge amount to a relatively small value, and to set a relatively large value without limiting the required discharge amount of the battery when the engine water temperature is high (see, for example, Patent Document 1). . In this hybrid vehicle, when the engine water temperature is low in the CD mode, the required discharge amount of the battery is limited to a relatively small value, so that the power from the engine is increased and the engine water temperature is increased. The deterioration of emissions when switching from to CS mode is suppressed.

JP 2011-051395 A

  In hybrid vehicles that can be driven electrically, when the engine water temperature is low when the engine is started during the electric drive after the system is started, the engine of the exhaust purification device attached to the exhaust system of the engine is warmed up. The catalyst warm-up operation is performed to make the ignition timing of the engine slower than usual. Since the ignition timing is retarded in an engine during catalyst warm-up operation, the fuel injection amount to some cylinders of the engine is smaller than the fuel injection amount to other cylinders, so the air-fuel ratio to the engine is lean. When lean imbalance occurs, misfiring tends to occur in some cylinders, and unburned fuel is discharged when misfiring occurs. In the hybrid vehicle described above, it is not possible to cope with a lean imbalance that occurs during the first engine start after the system is started.

  The main object of the hybrid vehicle of the present invention is to suppress the deterioration of emissions even when lean imbalance occurs at the time of the first engine start after the system is started.

  The hybrid vehicle of the present invention employs the following means in order to achieve the main object described above.

The hybrid vehicle of the present invention
A motor that outputs driving power, a battery that can supply electric power to the motor, a multi-cylinder engine in which an exhaust purification device having a catalyst that purifies exhaust is attached to an exhaust system, and when the engine is started When the temperature of the cooling water of the engine is less than the temperature required for warming up the catalyst in the exhaust gas purification device, the ignition timing of the engine is set to ignition after warming up in order to promote warming up of the catalyst. Control means for performing catalyst warm-up control that is later than the timing, and a first mode that preferentially runs on electric running that runs with power from the motor in a state where the operation of the engine is stopped, and the battery A second mode in which the engine is operated as necessary to maintain the charged amount within a predetermined charged amount range and travels using the power from the engine and the power from the motor. In the hybrid vehicle traveling by using any of the mode of the and,
When the engine is started while running using the first mode from system startup, the control means is configured such that the temperature of the cooling water of the engine is lower than the required warm-up temperature and the engine When the engine is in a specific lean imbalance state where the air-fuel ratio to the engine is in a lean state because the fuel injection amount to some cylinders is smaller than the fuel injection amount to other cylinders, the engine is shut down Is a means for performing either of prohibiting or switching to the second mode,
It is characterized by that.

  In the hybrid vehicle of the present invention, the engine is started while traveling using the first mode in which the vehicle travels by giving priority to the electric traveling that travels with the power from the motor in a state where the operation of the engine is stopped after the system is started. When the temperature of the engine cooling water is lower than the temperature required for warming up the catalyst in the exhaust emission control device, the fuel injection amount to some cylinders of the engine is the fuel injection amount to other cylinders. When the engine is in a specific lean imbalance state where the air-fuel ratio to the engine is in a lean state because it is less, it is necessary to prohibit engine shutdown or maintain the battery charge amount within a predetermined charge amount range The engine is operated in response to one of the two modes to switch to the second mode of traveling using the power from the engine and the power from the motor. That is, when the engine is in the specific lean imbalance state, either stopping the engine operation or switching to the second mode is executed. If it is prohibited to shut down the engine while the engine is in a specific lean imbalance state and the engine is to continue to run, there will be a slight deterioration in emissions due to catalyst warm-up not being completed. It is possible to suppress the deterioration of emissions when the engine is started after the next time. As a result, the deterioration of emissions can be suppressed as a whole. The engine operation when the engine stoppage is prohibited may be any operation that does not perform catalyst warm-up control. For example, an engine that performs idling operation or an engine that outputs constant power from the engine. Examples include those that operate constantly and those that operate the engine according to the power required for traveling. On the other hand, if the mode is switched to the second mode in the specific lean imbalance state, the catalyst warm-up control is not performed because it is necessary to travel using the power from the engine. Although the deterioration of the emission occurs, the deterioration of the emission due to misfire of some cylinders by the catalyst warm-up control in the specific lean balance state can be suppressed, and the deterioration of the emission can be suppressed as a whole.

  In such a hybrid vehicle of the present invention, the control means is a temperature at which the estimated temperature of the catalyst is lower than the temperature at which the catalyst is warmed up even in the specific lean imbalance state, but the function of the catalyst can be expected to some extent. As described above, when the temperature is equal to or higher than a predetermined estimated temperature, the prohibition of the engine operation and the switching to the second mode are not executed. This is because, when the temperature of the catalyst is equal to or higher than the predetermined estimated temperature, the function of the catalyst is expected to some extent, so even if some cylinders misfire by performing catalyst warm-up control in a specific lean imbalance state, unburned fuel Can be purified to some extent, and the deterioration of emissions can be suppressed. In this case, the predetermined estimated temperature may be determined in advance so as to decrease as the storage ratio, which is the ratio of the storage amount of the battery to the total capacity, decreases. The smaller the battery storage ratio, the lower the predetermined estimated temperature. The smaller the battery storage ratio is, the more the engine warm-up is stopped in a specific lean imbalance state by prohibiting engine shutdown and switching to the second mode. This is to perform the machine control and suppress the deterioration of the emission when the mode is shifted to the second mode.

  In the hybrid vehicle of the present invention, the required warm-up temperature may be determined in advance so as to decrease as the storage ratio, which is the ratio of the storage amount of the battery to the total capacity, decreases. The lower the battery storage ratio, the lower the required warm-up temperature. The smaller the battery storage ratio, the more the catalyst warm-up is performed in a specific lean imbalance state by prohibiting engine shutdown and switching to the second mode. This is to perform the machine control and suppress the deterioration of the emission when the mode is shifted to the second mode.

  The hybrid vehicle of the present invention includes a generator, and a planetary gear mechanism in which three rotating elements are connected to three axes of an output shaft of the engine, a rotating shaft of the generator, and a driving shaft connected to the axle. The motor may be connected to the drive shaft.

1 is a configuration diagram showing an outline of a configuration of a hybrid vehicle 20 as an embodiment of the present invention. 2 is a configuration diagram showing an outline of the configuration of an engine 22. FIG. 7 is a flowchart showing an example of a stop prohibition setting process routine executed by the hybrid electronic control unit 70. 5 is a flowchart showing an example of a mode switching processing routine executed by a hybrid electronic control unit 70. It is explanatory drawing which shows an example of the map for threshold value setting. It is explanatory drawing which shows an example of the map for threshold value setting. FIG. 11 is a configuration diagram showing an outline of a configuration of a hybrid vehicle 120 according to a modification. FIG. 11 is a configuration diagram showing an outline of a configuration of a hybrid vehicle 220 of a modified example. FIG. 11 is a configuration diagram showing an outline of a configuration of a hybrid vehicle 320 of a modified example. FIG. 11 is a configuration diagram showing an outline of a configuration of a hybrid vehicle 420 according to a modification.

  Next, the form for implementing this invention is demonstrated using an Example.

  FIG. 1 is a configuration diagram showing an outline of the configuration of a hybrid vehicle 20 as an embodiment of the present invention. In the hybrid vehicle 20 of the embodiment, as shown in the figure, a carrier is provided on an engine 22, an engine electronic control unit (hereinafter referred to as “engine ECU”) 24 that controls the drive of the engine 22, and a crankshaft 26 of the engine 22. A planetary gear 30 having a ring gear connected to a drive shaft 32 connected to the drive wheels 38a and 38b via a differential gear 37, and a rotor connected to the sun gear of the planetary gear 30, for example, is configured as a synchronous generator motor. Motor MG1, a motor MG2 configured as, for example, a synchronous generator motor and having a rotor connected to drive shaft 32, inverters 41 and 42 for driving motors MG1 and MG2, and switching of inverters 41 and 42 (not shown) By switching the element A motor electronic control unit (hereinafter referred to as “motor ECU”) 44 that drives and controls the motors MG1 and MG2, a system main relay 55, and inverters 41 and 42 exchange power with the motors MG1 and MG2. A high voltage battery 50 configured as a lithium-ion secondary battery having a voltage of 200 V, a battery electronic control unit (hereinafter referred to as “battery ECU”) 52 for managing the high voltage battery 50, each ECU and auxiliary machine 59 Are connected to a power line (hereinafter referred to as “low voltage system power line”) 54b, for example, a low voltage battery 58 configured as a lead storage battery having a rated voltage of 12V, inverters 41 and 42, and a high voltage. From a power line (hereinafter referred to as a “high voltage system power line”) 54 a that connects the battery 50. A DC / DC converter 57 that steps down the power and supplies it to the low voltage system power line 54b, a charger 60 that is connected to an external power source such as a household power source and can charge the high voltage battery 50, and controls the entire vehicle. A hybrid electronic control unit 70.

  The engine 22 is configured as a multi-cylinder internal combustion engine that can output power by using a hydrocarbon-based fuel such as gasoline or light oil, for example. As shown in FIG. The fuel is injected from the fuel injection valve 126, and the intake air and the gasoline are mixed. The mixture is sucked into the fuel chamber through the intake valve 128, and is generated by an electric spark by the spark plug 130. Explosive combustion is performed, and the reciprocating motion of the piston 132 pushed down by the energy is converted into the rotational motion of the crankshaft 26. Exhaust gas from the engine 22 is discharged to the outside air through a purification device 134 having a catalyst (three-way catalyst) that purifies harmful components such as carbon monoxide (CO), hydrocarbons (HC), and nitrogen oxides (NOx). The The engine ECU 24 is configured as a microprocessor centered on a CPU (not shown), and includes a ROM, a RAM, an input / output port, and a communication port in addition to the CPU. The engine ECU 24 includes signals from various sensors that detect the state of the engine 22, a crank position from the crank position sensor 140 that detects the rotational position of the crankshaft 26, and a water temperature sensor 142 that detects the temperature of cooling water in the engine 22. The cooling water temperature Tw from the cylinder, the in-cylinder pressure Pin from the pressure sensor 143 installed in the combustion chamber, the cam position sensor 144 that detects the rotational position of the intake valve 128 that performs intake and exhaust to the combustion chamber and the camshaft that opens and closes the exhaust valve , The throttle position from the throttle valve position sensor 146 for detecting the position of the throttle valve 124, the air flow meter signal AF from the air flow meter 148 attached to the intake pipe, and the temperature sensor also attached to the intake pipe. An intake air temperature from a support 149, an air-fuel ratio AF from an air-fuel ratio sensor 135a, such as oxygen signal from an oxygen sensor 135b is input via the input port. The engine ECU 24 also integrates various control signals for driving the engine 22, such as a drive signal to the fuel injection valve 126, a drive signal to the throttle motor 136 that adjusts the position of the throttle valve 124, and an igniter. The control signal to the ignition coil 138 and the control signal to the variable valve timing mechanism 150 that can change the opening / closing timing of the intake valve 128 are output via the output port. The engine ECU 24 is in communication with the hybrid electronic control unit 70, controls the operation of the engine 22 by a control signal from the hybrid electronic control unit 70, and outputs data related to the operation state of the engine 22 as necessary. . The engine ECU 24 also calculates the rotational speed of the crankshaft 26, that is, the rotational speed Ne of the engine 22 based on the crank position from the crank position sensor 140.

  The motor EUC 40 is configured as a microprocessor centered on a CPU (not shown), and includes a ROM, a RAM, an input / output port, and a communication port in addition to the CPU. Motor ECU 40 detects signals necessary for driving and controlling motors MG1 and MG2, such as signals from rotational position detection sensors 43 and 44 that detect the rotational positions of the rotors of motors MG1 and MG2, and motors detected by current sensors. Phase currents Iv and Iw applied to MG1 and MG2 are input, and a switching control signal to inverters 41 and 42 is output from motor ECU 40. The motor ECU 40 is in communication with the hybrid electronic control unit 70, controls the driving of the motors MG1 and MG2 by a control signal from the hybrid electronic control unit 70, and, if necessary, data on the operating state of the motors MG1 and MG2. Output to the hybrid electronic control unit 70. The motor ECU 40 also calculates the rotational speeds Nm1 and Nm2 of the motors MG1 and MG2 based on signals from the rotational position detection sensors 43 and 44.

  The battery ECU 52 is configured as a microprocessor centered on a CPU (not shown), and includes a ROM, a RAM, an input / output port, and a communication port in addition to the CPU. The battery ECU 52 is connected to signals necessary for managing the high voltage battery 50, for example, the battery voltage Vb from the voltage sensor 51 a installed between the terminals of the high voltage battery 50, and the output terminal of the high voltage battery 50. The charging / discharging current Ib from the current sensor 51b attached to the high-voltage power line 54a, the battery temperature Tb from the temperature sensor 51c attached to the high-voltage battery 50, and the like are input. Data regarding the state of the battery 50 is output to the hybrid electronic control unit 70 by communication. Further, the battery ECU 52 calculates a storage ratio SOC that is a ratio of the storage amount to the total capacity (storage capacity) based on the integrated value of the charge / discharge current Ib detected by the current sensor 51b in order to manage the high voltage battery 50. The input / output limits Win and Wout, which are the maximum allowable power that may charge / discharge the high voltage battery 50, are calculated based on the calculated storage ratio SOC and the battery temperature Tb.

  The charger 60 is connected to the high voltage system power line 54a via a relay 62, and an AC / DC converter 66 that converts AC power from an external power source supplied via a power plug 68 into DC power; A DC / DC converter 64 that converts the voltage of the DC power from the AC / DC converter 66 and supplies the converted voltage to the high voltage system power line 54a.

  The hybrid electronic control unit 70 is configured as a microprocessor centered on the CPU 72, and in addition to the CPU 72, a ROM 74 for storing processing programs, a RAM 76 for temporarily storing data, an input / output port and communication not shown. And a port. The hybrid electronic control unit 70 includes a shift signal SP from the shift position sensor 82 that detects a push signal from the power switch 80 and an operation position of the shift lever 81, and an accelerator pedal position sensor 84 that detects the amount of depression of the accelerator pedal 83. Accelerator opening degree Acc from the vehicle, brake pedal position BP from the brake pedal position sensor 86 that detects the depression amount of the brake pedal 85, vehicle speed V from the vehicle speed sensor 88, connection detection that detects connection of the power plug 68 to the external power source A connection detection signal or the like from the sensor 69 is input via the input port. From the hybrid electronic control unit 70, a drive signal to the system main relay 55 and the relay 62, a switching control signal to the DC / DC converter 64 and the AC / DC converter 66, and a DC / DC converter 57 and a DC / DC converter 64. The switching control signal is output through the output port.

  In the hybrid vehicle 20 of the embodiment, when the system is stopped at home or at a preset charging point, when the power plug 68 is connected to an external power source and the connection is detected by the connection detection sensor 69, the system main relay 55 And the relay 62 are turned on, the charger 60 is controlled, and the high voltage battery 50 is charged with electric power from the external power source. When the system is started after charging the high-voltage battery 50, the storage rate SOC of the high-voltage battery 50 is set to a threshold value Shv (for example, 20% or 30%) set to such an extent that the engine 22 can be started. In the state where the engine 22 is basically stopped, the vehicle travels in the electric travel priority mode (CD mode) in which priority is given to the electric travel that travels only with the power from the motor MG2, and the storage ratio SOC of the high voltage battery 50 is After reaching the threshold value Shv, charging / discharging of the high voltage battery 50 is involved, but basically the vehicle travels in a hybrid travel priority mode (CS mode) in which the hybrid vehicle traveling using power from the engine 22 is prioritized.

  In the electric travel priority mode (CD mode), the required torque Tr * to be output to the drive shaft 32 based on the accelerator opening degree Acc corresponding to the depression amount of the accelerator pedal 83 and the vehicle speed V, and the drive shaft based on the required torque Tr *. When the traveling power Pdrv obtained by multiplying the rotational speed Nr of 32 is set and the traveling power Pdrv is equal to or less than the output limit Wout as the allowable maximum power that may be output from the high voltage battery 50, the operation of the engine 22 is performed. The motor MG2 is controlled to output the travel power Pdrv from the motor MG2 and the required torque Tr * to be output to the drive shaft 32 in a state where the motor MG2 is stopped. When the traveling power Pdrv exceeds the output limit Wout, the traveling power Pdrv is output from the engine 22 on the predetermined operation line to start the engine 22 and efficiently operate the engine 22, and to the drive shaft 32. The engine 22, the motor MG <b> 1, and the motor MG <b> 2 are controlled so that the required torque Tr * is output, and the vehicle travels by hybrid travel. When the engine 22 is started for the first time after the system is started up, the cooling water temperature Tw from the water temperature sensor 142 is a predetermined warm-up as a temperature at which the catalyst of the purifier 134 attached to the exhaust system of the engine 22 needs to be warmed up. When the required temperature is less than a threshold value Twref (for example, 60 ° C. or 65 ° C.), the engine 22 is operated by catalyst warm-up control for promoting warm-up of the catalyst. As the catalyst warm-up control, for example, the ignition timing of the engine 22 is delayed (retarded) at a predetermined idling rotational speed or slightly higher than that during normal operation when the catalyst warm-up is completed. Or drive. In this case, it is possible to output no torque from the engine 22 or to output a slight torque. The reason for retarding the ignition timing compared to normal operation is to slow down the combustion by retarding the ignition timing, and to increase the energy discharged to the exhaust system as thermal energy out of the combustion energy. , Based on promoting warm-up of the catalyst of the purification device 134. When the traveling power Pdrv becomes equal to or less than the output limit Wout of the high-voltage battery 50 after the engine 22 is started, the operation of the engine 22 is stopped again, and the traveling power Pdrv is output from the motor MG2 to return to the electric traveling that travels. .

  In the hybrid travel priority mode (CS mode), the high-voltage battery 50 is configured so that the storage rate SOC of the high-voltage battery 50 is within a predetermined control range (for example, 35% to 45%, 40% to 60%, etc.). The required charging / discharging power Pb * is set, and the required vehicle power P * is set by subtracting the charging / discharging required power Pb * from the traveling power Pdrv, and the required vehicle power P * operates the engine 22 relatively efficiently. When the minimum possible power is equal to or greater than a predetermined driving threshold, the engine 22, the motor MG 1, and the motor MG 2 are configured so that the vehicle 22 requires the power P * and the requested torque Tr * is output to the drive shaft 32. To drive by hybrid driving. At this time, when the storage rate SOC of the high voltage battery 50 is within the control range, the charge / discharge required power Pb * is set to a value of 0, so that the high voltage battery 50 is not charged / discharged from the engine 22 to the vehicle. When the traveling power Pdrv is output as the required power P * and the storage rate SOC of the high voltage battery 50 exceeds the control range, a positive value for discharging is set in the charging / discharging required power Pb *. Therefore, the vehicle required power P * smaller than the traveling power Pdrv is output from the engine 22 with the discharge of the high voltage battery 50, and the storage ratio SOC of the high voltage battery 50 is below the control range. Sometimes, the charging / discharging required power Pb * is set to a negative value for charging. Use power Pdrv larger vehicle power demand P * is to be output. When the vehicle required power P * becomes less than the driving threshold value, the engine 22 cannot be operated relatively efficiently. Therefore, the operation of the engine 22 is stopped and the driving power Pdrv is output from the motor MG2 to shift to electric driving. . When the driver depresses the accelerator pedal 83 while the vehicle is running electrically and the vehicle power P * becomes equal to or greater than the driving threshold due to the increase of the driving power Pdrv, the engine 22 is started and the vehicle 22 requests the vehicle. The vehicle shifts to hybrid driving that outputs power P *. Even if the driver does not depress the accelerator pedal 83 during electric driving, if the electric driving is continued, the storage rate SOC of the high-voltage battery 50 becomes smaller. The charge / discharge required power Pb * having a negative value is set, and the vehicle required power P * becomes equal to or higher than the driving threshold value, so that the hybrid driving is performed.

  Next, the operation of the hybrid vehicle 20 of the embodiment, particularly the operation when the engine 22 is started while traveling in the electric travel priority mode (CD mode) will be described. FIG. 3 shows an example of a stop prohibition setting process routine executed by the electronic control unit 70 in order to perform a setting for prohibiting the operation stop of the engine 22 in the electric travel priority mode (CD mode) when the engine 22 is started. It is a flowchart to show. This routine is executed immediately after the engine 22 is started.

  When the stop prohibition setting processing routine is executed, the engine ECU 24 first prohibits the engine 22 from stopping operation such as the coolant temperature Tw, which is the coolant temperature of the engine 22, the predicted catalyst bed temperature Tcat, and the lean imbalance flag Flib. A process of inputting data necessary to set whether or not to perform is executed (step S100). Here, the coolant temperature Tw detected by the water temperature sensor 142 is input from the engine ECU 24 by communication. The predicted catalyst bed temperature Tcat is determined based on the cooling water temperature Tw by a routine not shown, the load of the engine 22 when the engine 22 is operated, the elapsed time after the operation of the engine 22 is stopped, and the like. It is assumed that the temperature of the catalyst is predicted and stored in a predetermined area of a RAM (not shown) of the engine ECU 24 from the engine ECU 24 by communication. The lean imbalance flag Fliv is a value when the air-fuel ratio to the engine 22 is lean (lean imbalance) because the fuel injection amount to some cylinders of the engine 22 is smaller than the fuel injection amount to other cylinders. This is a flag that is set to 1 and the value 0 is set when the lean imbalance is canceled. The lean imbalance is determined by determining that the lean imbalance has occurred when the fluctuation amount of the rotation speed Ne of the engine 22 (the fluctuation amount of the rotation fluctuation or the rotational angular velocity) is equal to or greater than a predetermined threshold value. It can be determined that the lean imbalance has not occurred when the value is less than the value. In the embodiment, the lean imbalance is determined. When it is determined that the lean imbalance occurs, the value 1 is set as the value of the lean imbalance flag Flib in the predetermined area of the RAM 76, and when it is determined that the lean imbalance does not occur. The value 0 is set as the value of the lean imbalance flag Flib in a predetermined area of the RAM 76, and the value of the lean imbalance flag Flib is read from the predetermined area of the RAM 76 and input.

  When the data is input in this manner, it is determined whether or not the driving mode is the electric driving priority mode (CD mode) (step S110). When the driving mode is the hybrid driving priority mode (CS mode), the electric driving priority mode (CD mode) is used. Since the setting for prohibiting the engine 22 from being stopped is unnecessary, this routine is terminated. Next, it is determined whether or not the engine 22 is started for the first time after the system is started (step S120). When the engine 22 is not started for the first time after the system is started, it is determined that it is not necessary to execute the catalyst warm-up control. Then, this routine is ended, and when the engine 22 is started for the first time after the system is started, the coolant temperature Tw is compared with a threshold value Twref for determining that the catalyst warm-up control needs to be executed (step S130). When the coolant temperature Tw is equal to or higher than the threshold value Twref, it is determined that it is not necessary to execute the catalyst warm-up control, and this routine is terminated. Here, the threshold value Twref is the temperature required for warm-up as described above, and for example, 60 ° C. or 65 ° C. can be used.

  When the engine 22 is started for the first time from the start of the system and the coolant temperature Tw is lower than the threshold value Twref, the lean imbalance flag Flib is checked (step S140). When the lean imbalance flag Flib is 0, that is, in the lean imbalance, If not, it is determined that no misfire occurs due to lean imbalance, and this routine is terminated. On the other hand, when the lean imbalance flag Fliv is 1, it is determined whether or not the predicted catalyst bed temperature Tcat is lower than the threshold value Tcref (step S150). When the predicted catalyst bed temperature Tcat is lower than the threshold value Tcref, the catalyst warm-up is performed. The setting for prohibiting the engine 22 from being stopped until completion is performed (step S160), and this routine is terminated. When the setting for prohibiting the operation stop of the engine 22 is performed, this setting is transmitted to the engine ECU 24, and the operation of the engine 22 is continued until the engine warm-up is completed by the engine ECU 24. Since the engine operation in this case may not be an operation based on catalyst warm-up control, for example, the engine 22 is idling at an idling speed (for example, 600 rpm or 800 rpm), or the engine 22 is rotated at a constant speed. The engine 22 is operated so as to output a constant power from the engine 22 by outputting a slight torque with a number (for example, 1000 rpm, 1200 rpm, etc.), or the engine 22 so that the traveling power Pdrv is output from the engine 22. Or driving. In the embodiment, the engine 22 is idling. In this way, by stopping the operation of the engine 22 and continuing the operation of the engine 22 without the catalyst warm-up control until the catalyst warm-up is completed, a slight emission due to the catalyst warm-up not being completed is achieved. Although the deterioration occurs, misfire that may occur by performing the catalyst warm-up control during the lean imbalance can be suppressed, and the deterioration of the emissions when the engine 22 is started the next time after the catalyst warm-up is finished quickly. Can be suppressed. As a result, the deterioration of emissions can be suppressed as a whole. Note that the completion of the catalyst warm-up is a threshold value (for example, 550 ° C., 600 ° C., 650 ° C., etc.) set in advance as the lower limit of the temperature range in which the catalyst predicted bed temperature Tcat is considered to be sufficiently activated. Judgment can be made when exceeding.

  If it is determined in step S150 that the predicted catalyst bed temperature Tcat is equal to or higher than the threshold value Tcref, this routine is terminated without setting for prohibiting the engine 22 from being stopped. The reason why the engine 22 is not prohibited from being stopped when the predicted catalyst bed temperature Tcat is equal to or higher than the threshold value Tcref is that the catalyst is not fully activated but functions to some extent. However, it is based on the fact that the deterioration of emissions is considered to be suppressed to some extent.

  According to the hybrid vehicle 20 of the embodiment described above, the driving mode is the electric driving priority mode (CD mode), the engine 22 is started for the first time after the system is started, the cooling water temperature Tw is lower than the threshold value Twref, and When the lean imbalance occurs and the predicted catalyst bed temperature Tcat is lower than the threshold value Tcref, the engine 22 is not stopped until the catalyst warm-up is completed, and the operation of the engine 22 that is not the catalyst warm-up control is continued. Thus, although a slight deterioration of the emission due to the catalyst warm-up not being completed occurs, misfires of some cylinders that can be caused by executing the catalyst warm-up control during the lean imbalance can be suppressed. As a result, the deterioration of emissions can be suppressed. In addition, since warming up of the catalyst can be completed quickly, it is possible to suppress deterioration of emissions when the engine 22 is started next time. As a result, it is possible to suppress the deterioration of emission as a whole.

  In the hybrid vehicle 20 of the embodiment, the driving mode is the electric driving priority mode (CD mode), the engine 22 is started for the first time after the system is started, the cooling water temperature Tw is lower than the threshold value Twref, and lean imbalance occurs. In addition, when the predicted catalyst bed temperature Tcat is lower than the threshold value Tcref, the engine 22 is prohibited from being stopped until the catalyst warm-up is completed. However, whether the predicted catalyst bed temperature Tcat is lower than the threshold value Tcref. Regardless of this, the engine 22 is stopped for the first time after the system is started, the cooling water temperature Tw is lower than the threshold value Twref, and the engine 22 is stopped until the catalyst warm-up is completed when the lean imbalance occurs. May be prohibited.

  In the hybrid vehicle 20 of the embodiment, even when the driving mode is the electric driving priority mode (CD mode), when the engine 22 is not started for the first time after the system is started, the cooling water temperature Tw of the engine 22 or the predicted catalyst bed temperature Tcat is set. Regardless, the catalyst warm-up control is not executed. However, even when the driving mode is the electric driving priority mode (CD mode) and the engine 22 is not started for the first time after the system is started, the cooling water temperature Tw of the engine 22 is When it is less than the threshold value Twref, the catalyst warm-up control may be executed. In this aspect, similarly to the embodiment, when the lean imbalance occurs, the engine 22 may be prohibited from being stopped until the catalyst warm-up is completed when the predicted catalyst bed temperature Tcat is lower than the threshold value Tcref.

  In the hybrid vehicle 20 of the embodiment, the driving mode is the electric driving priority mode (CD mode), the engine 22 is started for the first time after the system is started, the cooling water temperature Tw is lower than the threshold value Twref, and lean imbalance occurs. When the predicted catalyst bed temperature Tcat is less than the threshold value Tcref, the engine 22 is prohibited from being stopped until the catalyst warm-up is completed. It is good also as what changes to priority mode (CS mode). An example of a flowchart in this case is shown in FIG. In the mode switching process routine of FIG. 4, the travel mode is the electric travel priority mode (CD mode) (step S210), the engine 22 is started for the first time after the system is started (step S220), and the cooling water temperature Tw is the threshold value Twref. (Step S230). Furthermore, when the lean imbalance occurs (step S240) and the predicted catalyst bed temperature Tcat is lower than the threshold Tcref (step S250), the travel mode is switched to the hybrid travel priority mode (step S250). S260), this routine is finished. In the hybrid travel priority mode, basically, since the vehicle demands power P * obtained by subtracting the charge / discharge demand power Pb * from the travel power Pdrv is output from the engine 22 and travels, the catalyst warm-up control is not performed. Can be. As a result, misfire of some cylinders that can be caused by performing the catalyst warm-up control during lean imbalance can be suppressed, and deterioration of emissions due to misfire can be suppressed.

  In the hybrid vehicle 20 of the embodiment and its modification, whether the catalyst warm-up is necessary when the travel mode is the electric travel priority mode (CD mode) and the engine 22 is started for the first time after the system is started. Is determined based on whether or not the cooling water temperature Tw is lower than a predetermined threshold value Twref, but the threshold value Twref may be determined by the storage ratio SOC of the battery 50. For example, as shown in the threshold setting map illustrated in FIG. 5, when the power storage rate SOC is larger than a predetermined value (for example, 40%), a value that increases as the power storage rate SOC increases is used as the threshold value Twref. A constant value may be used as the threshold value Twref in a range less than the predetermined value. As described above, the threshold value Twref is increased as the power storage ratio SOC is increased. The greater the power storage ratio SOC is, the higher the frequency at which it is determined that catalyst warm-up is necessary. This is based on the fact that most of the traveling power Pdrv can be covered by the discharge from the battery 50 even when the catalyst is warmed up.

  In the hybrid vehicle 20 of the embodiment and its modification, the driving mode is the electric driving priority mode (CD mode), the engine 22 is started for the first time after the system is started, and the cooling water temperature Tw is lower than the threshold value Twref. When lean imbalance occurs, it is determined whether or not to stop the operation of the engine 22 or to switch to the hybrid travel priority mode (CS mode) based on whether or not the predicted catalyst bed temperature Tcat is lower than the threshold value Tcref. However, the threshold value Tcref may be determined by the storage ratio SOC of the battery 50. For example, as shown in the threshold setting map illustrated in FIG. 6, when the storage ratio SOC is larger than a predetermined value (for example, 40%), a value that increases as the storage ratio SOC increases is used as the threshold Tcref. A constant value may be used as the threshold value Tcref in a range less than the predetermined value. Thus, the threshold value Tcref is increased as the power storage rate SOC is increased by increasing the frequency of prohibition of engine shutdown and switching to the hybrid travel priority mode (CS mode) as the power storage rate SOC is increased. This is based on the fact that catalyst warm-up can be completed quickly while suppressing deterioration of emissions without performing catalyst warm-up control.

  In the hybrid vehicle 20 of the embodiment, the power of the motor MG2 is output to the drive shaft 32. However, as illustrated in the hybrid vehicle 120 of the modified example of FIG. 7, the drive shaft 32 is connected to the power of the motor MG2. It may be connected to an axle (an axle connected to the drive wheels 39a and 39b in FIG. 7) different from the other axle (the axle to which the drive wheels 38a and 38b are connected). Further, in the hybrid vehicle 20 of the embodiment, the power of the engine 22 is output to the drive shaft 32 connected to the drive wheels 38a and 38b via the planetary gear 30, but the hybrid vehicle 220 of the modified example of FIG. As illustrated, an inner rotor 232 connected to the crankshaft of the engine 22 and an outer rotor 234 connected to the drive shaft 32 that outputs power to the drive wheels 38a and 38b, and a part of the power of the engine 22 To the drive shaft 32 and a counter-rotor motor 230 that converts the remaining power into electric power.

  In the hybrid vehicle 20 of the embodiment, the power from the engine 22 is output to the drive shaft 32 connected to the drive wheels 38a and 38b via the planetary gear 30, and the power from the motor MG2 is output to the drive shaft 32. However, as illustrated in the hybrid vehicle 320 of the modified example of FIG. 9, the motor MG is attached to the drive shaft 32 connected to the drive wheels 38a and 38b via the transmission 330, and the clutch 329 is attached to the rotation shaft of the motor MG. The power from the engine 22 is output to the drive shaft 32 via the rotating shaft of the motor MG and the transmission 330, and the power from the motor MG is driven to the drive shaft via the transmission 330. It is good also as what outputs to. Alternatively, as illustrated in the hybrid vehicle 420 of the modification of FIG. 10, the power from the engine 22 is output to the drive shaft 32 connected to the drive wheels 38a and 38b via the transmission 430 and the power from the motor MG. May be output to an axle different from the axle to which the drive wheels 38a, 38b are connected (the axle connected to the wheels 39a, 39b in FIG. 10). That is, any type of hybrid vehicle may be used as long as it is a type of hybrid vehicle that can be electrically driven.

  The correspondence between the main elements of the embodiment and the main elements of the invention described in the column of means for solving the problems will be described. In the embodiment, the motor MG2 corresponds to “motor”, the battery 50 corresponds to “battery”, the engine 22 corresponds to “engine”, the stop prohibition setting processing routine of FIG. 3 and the mode switching processing routine of FIG. The hybrid electronic control unit 70, the engine ECU 24, and the motor EUC 40 that execute the functions correspond to “control means”.

  The correspondence between the main elements of the embodiment and the main elements of the invention described in the column of means for solving the problem is the same as that of the embodiment described in the column of means for solving the problem. Therefore, the elements of the invention described in the column of means for solving the problems are not limited. That is, the interpretation of the invention described in the column of means for solving the problems should be made based on the description of the column, and the examples are those of the invention described in the column of means for solving the problems. It is only a specific example.

  As mentioned above, although the form for implementing this invention was demonstrated using the Example, this invention is not limited at all to such an Example, In the range which does not deviate from the summary of this invention, it is with various forms. Of course, it can be implemented.

  The present invention can be used in the manufacturing industry of hybrid vehicles.

  20, 120, 220, 320, 420 Hybrid vehicle, 22 engine, 24 engine electronic control unit (engine ECU), 26 crankshaft, 30 planetary gear, 32 drive shaft, 37 differential gear, 38a, 38b drive wheel, 39a, 39b Wheel, 40 Motor electronic control unit (motor ECU), 41, 42 Inverter, 43, 44 Rotation position detection sensor, 50 High voltage battery, 51a Voltage sensor, 51b Current sensor, 51c Temperature sensor, 52 Electronic control unit for battery ( Battery ECU), 54a high voltage system power line, 54b low voltage system power line, 55 system main relay, 57 DC / DC converter, 58 low voltage battery, 60 charger, 62 relay, 64 DC / DC converter , 66 AC / DC converter, 68 power plug, 69 connection detection sensor, 70 hybrid electronic control unit (HVECU), 80 power switch, 81 shift lever, 82 shift position sensor, 83 accelerator pedal, 84 accelerator pedal position sensor, 85 Brake pedal, 86 Brake pedal position sensor, 88 Vehicle speed sensor, 122 Air cleaner, 124 Throttle valve, 126 Fuel injection valve, 128 Intake valve, 130 Spark plug, 132 Piston, 134 Purifier, 135a Air-fuel ratio sensor, 135b Oxygen sensor, 136, throttle motor, 138 ignition coil, 140 crank position sensor, 142 water temperature sensor, 143 pressure sensor, 144 cam position sensor 146 throttle valve position sensor, 148 an air flow meter, 149 temperature sensor, 150 a variable valve timing mechanism, 230 pair-rotor motor, 232 an inner rotor 232 outer rotor, 330, 430 transmission, MG, MG1, MG2 motor.

Claims (2)

A motor that outputs driving power, a battery that can supply electric power to the motor, a multi-cylinder engine in which an exhaust purification device having a catalyst that purifies exhaust is attached to an exhaust system, and when the engine is started When the temperature of the cooling water of the engine is less than the temperature required for warming up the catalyst in the exhaust gas purification device, the ignition timing of the engine is set to ignition after warming up in order to promote warming up of the catalyst. Control means for performing catalyst warm-up control that is later than the timing, and a first mode that preferentially runs on electric running that runs with power from the motor in a state where the operation of the engine is stopped, and the battery A second mode in which the engine is operated as necessary to maintain the charged amount within a predetermined charged amount range and travels using the power from the engine and the power from the motor. In the hybrid vehicle traveling by using any of the mode of the and,
When the engine is started while running using the first mode from system startup, the control means is configured such that the temperature of the cooling water of the engine is lower than the required warm-up temperature and the engine When the engine is in a specific lean imbalance state where the air-fuel ratio to the engine is in a lean state because the fuel injection amount to some cylinders is smaller than the fuel injection amount to other cylinders, the engine is shut down Is a means for performing either of prohibiting or switching to the second mode,
A hybrid vehicle characterized by that. The hybrid vehicle according to claim 1,
The control means has a predetermined estimated temperature that is predetermined as a temperature at which the estimated temperature of the catalyst is lower than the temperature at which the catalyst has been warmed up even in the specific lean imbalance state but the function of the catalyst can be expected to some extent. At the above time, it is means for preventing the engine from being stopped and switching to the second mode.
A hybrid vehicle characterized by that.

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