JP4293183B2 - Hybrid vehicle and control method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress the deterioration of a catalyst for purifying emission gas while satisfactorily securing a requested driving force when an accelerator operating status is put in an accelerator-off status. <P>SOLUTION: In a hybrid automobile 20, if a catalyst temperature Tcat is a threshold Tref2 or more when turning off an accelerator, the target number of revolutions Ne* of an engine 22 for activation of an engine brake act is set by using a map for setting second FC time target number of revolutions which is inclined to increase the number of revolutions of the engine 22 in comparison with a map for setting first FC time target number of revolutions in a normal operation (step S230). The engine 22 is operated according to the setting of intake air quantity and fuel cut by using the map for setting second FC time throttle opening which is inclined to increase a throttle opening in comparison with the map for setting first FC time throttle opening, and the engine 22 and the motors MG1 and MG2 are controlled so that a braking force based on a request torque Tr* can be output. <P>COPYRIGHT: (C)2007,JPO&amp;INPIT

Description

  The present invention relates to a hybrid vehicle and a control method thereof.

Conventionally, as an example of a hybrid vehicle, in order to suppress deterioration of an exhaust gas purification catalyst that is mainly in a high temperature state by being exposed to a lean atmosphere, when stopping the engine with intermittent operation of the engine, It is known to perform a process for stopping the fuel supply after performing a fuel increasing process for increasing the amount of fuel supplied to the combustion chamber as compared with the conventional state (see, for example, Patent Document 1). Other examples of hybrid vehicles include an engine, a drive motor connected to the engine via a clutch, a continuously variable transmission connected to the output shaft of the drive motor, and a continuously variable transmission. There is also known one provided with a drive shaft (for example, see Patent Document 2). In this hybrid vehicle, when the motor travels using only the drive motor as a power output source with the clutch engaged, the air taken into the engine driven by the drive motor is sent to the exhaust gas purification device, so that the temperature of the catalyst is increased. In order to prevent the exhaust gas purification performance from being lowered, the duration of drive by the drive motor is set shorter as the throttle opening is larger or the engine speed is higher.
JP 2004-176710 A JP 2004-162534 A

  By the way, in the hybrid vehicle as described above, when a deceleration request based on the accelerator off is made under a predetermined traveling condition accompanied by the operation of the engine, the engine brake is used by stopping the fuel supply to the engine (fuel cut). It is preferable to obtain a braking force as a required driving force. However, if the exhaust gas purification catalyst is in a high temperature state when the accelerator operation state is the accelerator off state under a predetermined condition and the fuel cut is performed, the exhaust gas purification catalyst is lean due to the fuel cut. There is a possibility of causing deterioration of the catalyst by heating to exposure to the atmosphere.

  Therefore, a hybrid vehicle and a control method thereof according to the present invention are intended to suppress deterioration of an exhaust gas purifying catalyst while satisfactorily securing a driving force required when an accelerator operation state becomes an accelerator off state. One. In addition, the hybrid vehicle and the control method thereof according to the present invention have an object of suppressing deterioration of the catalyst when the exhaust gas purification catalyst is still in a high temperature state when the accelerator operation state is in the accelerator off state. I will.

  The hybrid vehicle and the control method thereof according to the present invention employ the following means in order to achieve at least a part of the above-described object.

The hybrid vehicle according to the present invention is
An internal combustion engine;
Purification means including a catalyst for purifying exhaust gas discharged from the internal combustion engine;
Catalyst temperature acquisition means for acquiring the temperature of the catalyst;
Power power input / output means connected to the first axle as one of the axles and the output shaft of the internal combustion engine and capable of inputting / outputting power to / from the first axle and the output shaft with input / output of power and power When,
An electric motor capable of inputting / outputting power to / from a second axle that is either the first axle or an axle different from the first axle;
Power storage means capable of exchanging power between the power drive input / output means and the electric motor;
Requested driving force setting means for setting a requested driving force required for traveling based on the accelerator operation state;
When the accelerator operation state is the accelerator off state, and the acquired catalyst temperature is lower than a predetermined temperature, the intake air amount is set and the fuel supply is stopped according to the first constraint. While controlling the internal combustion engine, the power power input / output means, and the electric motor so that the internal combustion engine is operated and a driving force based on the set required driving force is output, When the temperature is equal to or higher than the predetermined temperature, the intake air amount is set according to the second constraint and the fuel supply is stopped according to the second constraint, which tends to increase the intake air amount as compared with the first constraint. Control means for controlling the internal combustion engine, the power drive input / output means, and the electric motor so that a driving force based on the set required driving force is output when the internal combustion engine is operated;
Is provided.

  In this hybrid vehicle, when the accelerator operation state is the accelerator off state and the acquired catalyst temperature is lower than a predetermined temperature, the intake air amount is set and the fuel supply is stopped according to the first constraint. The internal combustion engine is operated, and the internal combustion engine, the power drive input / output means and the electric motor are controlled so that a driving force based on the set required driving force is output, while the obtained temperature of the catalyst is predetermined. When the temperature is higher than the temperature, the internal combustion engine is operated with the intake air amount setting and the fuel supply stop according to the second constraint, which has a tendency to increase the intake air amount as compared with the first constraint. And the internal combustion engine, the power drive input / output means, and the electric motor are controlled so that a drive force based on the set required drive force is output. Thus, when the temperature of the catalyst is equal to or higher than a predetermined temperature when the accelerator operation state is the accelerator off state, the fuel supply can be performed by stopping the fuel supply to the internal combustion engine while increasing the intake air amount of the internal combustion engine. The engine brake is used to stop the engine and the required driving force based on the accelerator off is secured, while the intake air amount is increased and a large amount of air is sent to the purification means to suppress the temperature rise of the catalyst. It becomes possible to suppress deterioration of the catalyst for use.

  In the hybrid vehicle according to the present invention, when the accelerator operation state is the accelerator off state, and the acquired catalyst temperature is lower than the predetermined temperature, the first throttle is set as the first restriction. While setting the opening degree constraint and setting the target operating point of the internal combustion engine based on the set required driving force and the first operating point constraint, the obtained temperature of the catalyst is equal to or higher than the predetermined temperature. In some cases, a second throttle opening restriction that tends to increase the throttle opening as compared to the first throttle opening restriction is set as the second restriction, and the set required driving force is set. And a second operating point constraint that tends to increase the rotational speed of the internal combustion engine as compared to the first operating point constraint. The control means may further include target operation point setting means for setting a turning point, and the control means may control the intake air amount in accordance with the set throttle opening restriction when the accelerator operation state is in an accelerator off state. The internal combustion engine and the electric power are input so that the internal combustion engine is operated at the set target operating point with the setting and the stop of fuel supply, and a driving force based on the set required driving force is output. It may control the output means and the electric motor. Thus, when the temperature of the catalyst is equal to or higher than the predetermined temperature when the accelerator operation state is the accelerator off state, the throttle opening degree of the internal combustion engine is set to be large and the rotational speed of the internal combustion engine is further increased. Since more air can be sent to the purification means, it is possible to suppress the temperature rise of the catalyst satisfactorily and to suppress its deterioration.

  Furthermore, the hybrid vehicle according to the present invention may further comprise fuel supply stop prohibiting means for prohibiting stop of fuel supply to the internal combustion engine when the obtained temperature of the catalyst is in a predetermined temperature range. Is accompanied by an increase in the fuel supply amount for adjusting the temperature of the catalyst according to a predetermined fuel increase condition when the fuel supply stop prohibiting means is prohibited from stopping the fuel supply to the internal combustion engine. The internal combustion engine, the power power input / output means, and the electric motor may be controlled so that the internal combustion engine is operated and a driving force based on the set required driving force is output. In this way, when the temperature of the catalyst is in a predetermined temperature range, prohibiting the stop of the fuel supply and increasing the fuel supply amount in accordance with the predetermined fuel increase condition can suppress the catalyst temperature increase or promote the temperature decrease. By adjusting the temperature of the catalyst, even if the catalyst is exposed to a lean atmosphere when the prohibition of stopping the fuel supply is released, the deterioration of the catalyst can be suppressed as much as possible. Further, by combining such an increase process of the fuel supply amount with an increase process of the intake air amount accompanying the stop of the fuel supply to the internal combustion engine, the accelerator supply amount is increased due to insufficient fuel supply amount increase process. Even if the catalyst is still in a high temperature state when the operation state is the accelerator off state, it is possible to satisfactorily suppress the deterioration of the exhaust gas purifying catalyst.

  The hybrid vehicle according to the present invention may further include charge allowable power setting means for setting charge allowable power, which is power allowed for charging the power storage means based on a state of the power storage means, and the fuel supply The stop prohibiting means stops the fuel supply to the internal combustion engine when the acquired temperature of the catalyst is in the predetermined temperature range and the set charge allowable power is equal to or higher than a predetermined limit value as the charge power. May be prohibited. In a hybrid vehicle, when stopping the fuel supply to the internal combustion engine is prohibited, the driving force (braking force) based on the accelerator off may be provided by the regenerative braking force by the electric motor while the fuel supply to the internal combustion engine is continued. However, regeneration by such an electric motor may be limited due to the relationship with the chargeable power set based on the state of the power storage means. On the other hand, if the intake air amount increasing process accompanying the stop of the fuel supply to the internal combustion engine as described above is performed, the prohibition of the stop of the fuel supply is released based on the charge allowable power of the power storage means Thus, even when the accelerator operation state becomes the accelerator off state, even if the catalyst is in a high temperature state, it is possible to suppress the temperature rise of the catalyst and suppress its deterioration.

  Further, the fuel increase condition increases the fuel supply amount according to a first increase restriction when the set charge allowable power is equal to or greater than a temporary limit value which is a value larger than the limit value as the charge power. When the set allowable charging power is less than the temporary limit value as the charging power, the fuel supply amount is set according to the second increase restriction having a tendency to increase the fuel supply amount more than the first increase restriction. The amount may be increased. As described above, when the temperature of the catalyst is adjusted by increasing the fuel supply amount, the fuel supply amount to the internal combustion engine is further increased when the charge allowable power approaches the limit value to some extent, so that Thus, the temperature of the catalyst can be adjusted so that the deterioration of the catalyst can be suppressed when the prohibition of the fuel supply to the internal combustion engine is released and the fuel supply is stopped.

  In the hybrid vehicle according to the present invention, the power input / output means is connected to the first axle, the output shaft of the internal combustion engine, and a rotatable third shaft, and any two of these three shafts. And a three-axis power input / output means for inputting / outputting power determined based on power input / output to / from the remaining shaft, and a generator capable of inputting / outputting power to / from the third shaft. .

A hybrid vehicle control method according to the present invention includes an internal combustion engine, a purification means including a catalyst for purifying exhaust gas discharged from the internal combustion engine, a catalyst temperature acquisition means for acquiring the temperature of the catalyst, and any axle. Power power input / output means connected to a first axle and an output shaft of the internal combustion engine and capable of inputting / outputting power to / from the first axle and the output shaft with input / output of power and power; An electric motor capable of inputting / outputting power to / from a second axle which is either an axle or an axle different from the first axle; and an electric power input / output means and an electric storage means capable of exchanging electric power between the electric motor. A hybrid vehicle control method comprising:
When the accelerator operation state in the hybrid vehicle is in an accelerator off state, if the temperature of the catalyst acquired by the temperature acquisition means is less than a predetermined temperature, the setting of the intake air amount according to the first constraint and The internal combustion engine, the electric power drive input / output means, and the output power so that the internal combustion engine is operated with the stop of fuel supply and the driving force based on the required driving force set according to the accelerator operation state is output. When the temperature of the obtained catalyst is equal to or higher than the predetermined temperature while controlling the electric motor, the suction according to the second constraint has a tendency to increase the amount of intake air compared to the first constraint. The internal combustion engine and the electric power are output so that the internal combustion engine is operated with the air amount setting and the fuel supply stop, and the driving force based on the set required driving force is output. It is intended to include the step of controlling the the force output means and said motor.

  If the temperature of the catalyst is equal to or higher than a predetermined temperature when the accelerator operation state is in the accelerator-off state as in this method, if the fuel supply to the internal combustion engine is stopped while increasing the intake air amount of the internal combustion engine, Suppressing deterioration of exhaust gas purification catalyst by increasing intake air volume and suppressing catalyst temperature rise while ensuring required driving force based on accelerator off by using engine brake by stopping fuel supply It becomes possible to do.

Other hybrid vehicles according to the present invention are:
An internal combustion engine capable of outputting power to a drive shaft connected to an axle;
Purification means including a catalyst for purifying exhaust gas discharged from the internal combustion engine;
Catalyst temperature acquisition means for acquiring the temperature of the catalyst;
An electric motor connected to the drive shaft and an output shaft of the internal combustion engine and capable of motoring the internal combustion engine;
Power storage means capable of exchanging electric power with the electric motor;
Requested driving force setting means for setting a requested driving force required for traveling based on the accelerator operation state;
When the accelerator operation state is in an accelerator off state, and the acquired temperature of the catalyst is lower than a predetermined temperature, a first constraint for determining the intake air amount of the internal combustion engine is set and the When the target operating point of the internal combustion engine is set based on the set required driving force and the first operating point constraint, when the acquired temperature of the catalyst is equal to or higher than the predetermined temperature, the first operating point is set. The second constraint has a tendency to increase the intake air amount as compared to the above-mentioned constraint, and tends to increase the rotational speed of the internal combustion engine as compared to the set required driving force and the first operating point constraint. Target operating point setting means for setting a target operating point of the internal combustion engine based on a second operating point constraint with
When the accelerator operation state is an accelerator off state, the internal combustion engine is operated at the set target operation point with the intake air amount setting and the fuel supply stop according to the set restrictions. Control means for controlling the internal combustion engine and the electric motor so that a driving force based on the set required driving force is output;
Is provided.

Another hybrid vehicle control method according to the present invention includes an internal combustion engine capable of outputting power to a drive shaft connected to an axle, a purification means including a catalyst for purifying exhaust gas discharged from the internal combustion engine, and the drive shaft. And a control method for a hybrid vehicle comprising: an electric motor connected to the output shaft of the internal combustion engine and capable of motoring the internal combustion engine; and a storage means capable of exchanging electric power with the electric motor,
(A) When the accelerator operation state is in the accelerator off state and the temperature of the catalyst is lower than a predetermined temperature, the first setting for determining the intake air amount of the internal combustion engine and the travel are required. When the target operating point of the internal combustion engine is set based on the required driving force and the first operating point constraint, the temperature of the catalyst is equal to or higher than the predetermined temperature, compared with the first constraint. A second operating point has a tendency to increase the number of revolutions of the internal combustion engine as compared with the required driving force and the first operating point constraint while setting a second constraint that tends to increase the intake air amount Setting a target operating point of the internal combustion engine based on constraints;
(B) When the accelerator operating state is in the accelerator off state, the target operating point set in step (a) with the setting of the intake air amount and the stop of fuel supply in accordance with the constraints set in step (a). Controlling the internal combustion engine and the electric motor so that the internal combustion engine is operated and a driving force based on the required driving force is output;
Is included.

  Next, the best mode for carrying out the present invention will be described using examples.

  FIG. 1 is a schematic configuration diagram of a hybrid vehicle according to a first embodiment of the present invention. A hybrid vehicle 20 shown in FIG. 1 is connected to an engine 22, a three-shaft power distribution integration mechanism 30 connected to a crankshaft 26 as an output shaft of the engine 22 via a damper 28, and the power distribution integration mechanism 30. The motor MG1 capable of generating electricity, the reduction gear 35 attached to the ring gear shaft 32a as a drive shaft connected to the power distribution and integration mechanism 30, the motor MG2 connected to the reduction gear 35, and the entire power output device And an electronic control unit for hybrid (hereinafter referred to as “hybrid ECU”) 70.

The engine 22 is configured as an internal combustion engine that can output power using a hydrocarbon fuel such as gasoline or light oil. As can be seen from FIG. 2, the engine 22 takes in the air cleaned by the air cleaner 122 into the intake port via the throttle valve 124 and injects gasoline from the fuel injection valve 126 to mix intake air and gasoline. The air-fuel mixture is sucked into the combustion chamber through the intake valve 128 and explosively burned by an electric spark from the spark plug 130, 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 passes through a purification device 134 having an exhaust gas purification catalyst (three-way catalyst) that purifies harmful components such as carbon monoxide (CO), hydrocarbons (HC), and nitrogen oxides (NOx). It is discharged outside. The exhaust gas purifying catalyst of the purifying device 134 may be composed of an oxidation catalyst such as platinum (Pt) or palladium (Pd), a reduction catalyst such as rhodium (Rh), and a co-catalyst such as ceria (CeO ₂ ). . In this case, CO and HC contained in the exhaust gas are purified to water (H ₂ O) and carbon dioxide (CO ₂ ) by the action of the oxidation catalyst, and NOx contained in the exhaust gas is nitrogen (N ₂ ) and Purified to oxygen (O ₂ ).

  The engine 22 configured as described above is controlled by an engine electronic control unit (hereinafter referred to as engine ECU) 24. As shown in FIG. 2, the engine ECU 24 is configured as a microprocessor centered on a CPU 24a. In addition to the CPU 24a, a ROM 24b that stores a processing program, a RAM 24c that temporarily stores data, and an input / output (not shown) And a communication port. For example, the engine ECU 24 includes a cylinder position that is a crank position from a crank position sensor 140 that detects the rotational position of the crankshaft 26, a cooling water temperature from a water temperature sensor 142 that detects a temperature of cooling water in the engine 22, and a pressure in the combustion chamber. In-cylinder pressure from a pressure sensor 143 that detects internal pressure, a cam position from a cam position sensor 144 that detects the rotational position of an intake valve 128 that performs intake and exhaust to a combustion chamber, and a camshaft that opens and closes an exhaust valve, and a throttle valve 124 The throttle position from the throttle valve position sensor 146 for detecting the position of the engine, the signal from the air flow meter 148 provided in the intake pipe, the intake temperature from the temperature sensor 149 provided in the intake pipe, and the purifier 134. Temperature sensor 135 Et catalyst bed temperature Tcat and the like are 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, and controls the operation of the engine 22 by a control signal from the hybrid electronic control unit 70, and the data regarding the operation state of the engine 22 as necessary. Output to.

  The power distribution and integration mechanism 30 includes an external gear sun gear 31, an internal gear ring gear 32 arranged concentrically with the sun gear 31, a plurality of pinion gears 33 that mesh with the sun gear 31 and mesh with the ring gear 32, A planetary gear mechanism is provided that includes a carrier 34 that holds a plurality of pinion gears 33 so as to rotate and revolve, and that performs differential action using the sun gear 31, the ring gear 32, and the carrier 34 as rotational elements. The crankshaft 26 of the engine 22 is connected to the carrier 34, the motor MG1 is connected to the sun gear 31, and the reduction gear 35 is connected to the ring gear 32 via the ring gear shaft 32a. The power distribution and integration mechanism 30 includes the motor MG1. When functioning as a generator, power from the engine 22 input from the carrier 34 is distributed according to the gear ratio between the sun gear 31 side and the ring gear 32 side, and when the motor MG1 functions as an electric motor, the engine input from the carrier 34 The power from 22 and the power from the motor MG1 input from the sun gear 31 are integrated and output to the ring gear 32 side. The power output to the ring gear 32 is finally output from the ring gear shaft 32a to the drive wheels 63a and 63b of the vehicle via the gear mechanism 60 and the differential gear 62.

  Both the motor MG1 and the motor MG2 are configured as well-known synchronous generator motors that can operate as a generator and operate as an electric motor, and exchange power with the battery 50 via inverters 41 and 42. The power line 54 connecting the inverters 41 and 42 and the battery 50 is configured as a positive bus and a negative bus shared by the inverters 41 and 42, and the power generated by any one of the motors MG 1 and MG 2 It can be consumed by a motor. Therefore, the battery 50 is charged / discharged by electric power generated from one of the motors MG1 and MG2 or insufficient electric power. If the balance of electric power is balanced by the motors MG1 and MG2, the battery 50 is not charged / discharged. The motors MG1 and MG2 are both driven and controlled by a motor electronic control unit (hereinafter referred to as “motor ECU”) 40. The motor ECU 40 detects signals necessary for driving and controlling the motors MG1 and MG2, such as signals from rotational position detection sensors 43 and 44 that detect the rotational positions of the rotors of the motors MG1 and MG2, and current sensors (not shown). The phase current applied to the motors MG1 and MG2 is input, and a switching control signal to the inverters 41 and 42 is output from the motor ECU 40. The motor ECU 40 is in communication with the hybrid ECU 70, controls the driving of the motors MG1, MG2 by a control signal from the hybrid ECU 70, and outputs data related to the operating state of the motors MG1, MG2 to the hybrid ECU 70 as necessary.

  The battery 50 is managed by a battery electronic control unit (hereinafter referred to as “battery ECU”) 52. The battery ECU 52 receives signals necessary for managing the battery 50, for example, a voltage between terminals from a voltage sensor (not shown) installed between the terminals of the battery 50, and a power line 54 connected to the output terminal of the battery 50. The charging / discharging current from the attached current sensor (not shown), the battery temperature Tb from the temperature sensor 51 attached to the battery 50, and the like are input, and the battery ECU 52 communicates data regarding the state of the battery 50 as necessary. Is output to the hybrid ECU 70 and the engine ECU 24. The battery ECU 52 also calculates the remaining capacity (SOC) based on the integrated value of the charge / discharge current detected by the current sensor in order to manage the battery 50.

  The hybrid ECU 70 is configured as a microprocessor centered on the CPU 72, and includes a ROM 74 that stores a processing program, a RAM 76 that temporarily stores data, an input / output port and a communication port (not shown), in addition to the CPU 72. . The hybrid ECU 70 includes an ignition signal from the ignition switch 80, a shift position SP from the shift position sensor 82 that detects the shift position SP that is the operation position of the shift lever 81, and an accelerator pedal position sensor that detects the amount of depression of the accelerator pedal 83. The accelerator opening Acc from 84, the brake pedal position BP from the brake pedal position sensor 86 for detecting the depression amount of the brake pedal 85, the vehicle speed V from the vehicle speed sensor 88, and the like are input via the input port. As described above, the hybrid ECU 70 is connected to the engine ECU 24, the motor ECU 40, and the battery ECU 52 via the communication port, and exchanges various control signals and data with the engine ECU 24, the motor ECU 40, and the battery ECU 52.

  In the hybrid vehicle 20 of the embodiment, the shift position SP of the shift lever 81 includes a parking position used during parking, a reverse position for reverse travel, a neutral position for neutral travel, and a normal drive position for forward travel (hereinafter referred to as “D”). In addition to “position”, a brake position (hereinafter referred to as “B position”) that is selected mainly when the vehicle is traveling on a downhill at a relatively high speed is prepared. Driving that defines driving force setting restrictions for setting the required driving force required for traveling and driving point restrictions for setting the operating point of the engine 22 corresponding to the required driving force at the D position and the B position. Conditions are associated. That is, when the D position is selected as the shift position SP, the required torque Tr * as the required driving force according to the amount of depression of the accelerator pedal 83 by the driver within the power range as the driving force restriction corresponding to the D position is obtained. The target rotational speed Ne * and the target torque Te *, which are target operating points of the engine 22 corresponding to the required torque Tr *, are set in accordance with the operating point restrictions determined so that the engine 22 is efficiently operated. The Further, when the B position is selected as the shift position SP, the required torque Tr *, the target rotational speed Ne *, and the target torque Te * are set according to the driving force constraint and the operating point constraint corresponding to the B position. In this embodiment, the driving force constraint and the driving point constraint corresponding to the B position are basically the same as those corresponding to the D position, but the driving force constraint in the driving condition corresponding to the B position is the D position. The lower limit of the power range is set smaller (larger as braking force) than the driving force constraint under the corresponding driving conditions, and when the B position is selected, when the accelerator is off under the predetermined condition, compared to when the D position is selected A large braking force can be obtained.

  The hybrid vehicle 20 of the embodiment configured as described above is a request to be output to the ring gear shaft 32a as the drive shaft based on the accelerator opening Acc and the vehicle speed V corresponding to the depression amount of the accelerator pedal 83 by the driver. Torque Tr * is calculated, and operation of engine 22, motor MG1, and motor MG2 is controlled so that power corresponding to this required torque Tr * is output to ring gear shaft 32a. As the operation control mode of the engine 22, the motor MG1, and the motor MG2, the engine 22 is operated and controlled so that power corresponding to the required power is output from the engine 22, and all of the power output from the engine 22 is a power distribution integration mechanism. 30, a torque conversion operation mode for driving and controlling the motor MG1 and the motor MG2 so that the torque is converted by the motor MG1 and the motor MG2 and output to the ring gear shaft 32a, and the required power and the power required for charging and discharging the battery 50 The engine 22 is operated and controlled so that the power corresponding to the sum is output from the engine 22, and all or a part of the power output from the engine 22 with charge / discharge of the battery 50 is the power distribution integration mechanism 30 and the motor MG1. And the motor MG2 with torque conversion, the required power is ring gear A charge / discharge operation mode for driving and controlling the motor MG1 and the motor MG2 to be output to the shaft 32a, and a motor for controlling the operation so as to output the power corresponding to the required power from the motor MG2 to the ring gear shaft 32a. There are operation modes.

  Next, the operation of the hybrid vehicle 20 of the embodiment, particularly the operation of the hybrid vehicle 20 when the accelerator is off will be described. FIG. 3 is a flowchart showing an example of a drive control routine executed by the hybrid ECU 70 when the accelerator is off. This routine is repeatedly executed at predetermined time intervals (for example, every several milliseconds) when the accelerator operation state is the accelerator off state.

  When the accelerator-off-time drive control routine of FIG. 3 is started, first, the CPU 72 of the hybrid ECU 70 first detects the vehicle speed V from the vehicle speed sensor 88, the rotational speeds Nm1 and Nm2 of the motors MG1 and MG2, and the shift position from the shift position sensor 82. SP, the catalyst bed temperature Tcat from the temperature sensor 135, the value of the fuel cut prohibition flag Fc set through a later-described catalyst deterioration suppression determination routine, the charge / discharge required power Pb * to be charged / discharged by the battery 50, and the charging of the battery 50 Input processing of data necessary for control, such as input limit Win as charge allowable power that is allowable power, is executed (step S100). In this case, the rotational speeds Nm1 and Nm2 of the motors MG1 and MG2 are input from the motor ECU 40 by communication from those calculated based on the rotational positions of the rotors of the motors MG1 and MG2 detected by the rotational position detection sensors 43 and 44. To do. Further, with respect to the catalyst bed temperature Tcat, when the temperature sensor 135 of the purifier 134 is omitted, for example, the engine ECU 24 determines the rotational speed Ne of the engine 22, the intake air amount, an increase in the fuel injection amount described later, and the like. You may enter what is estimated. Further, the charge / discharge required power Pb * is input from the battery ECU 52 by communication. The input limit Win of the battery 50 is set based on the battery temperature Tb of the battery 50 detected by the temperature sensor 51 and the remaining capacity (SOC) of the battery 50 from the battery ECU 52 by communication. The input limit Win of the battery 50 sets a basic value of the input limit Win based on the battery temperature Tb, sets an input limit correction coefficient based on the remaining capacity (SOC) of the battery 50, and sets the input. It is possible to set by multiplying the basic value of the limit Win by a correction coefficient. FIG. 4 shows an example of the relationship between the battery temperature Tb and the input limit Win, and FIG. 5 shows an example of the relationship between the remaining capacity (SOC) of the battery 50 and the correction coefficient of the input limit Win.

  After the data input process in step S100, the required torque (braking torque) Tr * to be output to the ring gear shaft 32a as the drive shaft connected to the drive wheels 63a and 63b based on the input vehicle speed V and the shift position SP; A required power (deceleration power) P * required for vehicle travel is set (step S110). In this embodiment, the relationship between the accelerator opening Acc, the vehicle speed V, the shift position SP, and the required torque Tr * is stored in the ROM 74 as a required torque setting map that predetermines driving force setting, and the vehicle speed is set when the accelerator is off. When V and shift position SP are given, the required torque Tr * corresponding to both is derived from the map and set. FIG. 6 shows an example of the required torque setting map. Further, in the present embodiment, a value obtained by multiplying the set required torque Tr * by the rotation speed Nr (= Nm2 / Gr) of the ring gear shaft 32a and the charge / discharge required power Pb * to be charged / discharged by the battery 50 and the loss Loss The required power P * is set as the sum. Subsequently, it is determined whether or not the fuel cut prohibition flag Fc input in step S100 is a value of 0 (step S120). If the fuel cut prohibition flag Fc is a value of 1, fuel injection and ignition (fire) to the engine 22 is performed. If the fuel cut prohibition flag Fc is 0 when the process after S130 for outputting the required torque Tr * is performed with the continuation of the ring), the fuel injection to the engine 22 is stopped (fuel cut). The processes after S200 for outputting the required torque Tr * are executed. Here, the description of the accelerator-off drive control routine will be temporarily interrupted, and the catalyst deterioration suppression determination routine shown in FIG. 7 will be described.

  FIG. 7 is a flowchart showing an example of a catalyst deterioration suppression determination routine. This routine is repeatedly executed by the engine ECU 24 every predetermined time. When the catalyst deterioration suppression determination routine of FIG. 7 is started, the CPU 24a of the engine ECU 24 first needs to determine the catalyst bed temperature Tcat from the temperature sensor 135 provided in the purification device 134, the input limit Win of the battery 50, and the like. Data input processing is executed (step S300). In this case, the input limit Win of the battery 50 is input from the battery ECU 52 by communication. Further, the catalyst bed temperature Tcat may be input based on the rotational speed Ne of the engine 22, the intake air amount, an increase in the fuel injection amount described later, and the like. After the data input process in step S300, it is determined whether or not the input catalyst bed temperature Tcat is equal to or higher than a predetermined first threshold value Tref1 (step S310). The first threshold value Tref1 is determined based on a first target bed temperature T1 (for example, 920 ° C.) when the increase in the catalyst bed temperature Tcat is suppressed to such an extent that deterioration of the exhaust gas purification catalyst is suppressed. is there.

  When the catalyst bed temperature Tcat is equal to or higher than the first threshold value Tref1 and it is determined that the exhaust gas purification catalyst is in a high temperature state, it is determined whether or not the input limit Win input in step S300 is equal to or lower than the temporary limit value Win0. Determination is made (step S320). The temporary limit value Win0 as a threshold value related to the input limit Win of the battery 50 is the input of the battery 50 when the torque (braking torque) required when the accelerator is off is covered by the regenerative braking force by the motor MG2 without cutting the fuel. The limit value Win is defined as a value smaller than the limit value (minimum value as charging power) Win1, that is, a value as charging power that is large (with a margin), and is obtained through experiments and analysis in advance together with the limit value Win1. Value. Since the input limit Win is originally a negative value, the input limit Win is equal to or less than the temporary limit value Win0, that is, the input limit Win exceeds the temporary limit value Win0 as charging power. This means that a relatively large value (a value with a large absolute value) can be set. When the input limit Win is equal to or less than the temporary limit value Win0, the temporary prohibition flag Ft is set to a value 0 (step S330), and is set using a predetermined fuel injection amount setting map (not shown). As a map for setting an increase coefficient for increasing the fuel injection amount for the engine 22, a first OT increase coefficient setting map illustrated in FIG. 8A is read from the ROM 24b and set, and a predetermined throttle opening setting is set. A first TA correction map (not shown) for correcting the opening of the throttle valve 124 set using a map (not shown) is read from the ROM 24b and set (step S340), and further, fuel cut is prohibited to be prohibited. A fuel cut prohibition flag Fc, which is set to 0 when allowing fuel cut, is set to 1 (step S350). Once to end the emissions.

  As illustrated in FIG. 8A, the first OT increase coefficient setting map adjusts the temperature of the exhaust gas purification catalyst according to the target rotational speed Ne * of the engine 22 and the volumetric efficiency KL related to the intake air amount. In order to suppress the deterioration, the fuel injection amount increase coefficient is defined. Basically, the increase coefficient is increased as the target rotational speed Ne * and the volumetric efficiency KL increase. Yes. In this embodiment, the first OT increase coefficient setting map maintains the catalyst bed temperature Tcat substantially at the above-mentioned first target bed temperature T1 according to the target rotational speed Ne * of the engine 22 and the volumetric efficiency KL, and increases it. It is created so as to define an increase coefficient of the fuel injection amount for suppressing the fuel injection. As a result, when the first OT increase coefficient setting map is set, the amount of increase in the fuel injection amount is relatively small, so that the fuel consumption required for temperature adjustment to suppress the deterioration of the exhaust gas purification catalyst is reduced. Can do. The first TA correction map (not shown) cancels the deviation between the target torque Te * resulting from increasing the fuel injection amount based on the first OT increase coefficient setting map and the torque actually output from the engine 22. As described above, the throttle opening correction coefficient is created in advance in accordance with the target rotational speed Ne * and the target torque Te *. That is, the correction coefficient for the throttle opening in the first TA correction map is set, for example, so as to make the throttle opening smaller than normal in an operating region where the torque increases when the fuel injection amount is increased. The operating range in which the torque sometimes decreases is determined to make the throttle opening smaller than usual. Thereby, when the fuel injection amount increase correction is executed using the first OT increase coefficient setting map, the shock due to the deviation between the target torque Te * and the torque actually output from the engine 22 is reduced. be able to.

  On the other hand, if it is determined in step S320 that the input limit Win is greater than the temporary limit value Win0, the temporary prohibition flag that is set to 0 when the input limit Win is equal to or less than the temporary limit value Win0. After setting Ft to a value 1 (step S360), it is determined whether or not the input limit Win input in step S300 is equal to or less than the limit value Win1 (step S370). When the input limit Win is less than or equal to the limit value Win1, the first OT increase is used as a map for setting an increase coefficient for increasing the fuel injection amount for the engine 22 set using the fuel injection amount setting map described above. The second OT increase coefficient setting map illustrated in FIG. 8B having a tendency to increase the fuel injection amount more than the coefficient setting map is read from the ROM 24b and set, and the above-described throttle opening setting map is also described. A second TA correction map (not shown) for correcting the opening degree of the throttle valve 124 set using is read from the ROM 24b and set (step S380), and the fuel cut prohibition flag Fc is set to a value 1 ( Step S350), this routine is once ended. If it is determined in step S370 that the input limit Win exceeds the limit value Win1, the temporary prohibition flag Ft is set to 0 (step S410), and the fuel is set according to the state of the battery 50. A fuel cut prohibition flag Fc is set to 0 to cancel the prohibition of cut (step S420).

  The second OT increase coefficient setting map also adjusts the temperature of the exhaust gas purification catalyst according to the target rotational speed Ne * of the engine 22 and the volumetric efficiency KL related to the intake air amount, as illustrated in FIG. 8B. In order to suppress the deterioration, the fuel injection amount increase coefficient is defined. Basically, the increase coefficient is increased as the target rotational speed Ne * and the volumetric efficiency KL increase. Yes. In the present embodiment, the second OT increase coefficient setting map may deteriorate the catalyst bed temperature Tcat according to the target rotational speed Ne * of the engine 22 and the volumetric efficiency KL even if the exhaust gas purification catalyst is exposed to a lean atmosphere. It is created so as to define an increase coefficient of the fuel injection amount for lowering to a small second target bed temperature T2 (for example, 850 ° C.). That is, the second OT increase coefficient setting map is created so as to take a larger increase coefficient while the target rotational speed Ne * and the volumetric efficiency KL are relatively lower than the first OT increase coefficient setting map. When the 2OT increase coefficient setting map is set, the fuel injection amount increases basically as the vehicle speed V is higher than when the first OT increase coefficient setting map is set. Further, the second TA correction map (not shown) cancels the deviation between the target torque Te * resulting from the increase in the fuel injection amount based on the second OT increase coefficient setting map and the torque actually output from the engine 22. As described above, the throttle opening correction coefficient is created in advance in accordance with the target rotational speed Ne * and the target torque Te *. As a result, even when the fuel injection amount increase correction is executed using the second OT increase coefficient setting map, the shock caused by the deviation between the target torque Te * and the torque actually output from the engine 22 is reduced. can do.

  Here, the temporary limit value Win0, which is a threshold value for selecting either the first OT increase coefficient setting map or the second OT increase coefficient setting map, is a value larger than the limit value Win1 as described above. However, the temporary limit value Win0 is determined as follows on the assumption that the fuel injection amount is increased using the second OT increase coefficient setting map. That is, in this embodiment, the temporary limit value Win0 is the first target bed temperature T1 when the catalyst bed temperature Tcat suppresses the temperature rise to the extent that deterioration of the exhaust gas purification catalyst is suppressed according to the following equation (1). When the exhaust gas purification catalyst is exposed to a lean atmosphere, the second target is less likely to be deteriorated by increasing the fuel injection amount using the second OT increase coefficient setting map. The minimum time T required to decrease to the bed temperature T2 is obtained by experiment / analysis, and the value obtained by multiplying the maximum change amount ΔWin per unit time of the input restriction Win obtained by the experiment / analysis similarly by the obtained minimum time T It is determined by adding the limit value Win1.

  Win0 = Win1 + ΔWin · T (1)

  Incidentally, as described above, when the temporary prohibition flag Ft is set to the value 1 in step S360 and the second OT increase coefficient setting map is set in step S380, the catalyst bed temperature Tcat basically decreases. When the catalyst deterioration suppression determination routine is executed again, it may be determined that the catalyst bed temperature Tcat input in step S300 is less than the first threshold value Tref1, and the catalyst bed temperature Tcat is less than the first threshold value Tref1. If it is, it is determined whether or not the temporary prohibition flag Ft is a value 1 (step S390). If the temporary prohibition flag Ft is a value 1, the input catalyst bed temperature Tcat is the above-mentioned second target bed temperature. It is determined whether it is less than a second threshold value Tref2 determined based on T2 (step S400). When the catalyst bed temperature Tcat is equal to or higher than the second threshold value Tref2, it is determined whether or not the input input limit Win is equal to or lower than the limit value Win1 (step S370), and the input limit Win is equal to or lower than the limit value Win1. For example, the second OT increase coefficient setting map and the second TA correction map are read from the ROM 24b and set (step S380), and the fuel cut prohibition flag Fc is set to a value 1 to prohibit the fuel cut (step S350). ), This routine is temporarily terminated. If the input limit Win exceeds the limit value Win1, the temporary prohibition flag Ft is set to a value 0 (step S410), and the fuel cut is prohibited in order to cancel the fuel cut prohibition according to the state of the battery 50. The flag Fc is set to 0 (step S420). On the other hand, when the catalyst bed temperature Tcat is lower than the second threshold value Tref2, the catalyst bed temperature Tcat is reduced to the second target bed temperature T2, which is less likely to deteriorate even when the exhaust gas purification catalyst is exposed to a lean atmosphere. Is set to a value 0 (step S410), and a fuel cut prohibition flag Fc is set to a value 0 to cancel the fuel cut prohibition (step S420). Further, if it is determined in step S390 that the temporary prohibition flag Ft is 0, the catalyst bed temperature Tcat is kept at a relatively low temperature without increasing the fuel injection amount according to the second OT increase coefficient setting map. Therefore, in this case, the fuel cut prohibition flag Fc is set to 0 (step S420), assuming that the exhaust gas purification catalyst is less likely to deteriorate even if fuel cut is permitted.

  The time chart of FIG. 9 illustrates the transition of the input limit Win, the temporal transition of the catalyst bed temperature Tcat, the setting of the increase coefficient, the fuel cut prohibition flag Fc, and the temporary prohibition flag Ft when the above-described series of processing is executed. To do. Note that the input limit Win does not necessarily depend on a change with time, but in FIG. 9, it is shown as a change with time in order to make the description easy to understand. As can be seen from FIG. 9, when the first OT increase coefficient setting map is set according to the state of the battery 50 when the exhaust gas purification catalyst is in a high temperature state (Tcat ≧ Tref1), fuel injection to the engine 22 is performed according to the map. The amount is corrected to increase, and the catalyst bed temperature Tcat is basically maintained at the first target bed temperature T1. Further, when the gas purification catalyst is in a predetermined temperature range (for example, a region exceeding 850 ° C.) and the input limit Win of the battery 50 is within the range of the temporary limit value Win0 to the limit value Win1, the temporary prohibition flag Ft is set. The second OT increase coefficient setting map is set to the value 1, and the fuel injection amount for the engine 22 is corrected to be increased so that the catalyst bed temperature Tcat basically decreases to the second target bed temperature T2. become. As described above, the fuel injection amount for the engine 22 is further increased from the time when the input limit Win approaches the limit value Win1 to some extent (the time when the charging power becomes less than the temporary limit value Win0), based on the input limit Win. It becomes possible to adjust the temperature of the exhaust gas purification catalyst so that deterioration of the exhaust gas purification catalyst can be suppressed when the prohibition of fuel cut is canceled and the fuel cut is actually performed. The fuel cut prohibition flag Fc is set to a value of 1 when the catalyst bed temperature Tcat is in the predetermined temperature range and the input limit Win is equal to or less than the limit value Win1 (the limit value Win1 as charge power). . Further, when the input limit Win exceeds the limit value Win1 (when the charge power becomes less than the limit value Win1), the braking force based on the accelerator-off state is covered by the regenerative braking force by the motor MG2 while the fuel injection to the engine 22 is continued. In this case, the fuel cut prohibition flag Fc is set to 0 to cancel the fuel cut prohibition.

  Returning to FIG. 3 again, the accelerator-off-time drive control routine will be described. In step S120, if the fuel cut prohibition flag Fc input in step S100 is a value 1, that is, the exhaust gas is exhausted by the above-described catalyst deterioration suppression determination routine. When it is determined that the fuel cut to the engine 22 should be prohibited in order to suppress the deterioration of the exhaust gas purification catalyst according to the temperature of the purification catalyst and the state of the battery 50, the engine 22 as a command (engine command) to the engine 22 A command to continue the explosion combustion (firing) of the engine 22 is set (step S130), and the target rotation speed Ne * of the engine 22 is set to the rotation speed Ne0 when the explosion combustion is continued (step S140). . In the embodiment, the rotational speed Ne0 is, for example, the rotational speed during idling (800 to 1000 rpm). If the target rotational speed Ne * of the engine 22 is set, the calculation according to the following equation (2) is performed based on the set target rotational speed Ne * and the rotational speed Ne of the engine 22 input in step S100, and an explosion occurs. A torque command Tm1 * for the motor MG1 is set so that the rotational speed Ne of the engine 22 reaches the target rotational speed Ne * (= Ne0) while the combustion is continued (step S150). Expression (2) is a relational expression in feedback control for setting the rotation speed Ne of the engine 22 to the target rotation speed Ne * as the explosion combustion of the engine 22 continues, and the first term on the right side in the expression (2). “K1” is a gain of the proportional term, and “k2” of the second term on the right side is a gain of the integral term. These gains “k1” and “k2” are set to a smaller value than when a relatively large torque is output from the engine 22 because it is necessary to continue the explosion combustion of the engine 22. FIG. 10 is a collinear diagram showing the dynamic relationship between the rotational speed and torque of each rotating element in the power distribution and integration mechanism 30 when the explosion combustion of the engine 22 is continued. In the figure, the left S-axis indicates the rotational speed of the sun gear 31 that matches the rotational speed Nm1 of the motor MG1, the C-axis indicates the rotational speed of the carrier 34 that matches the rotational speed Ne of the engine 22, and the R-axis indicates the motor MG2. The rotational speed Nr of the ring gear 32 obtained by dividing the rotational speed Nm2 by the gear ratio Gr of the reduction gear 35 is shown. Further, two thick arrows on the R axis indicate that the torque acting on the ring gear shaft 32a by this torque output when the torque Tm1 is output from the motor MG1 and the torque Tm2 output from the motor MG2 via the reduction gear 35. The torque acting on the ring gear shaft 32a is shown. Equation (2) for obtaining the target rotational speed Nm1 * of the motor MG1 can be easily derived by using the rotational speed relationship in this alignment chart.

  Tm1 * ＝ k1 ・ (Ne * −Ne) + k2∫ (Ne * −Ne) ・ dt (2)

  When the torque command Tm1 * is set in this way, it is obtained by multiplying the input limit Win of the battery 50 input in step S100 according to the following equation (3) and the set torque command Tm1 * of the motor MG1 by the current rotational speed Nm1 of the motor MG1. A torque limit Tmin as a lower limit of the torque that may be output from the motor MG2 is calculated by dividing the deviation from the consumed power of the motor MG1 by the rotation speed Nm2 of the motor MG2 (step S160). Further, using the required torque Tr *, the torque command Tm1 *, the gear ratio ρ of the power distribution and integration mechanism 30 and the gear ratio Gr of the reduction gear 35, a temporary motor as a torque to be output from the motor MG2 according to the following equation (4): Torque Tm2tmp is calculated (step S170), and the torque command Tm2 * of the motor MG2 is set by limiting the calculated temporary motor torque Tm2tmp with the torque limit Tmin (step S180). By setting the torque command Tm2 * of the motor MG2 in this way, the required torque Tr * output to the ring gear shaft 32a can be basically set as a torque limited by the input limit Win of the battery 50. Equation (4) can be easily derived from the alignment chart of FIG. When the engine command and the torque commands Tm1 * and Tm2 * of the motors MG1 and MG2 are thus set, the engine command is transmitted to the engine ECU 24, and the torque commands Tm1 * and Tm2 * of the motors MG1 and MG2 are transmitted to the motor ECU 40 (step S190). .

Tmin = (Win−Tm1 * ・ Nm1) / Nm2 (3)
Tm2tmp = (Tr * + Tm1 * / ρ) / Gr (4)

  As described above, when it is determined in step S120 that the fuel cut prohibition flag is 1 and fuel cut is prohibited, the first or second OT increase coefficient setting map and the first or second TA are set as described above. Since the correction map is set, the engine ECU 24 that has received the engine command from the hybrid ECU 70 determines the fuel injection amount to the engine 22 obtained from the fuel injection amount setting map for continuing fuel injection in the first or second OT. While correcting with the increase coefficient obtained from the increase coefficient setting map, the position of the throttle valve 124 (throttle opening) obtained from the throttle opening setting map for continuing fuel injection is determined from the first or second TA correction map. Control to continue the explosion combustion of the engine 22 while correcting with the obtained correction coefficient Row. The motor ECU 40 that has received the torque commands Tm1 * and Tm2 * switches the switching elements of the inverters 41 and 42 so that the motor MG1 is driven according to the torque command Tm1 * and the motor MG2 is driven according to the torque command Tm2 *. Take control. As shown in FIG. 10, when the fuel cut is prohibited, the motor MG1 is driven and controlled while the engine 22 continues to explode, whereby the engine speed Ne is set to the target engine speed Ne *. It can be rapidly reduced to (= Ne0). At this time, as can be seen from FIG. 10, since a slight driving torque is output from the engine 22 and this driving torque acts on the ring gear shaft 32a as the output shaft, the motor MG2 is required torque (braking torque) Tr *. The sum of the torque based on the torque and the torque for canceling the drive torque is output.

  On the other hand, when it is determined in step S120 that the fuel cut prohibition flag Fc input in step S100 is 0, that is, when the above-described catalyst deterioration suppression determination routine determines that the fuel cut prohibition for the engine 22 is released. Sets a fuel cut command for stopping fuel injection and ignition as an engine command (step S200), and determines whether or not the catalyst bed temperature Tcat input in step S100 is less than the second threshold value Tref2 described above. (Step S210). If the catalyst bed temperature Tcat is lower than the second threshold value Tref2, as described above, the catalyst bed temperature Tcat is reduced to the second target bed temperature T2, which is less likely to deteriorate even if the exhaust gas purification catalyst is exposed to a lean atmosphere. In this case, the engine brake is applied using the first FC target rotation speed setting map fne1 (Pr *) for normal operation as the first operation point constraint as shown in FIG. When setting the target engine speed Ne * of the engine 22 and the throttle opening degree by the engine ECU 24, a normal first FC throttle opening degree setting map fta1 (Ne *) as shown in FIG. The fact that it should be used is set as an engine command (step S220). In the embodiment, the required power P * as the required driving force and the target rotation based on a coefficient that determines the share ratio of the engine 22 (corresponding to the engine brake) in the torque Tr * to be output to the ring gear shaft 32a determined in advance. The relationship with the number Ne * is determined in advance and stored in the ROM 74 as the first FC target speed setting map fne1 (Pr *). When the required power P * is given, the corresponding target speed Ne * is set. It was derived from the map and set. The coefficient indicating the engine brake equivalent may be set to 0.5, for example, or may be changed within a range from 0 to 1 according to the vehicle speed V. Further, the first FC throttle opening setting map fta1 (Ne *) indicates the relationship between the target rotational speed Ne * of the engine 22 and the throttle opening when the braking force by the engine brake is output from the engine 22 with fuel cut. It is predetermined so as to define the relationship, and is stored in the ROM 24b of the engine ECU 24.

  When the target rotational speed Ne * and the like are set in step S220 in this way, the processing in steps S150 to S180 described above is executed, and in step S190, the fuel cut command and the first FC throttle opening for normal operation are used as engine commands. The fact that setting map fta1 (Ne *) should be used is transmitted to engine ECU 24, and torque commands Tm1 * and Tm2 * of motors MG1 and MG2 are transmitted to motor ECU 40. The engine ECU 24 that has received the engine command stops the fuel supply and ignition to the engine 22, and also sets the position of the throttle valve 124 using the first FC throttle opening setting map fta1 (Ne *), and the torque command. The motor ECU 40 that has received Tm1 * and Tm2 * performs switching control of the switching elements of the inverters 41 and 42 according to the torque commands Tm1 * and Tm2 *. Thereby, the braking torque by the engine brake from the engine 22 and the braking force by the regeneration from the motor MG2 are output to the ring gear shaft 32a as the drive shaft. FIG. 13 shows an example of a collinear diagram showing a dynamic relationship between the rotation speed and torque of each rotary element in the power distribution and integration mechanism 30 when the engine brake is generated in the engine 22.

  On the other hand, if it is determined in step S210 that the catalyst bed temperature Tcat is equal to or higher than the second threshold value Tref2, the fuel injection amount is increased according to the first and / or second OT increase factor setting map. Since the input restriction Win exceeds the limit value Win1 and the catalyst bed temperature Tcat is equal to or higher than the threshold value Tref2, the fuel cut prohibition has been canceled. If fuel cut is performed on the engine 22 according to a normal procedure, the exhaust gas purification catalyst may be exposed to a lean atmosphere and deteriorated. For this reason, when the catalyst bed temperature Tcat is equal to or higher than the second threshold value Tref2, a normal time as shown in FIG. 11 is used in order to suppress the temperature rise of the exhaust gas purification catalyst by sending more air through the purification device 134. The second FC target rotational speed setting map fne2 (Pr *) as a second operating point constraint that tends to increase the rotational speed of the engine 22 compared to the first FC target rotational speed setting map fne1 (Pr *) ) Is used to set the target rotational speed Ne * of the engine 22 when the engine brake is applied, and when the throttle opening is set by the engine ECU 24, the first FC throttle opening is set as shown in FIG. Throttle opening at the second FC as a second constraint having a tendency to increase the throttle opening as compared to the map fta1 (Ne *) Titration, map FTA2 (Ne *) of the set as an engine command that should be used (step S230).

  The second FC target rotational speed setting map fne2 (Pr *) defines the relationship between the required power P * and the target rotational speed Ne * in the same manner as the first FC target rotational speed setting map fne1 (Pr *). And is stored in the ROM 74 of the hybrid ECU 70. Further, the second FC throttle opening setting map fta2 (Ne *) is similar to the first FC throttle opening setting map fta1 (Ne *) in the relationship between the target engine speed Ne * of the engine 22 and the throttle opening. Is stored in the ROM 24b of the engine ECU 24. Then, the amount of increase in the rotational speed relative to the first FC target rotational speed setting map fne1 (Pr *) in the second FC target rotational speed setting map fne2 (Pr *), and the second FC throttle opening setting map fta2 ( The increase in the throttle opening relative to the first FC throttle opening setting map fta1 (Ne *) in Ne *) is an experiment based on the amount of air required to suppress the temperature increase of the exhaust gas purification catalyst.・ It can be determined through analysis. Thus, when the engine command is set in step S230, the above-described processing of steps S150 to S190 is executed. In this case, the engine ECU 24 stops the fuel supply and ignition to the engine 22, sets the position of the throttle valve 124 using the second FC throttle opening setting map fta2 (Ne *), and the motor ECU 40 Switching control of the switching elements of the inverters 41 and 42 is performed according to the torque commands Tm1 * and Tm2 *. The ring gear shaft 32a serving as the drive shaft outputs braking torque generated by engine braking from the engine 22 and braking force generated by regeneration from the motor MG2. In this case, the two-dot chain line in FIG. As shown, the torque by the engine brake output from the engine 22 increases as the target rotational speed Ne * of the engine 22 increases.

  As described above, in the hybrid vehicle 20 of the embodiment, if the catalyst bed temperature Tcat is lower than the threshold value Tref2 when the accelerator operation state is the accelerator off state, the required power P * and the normal time Based on the target speed setting map fne1 (Pr *) for 1FC, the target speed Ne * of the engine 22 when the engine brake is applied is set as a target operating point, and then the first FC throttle for normal use The engine 22 is operated with intake air amount setting and fuel cut using the opening setting map fta1 (Ne *), and the driving force (braking force) based on the required torque Tr * is output. 22. Control motors MG1 and MG2. Moreover, in the hybrid vehicle 20, when the catalyst bed temperature Tcat is equal to or higher than the threshold value Tref2 when the accelerator operation state is the accelerator off state, the required power P * and the normal engine speed target speed setting for the first FC are set. Target rotation of the engine 22 when the engine brake is applied based on the second FC target rotation speed setting map fne2 (Pr *) that tends to increase the rotation speed of the engine 22 compared to the map fne1 (Pr *). After setting the number Ne * as a target operation point, the throttle opening of the second FC has a tendency to increase compared to the first FC throttle opening setting map fta1 (Ne *) for normal use. The engine 22 is operated with the intake air amount setting and fuel cut using the setting map fta2 (Ne *). Engine 22 so that the driving force based on the calculated torque Tr * (braking force) is output, and controls the motors MG1 and MG2.

  That is, in the hybrid vehicle 20, the fuel cut is performed when the catalyst bed temperature Tcat is in a predetermined temperature range (for example, a region exceeding 850 ° C.), and the input limit Win of the battery 50 is equal to or higher than the limit value Win1 as the charging power. It is forbidden. When the input limit Win of the battery 50 is equal to or greater than the temporary limit value Win0 as the charging power, the fuel injection amount is increased according to the first OT increase coefficient setting map, and the input limit Win is less than the temporary limit value Win0 as the charging power. The fuel injection is increased according to the second OT increase coefficient setting map, which has a tendency to increase the fuel injection amount as compared with the first OT increase coefficient setting map, but the input limit Win of the battery 50 is the limit value Win1 as the charging power. If it is less than that, the braking force based on the accelerator off cannot be supplied by the regenerative braking force by the motor MG2 while the fuel injection to the engine 22 is continued. In this case, the fuel cut is performed regardless of the state of the exhaust gas purification catalyst. Will be lifted. For this reason, in the hybrid vehicle 20, the input restriction Win becomes less than the limit value Win1 as the charging power before the fuel injection amount is increased sufficiently according to the first and / or second OT increase coefficient setting map, and the catalyst Even though the bed temperature Tcat is equal to or higher than the threshold value Tref2, the prohibition of fuel cut may be released. On the other hand, if the catalyst bed temperature Tcat is equal to or higher than the threshold value Tref2 when the accelerator operation state becomes the accelerator off state, the fuel cut is performed while increasing the intake air amount of the engine 22 and increasing the rotational speed of the engine 22. In this case, the amount of intake air is increased and the rotational speed of the engine 22 is increased while the braking force based on the accelerator-off is favorably secured by using the engine brake by fuel cut while suppressing the regeneration amount by the motor MG2. It is possible to satisfactorily suppress the deterioration of the exhaust gas purification catalyst by feeding a large amount of air through the device 134 and suppressing the temperature rise of the catalyst exhaust gas purification.

  As described above, the process for increasing the intake air amount accompanying the fuel cut and the process for increasing the rotational speed of the engine 22 cause the exhaust gas purification catalyst to be still hot when the accelerator is off due to insufficient fuel injection increase process. Even in this state, it is possible to suppress the deterioration of the exhaust gas purification catalyst. Therefore, it is extremely useful when combined with the fuel injection amount increasing process using the first and second OT increase coefficient setting maps described above. However, as the deterioration suppression process of the exhaust gas purification catalyst, at least one of the above-described increase process of the intake air amount and the process of increasing the rotation speed of the engine 22 may be executed independently regardless of the execution of the increase process. Needless to say. Further, as described above, it is possible to send more air to the purification device 134 by further increasing the rotational speed of the engine 22 while setting the throttle opening of the engine 22 large. From the viewpoint of suppressing the temperature rise of the engine 22, it may be omitted to increase the rotational speed of the engine 22, and when the catalyst bed temperature Tcat is equal to or higher than the threshold value Tref2 when the accelerator operation state is the accelerator off state, Only the throttle opening of the engine 22 may be set larger using the second FC throttle opening setting map fta2 (Ne *).

  The embodiments of the present invention have been described above using the embodiments. However, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the present invention. Needless to say.

  That is, in the hybrid vehicle 20 of the above embodiment, the ring gear shaft 32a as the drive shaft and the motor MG2 are connected via the reduction gear 35 that reduces the rotational speed of the motor MG2 and transmits it to the ring gear shaft 32a. Instead of the reduction gear 35, for example, a transmission that has two or three shift stages of Hi and Lo and shifts the rotation speed of the motor MG2 and transmits it to the ring gear shaft 32a may be adopted. Good.

  Further, in the hybrid vehicle 20 of the above embodiment, the power of the motor MG2 is decelerated by the reduction gear 35 and output to the ring gear shaft 32a. However, like the hybrid vehicle 120 as a modification shown in FIG. 14, the motor MG2 The transmission power is shifted by the transmission 65 and the axle (the axle connected to the wheels 63c and 63d in FIG. 14) is different from the axle to which the ring gear shaft 32a is connected (the axle to which the drive wheels 63a and 63b are connected). You may make it transmit.

  Furthermore, the hybrid vehicles 20 and 20B of the above embodiments output the power of the engine 22 to the ring gear shaft 32a as the drive shaft connected to the drive wheels 63a and 63b via the power distribution and integration mechanism 30. 15, an inner rotor 232 connected to the crankshaft 26 of the engine 22 and an outer rotor 234 connected to a drive shaft that outputs power to the drive wheels 63a and 63b, like a hybrid vehicle 220 as a modified example shown in FIG. And a counter-rotor motor 230 that transmits a part of the power of the engine 22 to the drive shaft and converts the remaining power into electric power.

1 is a schematic configuration diagram of a hybrid vehicle 20 according to an embodiment of the present invention. 2 is a schematic configuration diagram of an engine 22. FIG. It is a flowchart which shows an example of the drive control routine at the time of accelerator off performed by hybrid ECU70 of an Example. It is explanatory drawing which shows an example of the relationship between the battery temperature Tb in the battery 50, and the input / output restrictions Win and Wout. It is explanatory drawing which shows an example of the relationship between the remaining capacity (SOC) of the battery 50, and the correction coefficient of input / output restrictions Win and Wout. It is explanatory drawing which shows an example of the map for request | requirement torque setting. It is a flowchart which shows an example of the catalyst deterioration suppression determination routine performed by engine ECU24 of an Example. (A) is explanatory drawing which illustrates the 1st OT increase coefficient setting map, (b) is explanatory drawing which illustrates the 2nd OT increase coefficient setting map. The time illustrating the transition of the input limit Win, the temporal transition of the catalyst bed temperature Tcat, the increase coefficient, the fuel cut prohibition flag Fc, and the provisional prohibition flag Ft when the catalyst deterioration suppression determination routine of FIG. 7 is executed It is a chart. FIG. 5 is a collinear diagram illustrating a dynamic relationship between the rotation speed and torque of each rotary element in the power distribution and integration mechanism 30 when the explosion combustion of the engine 22 is continued. It is explanatory drawing which illustrates the 1st FC time target rotational speed setting map and the 2nd FC time target rotational speed setting map. It is explanatory drawing which illustrates the 1st FC throttle opening setting map and the 2nd FC throttle opening setting map. FIG. 6 is a collinear diagram illustrating a dynamic relationship between the rotational speed and torque of each rotary element in the power distribution and integration mechanism 30 when engine braking is generated in the engine 22. It is a schematic block diagram of the hybrid vehicle 120 of the modification. FIG. 11 is a schematic configuration diagram of a hybrid vehicle 220 of a modification example.

Explanation of symbols

  20, 120, 220 Hybrid vehicle, 22 engine, 24 engine electronic control unit (engine ECU), 24a, 72 CPU, 24b, 74 ROM, 24c, 76 RAM, 26 crankshaft, 28 damper, 30 power distribution integration mechanism, 31 sun gear, 32 ring gear, 32a ring gear shaft, 33 pinion gear, 34 carrier, 35 reduction gear, 40 electronic control unit for motor (motor ECU), 41, 42 inverter, 43, 44 rotational position detection sensor, 50 battery, 51 temperature sensor , 52 battery electronic control unit (battery ECU), 54 power line, 60 gear mechanism, 62 differential gear, 63a, 63b driving wheel, 63c, 63d wheel, 65 transmission, 70 electronic control for hybrid Unit (hybrid ECU), 80 ignition 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 Purification device, 135 Temperature 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 Air flow meter, 149 Temperature sensor, 150 Variable valve Timing mechanism, 230 pair-rotor motor, 232 an inner rotor, 234 outer rotor, MG1, MG2 motor.

Claims (5)

An internal combustion engine;
Purification means including a catalyst for purifying exhaust gas discharged from the internal combustion engine;
Catalyst temperature acquisition means for acquiring the temperature of the catalyst;
Power power input / output means connected to the first axle as one of the axles and the output shaft of the internal combustion engine and capable of inputting / outputting power to / from the first axle and the output shaft with input / output of power and power When,
An electric motor capable of inputting / outputting power to / from a second axle that is either the first axle or an axle different from the first axle;
Power storage means capable of exchanging power between the power drive input / output means and the electric motor;
Requested driving force setting means for setting a requested driving force required for traveling based on the accelerator operation state;
If the acquired catalyst temperature is lower than a predetermined temperature when the accelerator operation state is the accelerator off state, the internal combustion engine is based on the set required driving force and the first operating point constraint. If the obtained catalyst temperature is equal to or higher than the predetermined temperature when the accelerator operation state is the accelerator off state, the set required driving force and the first driving point are set. Target operating point setting means for setting a target operating point of the internal combustion engine based on a second operating point constraint that tends to increase the rotational speed of the internal combustion engine compared to the operating point constraint of
The accelerator when the temperature of the operation state is the acquisition when in the accelerator-off state catalyst is lower than the predetermined temperature, the setting of the first intake air amount in accordance with the throttle opening restriction and stop of the fuel supply wherein with one that controls said internal combustion engine and the electric power-mechanical power input output mechanism and the motor so that the driving force based on the set required driving force with the internal combustion engine is operated is outputted, the accelerator operation When the acquired temperature of the catalyst is equal to or higher than the predetermined temperature when the accelerator is in the off state, there is a second tendency to increase the throttle opening as compared with the first throttle opening restriction. output driving force of based on the set required driving force with the internal combustion engine with a stop configuration and the fuel supply amount of intake air in accordance with the throttle opening restriction is operation It said control means for controlling the internal combustion engine and the electric power-mechanical power input output mechanism and said electric motor so as to,
A hybrid car with The hybrid vehicle according to claim 1 ,
A fuel supply stop prohibiting means for prohibiting the stop of fuel supply to the internal combustion engine when the obtained temperature of the catalyst is in a predetermined temperature range;
The control means increases the fuel supply amount for adjusting the temperature of the catalyst according to a predetermined fuel increase condition when the fuel supply stop prohibiting means prohibits the fuel supply to the internal combustion engine from being stopped. The hybrid vehicle controls the internal combustion engine, the electric power drive input / output unit, and the electric motor so that the internal combustion engine is operated and the driving force based on the set required driving force is output. The hybrid vehicle according to claim 2 ,
Further comprising charge allowable power setting means for setting charge allowable power, which is power allowed for charging of the power storage means based on the state of the power storage means,
The fuel supply stop prohibiting means is configured to provide fuel for the internal combustion engine when the obtained temperature of the catalyst is in the predetermined temperature range and the set charge allowable power is equal to or higher than a predetermined limit value as charge power. A hybrid vehicle that prohibits the suspension of supply. The fuel increase condition increases the fuel supply amount in accordance with a first increase restriction when the set charge allowable power is equal to or greater than a temporary limit value which is a value larger than the limit value as the charge power and the setting When the charged allowable power becomes less than the temporary limit value as the charging power, the fuel supply amount is increased according to a second increase restriction that tends to increase the fuel supply amount more than the first increase restriction. The hybrid vehicle according to claim 3 , which is a vehicle. The power power input / output means is connected to the first axle, the output shaft of the internal combustion engine, and a rotatable third shaft, and based on power input / output to any two of these three shafts. a three shaft-type power input output assembly configured to input and output determined power to residual shaft, the hybrid vehicle according to any one of claims 1 to 4, and a third shaft capable of inputting and outputting power to the generators.

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