JP2010132086A - Power output device, vehicle including the same and method for controlling the power output device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress frequent start/stop of an internal combustion engine to sufficiently secure an operation stop state of the internal combustion engine. <P>SOLUTION: When intermittent engine operation is prohibited, it is decided that the intermittent operation of the engine 22 should be permitted when engine start output limit Woutes is not less than an intermittent operation permission threshold value Wouta larger than an intermittent operation prohibition threshold value Woutb as discharge power and when predicted starting output limit Woutpd that is a predicted value of power allowed for discharging of a battery 50 exceeds the intermittent operation prohibition threshold value Woutb at the start of the engine after a predetermined time tref elapses from the current time, and an intermittent operation prohibition flag is OFF. Thereby, the engine is prevented from restarting in an extremely short time after the engine stop while the intermittent operation of the engine is permitted. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a power output device that outputs power to a drive shaft, a vehicle including the same, and a control method for the power output device.

Conventionally, as this type of power output device, an engine, a planetary gear mechanism including a planetary carrier connected to the crankshaft of the engine, a first motor capable of generating electricity connected to the sun gear of the planetary gear mechanism, A device including a second motor that can output power to a ring gear shaft as a drive shaft connected to a ring gear of a planetary gear mechanism, and a battery that can exchange power with the first and second motors is known ( For example, see Patent Document 1). In this power output apparatus, when the intermittent operation of the engine is prohibited, if the battery temperature is equal to or higher than a predetermined temperature, the first value (W1) is set as a threshold value, and the battery temperature is lower than the predetermined temperature. If there is, the second value (W2) smaller than the first value is set as the threshold value. When the output limit, which is the power allowed for discharging the battery, is equal to or greater than the threshold value, the engine is intermittently operated. When the output limit is less than the threshold value, the engine intermittent operation is prohibited. Conventionally, a vehicle including a motor generator directly connected to an output shaft of an engine, a converter and a continuously variable transmission directly connected to the output shaft of the motor generator is known (see, for example, Patent Document 2). ). The motor generator of this vehicle functions as a starter for starting the engine, a traveling motor for motor traveling, an assist motor for assisting the engine, and a generator for charging the battery. In this vehicle, when the output of the motor generator is limited due to a decrease in the capacity of the battery, it is determined whether or not it is possible to start from the current vehicle stop state based on the motorable output obtained by subtracting the limited output from the rated output. When the vehicle can start, idle stop (automatic engine stop / restart) is permitted.
JP 2007-191034 A JP-A-2005-002866

  The power output apparatus described in Patent Document 1 determines whether to permit intermittent operation of the engine using a battery output limit and a threshold value based on the battery temperature, and uses a constant threshold value regardless of the battery temperature. The energy efficiency can be improved by optimizing the region in which the intermittent operation of the engine is permitted as compared with the case of determining whether the intermittent operation of the engine is permitted. However, even if the threshold value is changed according to the battery temperature, if the permitted region and the prohibited region of the intermittent operation of the engine are determined with a certain threshold as a boundary, every time the output limit of the battery changes across the threshold value, For example, there is a possibility that the engine is frequently started and stopped repeatedly, such as being restarted in a very short time after the engine is once stopped.

  Therefore, the power output apparatus according to the present invention, the vehicle including the power output apparatus, and the control method for the power output apparatus can sufficiently ensure the operation stop state of the internal combustion engine by suppressing frequent start / stop of the internal combustion engine. The main purpose.

  The power output apparatus according to the present invention, the vehicle including the power output apparatus, and the control method of the power output apparatus employ the following means in order to achieve the main object.

A first power output device according to the present invention comprises:
A power output device that outputs power to a drive shaft,
An internal combustion engine capable of outputting power to the drive shaft;
Electric motoring means capable of motoring the internal combustion engine;
An electric motor capable of outputting power to the drive shaft;
Power storage means capable of exchanging electric power with the electric motoring means and the electric motor;
Engine start output limit acquisition means for acquiring a start output limit which is electric power allowed for discharging of the power storage means at the start of the internal combustion engine;
Predicted start output limit acquisition means for acquiring a predicted start output limit that is a predicted value of electric power allowed to discharge the power storage means when starting the internal combustion engine after a predetermined time has elapsed since the present time;
When the operation stop of the internal combustion engine is permitted, it is determined that the operation stop of the internal combustion engine should be prohibited if the acquired output limit for starting is equal to or less than a predetermined operation stop prohibition threshold, and the internal combustion engine When the operation stop is prohibited, the acquired start output limit is not less than a predetermined operation stop permission threshold which is larger than the operation stop prohibition threshold as discharge power, and the acquired predicted start output limit is An operation stop permission determination means for determining that the operation stop of the internal combustion engine should be permitted if the operation stop prohibition threshold is exceeded;
Request torque setting means for setting a request torque that is a torque to be output to the drive shaft;
The internal combustion engine and the electric motoring means are configured such that the internal combustion engine is operated or stopped according to the determination result by the operation stop permission determination means and torque based on the set required torque is output to the drive shaft. And control means for controlling the electric motor;
Is provided.

  In this power output device, when the operation of the internal combustion engine is permitted to be stopped, the start output limit, which is the power allowed for discharging the power storage means when the internal combustion engine is started at the present time, is less than or equal to a predetermined operation stop prohibition threshold If it is, it is judged that the operation stop of the internal combustion engine should be prohibited. In addition, when the internal combustion engine is prohibited from being stopped, the start output limit is equal to or greater than a predetermined operation stop permission threshold that is greater than the operation stop prohibition threshold as discharge power, and the internal combustion engine after a predetermined time has elapsed since the present time. If the predicted start output limit, which is a predicted value of the power allowed to discharge the power storage means at the time of starting, exceeds the operation stop prohibiting threshold value, it is determined that the operation stop of the internal combustion engine should be permitted. Then, the internal combustion engine, the electric motoring means, and the electric motor are controlled so that the internal combustion engine is operated or stopped according to the determination result regarding the operation stop of the internal combustion engine and the torque based on the required torque is output to the drive shaft. The Thus, after setting the operation stop permission threshold for determining whether or not to permit the operation stop of the internal combustion engine to a value larger than the operation stop prohibition threshold, the start output limit is equal to or greater than the operation stop permission threshold, In addition, if the internal combustion engine is allowed to stop when the predicted start output limit exceeds the operation stop prohibition threshold, the output limit of the power storage means is reduced when the predetermined time elapses after the operation stop of the internal combustion engine is permitted. Therefore, it is very unlikely that the shutdown of the internal combustion engine is prohibited, so the internal combustion engine is restarted in a very short time after the internal combustion engine is stopped in a state where the shutdown of the internal combustion engine is permitted. This can be suppressed. Thereby, in this power output device, it is possible to suppress frequent start / stop of the internal combustion engine and to sufficiently ensure the operation stop state of the internal combustion engine to improve fuel consumption.

  The first power output device may further include output limit setting means for setting an output limit that is electric power allowed for discharging the power storage means based on a state of the power storage means. The output limit acquisition means for use may acquire the start output limit by adding a predetermined temporarily increased power to the set output limit. The predicted start output limit may be acquired by subtracting the product of the estimated reduction amount per unit time of the output limit and the predetermined time from the acquired start output limit. As a result, the start output limit and the predicted start output limit can be made more appropriate. Note that the estimated reduction amount of the output limit used to obtain the predicted start output limit conforms to the actual situation, such as a constant value determined through experiments and analysis, and a variable value that changes according to the operating state of the power output device. Any thing can be used.

  Further, the first power output device includes a required power setting means for setting a required power required for the drive shaft based on the set required torque, and the setting when the internal combustion engine is stopped. When the determined required power is equal to or greater than a start determination threshold value obtained by subtracting predetermined power from the acquired start output limit, the internal combustion engine is determined to be started, and when the internal combustion engine is in operation The set required power is less than or equal to a predetermined stop determination threshold value smaller than the start determination threshold value, and is less than a predicted start determination threshold value obtained by subtracting the predetermined power from the acquired predicted start output limit. Engine start / stop determination means for determining that the internal combustion engine should be stopped when the engine is stopped, and the control means is the operation stop permission / inhibition determination means. The internal combustion engine is operated or stopped according to the determination result by the engine start / stop determination means, and the internal combustion engine is output so that torque based on the set required torque is output to the drive shaft. The electric motoring means and the electric motor may be controlled.

  In this power output apparatus, when the internal combustion engine is stopped, it is determined that the internal combustion engine should be started if the required power is equal to or greater than a start determination threshold value obtained by subtracting predetermined power from the start output limit. Further, when the internal combustion engine is in operation, a predicted start determination threshold value obtained by subtracting the predetermined power from the predicted start output limit while the required power is equal to or less than a predetermined stop determination threshold value smaller than the start determination threshold value. If it is lower, it is determined that the internal combustion engine should be stopped. Then, the internal combustion engine is operated or stopped according to the determination result regarding the operation stop of the internal combustion engine and the determination result regarding the start / stop of the internal combustion engine, and a torque based on the required torque is output to the drive shaft. The electric motoring means and the electric motor are controlled. As described above, the stop determination threshold for determining whether or not to stop the internal combustion engine is set to a value smaller than the start determination threshold, the required power is equal to or less than the stop determination threshold, and falls below the predicted start determination threshold. If the internal combustion engine is stopped when the internal combustion engine is stopped, the internal combustion engine is started in relation to the required power when the predetermined time has elapsed after the internal combustion engine is stopped unless the amount of change in the required power becomes extremely large. Therefore, it is possible to prevent the engine from being restarted in a very short time after the internal combustion engine is stopped. Thereby, in this power output device, it is possible to suppress frequent start / stop of the internal combustion engine and to sufficiently ensure the operation stop state of the internal combustion engine to improve fuel consumption.

  Further, the start determination threshold value may be obtained by subtracting at least the electric power consumed by motoring of the electric motoring means when starting the internal combustion engine from the acquired start output limit. . Thereby, the start determination threshold value can be set to a more appropriate value.

  Further, the first power output device can input and output power and can exchange power with the power storage means, the second motor as the electric motoring means, the output shaft of the internal combustion engine, and the first Power distribution means connected to the three shafts of the rotating shaft of the motor 2 and the drive shaft, and for inputting / outputting the power based on the power input / output to / from any of the three shafts to / from the remaining shafts. Further, it may be provided.

  The power storage means may be a lithium ion secondary battery. That is, the lithium ion secondary battery has a characteristic that the output limit as the discharge allowable power changes relatively greatly in accordance with the change in the remaining capacity indicating the state of the battery. Even if the output limit fluctuates in accordance with the remaining capacity of the engine, it is possible to prevent the internal combustion engine from being frequently started and stopped from the relationship with the output limit and the like. Therefore, the present invention is extremely useful for a power output device including a lithium ion secondary battery as a power storage means. However, it goes without saying that the power output apparatus according to the present invention may include other types of power storage means other than the lithium ion secondary battery.

  A vehicle according to the present invention includes any one of the above-described power output devices and drive wheels connected to the drive shaft. In this vehicle, it is possible to suppress frequent starting / stopping of the internal combustion engine and sufficiently ensure the operation stop state of the internal combustion engine to improve fuel consumption. The resulting occupant discomfort can be suppressed, and the fuel consumption can be improved by sufficiently securing the operation stop state of the internal combustion engine.

A control method of the first power output device according to the present invention includes:
An internal combustion engine capable of outputting power to the drive shaft, an electric motoring means capable of motoring the internal combustion engine, an electric motor capable of outputting power to the drive shaft, and the electric motoring means and the motor exchange power. A power output device comprising a possible power storage means,
(A) A starting output limit, which is electric power allowed for discharging the power storage means when starting the internal combustion engine at the present time, and discharging the power storage means when starting the internal combustion engine after a predetermined time has elapsed from the present time. Obtaining a predicted start output limit that is a predicted value of the power to be output;
(B) When the operation stop of the internal combustion engine is permitted, the operation stop of the internal combustion engine should be prohibited if the start output limit acquired in step (a) is less than or equal to a predetermined operation stop prohibition threshold. And when the operation stop of the internal combustion engine is prohibited, the acquired start output limit is equal to or greater than a predetermined operation stop permission threshold that is larger than the operation stop prohibition threshold as discharge power. Determining that the operation stop of the internal combustion engine should be permitted if the predicted start output limit is greater than the operation stop prohibition threshold;
(C) The internal combustion engine is operated or stopped according to the determination result in step (b), and the internal combustion engine is configured to output a torque based on a required torque, which is a torque to be output to the drive shaft, to the drive shaft. Controlling the engine, the electric motoring means and the electric motor;
Is included.

  As in this method, the operation stop permission threshold for determining whether or not to permit the operation stop of the internal combustion engine is set to a value larger than the operation stop prohibition threshold, and the start output limit is equal to or greater than the operation stop permission threshold. If the internal combustion engine is allowed to stop when the predicted start output limit exceeds the shutdown prohibition threshold, the output limit of the storage means is limited when the predetermined time has elapsed after the stop of the internal combustion engine is permitted. Therefore, it is very unlikely that the internal combustion engine will be shut down, so the internal combustion engine is restarted in a very short time after the internal combustion engine is stopped. Can be suppressed. Therefore, according to this method, it is possible to suppress frequent start / stop of the internal combustion engine and to sufficiently ensure the operation stop state of the internal combustion engine to improve fuel consumption.

The second power output device according to the present invention is:
A power output device that outputs power to a drive shaft,
An internal combustion engine capable of outputting power to the drive shaft;
Electric motoring means capable of motoring the internal combustion engine;
An electric motor capable of outputting power to the drive shaft;
Power storage means capable of exchanging electric power with the electric motoring means and the electric motor;
Predicted start output limit acquisition means for acquiring a predicted start output limit that is a predicted value of electric power allowed to discharge the power storage means when starting the internal combustion engine after a predetermined time has elapsed since the present time;
Request torque setting means for setting a request torque that is a torque to be output to the drive shaft;
Requested power setting means for setting requested power required for the drive shaft based on the set requested torque;
When the internal combustion engine is stopped, it is determined that the internal combustion engine should be started if the set required power is equal to or greater than a predetermined start determination threshold, and when the internal combustion engine is in operation, the setting is performed. The internal combustion engine when the requested power is less than or equal to a predetermined stop determination threshold smaller than the start determination threshold and is less than a predicted start determination threshold obtained by subtracting predetermined power from the acquired predicted start output limit Engine start / stop determination means for determining that the engine should be stopped;
The internal combustion engine and the electric motoring means so that the internal combustion engine is operated or stopped according to the determination result by the engine start / stop determination means and torque based on the set required torque is output to the drive shaft. And control means for controlling the electric motor;
Is provided.

  In this power output apparatus, when the internal combustion engine is stopped, it is determined that the internal combustion engine should be started if the required power is equal to or greater than a predetermined start determination threshold value. Further, when the internal combustion engine is in operation, the required power is equal to or less than a predetermined stop determination threshold value that is smaller than the start determination threshold value, and is allowed to discharge the storage means when starting the internal combustion engine after a predetermined time has elapsed since the present time. It is determined that the internal combustion engine should be stopped if it falls below a predicted start determination threshold value obtained by subtracting predetermined power from the predicted start output limit, which is the predicted value of. Then, the internal combustion engine, the electric motoring means, and the electric motor are controlled so that the internal combustion engine is operated or stopped according to the determination result about the start / stop of the internal combustion engine and the torque based on the required torque is output to the drive shaft. The As described above, the stop determination threshold for determining whether or not to stop the internal combustion engine is set to a value smaller than the start determination threshold, the required power is equal to or less than the stop determination threshold, and falls below the predicted start determination threshold. If the internal combustion engine is stopped while the engine is stopped, the possibility that the internal combustion engine is started in relation to the required power at the time when the predetermined time has elapsed after the internal combustion engine is stopped unless the amount of change in the required power becomes extremely large. Since it becomes low, it can suppress restarting in a very short time after an internal combustion engine is stopped. Thereby, in this power output device, it is possible to suppress frequent start / stop of the internal combustion engine and to sufficiently ensure the operation stop state of the internal combustion engine to improve fuel consumption.

  The second power output device further includes engine start output limit acquisition means for acquiring a start output limit that is electric power allowed for discharging of the power storage means when the internal combustion engine is started at the present time. Alternatively, the start determination threshold value may be obtained by subtracting the predetermined power from the acquired start output limit. Thereby, the start determination threshold value can be set to a more appropriate value.

The control method of the second power output device according to the present invention is:
An internal combustion engine capable of outputting power to the drive shaft, an electric motoring means capable of motoring the internal combustion engine, an electric motor capable of outputting power to the drive shaft, and the electric motoring means and the motor exchange power. A power output device comprising a possible power storage means,
(A) obtaining a predicted start output limit that is a predicted value of electric power allowed to discharge the power storage means when starting the internal combustion engine after a predetermined time has elapsed since the present time;
(B) When the internal combustion engine is stopped, it is determined that the internal combustion engine should be started if the required power based on the required torque that is the torque to be output to the drive shaft is equal to or greater than a predetermined start determination threshold value. When the internal combustion engine is in operation, the required power is equal to or less than a predetermined stop determination threshold value smaller than the start determination threshold value, and a predetermined power is obtained from the predicted start output limit acquired in step (a). Determining that the internal combustion engine should be stopped if it is below a predicted start determination threshold value obtained by subtracting;
(C) The internal combustion engine and the electric motoring are operated so that the internal combustion engine is operated or stopped according to the determination result in step (b) and torque based on the set required torque is output to the drive shaft. Controlling the means and the motor;
Is included.

  As in this method, the stop determination threshold for determining whether to stop the internal combustion engine is set to a value smaller than the start determination threshold, the required power is equal to or less than the stop determination threshold, and the predicted start determination threshold is set to If the internal combustion engine is stopped when it is lower, the internal combustion engine can be started in relation to the required power when the predetermined time elapses after the internal combustion engine stops unless the amount of change in the required power becomes extremely large. Therefore, it is possible to prevent the internal combustion engine from being restarted in a very short time after being stopped. Therefore, according to this method, it is possible to suppress frequent start / stop of the internal combustion engine and to sufficiently ensure the operation stop state of the internal combustion engine to improve fuel consumption.

  Further, in the control method of the second power output apparatus, step (a) further obtains a starting output limit that is electric power allowed for discharging of the power storage means at the time of starting the internal combustion engine. The start determination threshold value may be obtained by subtracting the predetermined power from the acquired start output limit. Thereby, the start determination threshold value can be set to a more appropriate value.

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

  The engine 22 is an internal combustion engine that outputs power when supplied with hydrocarbon-based fuel such as gasoline or light oil. The fuel injection amount or ignition timing by an engine electronic control unit (hereinafter referred to as “engine ECU”) 24, Control of intake air volume etc. The engine ECU 24 receives signals from various sensors that are provided for the engine 22 and detect the operating state of the engine 22. The engine ECU 24 communicates with the hybrid ECU 70 to control the operation of the engine 22 based on a control signal from the hybrid ECU 70, a signal from the sensor, and the like, and to transmit data on the operation state of the engine 22 as necessary. It outputs to ECU70.

  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 rotating elements. A crankshaft 26 of the engine 22 is connected to the carrier 34, a motor MG1 is connected to the sun gear 31, and a reduction gear 35 is connected to the ring gear 32 via a ring gear shaft 32a. The power distribution and integration mechanism 30 distributes the power from the engine 22 input from the carrier 34 to the sun gear 31 side and the ring gear 32 side according to the gear ratio when the motor MG1 functions as a generator. , The power from the engine 22 input from the carrier 34 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 wheels 39a and 39b, which are drive wheels, via the gear mechanism 37 and the differential gear 38.

  Both the motor MG1 and the motor MG2 are configured as well-known synchronous generator motors that operate as generators and can operate as motors, and exchange power with the battery 50 that is a secondary battery via inverters 41 and 42. Do. 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 one of the motors MG1 and MG2 is used as the other. It can be consumed with the 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 electric power balance is balanced by the motors MG1 and MG2, the battery 50 is charged. It will not be 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 receives 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 detected phase current applied to the motors MG1 and MG2 and the like are input, and the motor ECU 40 outputs a switching control signal and the like to the inverters 41 and 42. The motor ECU 40 executes a rotation speed calculation routine (not shown) based on signals input from the rotation position detection sensors 43 and 44, and calculates the rotation speeds Nm1 and Nm2 of the rotors of the motors MG1 and MG2. Further, the motor ECU 40 communicates with the hybrid ECU 70, controls the driving of the motors MG1, MG2 based on the control signal from the hybrid ECU 70, and transmits data related to the operating state of the motors MG1, MG2 to the hybrid ECU 70 as necessary. Output.

  In the embodiment, the battery 50 is configured as a lithium ion secondary battery having a higher output density than, for example, a nickel metal hydride secondary battery, and the battery electronic control unit (hereinafter referred to as “battery ECU”) 52. Is managed by. The battery ECU 52 includes signals necessary for managing the battery 50, for example, an inter-terminal voltage Vb 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. A charge / discharge current Ib from a current sensor (not shown) installed in the battery 50, a battery temperature Tb from a temperature sensor 56 attached to the battery 50, and the like are input. Further, the battery ECU 52 outputs data related to the state of the battery 50 to the hybrid ECU 70 and the engine ECU 24 by communication as necessary. Further, in order to manage the battery 50, the battery ECU 52 calculates the remaining capacity SOC based on the integrated value of the charging / discharging current Ib detected by the current sensor, and charges / discharges the battery 50 based on the remaining capacity SOC. The required power Pb * is set, the input limit Win as the charge allowable power that is the power allowed for charging the battery 50, and the output limit Wout as the discharge allowable power that is the power allowed for discharging the battery 50 To do. The input limit Win of the battery 50 can be set by multiplying the base value corresponding to the battery temperature Tb by the correction coefficient for input limit corresponding to the remaining capacity SOC of the battery 50, and the output limit Wout depends on the battery temperature Tb. The base value can be set by multiplying the base limit value by an output limiting correction coefficient corresponding to the remaining capacity SOC of the battery 50. FIG. 2 shows an example of the relationship between the battery temperature Tb and the input / output restriction base value, and FIG. 3 shows an example of the relationship between the remaining capacity SOC of the battery 50, the input restriction correction coefficient, and the output restriction correction coefficient. As can be seen from these drawings, the battery 50, which is a lithium ion secondary battery, has an input limit Win as a charge allowable power and an output limit Wout as a discharge allowable power in accordance with a change in the remaining capacity SOC indicating the storage state. It has characteristics that change relatively greatly. That is, when the remaining capacity SOC is relatively high, the input limit Win of the battery 50 varies relatively greatly according to the change in the remaining capacity SOC, and the output limit Wout of the battery 50 is when the remaining capacity SOC is relatively low. Furthermore, it fluctuates relatively greatly according to the change in the remaining capacity SOC.

  The hybrid ECU 70 is configured as a microprocessor centered on the CPU 72, and includes a ROM 74 for storing a processing program, a RAM 76 for temporarily storing data, an input / output port and a communication port (not shown), and the like in addition to the CPU 72. The hybrid ECU 70 detects the ignition signal from the ignition switch (start switch) 80, the 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 the depression amount of the accelerator pedal 83. The accelerator opening Acc from the accelerator pedal position sensor 84, the brake pedal stroke BS from the brake pedal stroke sensor 86 for detecting the depression amount of the brake pedal 85, the vehicle speed V from the vehicle speed sensor 87, 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, the battery ECU 52, etc. via the communication port, and exchanges various control signals and data with the engine ECU 24, the motor ECU 40, the battery ECU 52, etc. ing.

  In the hybrid vehicle 20 of the embodiment configured as described above, the vehicle is connected to the wheels 39a and 39b which are driving wheels based on the accelerator opening Acc and the vehicle speed V corresponding to the depression amount of the accelerator pedal 83 by the driver. The required torque Tr * to be output to the ring gear shaft 32a as the drive shaft is calculated, and the engine 22, the motor MG1, and the motor MG2 are controlled so that the torque based on the required torque Tr * is output to the ring gear shaft 32a. . As an operation control mode of the engine 22, the motor MG1, and the motor MG2, the operation of the engine 22 is controlled so that power corresponding to the required torque Tr * is output from the engine 22, and all of the power output from the engine 22 is distributed. Necessary for torque conversion operation mode in which motor MG1 and motor MG2 are driven and controlled so that torque is converted by integrated mechanism 30, motor MG1 and motor MG2 and output to ring gear shaft 32a, and required torque Tr * and charge / discharge of battery 50 The engine 22 is operated and controlled so that a power corresponding to the sum of the power and the power is output from the engine 22, and all or a part of the power output from the engine 22 with charging / discharging of the battery 50 is a power distribution and integration mechanism. 30 and torque conversion by motor MG1 and motor MG2. Thus, a charge / discharge operation mode in which the motor MG1 and the motor MG2 are driven and controlled so that torque based on the required torque Tr * is output to the ring gear shaft 32a, and the engine 22 is stopped and torque based on the required torque Tr * is applied to the ring gear shaft 32a. There is a motor operation mode for driving and controlling the motor MG2 so as to output. Further, in the hybrid vehicle 20 of the embodiment, when a predetermined condition is satisfied under the torque conversion operation mode or the charge / discharge operation mode, intermittent operation for automatically stopping and starting the engine 22 is executed.

  Next, the operation of the hybrid vehicle 20 according to the embodiment, particularly the operation when the hybrid vehicle 20 is running with the engine 22 driven will be described. FIG. 4 is a flowchart illustrating an example of an engine operation drive control routine executed by the hybrid ECU 70 of the embodiment. This routine is repeatedly executed at predetermined time intervals (for example, every several milliseconds) when the accelerator pedal 83 is depressed while the hybrid vehicle 20 is running with the engine 22 operated. is there.

  At the start of the routine of FIG. 4, the CPU 72 of the hybrid ECU 70 determines the accelerator opening Acc from the accelerator pedal position sensor 84, the vehicle speed V from the vehicle speed sensor 87, the rotational speeds Nm1 and Nm2 of the motors MG1 and MG2, and the remaining capacity of the battery 50. Input processing of data necessary for control, such as the value of SOC, charge / discharge required power Pb *, input / output restrictions Win and Wout, and air conditioning operation flag Fac, is executed (step S100). Here, the rotational speeds Nm1 and Nm2 of the motors MG1 and MG2 are input from the motor ECU 40 by communication. Further, the remaining capacity SOC of the battery 50, the charge / discharge required power Pb *, and the input / output limits Win and Wout are input from the battery ECU 52 by communication. The air conditioning operation flag Fac is a value when an air conditioning on / off switch for instructing operation / stop of a passenger compartment air conditioning unit (not shown) mounted on the hybrid vehicle 20 provided on an instrument panel or the like in the passenger compartment is turned off. In addition to being set to 0, the value is set to 1 when the switch is turned on, and is input by communication from an air conditioning electronic control unit (not shown) that controls the passenger compartment air conditioning unit.

  After the data input process in step S100, the hybrid is set with a required torque Tr * to be output to the ring gear shaft 32a as the drive shaft connected to the wheels 39a and 39b based on the accelerator opening Acc and the vehicle speed V. The required travel power Pr * required for travel of the automobile 20 (ring gear shaft 32a) is set (step S110). In the embodiment, the relationship among the accelerator opening Acc, the vehicle speed V, and the required torque Tr * is determined in advance and stored in the ROM 74 as a required torque setting map. The required torque Tr * is the given accelerator opening. The one corresponding to Acc and the vehicle speed V is derived and set from the map. FIG. 5 shows an example of the required torque setting map. In the embodiment, the required travel power Pr * is set to a value obtained by multiplying the required torque Tr * by the rotational speed Nr of the ring gear shaft 32a. The rotational speed Nr of the ring gear shaft 32a can be obtained by dividing the rotational speed Nm2 of the motor MG2 by the gear ratio Gr of the reduction gear 35 or by multiplying the vehicle speed V by a conversion factor.

  Next, the engine start output, which is the power allowed to discharge the battery 50 when starting the engine 22 at the present time, is the sum of the output limit Wout input in step S100 and a predetermined temporary increase amount Wup (for example, about 6 kW). It sets as restriction Woutes (step S120). In the embodiment, the temporary increase amount Wup includes, for example, electric power (for example, about 5 kW) consumed by motoring (cranking) of the motor MG1 when the engine 22 is started once and power from the motor MG2. It is determined as the sum of electric power (for example, about 1 kW) required to output and continue running. If the engine start output limit Wout is set in this manner, the battery 50 is discharged when the engine 22 is started after a predetermined time tref (for example, about 20 to 30 seconds) has elapsed from the present time according to the following equation (1). A predicted start output limit Woutpd, which is a predicted value of allowable power, is calculated (step S130). In the embodiment, the predicted start output limit Woutpd is the average power consumption per unit time of the motor MG2 or the remaining capacity of the output limit Wout when the hybrid vehicle 20 travels under the motor operation mode obtained by experiment and analysis. It is obtained by subtracting the product of the estimated reduction amount ΔW (for example, a positive constant value) per unit time of the output limit Wout based on the degree of dependence on the SOC and the time tref from the engine start output limit Woutes.

  Woutpd = Woutes-ΔW · tref (1)

  After the process of step S130, it is determined whether the remaining capacity SOC of the battery 50 input in step S100 is less than a predetermined lower limit remaining capacity Sref (for example, a value of about 30 to 35%) (step S140). ). If the remaining capacity SOC is less than the lower limit remaining capacity Sref, the intermittent operation is turned off when the operation stop of the engine 22, that is, the intermittent operation is permitted, and turned on when the intermittent operation of the engine 22 is prohibited. The prohibition flag is turned on (step S150), and the charge / discharge request power Pb * input in step S100 from the sum of the required travel power Pr * and the loss Loss set in step S110 (however, the charge side is negative) ) Is set to the required power Pe * required for the engine 22 (step S160). Next, a target rotational speed Ne * and a target torque Te *, which are target operating points of the engine 22, are set based on the required power Pe * and transmitted to the engine ECU 24 (step S170). In the embodiment, the target rotational speed Ne * and the target torque Te * of the engine 22 are set based on a predetermined operation line and the required power Pe * in order to operate the engine 22 efficiently. FIG. 6 illustrates an operation line of the engine 22 and a correlation curve between the rotational speed Ne and the torque Te indicating that the required power Pe * is constant. As shown in the figure, the target rotational speed Ne * and the target torque Te * can be obtained as an intersection of the operation line and a correlation curve indicating that the required power Pe * (Ne * × Te *) is constant. it can. The engine ECU 24 that has received the target rotational speed Ne * and the target torque Te * from the hybrid ECU 70 sets the target intake air amount GA * based on the target rotational speed Ne * and the target torque Te *, and also sets the target intake air. A target opening Th * of an electronically controlled throttle valve (not shown) is set based on the amount GA *, and the opening of the electronically controlled throttle valve is set based on a throttle position from a throttle valve position sensor (not shown). A throttle motor (not shown) is controlled so that Further, the engine ECU 24 executes fuel injection control, ignition timing control, valve timing control, exhaust gas recirculation control, and the like in addition to such throttle opening degree control.

  If the target rotational speed Ne * and the target torque Te * of the engine 22 are set and transmitted, the target rotational speed Ne *, the rotational speed Nr (Nm2 / Gr) of the ring gear shaft 32a, and the gear ratio ρ ( The target rotational speed Nm1 * of the motor MG1 is calculated according to the following formula (2) using the number of teeth of the sun gear 31 / the number of teeth of the ring gear 32, and the calculated target rotational speed Nm1 * and the current rotational speed Nm1 Torque command Tm1 * for motor MG1 is set in accordance with the following equation (3) based on (step S180). Here, Expression (2) is a dynamic relational expression for the rotating element of the power distribution and integration mechanism 30. FIG. 7 illustrates a collinear diagram illustrating a dynamic relationship between the number of rotations and torque in the rotating elements of the power distribution and integration mechanism 30 when the engine 22 is operated. 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 central C-axis indicates the rotational speed of the carrier 34 that matches the rotational speed Ne of the engine 22, and the right R-axis. The axis indicates the rotational speed Nr of the ring gear 32 obtained by dividing the rotational speed Nm2 of the motor MG2 by the gear ratio Gr of the reduction gear 35. The two thick arrows on the R axis indicate the torque acting on the ring gear shaft 32a by this torque output when the motor MG1 outputs the torque Tm1, and the reduction gear 35 when the motor MG2 outputs the torque Tm2. And the torque acting on the ring gear shaft 32a via. Expression (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. Expression (3) is a relational expression in feedback control for rotating the motor MG1 at the target rotation speed Nm1 *. In Expression (3), “k1” in the second term on the right side is the gain of the proportional term. “K2” in the third term on the right side is the gain of the integral term.

Nm1 * = Ne * ・ (1 + ρ) / ρ-Nm2 / (Gr ・ ρ) (2)
Tm1 * =-ρ / (1 + ρ) ・ Te * + k1 ・ (Nm1 * -Nm1) + k2 ・ ∫ (Nm1 * -Nm1) dt (3)

  Subsequently, a temporary motor torque that is a temporary value of torque to be output from the motor MG2 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. Tm2tmp is calculated according to the following equation (4) (step S190). Further, the upper and lower limits of the torque that may be output from the motor MG2 using the input / output limits Win and Wout of the battery 50, the torque command Tm1 * for the motor MG1, and the current rotational speeds Nm1 and Nm2 of the motors MG1 and MG2 Torque limits Tmin and Tmax are calculated according to the following equations (5) and (6) (step S200). Then, a value obtained by limiting the temporary motor torque Tm2tmp with the torque limits Tmin and Tmax is set in the torque command Tm2 * for the motor MG2 (step S210). By setting the torque command Tm2 * for the motor MG2 in this way, the torque output to the ring gear shaft 32a can be set as a torque that is limited within the range of the input / output limits Win and Wout of the battery 50. Equation (4) can be easily derived from the alignment chart of FIG. If the torque commands Tm1 * and Tm2 * for the motors MG1 and MG2 are thus set, the torque commands Tm1 * and Tm2 * are transmitted to the motor ECU 40 (step S220), and this routine is temporarily terminated. The motor ECU 40 that has received the torque commands Tm1 * and Tm2 * drives the motor MG1 in accordance with the torque command Tm1 * and drives the switching elements of the inverters 41 and 42 so that the motor MG2 is driven in accordance with the torque command Tm2 *. Perform switching control.

Tm2tmp = (Tr * + Tm1 * / ρ) / Gr (4)
Tmin = (Win-Tm1 * ・ Nm1) / Nm2 (5)
Tmax = (Wout-Tm1 * ・ Nm1) / Nm2 (6)

  If it is determined in step S140 that the remaining capacity SOC of the battery 50 is equal to or greater than the lower limit remaining capacity Sref, is the vehicle speed V further input in step S100 greater than or equal to a predetermined intermittent prohibition vehicle speed Vref? It is determined whether or not (step S230). The intermittent prohibition vehicle speed Vref is set, for example, as a lower limit value of a vehicle speed range where the operation of the engine 22 is necessary and intermittent operation (operation stop of the engine 22) should be prohibited, and the state of the battery 50, the state of the engine 22, the hybrid vehicle It may be set so as to change according to the running state of 20 or the like. If the vehicle speed V is greater than or equal to the intermittent prohibition vehicle speed V, the intermittent prohibition flag is turned on in step S150, the above-described processing of steps S160 to S220 is executed, and this routine is temporarily terminated.

  On the other hand, if it is determined in step S140 that the remaining capacity SOC of the battery 50 is greater than or equal to the lower limit remaining capacity Sref, and if it is determined in step S150 that the vehicle speed V is less than the intermittent prohibition vehicle speed Vref, the process proceeds to step S120. The engine start output limit Woutes set in the above is equal to or higher than the intermittent permission threshold (operation stop permission threshold) Wouta that is set in advance as a lower limit value of the output limit that permits the intermittent operation while the intermittent operation of the engine 22 is prohibited. Further, the predicted start output limit Woutpd calculated in step S130 is set in advance to a value smaller than the intermittent permission threshold Wouta as the upper limit value of the output limit for prohibiting the intermittent operation of the engine 22 while permitting the intermittent operation. It is determined whether the intermittent prohibition threshold (operation stop prohibition threshold) Woutb is exceeded. (Step S240). If it is determined in step S240 that the engine start output limit Woutes is greater than or equal to the intermittent permission threshold Wouta and the predicted start output limit Woutpd exceeds the intermittent prohibition threshold Woutb, the intermittent operation of the engine 22 is permitted. The intermittent prohibition flag is turned off as much as possible (step S250). If it is not determined in step S240 that the engine start output limit Woutes is equal to or greater than the intermittent permission threshold Wouta and the predicted start output limit Woutpd exceeds the intermittent prohibition threshold Woutb, the engine start output limit is further increased. It is determined whether or not the output limit Woutes is equal to or less than the above-described intermittent prohibition threshold Woutb (step S260). If the engine start output limit Woutes is equal to or less than the intermittent prohibition threshold Woutb, the intermittent prohibition flag is turned on to prohibit the intermittent operation of the engine 22 (step S150), and the above-described steps S160 to S220 are executed. If the engine start output limit Woutes exceeds the intermittent prohibition threshold Woutb, the intermittent prohibition flag is held in the previous state (step S270), and it is determined whether the intermittent prohibition flag is turned on (step S270). S280) If the intermittent prohibition flag is turned on, the processes of steps S160 to S220 described above are executed.

  On the other hand, if the intermittent prohibition flag is turned off in step S250, or if it is determined that the intermittent prohibition flag is turned off in step S280, the engine 22 is compared with the required travel power Pr *. Start determination power (start determination threshold value) Pstart and stop determination power (stop determination threshold value) Pstop for determining whether to start or stop, and a predicted value of start determination power when a predetermined time tref has elapsed from the present time The predicted start determination power (predicted start determination threshold value) Pstartpd is set (step S290). The start determination power Pstart is consumed according to cranking by the motor MG1 for starting the engine 22 from the engine start output limit Woutes which is the sum of the output limit Wout and the temporary increase amount Wup according to the following equation (7). The product of the engine starting power Wcrk, which is generated power, the air conditioning power Wac required for the air conditioning of the passenger compartment by the air conditioning unit during the startup of the engine 22 and the air conditioning operation flag Fac ( If Fac = 0, the value is obtained by subtracting the value 0) and the power Wmrg for a predetermined margin. While the hybrid vehicle 20 is traveling with the engine 22 stopped, if the required traveling power Pr * becomes equal to or higher than the start determination power Pstart, it is determined that the engine 22 should be started. The stop determination power Pstop is obtained by subtracting a positive predetermined value α from the start determination power Pstart calculated as described above according to the following equation (8). Further, the predicted start determination power Pstartpd is calculated from the predicted start output limit Woutpd calculated in step S130 according to the following equation (9), as in the case of the start determination power Pstart, and the air conditioning start power Wcrk. This is obtained by subtracting the product of the electric power Wac and the air-conditioning operation flag Fac and the marginal electric power Wmrg. Here, the engine starting power Wcrk cancels the torque as a reaction force against the power input / output by the motor MG1 for cranking the engine 22 and the driving torque acting on the ring gear shaft 32a accompanying the cranking of the engine 22. Therefore, it is the sum (the sum of the generated power and the power consumption) of the power input / output by the motor MG2. In the hybrid vehicle 20 of the embodiment, when the engine 22 is started, the higher the vehicle speed V at the start of cranking by the motor MG1, the higher the rotational speed Nm1 of the motor MG1, the higher the negative side. The power required for cranking the engine 22 is reduced by that amount. Based on this, in the embodiment, a map (not shown) that defines the relationship between the vehicle speed V and the engine starting power Wcrk is created in advance, and the engine starting power Wcrk is the vehicle speed input in step S100 from the map. The one corresponding to V is derived. Further, in the embodiment, the air conditioning power Wac required for air conditioning in the passenger compartment is a constant value (for example, about several kW) determined through experiments and analysis based on the performance of the air conditioning unit and the like.

Pstart = Woutes-Wcrk-Fac / Wac-Wmrg (7)
Pstop = Pstart-α (8)
Pstartpd = Woutpd-Wcrk-Fac / Wac-Wmrg (9)

  If the start determination power Pstart, the stop determination power Pstop, and the predicted start determination power Pstartpd are set, the required travel power Pr * set in step S110 is equal to or less than the stop determination power Pstop and lower than the predicted start determination power Pstartpd. It is determined whether or not (step S300). If it is not determined in step S300 that the required travel power Pr * is equal to or less than the stop determination power Pstop and less than the predicted start determination power Pstartpd, the processes in steps S160 to S220 described above are executed. On the other hand, if it is determined in step S300 that the required travel power Pr * is equal to or less than the stop determination power Pstop and is less than the predicted start determination power Pstartpd, the engine stop is performed to stop the engine 22. The flag is turned on (step S310), and this routine is terminated. When the engine stop flag is thus turned on, the hybrid ECU 70 executes an engine stop control routine (not shown). In the engine stop control routine, in a state where the fuel supply to the engine 22 is stopped, for example, a negative torque for suppressing the rotation of the engine 22 is applied to the motor MG1 until the rotation speed Ne of the engine 22 reaches a predetermined rotation speed just before the stop. The torque command Tm1 * is set, and a positive torque for holding the piston at the timing when the rotation speed Ne reaches the rotation speed just before the stop is set as the torque command Tm1 * for the motor MG1, and further based on the required torque Tr * This is a process of setting the torque command Tm2 * of the motor MG2 so that torque is output to the ring gear shaft 32a. Then, the engine stop flag is turned off when restart of the engine 22 is instructed after the engine 22 is stopped.

  FIG. 8 illustrates how the setting state of the intermittent prohibition flag is changed by executing the above-described engine operation drive control routine. As shown in the figure, the battery 50 is charged by the electric power from the motor MG1 that generates power using the power of the engine 22 with the intermittent prohibition flag turned on or the regenerative electric power from the motor MG2, and the remaining capacity SOC of the battery 50 is reduced. The time at which the engine start output limit Woutes reaches the intermittent permission threshold Wouta due to the increase and the output limit Wout increasing as the discharge power is defined as t1 ′. When the engine start output limit Wouts exceeds the intermittent permission threshold Wouta (time t1 ′), intermittent operation of the engine 22 is permitted (intermittent prohibition flag off), and the engine start output limit Woutes is equal to or lower than the intermittent prohibition threshold Woutb. (Time t2 '), it is assumed that intermittent operation of the engine 22 is prohibited. Under such an assumption, the engine 22 is stopped almost simultaneously with the intermittent prohibition flag being turned off, and the average power consumption of the motor MG2 during the subsequent driving in the motor operation mode is reduced as described above. If it substantially coincides with ΔW, the engine start output limit Woutes changes (decreases) as shown by a dotted line in FIG. 8 and reaches the intermittent prohibition threshold Woutb at time t2 ′ when time t ′ has elapsed from time t1 ′. Accordingly, the intermittent operation of the engine 22 is prohibited (intermittent prohibition flag is turned on) and the engine 22 is started. The time t ′ from time t1 ′ to time t2 ′ becomes shorter as the degree of decrease in the output limit Wout increases.

  On the other hand, in the hybrid vehicle 20 of the embodiment, when the engine start output limit Woutes reaches the intermittent permission threshold Wouta, the intermittent operation of the engine 22 is not immediately permitted, and the engine start output limit Woutes is When the predicted start output limit Woutpd, which is equal to or higher than the intermittent permission threshold Wouta and is obtained by subtracting the product of the estimated decrease amount ΔW and the predetermined time tref from the engine start output limit Woutes, exceeds the intermittent prohibition threshold Woutb ( Time t1) The intermittent operation of the engine 22 is permitted (intermittent prohibition flag off) (steps S240 and S250 in FIG. 4). That is, in the above embodiment, when the engine start output limit Woutes is equal to or greater than the intermittent permission threshold Wouta, the output limit Wout of the battery 50 at the time (time t2) when the predetermined time tref has elapsed from that time (time t1). Therefore, the intermittent operation of the engine 22 is permitted on the condition that the possibility that the intermittent operation of the engine 22 is prohibited is extremely low. As a result, even if the engine 22 is stopped almost simultaneously with the intermittent prohibition flag being turned off, the average power consumption of the motor MG2 substantially coincides with the above-described estimated reduction amount ΔW when traveling in the motor operation mode thereafter. For example, as can be seen from FIG. 8, it is possible to permit the intermittent operation of the engine 22, that is, to stop the operation for a time longer than the above-described time t '(predetermined time tref), and in a state where the intermittent operation of the engine 22 is permitted. It can be suppressed that the engine 22 is restarted in a very short time after the engine 22 is stopped.

  FIG. 9 illustrates how the engine stop flag setting state is changed by executing the above-described engine operation drive control routine. As shown in the figure, the battery 50 is charged by the electric power from the motor MG1 that generates electric power using the power of the engine 22 or the regenerative electric power from the motor MG2, the remaining capacity SOC of the battery 50 increases, and the output limit Wout is discharged electric power. As a result, the start determination power Pstart and the stop determination power Pstop increase, and the time when the required travel power Pr * based on the required torque Tr * according to the driver's accelerator operation coincides with the stop determination power Pstop is t10 ′. To do. When the required travel power Pr * becomes equal to or less than the stop determination power Pstop during operation of the engine 22 (time t10 ′), the engine 22 is stopped (engine stop flag is turned on), and the required travel power Pr * while the engine 22 is stopped. Is assumed to be equal to or greater than the start determination power Pstart (time t20 ′), the engine 22 is started (engine stop flag is turned off). Under such an assumption, the required travel power Pr * is substantially constant, and the average power consumption of the motor MG2 during the travel in the motor operation mode after the engine 22 is stopped is equal to the estimated decrease amount ΔW. Since the start determination power Pstart and the stop determination power Pstop based on the engine start output limit Wouts (output limit Wout) change (decrease) as shown by the dotted line in FIG. 9, from time t10 ′. At time t20 ′ at which time t ″ has elapsed, the required travel power Pr * coincides with the start determination power Pstart, thereby starting the engine 22. Then, the time t from time t10 ′ to time t20 ′. ″ Becomes shorter as the degree of decrease in the output limit Wout increases.

  On the other hand, in the hybrid vehicle 20 of the embodiment, when the required travel power Pr * becomes equal to or less than the stop determination threshold value Pstop during the operation of the engine 22, the engine 22 is not immediately stopped and the required travel power Pr. When * is equal to or less than the stop determination power Pstop and is below the predicted start determination power Pstartpd obtained by subtracting the engine start power Wcrk from the above-described predicted start output limit Woutpd (time t10), the engine 22 is stopped ( The engine stop flag is turned on) (steps S300 and S310 in FIG. 4). That is, in the above-described embodiment, when the required travel power Pr * is equal to or less than the stop determination power Pstop, the required travel power Pr * at the time (time t20) when the predetermined time tref elapses from that time (time t10). Therefore, the engine 22 is allowed to be stopped on the condition that the possibility of starting the engine 22 is extremely low. As a result, the required travel power Pr * changes substantially constant, and the average power consumption of the motor MG2 during the travel in the motor operation mode after the engine stop flag is turned on and the engine 22 is stopped is reduced by the estimated decrease amount described above. If substantially equal to ΔW, as can be seen from FIG. 9, it is possible to stop the engine 22 for a time longer than the above-described time t ″ (predetermined time tref), and for a very short time after the engine 22 is stopped. Can be prevented from being restarted.

  As described above, in the hybrid vehicle 20 of the embodiment, when the intermittent operation (operation stop) of the engine 22 is permitted, the electric power is allowed to discharge the battery 50 when the engine 22 is started at the present time. If the engine start output limit Woutes is equal to or less than a predetermined intermittent prohibition threshold Woutb, it is determined that the intermittent operation of the engine 22 should be prohibited, and the intermittent prohibition flag is turned on (steps S260 and S150 in FIG. 4). In addition, when the intermittent operation of the engine 22 is prohibited, the engine start output limit Woutes is greater than or equal to the intermittent permission threshold Wouta, which is larger than the intermittent prohibition threshold Woutb, and after a predetermined time tref has elapsed since the present time. When the predicted start output limit Woutpd, which is a predicted value of the power allowed to discharge the battery 50 at the start of the engine 22, exceeds the intermittent prohibition threshold Woutb, it is determined that the intermittent operation of the engine 22 should be permitted, and the intermittent prohibition flag Is turned off (steps S240 and S250 in FIG. 4). Then, the engine 22 and the motors MG1 and MG2 are operated so that the engine 22 is operated or stopped according to the determination result regarding whether or not the intermittent operation of the engine 22 is permitted and torque based on the required torque Tr * is output to the ring gear shaft 32a. Are controlled (steps S160 to S220 and S310 in FIG. 4). Thus, after setting the intermittent permission threshold Wouta for determining whether or not to permit intermittent operation of the engine 22 to a value larger than the intermittent prohibition threshold Woutb, the engine start output limit Woutes is equal to or higher than the intermittent permission threshold Wouta. If the engine 22 is allowed to operate intermittently when the predicted start output limit Woutpd exceeds the intermittent prohibition threshold Woutb, the engine start output is output when a predetermined time tref elapses after the intermittent operation of the engine 22 is permitted. Since the possibility that the intermittent operation of the engine 22 is prohibited in relation to the limit Woutes (the output limit Wout of the battery 50) is extremely low, the engine 22 is stopped in a state where the intermittent operation of the engine 22 is permitted. Can be prevented from restarting in a very short time later . As a result, in the hybrid vehicle 20 of the embodiment, frequent start / stop of the engine 22 is suppressed to suppress an uncomfortable feeling of an occupant resulting from the start, and a sufficient operation stop state of the engine 22 is ensured to improve fuel efficiency. It becomes possible to plan.

  Further, as in the above embodiment, the engine start output limit Woutes is obtained by adding the temporary increase amount Wup to the output limit Wout set based on the temperature Tb and the remaining capacity SOC of the battery 50, and for engine start. If the product of the estimated reduction amount ΔW per unit time of the output limit Wouts and the predetermined time tref is subtracted from the output limit Woutes as the predicted start output limit Woutpd, the engine start output limit Woutes and the predicted start output limit Woutpd can be made more appropriate. However, the output limit Wout itself may be used as the engine start output limit Woutes without considering the temporary increase amount Wup. Further, a value obtained by subtracting the product of the estimated decrease amount ΔW and the predetermined time tref from the output limit Wout may be used as the predicted start output limit Woutpd. The estimated reduction amount ΔW of the output limit Wout used for obtaining the predicted start output limit Woutpd is the motors MG1 and MG2 when the hybrid vehicle 20 travels under various modes such as the torque change mode and the charge / discharge operation mode. May be based on the average power consumption per unit time, the dependence of the output limit Wout on the remaining capacity SOC, etc., and instead of a constant value, the traveling state of the hybrid vehicle 20 (for example, the vehicle speed V and the ring gear shaft 32a It may be a variable value that changes according to the rotational speed Nr or the like.

  Furthermore, in the hybrid vehicle 20 of the embodiment, when the engine 22 is stopped, the required travel power Pr * is calculated from the engine start output limit Woutes to the engine start power Wcrk, the air conditioning power Wac, and the marginal power Wmrg. It is determined that the engine 22 should be started if it is equal to or greater than the start determination power Pstart obtained by subtraction. Further, when the engine 22 is in operation, the required travel power Pr * is equal to or less than the stop determination power Pstop that is smaller than the start determination power Pstart by a predetermined value α, and the engine start power Wcrk is calculated from the predicted start output limit Woutpd. If it is below the predicted start determination power Pstartpd obtained by subtraction, it is determined that the engine 22 should be stopped (steps S300 and S310 in FIG. 4). When it is determined that the engine 22 should be stopped in relation to the required travel power Pr * when intermittent operation of the engine 22 is permitted, the engine 22 is stopped and a torque based on the required torque Tr * is generated. The engine 22 and the motor MG2 are controlled so as to be output to the ring gear shaft 32a. As described above, the stop determination power Pstop for determining whether or not to stop the engine 22 is set to a value smaller than the start determination power Pstart, and the required travel power Pr * is equal to or less than the stop determination power Pstop and is predicted. If the engine 22 is stopped when it is below the start determination power Pstartpd, it is requested when a predetermined time tref elapses after the engine 22 stops unless the change amount of the required travel power Pr * becomes extremely large. Since there is a low possibility that the engine 22 is started in relation to the travel power Pr *, it is possible to prevent the engine 22 from being restarted in a very short time after the engine 22 is stopped. As a result, in the hybrid vehicle 20 of the embodiment, frequent start / stop of the engine 22 is suppressed to suppress an uncomfortable feeling of an occupant resulting from the start, and a sufficient operation stop state of the engine 22 is ensured to improve fuel efficiency. It becomes possible to plan. It is assumed that the start determination power Pstart is obtained by subtracting the engine start power Wcrk, the air conditioning power Wac, and the marginal power Wmrg, which are the power consumed when the engine 22 is cranked, from the engine start output limit Woutes. However, it is not always necessary to consider the air conditioning power Wac and the marginal power Wmrg.

  The battery 50 mounted on the hybrid vehicle 20 of the embodiment is a lithium ion secondary battery, and the output limit Wout as the discharge allowable power changes relatively greatly according to the change in the remaining capacity SOC indicating the storage state. It has the characteristic to do. Therefore, if it is determined whether intermittent operation of the engine 22 is permitted or whether the engine 22 is started or stopped as described above, the output is output even if the output limit Wout varies depending on the remaining capacity SOC of the battery 50. The engine 22 is frequently started / stopped due to the relationship between the engine start output limit Woutes based on the limit Wout, the start determination power Pstart based on the output limit Wout and the required travel power Pr * compared with the predicted start determination power Pstartpd. Can be suppressed. However, it goes without saying that the battery 50 mounted on the hybrid vehicle 20 may be of a type other than the lithium ion secondary battery.

  Note that the processing in steps S140, S150, and S230 to S270 in FIG. 4 may be performed in the same manner while the hybrid vehicle 20 is running with the engine 22 stopped. Further, while the hybrid vehicle 20 is traveling with the engine 22 stopped, the same processing (first determination processing) as that in step S300 is performed, and the required traveling power Pr * is the stop determination power. In a case where it is not determined that it is equal to or less than Pstop and less than the predicted start determination power Pstartpd, a second determination process for determining whether or not the required travel power Pr * is equal to or greater than the start determination power Pstart may be executed. In this case, when an affirmative determination is made in the first determination process and when a negative determination is made in the second determination process, the engine stop flag is turned on, and when an affirmative determination is made in the second determination process, the engine The start flag may be turned off. Further, in the hybrid vehicle 20, the ring gear shaft 32a and the motor MG2 are connected via a reduction gear 35 that reduces the rotational speed of the motor MG2 and transmits it to the ring gear shaft 32a, but instead of the reduction gear 35, For example, a transmission that has two shift stages of Hi and Lo, or three or more shift stages, and changes the rotational speed of the motor MG2 and transmits it to the ring gear shaft 32a may be employed. Moreover, although the hybrid vehicle 20 decelerates the power of the motor MG2 by the reduction gear 35 and outputs it to the ring gear shaft 32a as a drive shaft, the application target of the present invention is not limited to this. That is, according to the present invention, as in a hybrid vehicle 120 as a modified example shown in FIG. 10, the power of the motor MG2 is connected to the ring gear shaft 32a (the axle to which the wheels 39a and 39b as drive wheels are connected). May be applied to those that output to different axles (axles connected to the wheels 39c, 39d in FIG. 10). Furthermore, the hybrid vehicle 20 may be configured as a so-called plug-in hybrid vehicle, in which the battery 50 can be charged with electric power from an external (outside the vehicle) charging device.

  Here, the correspondence between the main elements of the above-described embodiments and modifications and the main elements of the invention described in the column of means for solving the problems will be described. That is, in the above embodiment, the engine 22 capable of outputting power to the ring gear shaft 32a corresponds to “internal combustion engine”, the motor MG1 corresponds to “electric motoring means”, and can output power to the ring gear shaft 32a. The motor MG2 corresponds to the “electric motor”, the battery 50 capable of exchanging electric power with the motors MG1 and MG2 corresponds to the “power storage means”, and the process of step S120 in FIG. The hybrid ECU 70 that sets the engine start output limit Woutes, which is the power allowed for discharging the battery 50, corresponds to the “engine start output limit acquisition means”, and executes the process of step S130 of FIG. When the engine 22 is started after the time tref has elapsed, the electric power allowed for discharging the battery 50 The hybrid ECU 70 that calculates the predicted start output limit Woutpd, which is a measured value, corresponds to the “predicted start output limit acquisition means”, and the hybrid ECU 70 that executes the processing of steps S140, S150, and S230 to S270 in FIG. The hybrid ECU 70 that corresponds to the “stop permission determination unit” and executes the process of step S110 in FIG. 4 corresponds to the “required torque setting unit”. The engine 22 and the motors MG1 and MG2 are controlled so that torque based on the required torque Tr * is output to the ring gear shaft 32a, and the engine 22 is stopped when intermittent operation of the engine 22 is permitted. If it is determined that the engine 22 should be stopped, A combination of the hybrid ECU 70 that controls the engine 22 and the motors MG1 and MG2 so that torque based on the desired torque Tr * is output to the ring gear shaft 32a, and the engine ECU 24 and the motor ECU 40 corresponds to “control means”. . Further, the battery ECU 52 that sets the output limit Wout based on the temperature Tb and the remaining capacity SOC of the battery 50 corresponds to “output limit setting means”, and the hybrid ECU 70 that executes the process of step S110 of FIG. 4 corresponds to “engine start / stop determination means”, motor MG1 corresponds to “second electric motor”, and power distribution integration mechanism 30 corresponds to “means”. Corresponds to “power distribution means”.

  However, the “internal combustion engine” is not limited to the engine 22 that outputs power by receiving a hydrocarbon-based fuel such as gasoline or light oil, and may be of any other type such as a hydrogen engine. “Electric motor”, “electric motoring means”, and “second electric motor” are not limited to synchronous generator motors such as motors MG1 and MG2, and may be of any other type such as an induction motor. . The “engine start output limit acquisition means” is for considering the temporarily increased power as long as it can acquire the start output limit that is the power allowed for the discharge of the power storage means when the internal combustion engine is started at the present time. The present invention is not limited to this, and any other type such as one that does not consider the temporarily increased power may be used. “Predictive start output limit acquisition means” can acquire a predictive start output limit that is a predicted value of the power allowed to discharge the power storage means when starting the internal combustion engine after a predetermined time has elapsed since the present time. Any format can be used. The “operation stop permission determination means” determines that the operation stop of the internal combustion engine should be prohibited if the start output limit is equal to or less than the operation stop prohibition threshold when the operation stop of the internal combustion engine is permitted. When the engine stop is prohibited, the internal combustion engine indicates that the start output limit is greater than or equal to the operation stop permission threshold greater than the operation stop prohibition threshold and the predicted start output limit exceeds the operation stop prohibition threshold. As long as it is determined that the operation stop should be permitted, any type may be used. The “request torque setting means” is not limited to one that sets the required torque based on the accelerator opening and the vehicle speed as long as the request torque that is the torque to be output to the drive shaft can be set. Any other type may be used, such as setting the required torque based only on the degree. The “control means” includes an internal combustion engine, an electric motoring means, and an electric motor so that the internal combustion engine is operated or stopped according to a determination result related to the operation stop of the internal combustion engine, and torque based on the required torque is output to the drive shaft. If it is determined that the internal combustion engine should be stopped when it is determined that the operation stop of the internal combustion engine should be permitted, the internal combustion engine is stopped and torque based on the required torque is applied to the drive shaft. Any type other than the combination of the hybrid ECU 70, the engine ECU 24, and the motor ECU 40, such as a single electronic control unit, as long as it controls the internal combustion engine, the electric motoring means, and the electric motor so as to be output. It doesn't matter. The “output limit setting unit” may be of any type as long as it can set an output limit that is power allowed for discharging the power storage unit based on the state of the power storage unit. Further, the “engine start / stop determination means” should start the internal combustion engine when the internal combustion engine is stopped and the required running power is equal to or higher than a start determination threshold obtained by subtracting a predetermined power from the start output limit. And when the internal combustion engine is in operation, a predicted start determination obtained by subtracting the predetermined power from the predicted start output limit while the required travel power is not more than a predetermined stop determination threshold smaller than the start determination threshold. As long as it is determined that the internal combustion engine should be stopped when the value is below the threshold value, any type may be used. Further, the “power distribution means” is connected to three axes of the drive shaft, the output shaft of the internal combustion engine, and the rotation shaft of the second electric motor, and is used for power input / output to / from any two of these three shafts. Any other type such as a double pinion type planetary gear mechanism or a differential gear other than the power distribution and integration mechanism 30 may be used as long as the power based on it is input to and output from the remaining shaft. In any case, the correspondence between the main elements of the embodiments and the main elements of the invention described in the column of means for solving the problem is described in the column of means for the embodiment to solve the problem. This is an example for specifically describing the best mode for carrying out the invention, and does not limit the elements of the invention described in the column of means for solving the problem. In other words, the examples are merely specific examples of the invention described in the column for means for solving the problem, and the interpretation of the invention described in the column for means for solving the problem is described in the description of the column. Should be done on the basis.

  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.

  The present invention can be used in a power output apparatus, a vehicle manufacturing industry, and the like.

1 is a schematic configuration diagram of a hybrid vehicle 20 as a vehicle according to an embodiment of the present invention. It is explanatory drawing which shows an example of the relationship between battery temperature Tb and the base value of the input / output restriction | limiting of the battery 50. FIG. It is explanatory drawing which shows an example of the relationship between the remaining capacity SOC of the battery, the input restriction correction coefficient, and the output restriction correction coefficient. It is a flowchart which shows an example of the drive control routine at the time of engine operation performed by hybrid ECU70 of an Example. It is explanatory drawing which shows an example of the map for request | requirement torque setting. It is explanatory drawing which illustrates the correlation curve of the operating line of the engine 22, rotation speed Ne, and torque Te. 3 is an explanatory diagram showing an example of a collinear diagram showing a dynamic relationship between the number of rotations and torque in a rotating element of the power distribution and integration mechanism 30. FIG. It is a time chart which illustrates a mode that the drive control routine at the time of engine operation is performed and the setting state of an intermittent prohibition flag changes. It is a time chart which illustrates a mode that an engine operation time drive control routine is performed and the setting state of an engine stop flag changes. It is a schematic block diagram of the hybrid vehicle 120 which concerns on a modification.

Explanation of symbols

  20, 120 Hybrid vehicle, 22 engine, 24 electronic control unit (engine ECU) for engine, 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, 37 gear mechanism, 38 differential gear, 39a, 39b, 39c, 39d wheel, 40 electronic control unit for motor (motor ECU), 41, 42 inverter, 43, 44 rotational position detection sensor, 50 battery, 52 for battery Electronic control unit (battery ECU), 54 Electric power line, 56 Temperature sensor, 70 Hybrid electronic control unit (hybrid ECU), 72 CPU, 74 ROM, 76 RAM, 80 Ignition Switch, 81 shift lever, 82 shift position sensor, 83 accelerator pedal, 84 an accelerator pedal position sensor, 85 brake pedal, 86 a brake pedal stroke sensor, 87 vehicle speed sensor, MG1, MG2 motor.

Claims (12)

A power output device that outputs power to a drive shaft,
An internal combustion engine capable of outputting power to the drive shaft;
Electric motoring means capable of motoring the internal combustion engine;
An electric motor capable of outputting power to the drive shaft;
Power storage means capable of exchanging electric power with the electric motoring means and the electric motor;
Engine start output limit acquisition means for acquiring a start output limit which is electric power allowed for discharging of the power storage means at the start of the internal combustion engine;
Predicted start output limit acquisition means for acquiring a predicted start output limit that is a predicted value of electric power allowed to discharge the power storage means when starting the internal combustion engine after a predetermined time has elapsed since the present time;
When the operation stop of the internal combustion engine is permitted, it is determined that the operation stop of the internal combustion engine should be prohibited if the acquired output limit for starting is equal to or less than a predetermined operation stop prohibition threshold, and the internal combustion engine When the operation stop is prohibited, the acquired start output limit is not less than a predetermined operation stop permission threshold which is larger than the operation stop prohibition threshold as discharge power, and the acquired predicted start output limit is An operation stop permission determination means for determining that the operation stop of the internal combustion engine should be permitted if the operation stop prohibition threshold is exceeded;
Request torque setting means for setting a request torque that is a torque to be output to the drive shaft;
The internal combustion engine and the electric motoring means are configured such that the internal combustion engine is operated or stopped according to the determination result by the operation stop permission determination means and torque based on the set required torque is output to the drive shaft. And control means for controlling the electric motor;
A power output device comprising: The power output apparatus according to claim 1, wherein
Further comprising output limit setting means for setting an output limit that is electric power allowed to discharge the power storage means based on the state of the power storage means;
The engine start output limit acquisition means acquires the start output limit by adding a predetermined temporarily increased power to the set output limit,
The predicted start output limit acquisition means acquires the predicted start output limit by subtracting a product of the estimated reduction amount per unit time of the output limit and the predetermined time from the acquired start output limit. Power output device. The power output apparatus according to claim 1 or 2,
Requested power setting means for setting requested power required for the drive shaft based on the set requested torque;
When the internal combustion engine is stopped, it is determined that the internal combustion engine should be started when the set required power is equal to or greater than a start determination threshold value obtained by subtracting predetermined power from the acquired start output limit. In addition, when the internal combustion engine is in operation, the set required power is equal to or less than a predetermined stop determination threshold value smaller than the start determination threshold value, and the predetermined power is calculated from the acquired predicted start output limit. Engine start / stop determination means for determining that the internal combustion engine should be stopped if it is below a predicted start determination threshold obtained by subtracting
Further comprising
The control means is configured to start or stop the internal combustion engine in accordance with a determination result by the operation stop permission determination means and a determination result by the engine start / stop determination means, and a torque based on the set required torque is the drive A power output device that controls the internal combustion engine, the electric motoring means, and the electric motor so as to be output to a shaft. In the power output device according to claim 3,
The start determination threshold value is obtained by subtracting at least electric power consumed by motoring of the electric motoring means when starting the internal combustion engine from the acquired start output limit. In the power output device according to any one of claims 1 to 4,
A second electric motor as the electric motoring means capable of inputting / outputting power and exchanging electric power with the power storage means;
The remaining shaft is connected to the three shafts of the output shaft of the internal combustion engine, the rotating shaft of the second electric motor, and the drive shaft, and is based on the power input / output to / from any of these three shafts. Power distribution means to input and output to
A power output device further comprising:   The power output apparatus according to any one of claims 1 to 5, wherein the power storage means is a lithium ion secondary battery.   A vehicle comprising: the power output device according to any one of claims 1 to 6; and drive wheels connected to the drive shaft. An internal combustion engine capable of outputting power to the drive shaft, an electric motoring means capable of motoring the internal combustion engine, an electric motor capable of outputting power to the drive shaft, and the electric motoring means and the motor exchange power. A power output device comprising a possible power storage means,
(A) A starting output limit, which is electric power allowed for discharging the power storage means when starting the internal combustion engine at the present time, and discharging the power storage means when starting the internal combustion engine after a predetermined time has elapsed from the present time. Obtaining a predicted start output limit that is a predicted value of the power to be output;
(B) When the operation stop of the internal combustion engine is permitted, the operation stop of the internal combustion engine should be prohibited if the start output limit acquired in step (a) is less than or equal to a predetermined operation stop prohibition threshold. And when the operation stop of the internal combustion engine is prohibited, the acquired start output limit is equal to or greater than a predetermined operation stop permission threshold that is larger than the operation stop prohibition threshold as discharge power. Determining that the operation stop of the internal combustion engine should be permitted if the predicted start output limit is greater than the operation stop prohibition threshold;
(C) The internal combustion engine is operated or stopped according to the determination result in step (b), and the internal combustion engine is configured to output a torque based on a required torque, which is a torque to be output to the drive shaft, to the drive shaft. Controlling the engine, the electric motoring means and the electric motor;
A method for controlling a power output apparatus including: A power output device that outputs power to a drive shaft,
An internal combustion engine capable of outputting power to the drive shaft;
Electric motoring means capable of motoring the internal combustion engine;
An electric motor capable of outputting power to the drive shaft;
Power storage means capable of exchanging electric power with the electric motoring means and the electric motor;
Predicted start output limit acquisition means for acquiring a predicted start output limit that is a predicted value of electric power allowed to discharge the power storage means when starting the internal combustion engine after a predetermined time has elapsed since the present time;
Request torque setting means for setting a request torque that is a torque to be output to the drive shaft;
Requested power setting means for setting requested power required for the drive shaft based on the set requested torque;
When the internal combustion engine is stopped, it is determined that the internal combustion engine should be started if the set required power is equal to or greater than a predetermined start determination threshold, and when the internal combustion engine is in operation, the setting is performed. The internal combustion engine when the requested power is less than or equal to a predetermined stop determination threshold smaller than the start determination threshold and is less than a predicted start determination threshold obtained by subtracting predetermined power from the acquired predicted start output limit Engine start / stop determination means for determining that the engine should be stopped;
The internal combustion engine and the electric motoring means so that the internal combustion engine is operated or stopped according to the determination result by the engine start / stop determination means and torque based on the set required torque is output to the drive shaft. And control means for controlling the electric motor;
A power output device comprising: The power output apparatus according to claim 9, wherein
Engine start output limit acquisition means for acquiring a start output limit that is electric power allowed to discharge the power storage means at the start of the internal combustion engine;
The start determination threshold value is obtained by subtracting the predetermined power from the acquired start output limit. An internal combustion engine capable of outputting power to the drive shaft, an electric motoring means capable of motoring the internal combustion engine, an electric motor capable of outputting power to the drive shaft, and the electric motoring means and the motor exchange power. A power output device comprising a possible power storage means,
(A) obtaining a predicted start output limit that is a predicted value of electric power allowed to discharge the power storage means when starting the internal combustion engine after a predetermined time has elapsed since the present time;
(B) When the internal combustion engine is stopped, it is determined that the internal combustion engine should be started if the required power based on the required torque that is the torque to be output to the drive shaft is equal to or greater than a predetermined start determination threshold value. When the internal combustion engine is in operation, the required power is equal to or less than a predetermined stop determination threshold value smaller than the start determination threshold value, and a predetermined power is obtained from the predicted start output limit acquired in step (a). Determining that the internal combustion engine should be stopped if it is below a predicted start determination threshold value obtained by subtracting;
(C) The internal combustion engine and the electric motoring are operated so that the internal combustion engine is operated or stopped according to the determination result in step (b) and torque based on the set required torque is output to the drive shaft. Controlling the means and the motor;
A method for controlling a power output apparatus including: In the control method of the power output device according to claim 11,
Step (a) further obtains a starting output limit that is electric power allowed to discharge the power storage means at the time of starting the internal combustion engine at a current time,
The method for controlling a power output apparatus, wherein the start determination threshold value is obtained by subtracting the predetermined power from the acquired start output limit.

Images