JP6421729B2 - Catalyst warm-up method and catalyst warm-up control device for hybrid vehicle - Google Patents

Description

  The present invention relates to a catalyst warm-up method and a catalyst warm-up control device for a hybrid vehicle.

Conventionally, a hybrid vehicle has been proposed that warms up the catalyst efficiently when the catalyst of the engine exhaust system is at a low temperature (see, for example, Patent Document 1).
In this prior art, when the catalyst is warmed up, the engine, which is the driving source of the vehicle, is separated from the first electric motor and travels by the driving force of the first electric motor, and the engine is driven using the second electric motor (starter motor) as the engine load. The catalyst is warmed up.

JP 2014-94691 A

However, in the above-described conventional technology, when the catalyst is warmed up, when the power generated by the second electric motor is charged into the lead acid battery that is a driving power source for the auxiliary machinery, the battery capacity may be insufficient.
Moreover, if a high-capacity high-power battery is newly added to solve the shortage of capacity, the cost increases.

  The present invention has been made paying attention to the above-mentioned problem, and provides a catalyst warm-up method and a catalyst warm-up control device for a hybrid vehicle that can ensure the charge capacity at the time of catalyst warm-up at low cost. With the goal.

In order to achieve the above object, a catalyst warm-up method for a hybrid vehicle according to the present invention includes a drive source for a vehicle including an engine and a first electric motor, a clutch capable of connecting / disconnecting power transmission between the engine and the first electric motor, In a hybrid vehicle having a second electric motor directly connected to the engine and a converter that supplies a stepped down voltage of a high-power battery, the clutch is disengaged and the required driving force is While output is performed by one electric motor, the engine is driven using the second electric motor as a load, and the catalyst is warmed up until a warm-up termination condition is satisfied.
In the catalyst warm-up method for a hybrid vehicle according to the present invention, the power generated by the second motor is charged into the second low-voltage battery while the catalyst is warmed up.
Further, after the catalyst warm-up is completed, the first battery shut-off switch is shut off to disconnect the first low-voltage battery from the auxiliary machinery and the converter, and the converter step-down voltage is set to a lower voltage than the second low-voltage battery. The second low voltage battery is set and discharged by a load of auxiliary equipment until a predetermined chargeable capacity is obtained.

In the present invention, the electric power generated by the second electric motor when the catalyst is warmed up is charged in the second low-voltage battery. And after completion | finish of catalyst warm-up, a 2nd low voltage battery is discharged with the load of auxiliary machinery.
For this reason, the electric power generated with the 2nd electric motor can be used effectively, and it is excellent economically. Moreover, after the catalyst warm-up is completed, the power charged in the second low-voltage battery is discharged, and therefore, a second low-voltage battery having a capacity that allows charging during multiple catalyst warm-ups is used. In comparison, a low-capacity one can be used, and the cost can be suppressed.
In addition, at the time of discharging, the step-down voltage of the converter is set to a voltage lower than that of the second low-voltage battery, and the first low-voltage battery is disconnected from the auxiliary equipment and the converter. For this reason, the second low-voltage battery can be discharged in a short time, and the capacity required for charging at the next catalyst warm-up can be ensured. Therefore, even when a battery having a low battery capacity is used as the second low-voltage battery, charging when repeatedly performing catalyst warm-up is possible.
Therefore, it is possible to ensure the charge capacity when the catalyst is warmed up at low cost.

1 is an overall system diagram showing a hybrid vehicle that implements a catalyst warm-up method for a hybrid vehicle of a first embodiment. FIG. 5 is a shift characteristic diagram for setting a gear ratio in an AT controller that performs shift control of an automatic transmission applied to the hybrid vehicle. It is a figure which shows the EV-HEV selection map used when performing the mode selection process in the integrated controller of the said hybrid vehicle. FIG. 2 is a region diagram showing an electric travel (EV) mode region and a hybrid travel (HEV) mode region of the hybrid vehicle. FIG. 6 is a torque map used in the integrated controller, where (a) is a driving force characteristic line map showing a target steady driving torque characteristic used when obtaining the target steady driving torque, and (b) is when obtaining the assist torque of the motor generator. It is an assist torque map which shows the MG assist torque characteristic to be used. It is a characteristic diagram which shows the target charging / discharging amount characteristic with respect to the battery electrical storage state of the drive torque control apparatus of the said hybrid vehicle. It is a flowchart which shows the flow of a process at the time of catalyst warm-up conditions establishment in the said hybrid vehicle. It is a flowchart which shows the flow of the process at the time of discharge of a 2nd low voltage battery in the said hybrid vehicle. It is explanatory drawing at the time of the electric power generation by the starter motor in the catalyst warming-up of the said hybrid vehicle. It is explanatory drawing at the time of discharge of the 2nd low voltage battery after completion | finish of catalyst warm-up of the said hybrid vehicle. It is a time chart which shows the operation example during catalyst warming-up when the 2nd low voltage battery is chargeable in the said hybrid vehicle. It is a time chart which shows the operation example during catalyst warm-up when the 2nd low voltage battery cannot be charged in the said hybrid vehicle.

  Hereinafter, the best mode for realizing the catalyst warm-up method for a hybrid vehicle of the present invention will be described based on the embodiments shown in the drawings.

(Embodiment 1)
First, the configuration of the catalyst warm-up method and the catalyst warm-up control device for the hybrid vehicle in the first embodiment will be described.
In the description of this configuration, the configuration of the power control device for an electric vehicle in the first embodiment is defined as “power train system configuration”, “control system configuration”, “configuration of integrated controller”, “power system used for catalyst warm-up control”. ”And“ Catalyst warm-up control processing configuration ”.

[Powertrain configuration]
First, the power train system configuration of the hybrid vehicle that requires the catalyst warm-up method for the hybrid vehicle of the first embodiment will be described.
FIG. 1 is an overall system diagram illustrating a hybrid vehicle by rear wheel drive to which the catalyst warm-up method for a hybrid vehicle of the first embodiment is applied.

  As shown in FIG. 1, the hybrid vehicle in the first embodiment includes an engine Eng and a motor generator (first electric motor) MG as a drive source of the vehicle. The hybrid vehicle also includes a first clutch CL1, a second clutch CL2, an automatic transmission AT, and drive wheels RL and RR.

  The engine Eng is a gasoline engine or a diesel engine, and performs engine start control, engine stop control, and throttle valve opening control based on an engine control command from the engine controller 1.

  Further, the engine Eng includes a catalyst 101 in the exhaust system 100. The catalyst 101 sufficiently exhibits its purification ability at a temperature equal to or higher than a preset activation temperature.

  The first clutch CL1 is a clutch interposed between the engine Eng and the motor generator MG. The first clutch CL1 is engaged, including a half-clutch state, by a first clutch control hydraulic pressure generated by a first clutch hydraulic unit (not shown) based on a first clutch control command from the first clutch controller 5. Release is controlled.

  Motor generator MG is a synchronous motor generator in which a permanent magnet is embedded in a rotor and a stator coil is wound around a stator. The motor generator MG is controlled by applying a plurality of alternating currents such as a three-phase alternating current generated by the inverter 3 based on a control command from the motor controller 2. In addition, motor generator MG operates as an electric motor that is rotationally driven in response to the supply of electric power from high-power battery 4. The high-power battery 4 is a battery for driving the motor generator MG and is, for example, a high-voltage power supply of several hundred volts.

  Furthermore, when the rotor receives rotational energy from the engine Eng or the drive wheels RL and RR, the motor generator MG functions as a generator that generates electromotive force at both ends of the stator coil, and may charge the high-power battery 4. it can. The rotor of motor generator MG is connected to the transmission input shaft of automatic transmission AT via a damper.

  The second clutch CL2 is a clutch interposed between the motor generator MG and the drive wheels RL and RR. The second clutch CL2 is controlled for engagement / release including slip engagement and slip release by a control hydraulic pressure generated by a second clutch hydraulic unit (not shown) based on a second clutch control command from the AT controller 7. The As the second clutch CL2, for example, a wet multi-plate clutch or a wet multi-plate brake capable of continuously controlling the oil flow rate and hydraulic pressure with a proportional solenoid is used.

  The automatic transmission AT is a stepped transmission that automatically switches stepped gears such as five forward speeds and one reverse speed according to the vehicle speed, the accelerator opening degree, and the like. Therefore, the second clutch CL2 is not newly added as a dedicated clutch, but is an optimum clutch arranged in the torque transmission path among a plurality of frictional engagement elements that are engaged at each gear stage of the automatic transmission AT. Or choose a brake. Note that the second clutch CL2 does not use the frictional engagement element of the automatic transmission AT, and uses a dedicated clutch between the motor generator MG and the automatic transmission AT or between the automatic transmission AT and the drive wheels RL and RR. You may interpose between.

[Control system configuration]
Next, the control system of the hybrid vehicle will be described.
The hybrid vehicle control system in the first embodiment includes an engine controller 1, a motor controller 2, an inverter 3, a high-power battery 4, an AT controller 7, and an integrated controller 10. The engine controller 1, the motor controller 2, the first clutch controller 5, the AT controller 7, and the integrated controller 10 are connected via CAN communication lines (not shown) that can exchange information with each other. .

  The engine controller 1 inputs the engine speed information from the engine speed sensor 12, the target engine torque command from the integrated controller 10, and other necessary information. Then, a command for controlling the engine operating point (Ne, Te) is output to the throttle valve actuator of the engine Eng.

  The motor controller 2 inputs information from the resolver 13 that detects the rotor rotational position of the motor generator MG, a target MG torque command and a target MG rotational speed command from the integrated controller 10, and other necessary information. Then, a command for controlling the motor operating point (Nm, Tm) of motor generator MG is output to inverter 3. The motor controller 2 monitors the battery SOC that represents the charge capacity of the high-power battery 4, and this battery SOC information is used as control information for the motor generator MG and via a CAN communication line (not shown). To the integrated controller 10.

  The first clutch controller 5 inputs sensor information from a first clutch stroke sensor 15 that detects a stroke position of a hydraulic actuator (not shown), a target CL1 torque command from the integrated controller 10, and other necessary information. Then, a command for controlling the engagement / release of the first clutch CL1 is output to a first clutch hydraulic unit (not shown).

The AT controller 7 inputs information from an accelerator opening sensor 16, a vehicle speed sensor 17, and other sensors / switches 18 (transmission input rotation speed sensor, inhibitor switch, etc.). Then, when traveling with the D range selected, a control command for retrieving the optimum gear position by searching for the position where the operating point determined by the accelerator opening APO and the vehicle speed VSP exists on the shift map is obtained. Output to automatic transmission AT. In addition to the automatic shift control, the AT controller 7 gives a command for controlling the engagement / release of the second clutch CL2 to the second clutch hydraulic unit (not shown) when the target CL2 torque command is input from the integrated controller 10. The second clutch control to be output to is performed.
The shift map is a map in which an upshift line and a downshift line are written according to the accelerator opening APO and the vehicle speed VSP, and an example is shown in FIG.

[Configuration of integrated controller]
The integrated controller 10 manages the energy consumption of the entire vehicle and has a function for running the vehicle with the highest efficiency. That is, the integrated controller 10 inputs necessary information from the motor rotation speed sensor 19 for detecting the motor rotation speed Nm and other sensors / switches 18 and information via a CAN communication line (not shown). Then, a target engine torque command is output to the engine controller 1, a target MG torque command and a target MG rotation speed command are output to the motor controller 2, a target CL1 torque command is output to the first clutch controller 5, and a target CL2 torque command is output to the AT controller 7.

  FIG. 3 is a diagram showing an EV-HEV selection map used when mode selection processing is performed in the integrated controller 10. Thus, the integrated controller 10 determines the travel mode based on the accelerator opening APO and the vehicle speed VSP. Then, the target engine torque command, the target MG torque command, the target MG rotational speed command, the target CL1 torque command, and the target CL2 torque command are output according to the determined travel mode.

  Note that the engine start / stop line map set by the accelerator opening APO set for each vehicle speed shown in FIG. 4 is used for switching the travel mode described above, and the engine start / stop line depends on the battery SOC. And change. That is, the engine start line and the engine stop line decrease in a direction in which the accelerator opening decreases as the battery SOC decreases.

The engine is normally started by the driving force of the motor generator MG that is engaged with the electric power of the high-power battery 4 by engaging the first clutch CL1.
Further, when cold or when the battery SOC of the high-power battery 4 is lowered, the starter motor (second electric motor) SSG directly connected to the engine Eng is driven.
The starter motor SSG is driven as a motor by low voltage power (12 V) of a first low voltage battery 31 described later, and can be driven as a generator by an input from the engine Eng.

  The integrated controller 10 determines that the target engine torque command and the target MG torque command are based on the accelerator opening APO based on the target steady drive torque map shown in FIG. 5A and the MG assist torque map shown in FIG. And the vehicle speed VSP (transmission input rotation speed).

  Furthermore, the integrated controller 10 calculates a target power generation output based on the battery SOC using the traveling power generation request output map shown in FIG.

  Then, the integrated controller 10 inputs the accelerator opening APO, the target drive torque tFoO, the MG assist torque, the target mode, the vehicle speed VSP, and the target charge / discharge power (required power generation output) tP. Furthermore, from these input information, using these as the operating point reaching target, a transient target engine torque, target MG torque, target MG rotation speed, target CL1 torque, target CL2 torque, and target gear ratio are calculated. These calculation results are output to the controllers 1, 2, 5, and 7 via the CAN communication line.

[Configuration of power system used for catalyst warm-up control]
The integrated controller 10 executes catalyst warm-up control as necessary based on the catalyst temperature detected by the catalyst temperature sensor 14.
First, the structure of the electric power system used for this catalyst warm-up control will be described.

  Auxiliary machinery 20 is mounted on the hybrid vehicle. Examples of the auxiliary machines include a lighting device, an audio device, a wiper device, an electric steering device, an air conditioner, a meter device, a braking control device, and the like.

  The auxiliary machines 20 and the starter motor SSG described above are connected to the first low-voltage battery 31 via the low-voltage system circuit 21. Specifically, the first low-voltage battery 31 uses a 12V lead acid battery, and the low-voltage circuit 21 is supplied with low-voltage power of about 12V.

  Further, a DC-DC converter 40 is connected to the low voltage system circuit 21. The DC-DC converter 40 steps down the high voltage power (several hundred volts) of the high voltage battery 4 and supplies it to the low voltage system circuit 21. Note that the DC-DC converter 40 steps down to a voltage (about 13 V) slightly higher than the voltage of the low voltage system circuit 21 during normal times when catalyst warm-up control is not performed.

  Further, a second low voltage battery 32 is connected to the low voltage system circuit 21 in parallel with the first low voltage battery 31. As this 2nd low voltage battery 32, the 12V lithium ion battery with low internal resistance which can repeat charging / discharging in a short time is used. The second low voltage battery 32 can drive the starter motor SSG.

  The low voltage system circuit 21 includes a first battery cutoff relay switch 51, a second battery cutoff relay switch 52, and an energization control element 53. The energization states of the relay switches 51 and 52 and the energization control element 53 are switched by the battery control unit 50.

  The first battery cutoff relay switch 51 can connect and disconnect the first low-voltage battery 31 with respect to the low-voltage system circuit 21 (auxiliary machinery 20 and DC-DC converter 40), and is normally (when not energized). Is a closed switch.

  The second battery cutoff relay switch 52 can connect and disconnect the second low voltage battery 32 to and from the low voltage system circuit 21 (auxiliary machinery 20 and DC-DC converter 40), and is normally (when not energized). Is an open switch.

  The energization control element 53 is an element (MOS) that controls the amount of power supplied from the starter motor SSG and the second low voltage battery 32 side to the first low voltage battery 31 and the auxiliary machinery 20.

[Catalyst warm-up control processing configuration]
Next, the flow of the catalyst warm-up control process will be described with reference to FIGS.
7 and 8 are flowcharts showing the flow of the catalyst warm-up control process executed in the integrated controller and the battery controller.
FIG. 7 shows a flow of processing during catalyst warm-up that is executed when the warm-up condition of the catalyst 101 is satisfied. FIG. 8 shows a flow of processing when a warm-up termination condition is satisfied and a discharge processing described later is executed.

  Here, the catalyst warm-up condition is that the catalyst warm-up condition is established when the catalyst temperature detected by the catalyst temperature sensor 14 is less than or equal to the preset activity determination threshold. judge. The activity determination threshold is set to a value at which the catalyst 101 can exhibit a desired purification capacity at a temperature higher than that.

In step S101 that proceeds when the catalyst warm-up condition is satisfied, a process during catalyst warm-up is executed.
The catalyst warm-up process starts at the same time as the catalyst warm-up condition is satisfied. The catalyst warm-up process first runs with the driving force of the motor generator MG, and the engine Eng warms up the catalyst 101. Is driven at a constant rotational speed and constant torque required for the operation.

Therefore, first clutch CL1 is released, and engine Eng and motor generator MG are disconnected.
The target motor torque as a command value for motor generator MG is set to a value corresponding to the driver request drive torque (target steady drive torque).
In addition, the starter motor SSG generates power so as to provide a load for warming up the engine Eng.

Furthermore, in the first embodiment, the power generated by the starter motor SSG in the catalyst warm-up process is charged in the second low voltage battery 32. Therefore, the 2nd battery interruption | blocking relay switch 52 is closed and the 2nd low voltage battery 32 and the low voltage system circuit 21 are connected.
The energization control element 53 supplies a part of the generated power of the starter motor SSG to the auxiliary machinery 20 side and directly consumes power by the auxiliary machinery 20.

FIG. 9 shows a state of energization when this catalyst warm-up process is executed.
The electric power generated by the starter motor SSG is supplied and charged to the second low-voltage battery 32 via the closed second battery cutoff relay switch 52 as indicated by an arrow GV1. At this time, since the lithium ion battery having a low internal resistance value is used as the second low voltage battery 32, it can be charged efficiently in a short time.
A part of the generated power is supplied to the low voltage system circuit 21 via the energization control element 53 and directly consumed by the auxiliary machinery 20 as indicated by the dotted arrow GV2.

  Further, in the catalyst warm-up process, the DC-DC converter 40 steps down the power of the high-power battery 4 and supplies it to the low-voltage system circuit 21, and the power is supplied to the auxiliary machinery 20 as indicated by arrows DV1 and DV2. And supplied to the first low-voltage battery 31.

  Returning to FIG. 7, in step S <b> 102, which proceeds after the execution of the catalyst warm-up process in step S <b> 101, it is determined whether or not the warm-up end condition is satisfied. If the warm-up end condition is satisfied, the process proceeds to step S <b> 103. In this case, the process proceeds to step S107.

  Note that the warm-up termination condition is when the catalyst temperature is higher than the aforementioned activity determination threshold.

In step S103, which proceeds when the warm-up termination condition is satisfied, the catalyst warm-up process is terminated.
In this case, power generation by the starter motor SSG is first terminated.
Further, the driving of the engine Eng and the engagement and release of the first clutch CL1 are controlled according to the accelerator opening APO at that time, the traveling mode corresponding to the vehicle speed VSP, and the driver requested torque.

In step S107 that proceeds when the warm-up termination condition is not satisfied in step S102, it is determined whether or not the chargeable capacity of the second low-voltage battery 32 is equal to or less than the charging termination threshold. The charging end threshold is a value indicating that the second low voltage battery 32 is in a state close to full charge, and for example, a value indicating the vicinity of 90% of full charge is used.
If the chargeable capacity is larger than the charging end threshold value in step S107, the process returns to step S101, the catalyst warm-up process is executed, and the catalyst 101 is kept warmed up.

  On the other hand, when the chargeable capacity is equal to or less than the charging end threshold value in step S107 and the second low voltage battery 32 cannot be continuously charged, the process proceeds to step S108.

In step S108, the warm-up of the catalyst 101 is continued with the motor generator MG as a load instead of the starter motor SSG. That is, power generation by the starter motor SSG is stopped, the first clutch CL1 is engaged, and a load is applied to the engine Eng by the motor generator MG. Further, at this time, the engine torque is kept constant by being increased as compared with the power generation by the starter motor SSG. Note that the electric power generated by the motor generator MG is charged in the high-power battery 4.
Thereby, the power generation by the starter motor SSG and the charging of the second low voltage battery 32 are stopped, but the warming-up of the catalyst 101 can be continued.

  In step S109 following step S108, it is determined whether or not the warm-up end condition is satisfied. If the warm-up end condition is satisfied, the process proceeds to step S103. If the warm-up end condition is not satisfied, the process returns to step S107. Note that the warm-up end condition determination in step S109 is the same as in step S102.

The processing after step S104 following step S103 for ending the catalyst warm-up is processing for determining whether to discharge the second low-voltage battery 32 or not.
First, in step S104, it is determined whether or not there is a voltage increase request. If there is a voltage increase request, the process proceeds to step S105 to wait for discharge (standby). On the other hand, if there is no voltage increase request in step S104, the process proceeds to step S106, and the discharge process of the second low voltage battery 32 is executed.

  Here, the voltage increase request is a drive request by an auxiliary device that requires a power supply voltage of a predetermined level or higher in the auxiliary machinery 20. Examples of such auxiliary machines that require a power supply voltage exceeding a predetermined level include a wiper device, a headlight, an electric steering, and a braking device.

  The standby process in step S105 waits for the execution of a discharge process in step S106, which will be described later. During this standby, the process returns to step S104, and the determination as to whether or not there is a voltage increase request is repeated. Then, the standby is finished and the process proceeds to step S106.

Next, details of the discharge process executed in step S106 will be described with reference to the flowchart of FIG.
First, in step S201, a discharging process is executed, and the process proceeds to step S202.
In the discharging process, the first battery cutoff relay switch 51 is opened to set the circuit cutoff state, and the first low-voltage battery 31 is changed to the low-voltage system circuit 21 (auxiliaries 20, DC-DC converter 40, second low-voltage battery). 32).

  Further, in the discharging process, the step-down voltage of the DC-DC converter 40 is lowered to a voltage lower than the normal step-down voltage and lower than the voltage of the second low-voltage battery 32. For example, during normal discharge, the high voltage from the high-power battery 4 is stepped down to about 13V, and during this discharge process, the voltage is stepped down to around 12V.

In the energization control element 53, the energization from the second low-voltage battery 32 is allowed to pass to the low-voltage system circuit 21 side without being restricted, and the second battery cutoff relay switch 52 is closed. Thereby, as indicated by an arrow GV3 in FIG. 10, the power charged in the second low-voltage battery 32 is discharged by the load of the auxiliary machinery 20. At this time, since the lithium ion battery having a low internal resistance value is used for the second low voltage battery 32, the battery can be discharged in a short time.
Further, since the step-down voltage of the DC-DC converter 40 is set lower than normal, the second low-voltage battery 32 may be discharged to a voltage lower than the voltage used in the normal low-voltage circuit 21. it can.

  Next, in step S202, it is determined whether there is a catalyst warm-up request. And when there exists a catalyst warm-up request | requirement, it progresses to step S205, and when there is no catalyst warm-up request | requirement, it progresses to step S203. For example, if the engine Eng is stopped and the vehicle travels in the EV mode after the catalyst 101 is warmed up, the catalyst temperature may decrease during the discharge.

In step S203 which proceeds when there is no catalyst warm-up request, the process proceeds to step S204 while maintaining the process during discharge (KEEP).
Note that, during the maintenance of the in-discharge process (KEEP), when a request for increasing the voltage of the power consumption is made from the auxiliary equipment 20 described in step S104, the step-down voltage of the DC-DC converter 40 is set to the normal level. Return to value. Further, if the request for increasing the power supply voltage (voltage increase request) is eliminated during the maintenance of the process during discharge, the step-down voltage of the DC-DC converter 40 is lower than the value during discharge (second low-voltage battery voltage). Value).

  In step S204, it is determined whether or not the charge capacity of the second low-voltage battery 32 has decreased to a preset discharge end determination value. And when the charge capacity of the 2nd low voltage battery 32 falls to the discharge end judgment value, the discharge processing is ended.

At the end of this discharge process, the first battery cutoff relay switch 51 is closed, and the first low-voltage battery 31 is connected to the low-voltage system circuit 21 (auxiliary device 20 and DC-DC converter 40).
Further, the step-down voltage of the DC-DC converter 40 is returned to a normal value (for example, 13 V).

  Next, in step S205 which proceeds when there is a catalyst warm-up request in step S202, it is determined whether or not the allowable charge amount of the second low voltage battery 32 is larger than the chargeable determination value. If the allowable charge amount is larger than the chargeable determination value, the process proceeds to step S206. If the chargeable amount is equal to or less than the chargeable determination value, the process proceeds to step S203, and the discharging process is continued.

Here, the charge allowable amount of the second low-voltage battery 32 is a charge amount from the current charge amount to full charge.
The chargeable determination value is a value for determining whether or not the second low voltage battery 32 can be charged when power is generated by the starter motor SSG by the warm-up process of the catalyst 101. The chargeable determination value is, for example, a high value in the range of 70 to 90% of the maximum charge amount, and preferably about 90%.

  When the allowable charge amount of the second low voltage battery 32 is equal to or less than the chargeable determination value, the process proceeds to step S203, and the discharging process is continued. Further, in this case, although not shown, it is preferable to perform the processing of step S108 and step S109 in parallel, drive the engine Eng with the motor generator MG as a load, and warm up the catalyst 101.

(Operation of Embodiment 1)
Next, the operation of the first embodiment will be described based on the time charts of FIGS.
FIG. 11 shows an operation example when the catalyst 101 is warmed up by executing the catalyst warm-up process (step S101 in FIG. 7).
This operation example shows an operation when the ignition switch (not shown) is turned on at t11 to start the catalyst warm-up process, and the driver performs the start acceleration operation from time t12.

  In this case, when the ignition switch (not shown) at t11 is turned on, the system is activated, and based on the temperature detected by the catalyst temperature sensor 14, it is determined that there is a catalyst warm-up request, and catalyst warm-up is started. Execute middle processing.

  That is, as shown in the figure, the first clutch CL1 is released, the engine Eng is maintained at a rotation speed suitable for preset catalyst warm-up, a constant load is applied to the engine Eng by the starter motor SSG, and the engine torque is reduced to the catalyst A constant torque suitable for warming up 101 is maintained.

  Then, the electric power generated by driving the starter motor SSG as a load charges the second low-voltage battery 32 as shown by an arrow GV1 in FIG. During the warm-up of the catalyst, the second battery cutoff relay switch 52 is closed and the energization amount of the energization control element 53 is reduced, so that the power generated by the starter motor SSG is smoothly charged to the second low-voltage battery 32. can do.

In addition, by directly consuming a part of the electric power being charged by the auxiliary machinery 20, it is possible to reduce the charge / discharge amount in the second low voltage battery 32 with respect to the amount of power generated by warming up the catalyst 101.
This shortens the discharge time of the second low-voltage battery 32, which will be described later, enables more reliable discharge, increases the certainty of securing the charge allowance for the next charge, and also the second low-voltage battery. The durability of the battery 32 can be improved.

  Next, when the driver performs the start acceleration operation from time t12, the first clutch CL1 is released as described above, and therefore the motor generator MG is driven according to the driver request torque to start.

Then, acceleration is performed while shifting the automatic transmission AT according to the vehicle speed VSP, and the vehicle speed VSP is increased according to the driver's acceleration operation.
Even during this travel, until the catalyst 101 rises to a predetermined temperature and the warm-up end condition is satisfied, the engine Eng is driven at a constant rotational speed and constant torque, and the starter motor SSG is constant for catalyst warm-up. Power is generated with torque.

The electric power charged in the second low-voltage battery 32 in this way is immediately discharged by the load of the auxiliary machinery 20 when the catalyst 101 rises to a predetermined temperature and the warm-up termination condition is satisfied (FIG. 10).
Therefore, it is possible to reliably perform charging at the time of executing the next catalyst warm-up process.
Further, since the power charged in the second low-voltage battery 32 by the catalyst warm-up process is immediately discharged, the charge capacity of the second low-voltage battery 32 is obtained by a single catalyst warm-up process. What is necessary is just to be able to charge the amount of power generation. Therefore, as the second low-voltage battery 32, an inexpensive battery having a low capacity can be used as compared with a battery having a capacity capable of being charged a plurality of times.

  Furthermore, when the second low voltage battery 32 is discharged, the first battery cutoff relay switch 51 is opened to disconnect the first low voltage battery 31 from the low voltage system circuit 21. For this reason, compared with the case where the 1st low voltage battery 31 is connected to the low voltage system circuit 21, the 2nd low voltage battery 32 can be discharged in a short time.

  In addition, at this time, since the step-down voltage of the DC-DC converter 40 is lowered as compared with the normal time, the second low-voltage battery 32 can also be discharged in a short time. Moreover, when the power demand by the auxiliary machinery 20 becomes high, not only the power of the second low-voltage battery 32 but also the power of the high-power battery 4 can be supplied by the DC-DC converter 40. There is no possibility of adversely affecting the driving of 20.

Next, an operation example shown in the time chart of FIG. 12 will be described.
In this operation example, the chargeable capacity of the second low-voltage battery 32 is lower than the charging end threshold at time t21 when the catalyst warm-up request is generated, and the second low-voltage battery 32 is charged by the power generation of the starter motor SSG. Shows what happens when you can't.

In this case, after the catalyst warm-up condition is satisfied, the process immediately proceeds to step S108, and the engine Eng is driven with the motor generator MG as a load.
That is, the engine Eng is driven, the first clutch CL1 is engaged, and a constant load is applied to the engine Eng by the motor generator MG to generate electric power (steps S107 → S108). The power generation at this time is supplied from the inverter 3 to the high-power battery 4 and charged.

  Further, from the time t21 to the time t22 when the driver starts the start acceleration operation, the second clutch CL2 is released to keep the vehicle stopped.

  Thereafter, when the driver starts the start acceleration operation at time t22, the second clutch CL2 is engaged and started in accordance with the start acceleration operation while keeping the engine torque constant.

Further, as the driver request torque increases, the load by the motor generator MG is reduced. When the driver request torque is insufficient with a constant engine torque, the motor generator MG is driven as an electric motor to compensate for the shortage.
Therefore, even when the second low-voltage battery 32 cannot be charged, the engine Eng can be driven at a constant rotation speed and a constant torque, and the catalyst 101 can be warmed up.

(Effect of Embodiment 1)
The effects of the catalyst warm-up method for the hybrid vehicle of the first embodiment are listed below.
1) The catalyst warm-up method for the hybrid vehicle in the first embodiment is as follows:
A vehicle drive source including a motor generator MG as a first electric motor driven by the engine Eng and the high-power battery 4;
A first clutch CL1 capable of connecting / disconnecting power transmission between the engine Eng and the motor generator MG;
A starter motor SSG as a second electric motor directly connected to the engine Eng;
A DC-DC converter 40 connected to the vehicle auxiliary equipment 20 and the first low-voltage battery 31 to supply the high-voltage battery 4 with a reduced voltage;
In a hybrid vehicle equipped with
In the hybrid vehicle, the second low-voltage battery 32 connected to the auxiliary machinery 20 and the DC-DC converter 40 in parallel with the first low-voltage battery 31, the first low-voltage battery 31, the auxiliary machinery 20 and the DC- A first battery cutoff relay switch 51 that can be connected to and disconnected from the DC converter 40,
Based on the establishment of the warm-up condition of the catalyst 101 provided in the exhaust system 100 of the engine Eng, the first clutch CL1 is released and the driver requested torque is output by the motor generator MG. The catalyst 101 is warmed up until it is driven and the warm-up termination condition is satisfied,
During the warm-up of the catalyst 101, the second low-voltage battery 32 is charged with the power generated by the starter motor SSG,
After the catalyst warm-up is completed, the first battery cutoff relay switch 51 is cut off to disconnect the first low voltage battery 31 from the low voltage system circuit 21, and the step-down voltage of the DC-DC converter 40 is supplied from the second low voltage battery 32. Is set to a low voltage, and the second low voltage battery 32 is discharged by the load of the auxiliary machinery 20 until a predetermined chargeable capacity is obtained.
Thus, since the electric power generated by the starter motor SSG during the catalyst warm-up is charged to the second low voltage battery 32 of the low voltage system (about 12V) used by the auxiliary machinery 20, the second low voltage battery 32 is charged. It is not necessary to step down the voltage to a voltage that can be consumed by the auxiliary machinery 20 during the discharge. For this reason, efficient charging / discharging can be performed without causing an electrical loss due to step-down, and the electric power can be effectively used.
In addition, since the electric power charged in the second low voltage battery 32 is discharged after the warm-up of the catalyst, the second low voltage battery 32 having a smaller capacity than that in which charging is performed a plurality of times is used. The cost can be reduced.
Moreover, when the second low-voltage battery 32 is discharged, the first battery cutoff relay switch 51 is opened to disconnect the first low-voltage battery 31 from the low-voltage circuit 21 and the step-down voltage of the DC-DC converter 40 is changed to the second voltage drop. The voltage is lower than that of the low voltage battery 32.
For this reason, it is possible to discharge the second low-voltage battery 32 to a voltage lower than that of the first low-voltage battery 31. Therefore, as compared with the case where the first low-voltage battery 31 is not disconnected, it is possible to secure a larger charge capacity of the second low-voltage battery 32 at the next catalyst warm-up.
In addition, by disconnecting the first low-voltage battery 31 as described above, the discharge rate of the second low-voltage battery 32 can be increased as compared with the case where the disconnection is not performed. For this reason, the second low-voltage battery 32 can be discharged in a short time, and the necessary charge capacity can be secured early. As a result, when the next catalyst warm-up condition is satisfied, it is possible to suppress the occurrence of a problem that the catalyst cannot be warmed up due to the lack of chargeable capacity.

2) The catalyst warm-up method for the hybrid vehicle in the first embodiment is as follows:
A lithium ion battery is used as the second low voltage battery 32 used for charging and discharging during catalyst warm-up.
Therefore, since the lithium ion battery has a small internal resistance and can be charged with a large current, a high load can be continuously applied to the engine Eng during catalyst warm-up even at a low voltage. Moreover, even if it charges / discharges repeatedly, it is hard to deteriorate and it is excellent in durability.

3) The catalyst warm-up method for the hybrid vehicle of the first embodiment is as follows:
The disconnection of the first low-voltage battery 31, the setting of the step-down voltage of the DC-DC converter 40, and the discharge of the second low-voltage battery 32 after the catalyst warm-up end are executed simultaneously with the establishment of the warm-up end condition. Features.
As described above, the discharge of the second low-voltage battery 32 is immediately performed as soon as the warm-up termination condition is satisfied, so that the discharge can be terminated early and prepared for the next catalyst warm-up. Thereby, when the catalyst warm-up condition is satisfied for the next time, it is possible to suppress the occurrence of a problem that the catalyst cannot be warmed up due to the shortage of the chargeable capacity of the second low-voltage battery 32.

4) The catalyst warm-up method for the hybrid vehicle in the first embodiment is as follows:
A part of the electric power generated by the starter motor SSG during the catalyst warm-up is supplied to the auxiliary machinery 20 through the energization control element 53 together with the charging of the second low-voltage battery 32.
Thus, by consuming a part of the generated power directly by the auxiliary machinery 20, the charge / discharge loss due to the second low voltage battery 32 can be reduced and the charge amount of the second low voltage battery 32 can be reduced. The discharge time can be shortened.
Thereby, when the next catalyst warm-up condition is established, it is possible to further suppress the occurrence of a problem that the catalyst cannot be warmed up due to the lack of chargeable capacity of the second low-voltage battery 32.

5) The catalyst warm-up method for the hybrid vehicle of the first embodiment is as follows:
When there is a high voltage supply request from the auxiliary machinery 20 during the discharge of the second low voltage battery 32 after the catalyst warm-up is completed, the DC-DC converter 40 set lower than the voltage of the second low voltage battery 32. The step-down voltage is increased in response to a high voltage supply request.
Therefore, in response to a high voltage power request from the auxiliary machinery 20 having a high power supply voltage, it is possible to reliably supply power according to the request.

6) The catalyst warm-up method for the hybrid vehicle of the first embodiment is as follows:
When the chargeable capacity of the second low-voltage battery 32 is insufficient during catalyst warm-up, the catalyst warm-up is performed using the motor generator MG as a load by engaging the first clutch CL1 instead of the starter motor SSG. To do.
Therefore, even if the chargeable capacity of the second low-voltage battery 32 is insufficient and the catalyst warm-up operation cannot be performed in the state where the first clutch CL1 is disconnected, the catalyst warm-up operation is possible, so the exhaust gas purification performance is deteriorated. Can be suppressed.

7) The catalyst warm-up device for the hybrid vehicle of the first embodiment is
A motor generator MG as a first electric motor driven by an engine Eng and a high-power battery 4 as a drive source of the vehicle;
A motor generator MG as a first electric motor driven by an engine Eng and a high-power battery 4 as a drive source of the vehicle;
A first clutch CL1 capable of connecting / disconnecting power transmission between the engine Eng and the motor generator MG;
A starter motor SSG as a second electric motor directly connected to the engine Eng;
A DC-DC converter 40 connected to the vehicle auxiliary equipment 20 and the first low-voltage battery 31 to supply the high-voltage battery 4 with a reduced voltage;
Based on the establishment of the warm-up condition of the catalyst 101 provided in the exhaust system 100 of the engine Eng, the first clutch CL1 is released and the required driving force is output by the motor generator MG, while the engine Eng is operated with the starter motor SSG as a load. An integrated controller 10 and a battery control unit 50 that are driven to warm up the catalyst 101 until a warm-up termination condition is satisfied;
In a warm-up control device for a hybrid vehicle equipped with
In the vehicle, the second low-voltage battery 32 and the first low-voltage battery 31 connected to the auxiliary machinery 20 and the DC-DC converter 40 in parallel with the first low-voltage battery 31 are connected to the auxiliary machinery 20 and the DC-DC. A first battery cutoff relay switch 51 that can be connected to and disconnected from the converter 40, and
The integrated controller 10 and the battery control unit 50 are
During the warm-up of the catalyst 101, the second low-voltage battery 32 is charged with the power generated by the starter motor SSG,
After the catalyst warm-up is completed, the first battery cut-off relay switch 51 is cut off to disconnect the first low-voltage battery 31, and the step-down voltage of the DC-DC converter 40 is set to a voltage lower than that of the second low-voltage battery 32. The second low voltage battery 32 is discharged by the load of the auxiliary machinery 20 until a predetermined chargeable capacity is obtained.
Therefore, the effect described in 1) above is achieved.
Further, the starter motor SSG and the second low voltage battery 32 can be shared with an existing idle stop system, and the cost can be reduced by sharing.

  As described above, the catalyst warm-up method and the catalyst warm-up control device for a hybrid vehicle according to the present invention have been described based on the embodiment. However, the specific configuration is not limited to this embodiment, and Design changes and additions are permitted without departing from the spirit of the invention according to each claim of the scope.

For example, in the embodiment, an example in which a lithium ion battery is used as the second low voltage battery has been described. However, the present invention is not limited to this, and other batteries such as a lithium nickel metal hydride battery can be used. In short, the second low-voltage battery may be any battery that has a low internal resistance and can be repeatedly charged and discharged without significant deterioration.
In the first embodiment, an example in which a part of the generated power is consumed by the auxiliary machinery during power generation by the starter motor has been described. However, the second low-voltage battery may be charged with all of the generated power. In this case, an element for controlling the energization amount is not necessary, and it can be simply replaced with an open / close switch. Further, the second battery cutoff relay switch can be omitted.

4 High Power Battery 10 Integrated Controller 20 Auxiliary Equipment 31 First Low Voltage Battery 32 Second Low Voltage Battery 40 DC-DC Converter 50 Battery Control Unit 51 First Battery Disconnect Relay Switch 100 Exhaust System 101 Catalyst CL1 First Clutch Eng Engine MG Motor generator (first electric motor)
SSG starter motor (second electric motor)

Claims (7)

A vehicle drive source including a first electric motor driven by an engine and a high-power battery;
A clutch capable of connecting / disconnecting power transmission between the engine and the first electric motor;
A second electric motor directly connected to the engine;
A converter that steps down the voltage of the high-power battery and supplies it to the vehicle auxiliary equipment and the first low-voltage battery;
In a hybrid vehicle equipped with
The hybrid vehicle includes a second low-voltage battery connected to the auxiliary devices and the converter in parallel with the first low-voltage battery, and the first low-voltage battery to the auxiliary devices and the converter. A first battery cutoff switch that can be connected and disconnected,
When the warm-up condition of the catalyst provided in the exhaust system of the engine is satisfied, the clutch is released and the required driving force is output by the first motor, while the engine is driven with the second motor as a load. Warm up the catalyst until the warm-up termination condition is met,
During warming up of the catalyst, the second low voltage battery is charged with the power generated by the second electric motor,
After the catalyst warm-up is completed, the first battery cutoff switch is shut off to disconnect the first low-voltage battery, the step-down voltage of the converter is set to a voltage lower than that of the second low-voltage battery, and the first (2) A catalyst warm-up method for a hybrid vehicle, wherein the low-voltage battery is discharged by a load of the auxiliary equipment until a predetermined chargeable capacity is obtained. The catalyst warm-up method for a hybrid vehicle according to claim 1,
A method for warming up a catalyst for a hybrid vehicle, wherein a lithium ion battery is used as the second low-voltage battery used for charging and discharging when the catalyst is warmed up. In the catalyst warm-up method of the hybrid vehicle according to claim 1 or 2,
After the catalyst warm-up is completed, the first low-voltage battery is disconnected, the step-down voltage of the converter is set, and the second low-voltage battery is discharged simultaneously with the establishment of the warm-up termination condition. A catalyst warm-up method for a hybrid vehicle. In the catalyst warm-up method of the hybrid vehicle of any one of Claims 1-3,
A method for warming up a catalyst for a hybrid vehicle, comprising supplying a part of electric power generated by the second electric motor to the auxiliary equipment during warming up of the catalyst. In the catalyst warm-up method for a hybrid vehicle according to any one of claims 1 to 4,
When there is a high voltage supply request from the auxiliary equipment during the discharge of the second low voltage battery after the catalyst warm-up is completed, the voltage of the converter is set lower than the voltage of the second low voltage battery. A method for warming up a catalyst for a hybrid vehicle, wherein the voltage is increased according to the high voltage supply request. The catalyst warm-up method for a hybrid vehicle according to any one of claims 1 to 5,
When the chargeable capacity of the second low-voltage battery is insufficient when the catalyst is warmed up, the clutch is engaged, and the catalyst is warmed up using the first motor as a load instead of the second motor. A catalyst warm-up method for a hybrid vehicle. A first electric motor driven by an engine and a high-power battery as a vehicle drive source;
A clutch capable of connecting / disconnecting power transmission between the engine and the first electric motor;
A second electric motor directly connected to the engine;
A converter that steps down the voltage of the high-power battery and supplies it to the vehicle auxiliary equipment and the first low-voltage battery;
Based on the establishment of a warm-up condition of a catalyst provided in the exhaust system of the engine, the clutch is released and the required driving force is output by the first motor, while the engine is driven with the second motor as a load. A controller for warming up the catalyst until a warm-up termination condition is satisfied,
In a warm-up control device for a hybrid vehicle equipped with
In the hybrid vehicle, a second low voltage battery connected to the auxiliary devices and the converter in parallel with the first low voltage battery, and the first low voltage battery are connected to the auxiliary devices and the converter. A first battery disconnect switch that can be connected and disconnected,
The controller is
During warming up of the catalyst, the second low voltage battery is charged with the power generated by the second electric motor,
After the catalyst warm-up is completed, the first battery cutoff switch is shut off to disconnect the first low-voltage battery, the step-down voltage of the converter is set to a voltage lower than that of the second low-voltage battery, and the first (2) A catalyst warm-up control device for a hybrid vehicle, wherein a process of discharging the low-voltage battery by a load of the auxiliary machinery is performed until a predetermined chargeable capacity is obtained.