JP2008230409A - Hybrid vehicle and control method of hybrid vehicle - Google Patents

Abstract

To provide a hybrid vehicle capable of suppressing a significant deterioration in acceleration performance during EV traveling.
When the EV priority switch is turned on, the travel mode control unit further increases the accelerator opening by a predetermined amount ΔACC when the driving torque reaches the EV travelable maximum torque Tev_max according to the increase in the accelerator opening. The driving torque is maintained at the maximum EV-travelable torque Tev_max until the EV travel is maintained. Then, when the accelerator opening further increases beyond the predetermined amount ΔACC, the traveling mode control unit cancels the maintenance of the driving torque, and switches the traveling mode from EV traveling to HV traveling according to the increase in driving torque.
[Selection] Figure 4

Description

  The present invention relates to a hybrid vehicle equipped with an internal combustion engine and an electric motor as a power source for running the vehicle, and a control method therefor.

  In recent years, hybrid vehicles have attracted attention as environmentally friendly vehicles. A hybrid vehicle is a vehicle in which, in addition to a conventional engine, a power storage device, an inverter, and a motor driven by the inverter are mounted as a power source for traveling the vehicle.

  In such a hybrid vehicle, both the engine and the motor are driven, in which the engine is stopped and the vehicle is driven only by the motor (hereinafter also referred to as “EV mode”, and the EV mode is also referred to as “EV travel”). 2. Description of the Related Art There is known a vehicle capable of traveling by switching between traveling modes (hereinafter referred to as “HV mode” and traveling in HV mode is also referred to as “HV traveling”).

Japanese Patent Laying-Open No. 2003-333705 (Patent Document 1) discloses such a hybrid vehicle. In this hybrid vehicle, when generating power by driving the engine when the EV travel switch giving priority to EV travel is turned on, the power generation target value is lowered compared to when the EV travel switch is not turned on. The engine is driven. Accordingly, the output of the engine is suppressed, and the vehicle travels according to the driver's intention to limit the drive of the engine and prioritize EV travel (see Patent Document 1).
JP 2003-333705 A JP-A-6-48190 JP 2005-271618 A

  A user who turns on the EV travel switch desires EV travel as much as possible in order to improve fuel consumption and reduce exhaust gas output. On the other hand, even during EV travel, if the accelerator opening increases, the engine starts and output torque corresponding to the accelerator opening is secured. Therefore, a user who desires EV traveling needs to adjust the accelerator opening to be lower than the threshold value of the accelerator opening at which the engine is started. As a result, the acceleration performance may be impaired.

  In particular, such a problem is assumed to be significant in a hybrid vehicle in which the power storage device can be charged from a power source (such as a system power source) outside the vehicle. That is, in a hybrid vehicle having an external charging function, a power storage device having a larger capacity than that of a conventional hybrid vehicle (hybrid vehicle not having an external charging function) is mounted, and the upper limit of traveling power that can be traveled by EV is raised. Driving in mode is a prerequisite. And it is assumed that many users desire EV driving. Therefore, as described above, the accelerator opening is kept low, and as a result, the acceleration performance can be greatly impaired.

  Therefore, the present invention has been made to solve such a problem, and an object of the present invention is to provide a hybrid vehicle capable of suppressing a significant deterioration in acceleration performance during EV traveling.

  Another object of the present invention is to provide a control method for a hybrid vehicle capable of suppressing a significant deterioration in acceleration performance during EV traveling.

  According to this invention, the hybrid vehicle operates both the internal combustion engine, the electric motor as a power source for traveling the vehicle, the first mode (EV mode) in which the internal combustion engine is stopped and travels, and the internal combustion engine and the electric motor. And a control unit that controls switching of the travel mode including the second mode (HV mode) for traveling. When the driving torque reaches a specified value in response to an increase in the accelerator opening during traveling in the first mode, the control unit maintains the driving torque at the specified value until the accelerator opening further increases by a predetermined amount. When the degree exceeds the predetermined amount and further increases, the traveling mode is switched from the first mode to the second mode.

Preferably, the specified value is a maximum driving torque that can travel in the first mode.
Preferably, the hybrid vehicle further includes an input device for restricting the transition from the first mode to the second mode. When the transition from the driving mode is restricted by the input from the input device, the controller opens the accelerator opening when the driving torque reaches a specified value in accordance with the increase in the accelerator opening during traveling in the first mode. The driving torque is maintained at a specified value until the predetermined amount further increases, and when the accelerator opening further increases beyond the predetermined amount, the traveling mode is switched from the first mode to the second mode. On the other hand, when the transition from the driving mode is not limited by the input from the input device, the control unit first determines that the driving torque reaches the specified value according to the increase in the accelerator opening degree during the traveling in the first mode. The driving mode is switched from the mode No. 2 to the second mode.

Preferably, the control unit decreases the predetermined amount as the acceleration opening rate increases.
Preferably, the hybrid vehicle further includes a power storage device that supplies electric power to the electric motor. The control unit decreases the predetermined amount as the state amount indicating the state of charge of the power storage device is smaller.

  Preferably, the hybrid vehicle further includes a power storage device that supplies electric power to the electric motor. The control unit variably sets the predetermined amount according to the temperature of the power storage device.

  Preferably, the hybrid vehicle further includes a charging device configured to receive power supplied from the outside of the vehicle and charge the power storage device.

  More preferably, the charging device includes another electric motor, first and second inverters, an inverter control unit, and a power receiving unit. The first and second inverters are provided corresponding to the electric motor and the other electric motor, respectively. The inverter control unit controls the first and second inverters. The power receiving unit receives power supplied from outside the vehicle. The electric motor includes a first multiphase winding connected in a star shape as a stator winding. Another electric motor includes a second multiphase winding connected in a star shape as a stator winding. The power receiving unit is connected to the first neutral point of the first multiphase winding and the second neutral point of the second multiphase winding, and receives the electric power received from the outside of the vehicle from the first and second points. Output to the neutral point. The inverter control unit controls the first and second inverters so that the AC power applied from the vehicle exterior to the first and second neutral points by the power receiving unit is converted into DC power and output to the power storage device.

  According to the present invention, the hybrid vehicle control method includes a first mode (EV mode) in which the internal combustion engine and an electric motor as a power source for vehicle travel are mounted and the internal combustion engine is stopped to travel. And a control method for a hybrid vehicle capable of traveling in any one of the second modes (HV mode) in which both the internal combustion engine and the electric motor are operated, and includes first to fourth steps. In the first step, it is determined whether or not the drive torque has reached a specified value in accordance with an increase in the accelerator opening during traveling in the first mode. In the second step, when it is determined that the drive torque has reached the specified value, the drive torque is maintained at the specified value until the accelerator opening is further increased by a predetermined amount. In the third step, it is determined whether or not the accelerator opening has further increased beyond a predetermined amount. In the fourth step, when it is determined that the accelerator opening has further increased beyond a predetermined amount, the traveling mode is switched from the first mode to the second mode.

Preferably, the specified value is a maximum driving torque that can travel in the first mode.
Preferably, the hybrid vehicle control method further includes fifth and sixth steps. In the fifth step, it is determined whether or not the transition of the traveling mode is restricted by the input device for restricting the transition from the first mode to the second mode. In the sixth step, when it is determined that the transition of the traveling mode is not restricted, the first torque is reached when the driving torque reaches a specified value in accordance with the increase in the accelerator opening degree while traveling in the first mode. The travel mode is switched from the mode to the second mode. Then, when it is determined in the fifth step that the transition of the travel mode is restricted, the first to fourth steps are executed.

  Preferably, in the third step, the predetermined amount is set to a smaller value as the acceleration opening rate increases.

  Preferably, in the third step, the predetermined amount is set to a smaller value as the state amount indicating the state of charge of the power storage device is smaller.

  Preferably, in the third step, the predetermined amount is variably set according to the temperature of the power storage device.

  In the present invention, there is provided an accelerator opening region in which the drive torque is maintained at a specified value even when the accelerator opening increases, and the first mode (EV) when the accelerator opening further increases beyond that region. Mode) to the second mode (HV mode), the travel mode is immediately switched from the first mode to the second mode even if the accelerator opening exceeds the accelerator opening at which the drive torque reaches the specified value. There is no.

  Therefore, according to the present invention, it is easy to maintain the traveling in the first mode without suppressing the accelerator opening. As a result, it is possible to prevent the acceleration performance from being greatly impaired during traveling in the first mode (EV traveling).

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.

  FIG. 1 is an overall block diagram showing a power train of a hybrid vehicle according to an embodiment of the present invention. Referring to FIG. 1, hybrid vehicle 100 includes wheels 2, motor generators MG <b> 1 and MG <b> 2, power split device 3, and engine 4. Hybrid vehicle 100 includes power storage device B, boost converter 10, capacitors C1 and C2, inverters 20 and 30, ECU (Electronic Control Unit) 50, accelerator opening sensor 55, and EV priority switch 60. And a display unit 65. Hybrid vehicle 100 further includes a power receiving unit 40 and power lines ACL1 and ACL2.

  Power split device 3 is coupled to motor generators MG1 and MG2 and engine 4 to distribute power between them. For example, as the power split device 3, a planetary gear having three rotation shafts of a sun gear, a planetary carrier, and a ring gear can be used. These three rotating shafts are connected to the rotating shafts of engine 4 and motor generators MG1, MG2, respectively. For example, engine 4 and motor generators MG1 and MG2 can be mechanically connected to power split device 3 by hollowing the rotor of motor generator MG1 and passing the crankshaft of engine 4 through the center thereof.

  The power generated by the engine 4 is distributed by the power split device 3 to the wheels 2 and the motor generator MG1. That is, engine 4 is incorporated in hybrid vehicle 100 as a power source that drives wheels 2 and motor generator MG1. Motor generator MG1 operates as a generator driven by engine 4 and is incorporated in hybrid vehicle 100 as an electric motor that can start engine 4, and motor generator MG2 drives wheels 2. It is incorporated in the hybrid vehicle 100 as a motive power source.

  The positive electrode of power storage device B is connected to positive electrode line PL1, and the negative electrode of power storage device B is connected to negative electrode line NL1. Capacitor C1 is connected between positive electrode line PL1 and negative electrode line NL1. Boost converter 10 is connected between positive electrode line PL1 and negative electrode line NL1, and positive electrode line PL2 and negative electrode line NL2. Capacitor C2 is connected between positive electrode line PL2 and negative electrode line NL2. Inverter 20 is connected between positive and negative lines PL2, NL2, and motor generator MG1. Inverter 30 is connected between positive and negative lines PL2, NL2, and motor generator MG2.

  Motor generator MG1 includes Y-connected three-phase coil 7 as a stator coil, and is connected to inverter 20 via a three-phase cable. Motor generator MG2 also includes Y-connected three-phase coil 8 as a stator coil, and is connected to inverter 30 via a three-phase cable. The power line ACL1 is connected to the neutral point N1 of the three-phase coil 7, and the power line ACL2 is connected to the neutral point N2 of the three-phase coil 8.

  The power storage device B is a rechargeable DC power source, and includes, for example, a secondary battery such as nickel metal hydride or lithium ion. Power storage device B outputs DC power to boost converter 10. In addition, power storage device B is charged by receiving power output from boost converter 10. Note that a large-capacity capacitor may be used as the power storage device B. Capacitor C1 smoothes the voltage fluctuation component between positive line PL1 and negative line NL1.

  Boost converter 10 boosts the DC voltage output from power storage device B based on signal PWC from ECU 50 and outputs the boosted voltage to positive line PL2. Boost converter 10 steps down DC voltage output from inverters 20 and 30 to the voltage level of power storage device B based on signal PWC to charge power storage device B. Boost converter 10 is formed of, for example, a step-up / step-down chopper circuit.

  Capacitor C2 smoothes the voltage fluctuation component between positive line PL2 and negative line NL2. Inverters 20 and 30 convert DC power supplied from positive electrode line PL2 and negative electrode line NL2 into AC power and output the AC power to motor generators MG1 and MG2, respectively. Inverters 20 and 30 convert AC power generated by motor generators MG1 and MG2 into DC power, respectively, and output it as regenerative power to positive line PL2 and negative line NL2.

  Each of inverters 20 and 30 is formed of a bridge circuit including switching elements for three phases, for example. Inverters 20 and 30 drive corresponding motor generators by performing switching operations in accordance with signals PWI1 and PWI2 from ECU 50, respectively.

  In addition, inverters 20 and 30 provide electric power supplied from ECU 70 to neutral points N1 and N2 via power receiving unit 40 and power lines ACL1 and ACL2 when ECU 50 charges power storage device B from power supply 70 outside the vehicle. Is converted into DC power based on the signals PWI1 and PWI2 from, and the converted DC power is output to the positive line PL2.

  Motor generators MG1 and MG2 are three-phase AC motors, for example, three-phase AC synchronous motors. Motor generator MG1 generates three-phase AC power using the power of engine 4 and outputs the generated three-phase AC power to inverter 20. Motor generator MG1 generates driving force by the three-phase AC power received from inverter 20, and starts engine 4. Motor generator MG <b> 2 generates vehicle driving torque by the three-phase AC power received from inverter 30. Motor generator MG2 generates three-phase AC power and outputs it to inverter 30 during regenerative braking of the vehicle.

  The power receiving unit 40 is an input terminal for inputting electric power supplied from a power supply 70 outside the vehicle, and includes, for example, a charging plug or a connector.

  The accelerator opening sensor 55 detects the accelerator opening ACC corresponding to the operation amount of the accelerator pedal, and outputs the detected value to the ECU 50. The EV priority switch 60 is an operation switch for restricting the transition from the EV mode to the HV mode, and activates the signal EV output to the ECU 50 when turned on by the user. The display unit 65 receives the display signal DISP from the ECU 50 and displays the accelerator opening to the driver.

  ECU 50 generates signal PWC for driving boost converter 10 and signals PWI1 and PWI2 for driving motor generators MG1 and MG2, respectively. Boosted converter 10 and inverter 20 generate the generated signals PWC, PWI1 and PWI2, respectively. , 30.

  Further, the ECU 50 operates the engine 4 based on the accelerator opening ACC, the vehicle state, and the signal EV from the EV priority switch 60 to operate (HV mode) or stops the engine 4 by a method described later. Thus, the control unit controls whether to travel using only the motor generator MG2 (EV mode). Further, the ECU 50 generates a display signal DISP for displaying the accelerator opening degree on the display unit 65 and outputs the display signal DISP to the display unit 65.

  In addition, when power storage device B is charged from power supply 70 outside the vehicle, ECU 50 converts electric power from power supply 70 applied to neutral points N1 and N2 to DC power and supplies positive line PL2 and negative line NL2. Signals PWI1 and PWI2 for controlling inverters 20 and 30 are generated so as to be output.

  FIG. 2 is a functional block diagram of ECU 50 shown in FIG. Referring to FIG. 2, ECU 50 includes a converter control unit 82, first and second inverter control units 84 and 86, a charge control unit 88, and a travel mode control unit 90.

  Converter control unit 82 includes voltage VB of power storage device B, voltage VDC between positive line PL2 and negative line NL2, rotation speeds MRN1, MRN2 of motor generators MG1, MG2, and motor generators MG1, MG2 received from travel mode control unit 90. Based on the torque command values TR1 and TR2, the signal PWC for driving the boost converter 10 is generated, and the generated signal PWC is output to the boost converter 10. Each of voltages VB, VDC and rotation speeds MRN1, MRN2 is detected by a sensor (not shown).

  First inverter control unit 84 generates signal PWI1 for driving motor generator MG1 based on voltage VDC, motor current MCRT1 and rotor rotational position θ1 of motor generator MG1, and torque command value TR1, and generates the signal PWI1. The signal PWI1 is output to the inverter 20. Each of motor current MCRT1 and rotor rotational position θ1 is detected by a sensor (not shown).

  Second inverter control unit 86 generates signal PWI2 for driving motor generator MG2 based on voltage VDC, motor current MCRT2 and rotor rotational position θ2 of motor generator MG2, and torque command value TR2, and generates the signal PWI2. The signal PWI2 is output to the inverter 30. Each of motor current MCRT2 and rotor rotational position θ2 is detected by a sensor (not shown).

  Here, first and second inverter control units 84 and 86 are based on zero-phase voltage command values AC1 and AC2 from charging control unit 88 when power storage device B is charged from power supply 70 outside the vehicle. Signals PWI1 and PWI2 are generated, and the generated signals PWI1 and PWI2 are output to inverters 20 and 30, respectively.

  Charging control unit 88 is based on voltage VAC and current IAC of AC power applied from power supply 70 to neutral points N1 and N2 when signal CHRG instructing charging from power supply 70 to power storage device B is activated. As described later, zero-phase voltage command values AC1 and AC2 for operating motor generators MG1 and MG2 and inverters 20 and 30 as a single-phase PWM converter are generated, and the generated zero-phase voltage command values AC1 and AC2 are generated. Output to the first and second inverter control units 84 and 86, respectively.

  Signal CHRG is activated, for example, when the user gives an instruction to start charging when power receiving unit 40 is receiving power from power supply 70. Zero phase voltage command values AC1 and AC2 are command values for controlling a zero voltage vector (described later) of inverters 20 and 30. The voltage VAC and the current IAC are detected by a voltage sensor and a current sensor not shown, respectively.

  Traveling mode control unit 90 receives accelerator opening ACC, vehicle speed SPD, shift position SP, state quantity SOC indicating a state of charge (SOC) of power storage device B, and signal EV from EV priority switch 60. . Then, traveling mode control unit 90 determines a traveling mode based on these signals by a method described later, generates torque command values TR1 and TR2 based on the determined traveling mode, and converts converter control unit 82 and first control unit 82. And output to the second inverter control units 84 and 86. Moreover, the traveling mode control unit 90 generates a display signal DISP for displaying the accelerator opening on the display unit 65 and outputs the display signal DISP to the display unit 65.

  The vehicle speed SPD and the shift position SP are detected by a vehicle speed sensor and a shift position sensor (not shown), respectively. Further, state quantity SOC is calculated based on voltage VB and charge / discharge current of power storage device B by a battery ECU (not shown).

  FIG. 3 is a diagram for schematically explaining the selection range of the travel mode. Referring to FIG. 3, the horizontal axis indicates the traveling power of the vehicle, and the vertical axis indicates the SOC of the power storage device. Region A1 shows an EV travel region of a conventional hybrid vehicle (a hybrid vehicle not having an external charging function), and region A2 shows an EV travel region that is enlarged when the EV travel switch is turned on in the conventional hybrid vehicle. Show. Region A3 including regions A1 and A2 indicates the EV travel region of hybrid vehicle 100 according to this embodiment, and region A4 other than region A3 indicates the HV travel region.

  The hybrid vehicle 100 according to this embodiment can charge the power storage device B from the power supply 70 outside the vehicle, and the EV traveling area is greatly expanded. Specifically, the capacity of the power storage device B is increased, and as shown in FIG. 3, the upper limit of traveling power that can be traveled by EV (P3) and the lower limit of SOC (S3) are achieved.

  In this hybrid vehicle 100, EV traveling is premised, and it is assumed that many users desire EV traveling. In the conventional hybrid vehicle, as shown in FIG. 3, even when the EV travel switch is turned on, the EV travel area is limited and HV travel is main. Not so conscious of switching to HV mode. On the other hand, in hybrid vehicle 100 on the premise of EV traveling, it is assumed that the user is greatly conscious of switching from EV mode to HV mode, and the user has to open the accelerator so that the traveling power does not exceed P3. Adjust. However, it is difficult to adjust the accelerator opening in the vicinity of the switching point of the driving mode, and a user who desires EV traveling has to keep the accelerator opening low, and the acceleration performance may be hindered. .

  Therefore, in the embodiment according to the present invention, when the driving torque reaches the maximum EV travelable torque according to the increase in the accelerator opening during EV traveling, the driving torque is maintained until the accelerator opening further increases by a predetermined amount. When the accelerator opening further increases beyond a predetermined amount, the traveling mode is switched from the EV mode to the HV mode. As a result, the user can easily maintain EV travel without reducing the accelerator opening.

  FIG. 4 is a diagram showing the relationship between the accelerator opening and the driving torque. Referring to FIG. 4, when the accelerator opening is increased from the accelerator-off state (accelerator opening 0%), the drive torque increases along the solid line k1. When the accelerator opening is ACC1, the drive torque reaches the maximum EV travelable torque Tev_max.

  Here, when the EV priority switch 60 (FIG. 1) is turned off, if the accelerator opening is further increased from ACC1, the drive torque increases along the dotted line k3 beyond the maximum EV travelable torque Tev_max. To HV driving.

  On the other hand, when the EV priority switch 60 is turned on, the drive torque is maintained at the maximum EV travelable torque Tev_max from the time when the accelerator opening is ACC1 to ACC2 that is larger than the ACC1 by a predetermined amount ΔACC, and EV travel is maintained. . When the accelerator opening exceeds ACC2, the drive torque increases from the EV travelable maximum torque Tev_max along the solid line k2, and is switched from EV travel to HV travel.

  Therefore, even if the driving torque exceeds the accelerator opening (ACC1) at which the EV traveling maximum torque Tev_max is reached, the EV traveling is maintained unless the accelerator opening further increases by a predetermined amount ΔACC. It is not necessary to keep the accelerator opening lower than ACC1 in order to maintain traveling. In the section where the accelerator opening is ACC1 to ACC2, the driving torque is the EV traveling maximum torque Tev_max. Therefore, acceleration performance can be secured while maintaining EV traveling.

  Note that a user who does not wish to maintain EV travel can obtain drive torque that varies linearly over the entire accelerator opening by turning off the EV priority switch 60.

  FIG. 5 is a flowchart for illustrating a control structure of travel mode control unit 90 shown in FIG. This flowchart is called from the main routine and executed at regular time intervals or when a predetermined condition is satisfied.

  Referring to FIG. 5, travel mode control unit 90 calculates vehicle drive torque based on accelerator opening ACC and vehicle state (vehicle speed and shift position) (step S10). Next, the traveling mode control unit 90 determines whether or not the EV priority switch 60 is turned on based on the signal EV from the EV priority switch 60 (step S20).

  If it is determined that EV priority switch 60 is turned on (YES in step S20), traveling mode control unit 90 determines whether or not the drive torque calculated in step S10 has reached a specified value (step S20). S30). Note that this specified value is the EV travelable maximum torque Tev_max.

  If it is determined that the drive torque has reached the specified value (YES in step S30), travel mode control unit 90 determines that the amount of increase in accelerator opening ACC from when drive torque has reached the specified value is a predetermined amount ΔACC. It is determined whether or not it has been exceeded (step S40).

  If it is determined that the amount of increase in accelerator opening degree ACC is equal to or smaller than predetermined amount ΔACC (NO in step S40), traveling mode control unit 90 maintains the drive torque at a specified value, that is, EV traveling maximum torque Tev_max (step S40). S50). That is, the traveling mode is maintained in the EV mode. Then, the traveling mode control unit 90 generates a display signal DISP for displaying the accelerator opening (that is, ACC1 in FIG. 4) when the driving torque reaches the specified value, and outputs the display signal DISP to the display unit 65 (step S60). ).

  On the other hand, when it is determined in step S40 that the increase amount of accelerator opening degree ACC exceeds predetermined amount ΔACC (YES in step S40), traveling mode control unit 90 cancels the maintenance of the drive torque (step S70). Therefore, the drive torque becomes larger than a specified value, that is, the EV traveling maximum torque Tev_max, and the traveling mode is switched from the EV mode to the HV mode. Then, traveling mode control unit 90 outputs display signal DISP corresponding to the current accelerator opening to display unit 65, and the current accelerator opening is displayed on display unit 65 (step S80).

  If it is determined in step S30 that the drive torque is lower than the specified value (NO in step S30), travel mode control unit 90 sets the travel mode to the EV mode (step S90), and then proceeds to step S80. .

  If it is determined in step S20 that EV priority switch 60 is turned off (NO in step S20), traveling mode control unit 90 determines whether or not the drive torque calculated in step S10 is equal to or greater than a specified value. Is determined (step S100).

  When traveling mode control unit 90 determines that the driving torque is smaller than the specified value (NO in step S100), it sets the traveling mode to the EV mode (step S110), and determines that the driving torque is equal to or greater than the specified value (step S110). In step S100, YES), the travel mode is set to the HV mode (step S120).

  6 is a diagram showing a display state of the display unit 65 shown in FIG. Referring to FIG. 6, display unit 65 includes a first display unit 110 and a second display unit 112. The first display unit 110 displays the accelerator opening in the range of 0% (fully closed) to 100% (fully opened) based on the display signal DISP from the ECU 50. In addition, the range of the area | region 111 shown with a diagonal line shows an accelerator opening.

  The second display unit 112 is provided corresponding to the first display unit 110 and includes regions 116 and 118. A region 116 indicates a range of accelerator opening for EV traveling, and a region 118 indicates a range of accelerator opening for HV traveling.

  The display unit 65 displays the relationship between the accelerator opening and the travel mode. Then, the driver who desires to maintain the EV travel can adjust the accelerator so that the accelerator opening displayed on the first display unit 110 does not enter the range of the region 118 of the second display unit 112. .

  Here, when there is no accelerator opening range where the driving torque is maintained at the maximum EV traveling torque, it is difficult to adjust the accelerator opening in the vicinity of the switching point from EV traveling to HV traveling, The driver tries to maintain EV travel by keeping the accelerator opening low.

  On the other hand, in this embodiment, an accelerator opening region where the driving torque is maintained at the maximum EV traveling torque is provided, and in this region, the accelerator opening when the driving torque reaches the EV traveling maximum torque is displayed. Thus (step S60 in FIG. 5), the driver can easily maintain EV travel without reducing the accelerator opening.

  Next, the operation of inverters 20 and 30 when power storage device B is charged from power supply 70 outside the vehicle will be described.

  FIG. 7 is a circuit diagram schematically showing a configuration of a charging device formed by inverters 20 and 30 and motor generators MG1 and MG2 when power storage device B is charged from power supply 70 outside the vehicle.

  Referring to FIG. 7, each of inverters 20 and 30 is formed of a three-phase bridge circuit as described above, and there are eight patterns of on / off combinations of six switching elements in each inverter. Two of the eight switching patterns have zero interphase voltage, and such a voltage state is called a zero voltage vector. For the zero voltage vector, the three switching elements of the upper arm can be regarded as the same switching state (all on or off), and the three switching elements of the lower arm can also be regarded as the same switching state.

  When charging power storage device B from power supply 70, inverters 20 and 30 control the zero voltage vector based on zero-phase voltage command values AC1 and AC2 generated by charge control unit 88 of ECU 50, respectively. Therefore, when the power storage device B is charged from the power supply 70, the three switching elements of the upper arm of each inverter can be regarded as the same switching state, and the three switching elements of the lower arm can be regarded as the same switching state. Therefore, in FIG. 7, the three switching elements of the upper arm of the inverter 20 are collectively shown as an upper arm 20A, and the three switching elements of the lower arm of the inverter 20 are collectively shown as a lower arm 20B. Similarly, the three switching elements of the upper arm of the inverter 30 are collectively shown as an upper arm 30A, and the three switching elements of the lower arm of the inverter 30 are collectively shown as a lower arm 30B. That is, in FIG. 7, a zero-phase equivalent circuit of the inverters 20 and 30 is shown.

  7 can be regarded as a single-phase PWM converter formed by motor generators MG1, MG2 and inverters 20, 30 with single-phase AC power from power supply 70 as an input. Therefore, by controlling the zero phase voltage command values AC1 and AC2, the zero voltage vector is changed in the inverters 20 and 30, and switching control is performed so that the inverters 20 and 30 operate as an arm of a single phase PWM converter. AC power from the power supply 70 applied via ACL1 and ACL2 can be converted into DC power and output to the positive electrode line PL2 and the negative electrode line NL2.

  As described above, in this embodiment, there is provided an accelerator opening region in which the drive torque is maintained at the specified value (maximum EV travelable torque) even if the accelerator opening increases, and the accelerator is exceeded beyond that region. Since the travel mode is switched from the EV mode to the HV mode when the opening further increases, even if the accelerator opening exceeds the accelerator opening at which the drive torque reaches the specified value, the EV travel is not immediately switched to the HV travel. Therefore, according to this embodiment, it becomes easy to maintain EV traveling without suppressing the accelerator opening degree low. As a result, it is possible to suppress the acceleration performance from being greatly impaired during EV traveling.

  In the above description, the predetermined amount ΔACC that defines the accelerator opening range where the drive torque is maintained at the specified value (maximum EV travelable torque) is smaller as the increase rate of the accelerator opening is larger, as shown in FIG. It may be set to a value. As a result, the greater the speed of increase in the accelerator opening, the shorter the drive torque maintenance interval and the faster the transition from EV travel to HV travel, so a driver who wants to secure a large acceleration force by depressing the accelerator pedal rapidly. Can reflect the intentions.

  Further, as shown in FIG. 9, the smaller the SOC of power storage device B, the smaller the predetermined amount ΔACC may be set. As a result, the smaller the SOC is, the shorter the driving torque maintaining section is, and the transition from EV traveling to HV traveling is accelerated, so that the burden on power storage device B can be reduced.

  Furthermore, as shown in FIG. 10, the predetermined amount ΔACC may be variably set according to the temperature TB of the power storage device B. More specifically, the predetermined amount ΔACC may be reduced when the power storage device B is at a low temperature and a high temperature. As a result, the drive torque maintaining section is shortened when the power storage device B is at a low temperature and at a high temperature, and the transition from the EV traveling to the HV traveling is accelerated, so that the burden on the power storage device B can be reduced.

  In the above-described embodiment, the hybrid vehicle is of a series / parallel type in which the power of the engine 4 can be divided and transmitted to the axle and the motor generator MG1 by the power split device 3. However, the present invention is also applicable to a so-called series type hybrid vehicle that uses engine 4 only for driving motor generator MG1 and generates the driving force of the vehicle only by motor generator MG2.

  In the above description, the hybrid vehicle can charge power storage device B from power supply 70 outside the vehicle. However, the scope of application of the present invention is limited to a hybrid vehicle that can charge power storage device from a power supply outside the vehicle. It is not a thing. However, as described above, in a hybrid vehicle in which the power storage device can be charged from a power source outside the vehicle, EV traveling is premised, and it is assumed that the user is greatly aware of switching from the EV mode to the HV mode. The present invention that can easily maintain the EV traveling is particularly useful in a hybrid vehicle that can charge the power storage device from a power source outside the vehicle.

  In the above, AC power from power supply 70 is applied to neutral points N1 and N2 of motor generators MG1 and MG2, and power storage device B is charged using motor generators MG1 and MG2 and inverters 20 and 30. However, a dedicated charging inverter for charging the power storage device B from the power source 70 may be provided separately. However, according to the above embodiment, it is not necessary to separately provide an inverter dedicated to charging, so that the cost can be reduced and the weight of the vehicle can be reduced.

  In the above, engine 4 corresponds to “internal combustion engine” in the present invention, and motor generator MG2 corresponds to “electric motor” in the present invention. Further, traveling mode control unit 90 of ECU 50 corresponds to “control unit” in the present invention, and EV priority switch 60 corresponds to “input device” in the present invention.

  Further, motor generator MG1 corresponds to “another electric motor” in the present invention, and inverters 20 and 30 correspond to “second inverter” and “first inverter” in the present invention, respectively. Further, ECU 50 corresponds to “inverter control unit” in the present invention, and three-phase coils 7 and 8 are “second multiphase winding” and “first multiphase winding” in the present invention, respectively. Corresponding to

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims for patent, and is intended to include meanings equivalent to the scope of claims for patent and all modifications within the scope.

1 is an overall block diagram showing a power train of a hybrid vehicle according to an embodiment of the present invention. It is a functional block diagram of ECU shown in FIG. It is a figure for demonstrating schematically the selection range of driving mode. It is the figure which showed the relationship between an accelerator opening and a drive torque. 3 is a flowchart for illustrating a control structure of a travel mode control unit shown in FIG. 2. It is the figure which showed the display state of the display part shown in FIG. FIG. 3 is a circuit diagram schematically showing a configuration of a charging device formed by an inverter and a motor generator when a power storage device is charged from a power supply external to the vehicle. It is the figure which showed the relationship between the increase speed of an accelerator opening, and predetermined amount (DELTA) ACC. It is the figure which showed the relationship between SOC of an electrical storage apparatus, and predetermined amount (DELTA) ACC. It is the figure which showed the relationship between the temperature of an electrical storage apparatus, and predetermined amount (DELTA) ACC.

Explanation of symbols

  2 wheels, 3 power split devices, 4 engines, 7, 8 three-phase coil, 10 boost converter, 20, 30 inverter, 20A, 30A upper arm, 20B, 30B lower arm, 40 power receiving unit, 50 ECU, 55 accelerator opening Sensor, 60 EV priority switch, 65 display unit, 70 power supply, 82 converter control unit, 84 first inverter control unit, 86 second inverter control unit, 88 charge control unit, 90 travel mode control unit, 100 hybrid vehicle, 110 1st display part, 112 2nd display part, 111, 116, 118 area | region, B electrical storage apparatus, C1, C2 capacitor | condenser, PL1, PL2 positive electrode line, NL1, NL2 negative electrode line, MG1, MG2 motor generator, N1, N2 Neutral point, ACL1, ACL2 power line.

Claims (14)

An internal combustion engine;
An electric motor as a power source for vehicle travel;
A control unit that controls switching of a travel mode including a first mode that travels with the internal combustion engine stopped and a second mode that travels by operating both the internal combustion engine and the electric motor;
When the driving torque reaches a specified value in response to an increase in the accelerator opening during traveling in the first mode, the control unit sets the driving torque to the specified value until the accelerator opening further increases by a predetermined amount. The hybrid vehicle is maintained and switches the travel mode from the first mode to the second mode when the accelerator opening further increases beyond the predetermined amount.   The hybrid vehicle according to claim 1, wherein the specified value is a maximum drive torque that can travel in the first mode. An input device for restricting the transition from the first mode to the second mode;
When the transition from the travel mode is restricted by an input from the input device, the control unit sets the drive torque to the specified value according to an increase in the accelerator opening while traveling in the first mode. When reaching, the driving torque is maintained at the specified value until the accelerator opening further increases by the predetermined amount, and when the accelerator opening further increases beyond the predetermined amount, the second mode is changed from the first mode. Switch the driving mode to
When the transition from the travel mode is not restricted by an input from the input device, the control unit sets the drive torque to the specified value according to an increase in the accelerator opening while traveling in the first mode. 3. The hybrid vehicle according to claim 1, wherein upon reaching, the traveling mode is switched from the first mode to the second mode. 4.   The hybrid vehicle according to any one of claims 1 to 3, wherein the control unit decreases the predetermined amount as the rate of increase in the accelerator opening increases. A power storage device for supplying electric power to the electric motor;
The hybrid vehicle according to any one of claims 1 to 4, wherein the control unit decreases the predetermined amount as the state amount indicating the state of charge of the power storage device decreases. A power storage device for supplying electric power to the electric motor;
The hybrid vehicle according to claim 1, wherein the control unit variably sets the predetermined amount according to a temperature of the power storage device.   The hybrid vehicle according to any one of claims 1 to 6, further comprising a charging device configured to be able to charge the power storage device by receiving electric power applied from outside the vehicle. The charging device is:
Another motor,
First and second inverters provided corresponding to the electric motor and the other electric motor, respectively;
An inverter control unit for controlling the first and second inverters;
Including a power receiving unit that receives power supplied from outside the vehicle,
The electric motor includes a star-connected first multiphase winding as a stator winding,
The another electric motor includes a second multiphase winding connected in a star shape as a stator winding,
The power receiving unit is connected to a first neutral point of the first multiphase winding and a second neutral point of the second multiphase winding, and receives power received from outside the vehicle. Output to the 1st and 2nd neutral point,
The inverter control unit converts the AC power applied to the first and second neutral points from the outside of the vehicle by the power receiving unit into DC power and outputs the DC power to the power storage device. The hybrid vehicle according to claim 7 which controls an inverter. A first mode in which an internal combustion engine and an electric motor as a power source for vehicle travel are mounted, and the internal combustion engine is stopped and traveled, and a second mode in which both the internal combustion engine and the motor are operated to travel A method for controlling a hybrid vehicle capable of traveling in any of the traveling modes,
A first step of determining whether or not the drive torque has reached a specified value in accordance with an increase in accelerator opening during traveling in the first mode;
A second step of maintaining the drive torque at the specified value until the accelerator opening is further increased by a predetermined amount when it is determined that the drive torque has reached the specified value;
A third step of determining whether or not the accelerator opening has further increased beyond the predetermined amount;
A hybrid vehicle control method comprising: a fourth step of switching the travel mode from the first mode to the second mode when it is determined that the accelerator opening has further increased beyond the predetermined amount. .   The method for controlling a hybrid vehicle according to claim 9, wherein the specified value is a maximum driving torque that can travel in the first mode. A fifth step of determining whether or not the transition of the travel mode is restricted by an input device for restricting the transition from the first mode to the second mode;
When it is determined that the transition of the traveling mode is not restricted, the first torque is reached when the driving torque reaches the specified value in accordance with the increase in the accelerator opening degree while traveling in the first mode. And a sixth step of switching the travel mode from the mode to the second mode,
The hybrid vehicle control according to claim 9 or 10, wherein when it is determined in the fifth step that the transition of the travel mode is restricted, the first to fourth steps are executed. Method.   The hybrid vehicle control method according to any one of claims 9 to 11, wherein, in the third step, the predetermined amount is set to a smaller value as the rate of increase of the accelerator opening is larger.   The hybrid vehicle according to any one of claims 9 to 12, wherein, in the third step, the predetermined amount is set to a smaller value as the state amount indicating the state of charge of the power storage device is smaller. Control method.   The method for controlling a hybrid vehicle according to any one of claims 9 to 12, wherein, in the third step, the predetermined amount is variably set according to a temperature of the power storage device.

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