Hybrid vehicle

Abstract

To provide a hybrid vehicle that can protect components and reduce a decrease in drivability when the output power of a battery is increased during warm-up of a catalyst device.SOLUTION: A hybrid vehicle includes a control device that performs travel control and battery control. The battery control includes: first discharge control that, when a battery is not in a warm-up state of a catalyst device, sets a lower limit voltage of the battery to a first lower limit value and also sets battery dischargeable power to a first upper limit value; and second discharge control that, when the battery is in a warm-up state of the catalyst device, sets the lower limit voltage of the battery to a second lower limit value that is smaller than the first lower limit value and also sets the battery dischargeable power to a second upper limit value that is larger than the first upper limit value. The travel control includes transient control for causing the battery to output power that is a sum of the battery dischargeable power and a temporary increase. The control device is configured to: set the increase to a first increase amount during executing the first discharge control; and set the increase to a second increase amount smaller than the first increase amount during executing the second discharge control.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a hybrid vehicle. [Background technology]

[0002] Patent Document 1 discloses a hybrid vehicle equipped with a catalytic converter that purifies engine exhaust. In the configuration described in Patent Document 1, when the required power can be met with the battery's output power when it is necessary to warm up the catalytic converter, the engine is driven at idle speed to warm up the catalytic converter using exhaust heat. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-042700 Summary of the Invention [Problem to be solved by the invention]

[0004] In the configuration described in Patent Document 1, even if the catalytic converter needs to be warmed up, the catalytic converter is not warmed up if the required power exceeds the battery's output limit. Therefore, it is conceivable to relax the battery's output limit when the catalytic converter needs to be warmed up.

[0005] However, when the battery output limit is relaxed, the voltage drop increases as the output power increases. Therefore, if more power than expected is used during the catalyst warm-up, the voltage drop will also be larger than expected, which could cause the battery voltage to reach the lower limit voltage early and even fall below the lower limit voltage. Falling below the lower limit voltage is undesirable from the perspective of component protection. To protect components, the motor output torque is limited when the battery voltage reaches the lower limit voltage. In this case, the driving force is limited early, resulting in shocks, sluggishness, and other problems.

[0006] The present invention has been made in consideration of the above circumstances, and aims to provide a hybrid vehicle that can protect components while suppressing a decline in driving performance when the battery output power is increased during warm-up of the catalytic converter. [Means for solving the problem]

[0007] The present invention relates to a hybrid vehicle equipped with an internal combustion engine, an electric motor, a battery that stores electric power to be supplied to the electric motor, a catalytic converter that purifies exhaust gas emitted from the internal combustion engine, and a control device that executes driving control for controlling the internal combustion engine and the electric motor, and also executes battery control for managing the battery, wherein the battery control comprises first discharge control that sets a lower limit voltage of the battery to a first lower limit value when the catalytic converter is not warming up, and controls discharge of the battery in a first setting state in which the dischargeable power of the battery is set to a first upper limit value, and when the catalytic converter is warming up, sets a lower limit voltage of the battery to a second lower limit value that is smaller than the first lower limit value, and controls the dischargeable power of the battery to a and a second discharge control that controls the discharge of the battery in a second setting state set to a second upper limit value that is greater than the first upper limit value, and the driving control includes a setting control that sets an increment when temporarily increasing the output power of the battery, and a transient control that drives the vehicle by outputting power from the battery that is the sum of the dischargeable power of the battery and the increment, and the control device sets the increment to a first increment while the first discharge control is being executed, and sets the increment to a second increment that is smaller than the first increment while the second discharge control is being executed, and when the transient control is executed while the second discharge control is being executed, causes the battery to output power that is the sum of the second upper limit value and the second increment. [Effects of the Invention]

[0008] In the present invention, when the output power of the battery is increased during warm-up of the catalyst device, it is possible to prevent a decrease in driving performance while protecting the components. [Brief explanation of the drawings]

[0009] [Figure 1]1 is a diagram schematically illustrating a hybrid vehicle according to an embodiment. [Figure 2] FIG. 4 is a diagram for explaining dischargeable power and a lower limit voltage of a battery in a steady state. [Figure 3] FIG. 10 is a diagram for explaining transient dischargeable power. [Figure 4] FIG. 10 is a diagram for explaining a state in which the output power of the battery is temporarily increased during catalyst warm-up. [Figure 5] FIG. 10 is a flowchart illustrating a setting process flow. [Figure 6] FIG. 10 is a diagram for explaining control in a comparative example. [Figure 7] FIG. 10 is a diagram for explaining control in another comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0010] A hybrid vehicle according to an embodiment of the present invention will be specifically described below, although the present invention is not limited to the embodiment described below.

[0011] 1 is a diagram illustrating a hybrid vehicle according to an embodiment. The hybrid vehicle 1 includes an engine (ENG) 2, a first motor (MG1) 3, a second motor (MG2) 4, a power split device 5, a PCU 6, a battery 7, and a control device 20.

[0012] The hybrid vehicle 1 is equipped with an engine 2, a first motor 3, and a second motor 4 as power sources. The engine 2 is an internal combustion engine such as a gasoline engine. The first motor 3 and the second motor 4 are both motor generators that function as electric motors and generators, and are composed of electric motors such as synchronous motors (three-phase AC motors). The first motor 3 mainly functions as a generator. The second motor 4 mainly functions as an electric motor. The first motor 3 and the second motor 4 are electrically connected to a PCU 6. The first motor 3 is electrically connected to the second motor 4 via the PCU 6. Electric power generated by the first motor 3 is supplied to the second motor 4 via the PCU 6, and torque can be output from the second motor 4 using this electric power.

[0013] The PCU 6 includes a first inverter that drives the first motor 3 and a second inverter that drives the second motor 4. The PCU 6 is electrically connected to the battery 7. Each of the motors 3, 4 is electrically connected to the battery 7 via the PCU 6. The first motor 3 is electrically connected to the battery 7 via the first inverter. The second motor 4 is electrically connected to the battery 7 via the second inverter. The battery 7 is a secondary battery that stores power to be supplied to each of the motors 3, 4. The battery 7 can store power generated by each of the motors 3, 4. The battery 7 is configured as a battery pack including a plurality of battery modules, each of which has a plurality of stacked battery cells.

[0014] The power split mechanism 5 splits the power output by the engine 2 between the first motor 3 side and the drive shaft 11 side. The power split mechanism 5 is composed of a single-pinion planetary gear mechanism. The power split mechanism 5 includes a sun gear 5S, a ring gear 5R, and a carrier 5C that holds a pinion gear meshed with the sun gear 5S and the ring gear 5R so that the pinion gear can rotate and revolve. The sun gear 5S is connected to the first motor 3. The carrier 5C is connected to the engine 2. The ring gear 5R is the output element of the power split mechanism 5 and outputs power toward the drive shaft 11. An output gear 8 is connected to the ring gear 5R. The ring gear 6R and the output gear 8 rotate integrally. The output gear 8 is connected to a differential mechanism 10 via a counter gear mechanism 9. The counter gear mechanism 9 includes a counter driven gear, a counter drive gear, and a counter shaft. The differential mechanism 10 includes a differential ring gear and is connected to drive wheels 12 via a drive shaft 11.

[0015] In the hybrid vehicle 1, the torque output by the second motor 4 can be added to the torque transmitted from the power split mechanism 5 to the drive shaft 11. The second motor 4 is connected to a counter gear mechanism 9 via a reduction gear 13. The engine 2, first motor 3, and second motor 4 are all connected to the drive shaft 11 via the counter gear mechanism 9 and a differential mechanism 10. The hybrid vehicle 1 can operate in an HV driving mode in which it runs using the torque output by the engine 2, and an EV driving mode in which it runs only using the torque output by the second motor 4. In the HV driving mode, the torque output by the second motor 4 can be added.

[0016] The control device 20 is an electronic control device that controls the hybrid vehicle 1. The control device 20 includes a microcomputer equipped with a CPU, RAM, ROM, and an input / output interface. The control device 20 processes signals according to a program pre-stored in the ROM. Signals are input to the control device 20 from various sensors mounted on the hybrid vehicle 1. For example, the control device 20 receives a vehicle speed signal from a vehicle speed sensor that detects the vehicle speed, an accelerator position signal from an accelerator position sensor that detects the amount of accelerator pedal operation, a temperature signal from a temperature sensor that detects the temperature of the battery 7, a current signal from a current sensor that detects the input / output current of the battery 7, and a voltage signal from a voltage sensor that detects the voltage of the battery 7. The control device 20 executes various controls based on the signals input from the various sensors. In this case, the control device 20 performs calculations using the input data and pre-stored data and outputs the calculation results as command signals.

[0017] The control device 20 is configured to include a hybrid electronic control device (HV-ECU), a motor electronic control device (MG-ECU), and a battery electronic control device (battery ECU). The control device 20 executes driving control to control the engine 2 and each of the motors 3 and 4, and executes battery control to manage the battery 7. The HV-ECU of the control device 20 outputs command signals to the engine 2, electrically controlling the output, start, and stop of the engine 2. The engine 2 is electrically controlled by the control device 20 for fuel injection, ignition timing, etc. The MG-ECU of the control device 20 outputs command signals to the PCU 6, controlling the motor torque of each of the motors 3 and 4. The battery ECU of the control device 20 manages and monitors the battery 7.

[0018] The control device 20 performs discharge control to control the discharge of the battery 7 as the battery control. The control device 20 sets a lower limit voltage Vmin of the battery 7 and a dischargeable power Wout of the battery 7. The lower limit voltage Vmin is a value set to achieve component protection. The dischargeable power Wout is the maximum power that can be output, which specifies the limit on the output power of the battery 7. The dischargeable power Wout indicates the output limit of the battery 7. The control device 20 calculates the dischargeable power Wout based on the SOC, which indicates the state of charge of the battery 7, and the temperature of the battery 7. The control device 20 calculates the SOC based on the input / output current of the battery 7, the battery voltage, etc.

[0019] As a driving control, the control device 20 calculates a required driving force based on the accelerator opening and the vehicle speed. The control device 20 calculates a required power based on the required driving force and the vehicle speed. The control device 20 sets a target rotation speed and a target torque of the engine 2 based on the required power.

[0020] The hybrid vehicle 1 is equipped with a catalytic converter 14 that purifies the exhaust gas from the engine 2. The catalytic converter 14 is provided in the exhaust pipe of the engine 2. The hybrid vehicle 1 can warm up the catalytic converter 14 using the exhaust heat of the engine 2. When it is necessary to warm up the catalytic converter 14, the control device 20 controls the engine 2 to an idle state to warm up the catalytic converter 14 using the exhaust heat. The idle state refers to an operating state in which the rotation speed of the engine 2 is controlled to an idle rotation speed, and the engine 2 is rotating without outputting torque.

[0021] The hybrid vehicle 1 is configured to anticipate the need to increase the output power of the battery 7 while the catalytic converter 14 is warming up due to stricter exhaust gas regulations. Simply increasing the number of battery cells included in the battery 7 could be considered. However, increasing the number of battery cells would result in the battery 7 becoming larger and heavier. Therefore, the hybrid vehicle 1 is configured to increase the output power of the battery 7 by improving its usage while keeping the number of battery cells included in the battery 7 the same.

[0022] The control device 20 executes the battery control shown in Fig. 2 and the driving control shown in Fig. 3. As shown in Fig. 2, the control device 20 sets the lower limit voltage Vmin of the battery 7 to a first lower limit value Vmin1 and sets the dischargeable power Wout_s in a steady state to a first upper limit value Wout_s1. The first upper limit value Wout_s1 is the power whose output duration until the voltage of the battery 7 reaches the first lower limit value Vmin1 when the battery 7 continues to discharge at the dischargeable power Wout is a first duration. The first duration is 10 seconds. In other words, the power that reaches the lower limit voltage Vmin when the battery 7 is discharged at the dischargeable power Wout for 10 seconds is the first upper limit value Wout_s1. A state in which the lower limit voltage Vmin is set to the first lower limit value Vmin1 and the dischargeable power Wout_s in a steady state is set to the first upper limit value Wout_s1 is a first setting state.

[0023] 3, the control device 20 can cause the battery 7 to output a transient dischargeable power Wout_t, which is the sum of the dischargeable power Wout_s in the steady state and a temporary increase ΔW. The transient dischargeable power Wout_t is the power that, when discharged continuously at the dischargeable power Wout_t, causes the output duration until the voltage of the battery 7 reaches the lower limit voltage Vmin is 1 second.

[0024] As an example of conventional control, the control of the comparative example shown in FIG. 6 can be considered. The control of the comparative example includes battery control and driving control. The battery control of the comparative example includes control to increase the dischargeable power W1 in a steady state when the catalyst is warming up compared to when catalyst warming up is not required. The definition of the dischargeable power W1 is the same as the definition of the first upper limit value Wout_s1. The dischargeable power W1 is the power at which the battery voltage reaches the lower limit voltage V1 in 10 seconds when the battery continues to discharge at the dischargeable power W1. In the battery control of the comparative example, the dischargeable power W1 in a steady state is set to different values ​​when catalyst warming up is not required and when the catalyst is warming up. The battery control of the comparative example includes control to increase the dischargeable power W1 in a steady state by lowering the lower limit voltage V1 of the battery when the catalyst is warming up. The lower limit voltage V1 is smaller when the catalyst is warming up than when the catalyst is not warming up.

[0025] As shown in Figure 6, the driving control of the comparative example includes transient control that temporarily increases the output power of the battery. The transient control is control that adds a preset increase ΔW to the dischargeable power W1 in a steady state. When transient control is performed during catalyst warm-up, the battery outputs transient dischargeable power W2, which is the sum of the dischargeable power W1 in a steady state increased by the battery control and the increase ΔW temporarily increased by the driving control.

[0026] To increase the output power during catalyst warm-up, the control of the comparative example shown in FIG. 6 can be replaced with another comparative example shown in FIG. 7. In the comparative example shown in FIG. 7, control is executed to further increase the battery output power during catalyst warm-up. The definition of the dischargeable power W11 in a steady state is changed during catalyst warm-up. The dischargeable power W11 in a steady state when the catalyst is not warming up is the power at which the battery voltage reaches the lower limit voltage V11 after 10 seconds of power consumption. In contrast, the dischargeable power W11 in a steady state when the catalyst is warming up is the power at which the battery voltage reaches the lower limit voltage V11 after 5 seconds of power consumption. In this case, if the temporary increase ΔW remains the same as in FIG. 6, the transient dischargeable power W12, which is the sum of the dischargeable power W11 in the steady state and the temporary increase ΔW during catalyst warm-up, becomes larger than expected. This may cause the battery voltage to fall below the lower limit voltage V11.

[0027] Therefore, as shown in Figure 4, the control device 20 is configured to change the definition of the dischargeable power Wout_s in a steady state in battery control from 10 seconds to 5 seconds and use the battery 7, and to change the temporary increase ΔWout in output power in driving control accordingly. The dischargeable power Wout_s in a steady state is set to a different value when the catalytic converter 14 is not warming up and when the catalytic converter 14 is warming up. The temporary increase ΔWout is set to a different value when the catalytic converter 14 is not warming up and when the catalytic converter 14 is warming up. The control device 20 executes control to increase the output power of the battery 7 more than before, only while the catalytic converter 14 is warming up. This achieves component protection for the hybrid vehicle 1.

[0028] In the cell control, the control device 20 executes control to raise the dischargeable power Wout in a steady state from a first upper limit value Wout_s1 to a second upper limit value Wout_s2 by lowering the lower limit voltage Vmin of the battery 7 from a first lower limit value Vmin1 to a second lower limit value Vmin2 when the catalyst is being warmed up. The control device 20 executes first discharge control when the catalytic converter 14 is not being warmed up, and executes second discharge control when the catalytic converter 14 is being warmed up. The cell control includes first discharge control and second discharge control. The first discharge control is discharge control that controls the discharge of the battery 7 in a first setting state in which the lower limit voltage Vmin of the battery 7 is set to the first lower limit value Vmin1 when the catalytic converter 14 is not being warmed up, and the dischargeable power Wout_s of the battery 7 in a steady state is set to the first upper limit value Wout_s1. The second discharge control is a discharge control that controls the discharge of the battery 7 in a second setting state in which, when the catalytic device 14 is warming up, the lower limit voltage Vmin of the battery 7 is set to a second lower limit value Vmin2 that is smaller than the first lower limit value Vmin1, and the dischargeable power Wout_s of the battery 7 in a steady state is set to a second upper limit value Wout_s2 that is larger than the first upper limit value Wout_s1.

[0029] The first upper limit value Wout_s1 is set to a power such that the output duration until the voltage of the battery 7 reaches the first lower limit value Vmin1 when the battery 7 continues to discharge at the dischargeable power Wout_s in a steady state is a first duration. The first duration is, for example, 10 seconds. The second upper limit value Wout_s2 is set to a power such that the output duration until the voltage of the battery 7 reaches the second lower limit value Vmin2 when the battery 7 continues to discharge at the dischargeable power Wout_s in a steady state is a second duration that is shorter than the first duration. The second duration is, for example, 5 seconds.

[0030] In the driving control, the control device 20 performs transient control in which transient dischargeable power Wout_t, which is the sum of the dischargeable power Wout_s of the battery 7 in a steady state and a temporary increase ΔWout, is output from the battery 7 for driving. The control device 20 performs setting control to set the increase ΔWout when temporarily increasing the output power of the battery 7. The driving control includes setting control and transient control. While performing the first discharge control, the control device 20 sets the increase ΔWout to a first increase ΔWout1. While performing the second discharge control, the control device 20 sets the increase ΔWout to a second increase ΔWout2 that is smaller than the first increase ΔWout1.

[0031] The first increase amount ΔWout1 is set to a power such that when the battery 7 continues to output power obtained by adding the increase amount ΔWout to the first upper limit value Wout_s1, the output duration until the voltage of the battery 7 reaches the first lower limit value Vmin1 is a third duration that is shorter than the second duration. The third duration is, for example, one second. The second increase amount ΔWout2 is set to a power such that when the battery 7 continues to output power obtained by adding the increase amount ΔWout to the second upper limit value Wout_s2, the output duration until the voltage of the battery 7 reaches the second lower limit value Vmin2 is the third duration.

[0032] 5 is a flowchart showing the setting process flow. The control shown in FIG.

[0033] The control device 20 determines whether the catalytic converter 14 is currently warming up (step S1).

[0034] If the catalytic converter 14 is being warmed up (step S1: Yes), the control device 20 sets the lower limit voltage Vmin of the battery 7 to the lower limit voltage in 5 seconds (step S2). In step S2, the lower limit voltage Vmin is lowered from the first lower limit value Vmin1 that is set when the catalytic converter 14 is not being warmed up. The control device 20 sets the lower limit voltage Vmin to the second lower limit value Vmin2.

[0035] The control device 20 sets the dischargeable power Wout_s in the steady state based on the lower limit voltage at 5 seconds (step S3). In step S3, the definition of the dischargeable power Wout_s in the steady state is changed to 5 seconds. The control device 20 sets the dischargeable power Wout_s based on the second lower limit value Vmin2. The control device 20 sets the dischargeable power Wout_s in the steady state to a second upper limit value Wout_s2 that is greater than the first upper limit value Wout_s1 that is set when the catalyst is not warming up.

[0036] The control device 20 sets an increment ΔWout for temporarily increasing the output power of the battery 7 based on the lower limit voltage in 5 seconds (step S4). In step S4, the temporary increment ΔWout is set to a second increment ΔWout2.

[0037] The control device 20 sets the transient dischargeable power Wout_t to the power obtained by adding the temporary increase ΔWout to the dischargeable power Wout_s in the steady state (step S5). In step S5, the transient dischargeable power Wout_t2 is set to the sum of the second upper limit value Wout_s2 set in step S3 and the second increase ΔWout2 set in step S4. After the processing of step S5 is performed, this control routine ends.

[0038] If the catalytic converter 14 is not warming up (step S1: No), the control device 20 sets the lower limit voltage Vmin of the battery 7 to the lower limit voltage in 10 seconds (step S6). In step S6, the lower limit voltage Vmin is set to the first lower limit value Vmin1.

[0039] The control device 20 sets the dischargeable power Wout_s in the steady state based on the lower limit voltage for 10 seconds (step S7). In step S7, the definition of the dischargeable power Wout_s in the steady state is set to 10 seconds. The control device 20 sets the dischargeable power Wout_s to a first upper limit value Wout_s1.

[0040] The control device 20 sets an increment ΔWout for temporarily increasing the output power of the battery 7 based on the lower limit voltage for 10 seconds (step S8). In step S8, the temporary increment ΔWout is set to a first increment ΔWout1. After the processing of step S8 is performed, this control routine proceeds to step S5.

[0041] When the process proceeds from step S8 to step S5, the value obtained by adding the first upper limit value Wout_s1 set in step S7 to the first increment ΔWout1 set in step S8 is set as the transient dischargeable power Wout_t1.

[0042] As described above, according to the embodiment, when the dischargeable power Wout_s in the steady state is increased during catalyst warm-up, the voltage of the battery 7 is less likely to drop to the lower limit voltage Vmin. This makes it possible to prevent the output torque of the motor from being limited due to the voltage of the battery 7 reaching the lower limit voltage Vmin during catalyst warm-up. As a result, it is possible to prevent a decrease in driving performance during catalyst warm-up while protecting the components. [Explanation of symbols]

[0043] 1. Hybrid vehicles 2 engines 3 First motor 4 Second motor 7 Battery 14 Catalytic converter 20 Control device

Claims

1. an internal combustion engine; An electric motor, a battery that stores power to be supplied to the electric motor; a catalytic converter that purifies exhaust gas discharged from the internal combustion engine; a control device that performs a driving control for controlling the internal combustion engine and the electric motor, and also performs a battery control for managing the battery; A hybrid vehicle equipped with The battery control a first discharge control for controlling the discharge of the battery in a first setting state in which the lower limit voltage of the battery is set to a first lower limit value and the dischargeable power of the battery is set to a first upper limit value when the catalytic converter is not being warmed up; a second discharge control for controlling discharge of the battery in a second setting state in which a lower limit voltage of the battery is set to a second lower limit value that is lower than the first lower limit value and a dischargeable power of the battery is set to a second upper limit value that is higher than the first upper limit value when the catalytic converter is being warmed up; The driving control includes: A setting control that sets an increment when temporarily increasing the output power of the battery; and transient control for running the vehicle by outputting from the battery power equal to the sum of the dischargeable power of the battery and the increased power, The control device The increase is set to a first increase amount while the first discharge control is being executed, During execution of the second discharge control, the increase is set to a second increase amount that is smaller than the first increase amount; When the transient control is executed while the second discharge control is being executed, the power output from the battery is equal to the second upper limit value plus the second increase amount. A hybrid vehicle characterized by

2. the first upper limit value is set to a power such that when the battery continues to discharge at the dischargeable power, the output duration until the voltage of the battery reaches the first lower limit value is a first duration, The second upper limit value is set to a power such that when the battery continues to discharge at the dischargeable power, the output duration until the voltage of the battery reaches the second lower limit value is a second duration that is shorter than the first duration.

2. The hybrid vehicle according to claim 1.

3. the first increase amount is set to a power such that when the battery continues to output power equal to the first upper limit value plus the increase amount, the output duration until the voltage of the battery reaches the first lower limit value is a third duration time that is shorter than the second duration time, The second increase amount is set to a power such that when the battery continues to output power obtained by adding the increase amount to the second upper limit value, the output duration until the battery voltage reaches the second lower limit value is the third duration.

3. The hybrid vehicle according to claim 2.

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