JP2022014156A - Plug-in hybrid vehicle and control method of plug-in hybrid vehicle - Google Patents

Abstract

To properly suppress clogging of a filter for collecting particulate matter in exhaust gas of an engine in a plug-in hybrid vehicle.SOLUTION: A PCU 60 is configured to allow a travel torque of a vehicle 1 to be outputted by using electric power discharged from a battery 80, and also to allow electric power generated by using a torque of the engine 10 to be charged to the battery 80. An ECU 100 controls the engine 10, and also controls the PCU 60 so as to suppress electric power that can be outputted from the battery 80 when the SOC of the battery 80 is lower than a prescribed value. The ECU 100 controls the engine 10 and the PCU 60 so that a vehicle 1 can travel by using electric power stored in the battery 80 without starting up the engine 10 until the SOC of the battery 80 reaches a lower limit SOC in an allowable range. The larger the amount of the particulate matter deposited on the filter 30 becomes, the higher the ECU 100 makes the lower limit SOC.SELECTED DRAWING: Figure 4

Description

The present disclosure relates to a plug-in hybrid vehicle and a control method of the plug-in hybrid vehicle, and more specifically, to a control technique of the plug-in hybrid vehicle provided with a filter for collecting particulate matter in the exhaust gas from the engine. ..

A vehicle configuration provided with a filter for collecting particulate matter (PM: Particulate Matter) in the exhaust gas from an engine is known. As the vehicle travels, PM may accumulate on the filter. Therefore, a technique for reducing the amount of PM deposited in the filter has been proposed.

For example, in the hybrid vehicle disclosed in Japanese Patent Application Laid-Open No. 2019-151260 (Patent Document 1), when the remaining capacity (SOC: State Of Charge) of the battery falls below the switching threshold value, the CD (Charge Depleting) mode is changed to CS (Charge Sustaining). ) Switch to mode. This hybrid vehicle uses a smaller value as the switching threshold value (in other words, the switching threshold value is lowered) when the PM accumulation amount is equal to or more than the predetermined accumulation amount, as compared with the case where the PM accumulation amount is less than the predetermined accumulation amount.

JP-A-2019-151260

In general, a hybrid vehicle controls the engine so that the SOC of the battery is maintained near a predetermined target value. Therefore, in a hybrid vehicle, driving and stopping of the engine are frequently repeated (so-called HV running).

On the other hand, the plug-in hybrid vehicle is configured to perform EV driving without starting the engine until the SOC of the battery falls below the allowable range (the lower limit SOC of the allowable range is reached). The lower limit SOC is often a low value. Moreover, the capacity of the battery mounted on a typical plug-in hybrid vehicle is significantly larger than the capacity of the battery mounted on a typical hybrid vehicle. Therefore, when the battery is fully charged, the plug-in hybrid vehicle can travel EV over a long distance.

Further, PM emission from the engine becomes remarkable at the time of cold start when the temperature of the engine is low. Therefore, a hybrid vehicle that frequently drives the engine warms up the engine immediately after the system is started. As a result, the amount of PM generated can be reduced. On the other hand, in the plug-in hybrid vehicle, the engine is not warmed up immediately after the system is started because the engine is driven infrequently. Therefore, when the engine of the plug-in hybrid vehicle is started, the amount of PM generated tends to be large. That is, PM is likely to be deposited on the filter.

The PM deposited on the filter can be removed by heating the filter to a high temperature using exhaust gas and burning the PM. However, in a plug-in hybrid vehicle in which the engine is driven infrequently, there are few opportunities to remove PM.

Due to such circumstances, the filter is likely to be blocked in the plug-in hybrid vehicle. Excessive blockage of the filter can cause the filter to become clogged and increase the back pressure of the engine, which can damage the engine. In addition, when the PM deposited on the filter is burned, the temperature of the filter rises excessively, and the filter and the catalyst present in the subsequent stage may be damaged. In order to protect the engine and catalyst, the engine output must be reduced. This may reduce the drivability of the plug-in hybrid vehicle.

The present disclosure has been made to solve the above problems, and an object of the present disclosure is to appropriately block a filter that collects particulate matter (PM) in engine exhaust in a plug-in hybrid vehicle. It is to suppress the deterioration of drivability while suppressing it.

(1) The plug-in hybrid vehicle according to the aspect of the present disclosure includes an engine, a filter, a power storage device, an electric drive device, and a control device. The filter collects particulate matter in the exhaust of the engine. The electric drive device can output the traveling torque of the plug-in hybrid vehicle by using the electric power discharged from the electric storage device, and can charge the electric storage device by the electric power generated by using the torque of the engine. The control device controls the engine and also controls the electric drive device so as to suppress the electric power that can be output from the power storage device when the SOC of the power storage device is lower than a predetermined value. The control device is an engine and an electric drive device so that the plug-in hybrid vehicle runs using the electric power stored in the power storage device without starting the engine until the SOC of the power storage device reaches the lower limit SOC of the allowable range. To control. The control device raises the lower limit SOC as the amount of particulate matter deposited on the filter increases.

(2) Prior to starting the engine, the control device adjusts the lower limit SOC according to the amount of particulate matter deposited on the filter, and when the SOC of the power storage device reaches the lower limit SOC and starts the engine, the output of the engine. Take control.

In the configurations (1) and (2) above, the larger the amount of particulate matter deposited on the filter, the higher the lower limit SOC. The output power from the engine decreases as the amount of particulate matter deposited increases, but by raising (raising) the lower limit SOC, the timing of switching from EV running to HV running of the plug-in hybrid vehicle can be accelerated. As a result, since the engine is started while sufficient power remains in the power storage device, it is possible to avoid suppressing the output power from the power storage device (Wout limitation described later). Therefore, it is possible to compensate for the decrease in output power from the engine by using a power storage device. Further, it is possible to warm up the engine to a temperature at which the generation of PM can be suppressed without excessively increasing the output power from the engine. Therefore, according to the configurations (1) and (2) above, it is possible to suppress the deterioration of drivability while appropriately suppressing the blockage of the filter.

(3) The control device adjusts the lower limit SOC according to the temperature of the engine in addition to the accumulated amount of particulate matter.

The amount of particulate matter emitted from the engine increases or decreases depending on the temperature of the engine. Therefore, according to the configuration of (3) above, the lower limit SOC is adjusted in consideration of the temperature of the engine in addition to the accumulated amount of particulate matter. As a result, the blockage of the filter can be suppressed more appropriately.

(4) Output control includes suppression control and raising control. The suppression control is a control that suppresses the torque of the engine and discharges the power storage device by outputting the insufficient torque due to the suppression of the torque from the electric drive device. The raising control is a control in which the torque of the engine is raised and the surplus torque due to the raising of the torque is input to the electric drive device to charge the power storage device. The control device executes suppression control when the lower limit SOC is raised, and raises control when the lower limit SOC is lowered.

(5) The control device has a first reference amount and a second reference amount larger than the first reference amount with respect to the deposited amount of the particulate matter. The control device raises the lower limit SOC when the accumulated amount of particulate matter is between the first reference amount and the second reference amount, and executes suppression control when the SOC of the power storage device reaches the lower limit SOC after raising. do. The control device lowers the lower limit SOC when the accumulated amount of the particulate matter exceeds the second reference amount, and executes the raising control when the SOC of the power storage device reaches the lower limit SOC after the lowering.

Although the details will be described later, the amount of particulate matter generated can be suppressed by the suppression control, and the amount of particulate matter deposited can be reduced by the raising control. In the configurations (4) and (5) above, suppression control and lower limit SOC increase are combined, and raising control and lower limit SOC reduction are combined. By appropriately combining suppression control / raising control and raising / lowering of the lower limit SOC, it is possible to more effectively suppress the generation amount of particulate matter and reduce the deposition amount. Therefore, according to the configurations (4) and (5) above, the blockage of the filter can be suppressed more appropriately.

(6) The plug-in hybrid vehicle further includes a temperature sensor that detects a temperature related to the temperature of the engine. The control device adjusts the lower limit SOC according to the amount of particulate matter deposited and the associated temperature.

(7) In the control device, when the deposited amount of the particulate matter exceeds the first reference amount and the related temperature is lower than the first reference temperature, the deposited amount of the particulate matter falls below the first reference amount. Moreover, the upper limit of the lower limit SOC is increased as compared with the case where the related temperature is lower than the first reference temperature.

(8) The control device increases the lower limit SOC increase as the amount of particulate matter deposited increases and the associated temperature decreases.

(9) The temperature sensor detects at least one of the intake air temperature of the engine and the cooling water temperature of the engine as the related temperature.

In the configurations (6) to (9) above, when the suppression control is executed, the lower limit SOC increase range is set according to the amount of particulate matter deposited and the related temperature. As a result, it is possible to more effectively suppress the amount of PM generated.

(10) In the control device, when the deposited amount of the particulate matter exceeds the second reference amount and the related temperature is lower than the second reference temperature, the deposited amount of the particulate matter falls below the second reference amount. Moreover, the lower limit SOC is reduced more than when the related temperature is lower than the second reference temperature.

(11) When the execution condition of the raising control is satisfied, the control device increases the lower limit SOC reduction width as the amount of deposited particulate matter increases and the related temperature decreases.

(12) The temperature sensor detects at least one of the engine exhaust temperature and the filter temperature as the related temperature.

In the configurations (10) to (12), the lower limit SOC reduction range is set according to the amount of particulate matter deposited and the related temperature when the raising control is executed. This makes it possible to more effectively reduce the amount of PM deposited.

(13) The plug-in hybrid vehicle further includes another temperature sensor that detects the temperature of the power storage device. When the temperature of the power storage device is higher than the reference temperature, the control device increases and lowers the lower limit SOC as compared with the case where the temperature of the power storage device is lower than the reference temperature.

When the temperature of the power storage device is lower than a predetermined temperature (for example, when the temperature is extremely low), it is desirable to suppress the charge / discharge power of the power storage device from the viewpoint of protecting the power storage device. On the contrary, when the temperature of the power storage device is higher than the predetermined temperature, the output of the engine can be adjusted by using the charge / discharge of the power storage device by increasing the raising width and the lowering width of the lower limit SOC. Therefore, according to the configuration of (13) above, it is possible to achieve both protection and utilization of the power storage device.

(14) In the control method of the plug-in hybrid vehicle according to another aspect of the present disclosure, the plug-in hybrid vehicle is derived from the engine, the filter for collecting the particulate matter in the exhaust of the engine, the power storage device, and the power storage device. It is equipped with an electric drive device that can output the running torque of the plug-in hybrid vehicle using the discharged power and can charge the power storage device with the power generated by using the torque of the engine. The control method includes the first to third steps. The first step is a step of controlling the electric drive device so as to suppress the electric power that can be output from the power storage device when the SOC of the power storage device is lower than a predetermined value. The second step is a step in which the plug-in hybrid vehicle runs using the electric power stored in the power storage device without starting the engine until the SOC of the power storage device reaches the lower limit SOC of the allowable range. The third step is to increase the lower limit SOC as the amount of particulate matter deposited on the filter increases.

According to the method (14) above, it is possible to suppress the deterioration of drivability while appropriately suppressing the blockage of the filter, as in the configuration of the above (1).

According to the present disclosure, in a plug-in hybrid vehicle, it is possible to suppress a decrease in drivability while appropriately suppressing a blockage of a filter.

FIG. 3 is a block diagram schematically showing an overall configuration of a vehicle according to the first embodiment. It is a figure which shows the structural example of an engine and an engine sensor. It is a figure for contrasting the driving pattern of a hybrid vehicle, and the driving pattern of a plug-in hybrid vehicle. It is a time chart which shows an example of the battery control in preparation for the engine output drop in Embodiment 1. FIG. It is a conceptual diagram for demonstrating battery control in preparation for a decrease in engine output. It is a figure which shows an example of the SOC dependence of the control upper limit value (output upper limit power Wout) of the electric power which can be output from a battery. It is a conceptual diagram for demonstrating an example of a control map used in battery control in preparation for a decrease in engine output. It is a flowchart which shows the processing procedure of the battery control which is executed in order to reduce the accumulation amount (GPF accumulation amount D) of the particulate matter on the filter in Embodiment 1. FIG. It is a figure for demonstrating suppression control. It is a figure which shows the control at a normal time for comparison. It is a figure for demonstrating the raising control. It is a conceptual diagram for demonstrating an example of the adjustment mode of the lower limit SOC according to the GPF accumulation amount. It is a time chart which shows an example of the time transition of SOC with the adjustment of the lower limit SOC. It is a conceptual diagram for demonstrating an example of a control map used for suppression control. It is a conceptual diagram for demonstrating an example of a control map used for raising control. It is a conceptual diagram for demonstrating another example of the SOC pull-up map. It is a flowchart which shows the processing procedure of the battery control which is executed in order to reduce the GPF accumulation amount D in Embodiment 2. FIG. It is a time chart which shows the transition of each parameter in a comparative example. It is a time chart which shows the transition of each parameter in Embodiment 2.

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

[Embodiment 1]
<Structure of plug-in hybrid vehicle>
FIG. 1 is a block diagram schematically showing an overall configuration of a vehicle according to the first embodiment. With reference to FIG. 1, in the present embodiment, the vehicle 1 is a plug-in hybrid vehicle (PHV (Plug-in Hybrid Vehicle) or PHEV (Plug-in Hybrid Electric Vehicle)), and is located outside the vehicle 1. It is configured to enable plug-in charging by the power supplied from the provided charging equipment (not shown).

The vehicle 1 includes an engine 10, an engine sensor 11, a catalyst device 20, a catalyst temperature sensor 21, a filter 30, motor generators (MGs: Motor Generators) 41 and 42, a power split mechanism 51, and a drive shaft 52. A speed reducer 53, a drive wheel 54, a power control unit (PCU) 60, an inlet 71, a charging relay 72, a system main relay (SMR) 73, and a battery 80. A battery sensor 81, an outside temperature sensor 90, and an electronic control unit (ECU) 100 are provided.

The engine 10 outputs a driving force for the vehicle 1 to travel according to a control command from the ECU 100. In this embodiment, a gasoline engine is adopted as the engine 10. However, the fuel of the engine 10 is not limited to gasoline, and may be another liquid fuel such as diesel fuel or biofuel (ethanol or the like). Alternatively, the fuel of the engine 10 may be a gaseous fuel (propane gas or the like).

The engine sensor 11 comprehensively describes various sensors that detect the state of the engine 10. The engine 10 and the engine sensor 11 will be described in more detail with reference to FIG.

The catalyst device 20 is provided in the exhaust flow path of the engine 10. The catalyst device 20 includes, for example, a three-way catalytic converter. The catalyst device 20 oxidizes an unburned component (for example, hydrocarbon (HC) or carbon monoxide (CO)) contained in the exhaust gas discharged from the engine 10, or an oxidizing component (for example, nitrogen oxide (NOx)). To reduce.

The catalyst temperature sensor 21 detects the temperature (catalyst temperature) Tc of the catalyst device 20 and outputs the detection result to the ECU 100.

The filter 30 is located in the exhaust flow path of the engine 10 on the downstream side of the catalyst device 20 (in the example of FIG. 2 described later, the position on the downstream side of the first catalyst 201 and the position on the upstream side of the second catalyst 202). It is provided. The filter 30 collects PM discharged from the engine 10. In the present embodiment, since the engine 10 is a gasoline engine, a GPF (Gasoline Particulate Filter) is adopted as the filter 30. Hereinafter, the amount of PM deposited on the filter 30 is also referred to as “GPF accumulated amount D”. For example, when the engine 10 is a diesel engine, the filter 30 is a DPF (Diesel Particulate Filter).

A pressure sensor 31 is provided on the upstream side of the filter 30 in the exhaust flow path of the engine 10. The pressure sensor 31 detects the pressure (upstream pressure) Pop at a position upstream of the filter 30. Further, a pressure sensor 32 is provided on the downstream side of the filter 30 in the exhaust flow path. The pressure sensor 32 detects the pressure (downstream side pressure) Pdw at a position downstream of the filter 30. Each pressure sensor outputs the detection result to the ECU 100.

Each of the motor generators 41 and 42 is, for example, a three-phase alternating current rotary electric machine in which a permanent magnet is embedded in a rotor (not shown). The motor generators 41 and 42 are both driven by the PCU 60.

The motor generator 41 is connected to the crankshaft of the engine 10 via the power split mechanism 51. The motor generator 41 uses the electric power of the battery 80 to rotate the crankshaft of the engine 10. Further, the motor generator 41 can also generate electricity by using the power of the engine 10. The AC power generated by the motor generator 41 is converted into DC power by the PCU 60 and charged into the battery 80. Further, the AC power generated by the motor generator 41 may be supplied to the motor generator 42.

The motor generator 42 rotates the drive shaft 52 using at least one of the electric power from the battery 80 and the electric power generated by the motor generator 41. Further, the motor generator 42 can also generate electricity by regenerative braking. The AC power generated by the motor generator 42 is converted into DC power by the PCU 60 and charged into the battery 80.

It is not essential that the vehicle 1 is equipped with two motor generators 41 and 42. The vehicle 1 may be a so-called one-motor hybrid vehicle.

The power split mechanism 51 mechanically connects the three elements of the crankshaft of the engine 10, the rotation shaft (not shown) of the motor generator 41, and the drive shaft 52. The power split mechanism 51 is, for example, a planetary gear mechanism including a sun gear 511, a pinion gear 512, a carrier 513, and a ring gear 514.

The drive shaft 52 is connected to the drive wheels 54 via the speed reducer 53. The speed reducer 53 transmits the power from the power split mechanism 51 or the motor generator 42 to the drive wheels 54. Further, the reaction force received by the drive wheels 54 from the road surface is transmitted to the motor generator 42 via the speed reducer 53 and the power split mechanism 51. As a result, the motor generator 42 generates electricity during regenerative braking.

The PCU 60 converts the DC power stored in the battery 80 into AC power, and supplies the AC power to the motor generators 41 and 42. Further, the PCU 60 converts the AC power generated by the motor generators 41 and 42 into DC power, and supplies the DC power to the battery 80. The PCU 60 includes, for example, a converter provided corresponding to the motor generator 41, a converter provided corresponding to the motor generator 42, and an inverter (none of which is shown). The motor generators 41 and 42, the power split mechanism 51, and the PCU 60 correspond to the "electric drive device" according to the present disclosure.

The inlet 71 is configured to allow the charging connector (not shown) of the charging cable to be inserted with mechanical connection such as fitting. With the insertion of the charging connector into the inlet 71, an electrical connection between the vehicle 1 and the charging equipment is secured. Further, the ECU 100 of the vehicle 1 and the control device of the charging equipment can transmit and receive various information such as signals and data to and from each other by communication according to a communication standard such as CAN (Controller Area Network).

The charging relay 72 is electrically connected between the inlet 71 and the PCU 60, and between the inlet 71 and the SMR 73. The SMR 73 is electrically connected between the PCU 60 and the battery 80. The closing / opening of the charging relay 72 and the SMR 73 is controlled in response to a command from the ECU 100. By closing the SMR 73, power can be transmitted between the PCU 60 and the battery 80. By closing the charging relay 72 and closing the SMR 73, electric power can be transmitted between the inlet 71 and the battery 80.

The battery 80 discharges electric power for driving the motor generators 41 and 42. Further, the battery 80 is charged by the electric power generated by the motor generators 41 and 42. As the battery 80, a secondary battery such as a lithium ion battery or a nickel hydrogen battery can be adopted. The battery 80 corresponds to the "power storage device" according to the present disclosure. A capacitor such as an electric double layer capacitor may be used as a "storage device".

The battery sensor 81 includes a voltage sensor, a current sensor, and a temperature sensor (none of which is shown). The voltage sensor detects the voltage Vb of the battery 80. The current sensor detects the current Ib input / output to / from the battery 80. The temperature sensor detects the temperature (battery temperature) Tb of the battery 80. Each sensor outputs the detection result to the ECU 100. The ECU 100 can estimate the SOC of the battery 80 based on the voltage Vb, the current Ib, and the battery temperature Tb of the battery 80. This temperature sensor corresponds to the "other temperature sensor" according to the present disclosure.

The outside air temperature sensor 90 detects the temperature (outside air temperature) Ta of the outside air of the vehicle 1 and outputs the detection result to the ECU 100.

The ECU 100 includes a processor 101 such as a CPU (Central Processing Unit), a memory 102 such as a ROM (Read Only Memory) and a RAM (Random Access Memory), an input / output port (not shown), and a counter (not shown). And include. The processor 101 executes a control program. The memory 102 stores various control programs, maps, and the like. Input / output ports control the transmission and reception of various signals. The counter measures time.

The ECU 100 controls the devices so that the vehicle 1 is in a desired state based on the signals from each sensor and the map and the program stored in the memory 102. More specifically, first, the ECU 100 determines the required driving force of the vehicle 1 according to the accelerator opening degree, the vehicle speed, and the like, and calculates the required power of the engine 10 from the required driving force. The ECU 100 determines from the required power of the engine 10, for example, an engine operating point (engine rotation speed Ne and engine torque Te) at which the fuel consumption of the engine 10 is minimized so that the system efficiency with respect to the required power of the engine 10 is optimized. Combination) is determined. Then, the ECU 100 generates a torque command for driving the motor generators 41 and 42 and controls the PCU 60 so that the engine 10 operates at the engine operating point, and controls each part of the engine 10 (throttle valve 14 described later). , Injector 17, spark plug 18, etc.).

The ECU 100 may be divided into a plurality of ECUs for each function. For example, the ECU 100 may include an engine ECU that controls the engine 10, a battery ECU that manages the battery 80, and an integrated ECU that integrally controls the entire vehicle 1.

<Engine configuration>
FIG. 2 is a diagram showing a configuration example of the engine 10 and the engine sensor 11. With reference to FIG. 2, the actual engine 10 is provided with a plurality of cylinders (cylinders). However, in order to prevent the drawings from becoming complicated, only one cylinder is typically shown in FIG.

In addition to the engine sensor 11, the engine 10 includes an air cleaner 12, an intake duct 13, a throttle valve 14, a surge tank 15, an intake manifold 16, an injector 17, a spark plug 18, and an exhaust manifold 19. .. The engine sensor 11 includes an air flow meter 111, an intake air temperature sensor 112, a throttle opening degree sensor 113, a cooling water temperature sensor 114, a knock sensor 115, a crank position sensor 116, and an air-fuel ratio sensor 117.

The air cleaner 12 removes foreign matter such as dust contained in the air (intake air) sucked from the outside of the vehicle.

The intake duct 13 connects between the air cleaner 12 and the surge tank 15, and houses the throttle valve 14 inside the air cleaner 12 and the surge tank 15.

The throttle valve 14 is controlled to open and close the intake duct 13 in conjunction with the depression of the accelerator pedal (not shown) by the user.

The surge tank 15 is provided between the intake duct 13 and the intake manifold 16 to alleviate changes in the flow rate of intake air from outside the vehicle and provide a space for supplying stable air to each cylinder.

The intake manifold 16 includes a plurality of intake branch pipes provided corresponding to the plurality of cylinders, and connects the surge tank 15 and each cylinder.

In this example, the injector 17 is provided in the combustion chamber of the cylinder and injects fuel into the combustion chamber (direct injection type). By mixing the air sucked from the air cleaner 12 and the fuel injected from the injector 17, an air-fuel mixture is generated in the combustion chamber.

The spark plug 18 is provided at the top of the combustion chamber and ignites the air-fuel mixture in the combustion chamber. When the air-fuel mixture is ignited and burned, the pressure in the combustion chamber increases, the piston is pushed down, and the crankshaft rotates. The air-fuel mixture (exhaust gas) after combustion is discharged from the combustion chamber when the exhaust valve is opened.

The exhaust manifold 19 is provided between each cylinder and the catalyst device 20 (more specifically, the first catalyst 201). The exhaust gas discharged from the combustion chamber is purified by the catalyst device 20 (first catalyst 201 and second catalyst 202), and then discharged from the main muffler (silencer) 22 to the outside of the vehicle.

The air flow meter 111 detects the amount of intake air from the air cleaner 12. The intake air temperature sensor 112 detects the temperature of the air sucked into the engine 10 (engine intake air temperature). The throttle opening sensor 113 detects the opening degree (throttle opening degree) of the throttle valve 14. The cooling water temperature sensor 114 is provided in a cooling path (not shown) of the cooling water of the engine 10 and detects the temperature (cooling water temperature) Tw of the cooling water. The knock sensor 115 is provided on the cylinder block and detects the magnitude of vibration of the engine 10. The crank position sensor 116 detects the rotation speed (engine rotation speed) Ne of the crankshaft. The air-fuel ratio sensor 117 is provided on the exhaust manifold 19 and detects the oxygen concentration in the exhaust gas. Each sensor outputs the detection result to the ECU 100.

<Battery control in preparation for engine output drop>
FIG. 3 is a diagram for comparing the traveling pattern of the hybrid vehicle and the traveling pattern of the plug-in hybrid vehicle. In FIG. 3, the horizontal axis represents the elapsed time and the vertical axis represents the SOC of the battery. The upper part of FIG. 3 shows the driving pattern of the hybrid vehicle, and the lower part shows the driving pattern of the plug-in hybrid vehicle.

Generally, the hybrid vehicle controls the engine so that the SOC of the battery is maintained within a predetermined range including a predetermined target value (also referred to as an SOC control center). Therefore, in the hybrid vehicle, the driving and stopping of the engine are frequently repeated (HV running), and the driving frequency of the engine is high. Further, PM emission from the engine becomes remarkable at the time of cold start when the temperature of the engine is low. Therefore, in a hybrid vehicle having a high engine drive frequency, the amount of PM generated is reduced by warming up the engine immediately after the system is started. Further, as will be described in detail later, the PM deposited on the filter can be removed by heating the filter to a high temperature using exhaust gas and burning the PM (regeneration of the filter).

On the other hand, the vehicle 1 which is a plug-in hybrid vehicle runs EV without starting the engine 10 until the SOC of the battery 80 reaches the lower limit of the allowable range (hereinafter, referred to as “lower limit SOC”). It is configured to do. The lower limit SOC varies depending on the vehicle type, but is often as low as about 10% to 20%. Further, the capacity of the battery 80 mounted on the vehicle 1 is significantly (for example, about 10 times) larger than the capacity of the battery mounted on a typical hybrid vehicle. Therefore, when the battery 80 is fully charged, the vehicle 1 can travel EV over a long distance (for example, several tens of kilometers). Therefore, the driving frequency of the engine 10 of the vehicle 1 is low.

Since the driving frequency of the engine 10 of the vehicle 1 is low, the engine 10 is not always warmed up immediately after the system is started. Therefore, when the vehicle 1 starts the engine 10 (when the EV traveling is stopped and the vehicle shifts to the HV traveling), the amount of PM generated becomes large and the PM tends to be deposited on the filter 30. Further, since the driving frequency of the engine 10 is low, there are few opportunities to remove the accumulated PM in the vehicle 1.

As described above, in the vehicle 1, the filter 30 is likely to be blocked. If the filter 30 is blocked excessively, the filter 30 becomes clogged and the pressure inside the exhaust manifold 19 (also called back pressure or exhaust pressure) rises, resulting in a state called pump-up, and the engine 10 (particularly the exhaust). The valve) can be damaged. Specifically, the exhaust valve does not completely close, and physical collision with the rising piston may cause damage (damage). Further, the temperature of the filter 30 rises excessively when the PM deposited on the filter 30 is burned, and the filter 30 and the catalyst device 20 provided in the subsequent stage of the filter 30 may be damaged. In order to protect the engine 10 and the catalyst device 20, the engine output must be reduced. In view of such circumstances, in the first embodiment, a configuration is adopted in which the output decrease of the engine 10 is compensated by using the battery 80 in anticipation of the output decrease of the engine 10 prior to the start of the engine 10.

In the following, the required output of the entire vehicle 1 will be referred to as "vehicle required power". The output from the engine 10 is also referred to as "engine power Pe". The output of the motor generator 42 using the discharge power from the battery 80 is also referred to as “motor power Pm”.

In the first embodiment, the “GPF deposition level”, which is an index indicating the degree of increase in the amount of PM deposited on the filter 30 (GPF deposition amount D), is defined. The GPF deposition level is divided into, for example, four stages. The state in which the filter 30 is not blocked at all corresponds to level 0, and the state in which the filter 30 is completely blocked corresponds to level 3. However, the division of the GPF deposition level into four stages is merely an example, and it may be divided into two stages or three stages, or it may be divided into five or more stages. The same applies to the example described in the second embodiment described later.

FIG. 4 is a time chart showing an example of battery control in preparation for a decrease in engine output according to the first embodiment. In FIG. 4, the horizontal axis represents the elapsed time. The vertical axis represents the GPF accumulated amount D, the maximum output from the engine 10, the GPF accumulated amount level, and the lower limit SOC of the battery 80 (the SOC in which the vehicle 1 stops EV running and starts the engine 10) in order from the top. ..

In the example shown in FIG. 4, it is assumed that PM is not deposited on the filter 30 at the initial time t0 (GPF deposition amount D = 0) and the GPF deposition level is 0. The GPF deposit amount D basically increases monotonically as the time elapses at time t1, t2, t3. When PM is deposited on the filter 30, the engine power Pe decreases according to the degree of accumulation, even if the amount is small. Therefore, as the GPF deposit amount D increases monotonically, the maximum output from the engine 10 also monotonically decreases.

The GPF deposition level gradually increases as the GPF deposition amount D increases. In the first embodiment, during EV traveling of the vehicle 1 (that is, during the period when the SOC of the battery 80 exceeds the lower limit SOC), the lower limit SOC is gradually raised in conjunction with the GPF deposition level. This makes it possible to compensate for the decrease in engine power Pe by the motor power Pm, as described below.

It is not essential to raise the lower limit SOC step by step. For example, by setting the number of divisions of the GPF deposition level to a sufficiently large number, it is possible to raise the lower limit SOC smoothly (substantially continuously).

FIG. 5 is a conceptual diagram for explaining battery control in preparation for a decrease in engine output. FIG. 5 schematically shows the ratio of the engine power Pe and the motor power Pm to the required power of the vehicle. With reference to FIG. 3, as the GPF deposition level rises, the share of engine power Pe (denoted as ENG) decreases, and the share of motor power Pm (denoted as BAT) compensates for this. To increase. Note that FIG. 5 illustrates a situation in which the required power of the vehicle is insufficient even if the engine power Pe and the motor power Pm are added together, as an example of the case where the GPF accumulation level = 3.

FIG. 6 is a diagram showing an example of SOC dependence of the control upper limit value (output upper limit power) Wout of the power that can be output from the battery 80. In FIG. 6, the horizontal axis represents the SOC of the battery 80, and the vertical axis represents the output upper limit power Wout of the battery 80.

With reference to FIG. 6, when the SOC of the battery 80 is larger than Sc1 and less than Sc2 (Sc1 <SOC <Sc2), the SOC of the battery 80 is Sc2 or more (Sc2 ≦ SOC). , Output upper limit power Wout is small. Further, when the SOC of the battery 80 is larger than Sc1 and less than Sc2, the output upper limit power Wout also decreases as the SOC of the battery 80 decreases. A decrease in the output upper limit power Wout means that the output from the battery 80 is more severely limited. In addition, Sc2 corresponds to the "predetermined value" according to the present disclosure.

As mentioned above, the lower bound SOC is a sufficiently low value (eg, 10% to 20%) and may be within (or near) the SOC range between Sc1 and Sc2. Therefore, when the engine 10 is started, the output from the battery 80 may be limited by the output upper limit power Wout. Therefore, in the first embodiment, the lower limit SOC is raised in accordance with the increase in the GPF deposition level, and the output limitation from the battery 80 due to the output upper limit power Wout is relaxed. This makes it possible to output sufficient electric power from the battery 80 so that the shortage of the engine power Pe can be supplemented by the motor power Pm.

<Control map>
The amount of PM emitted from the engine 10 shows a strong temperature dependence with respect to the temperature of the engine 10 (see FIG. 9 for details of the PM generation mechanism). Therefore, it is preferable to consider the temperature of the engine 10 when setting the lower limit SOC. Specifically, the cooling water temperature Tw of the engine 10 can be used. Then, a control map can be prepared in which the cooling water temperature Tw is associated with the lower limit SOC in addition to the GPF deposition level.

FIG. 7 is a conceptual diagram for explaining an example of a control map used in battery control in preparation for a decrease in engine output. With reference to FIG. 7, the control map MP is a two-dimensional map including the GPF deposition level and the cooling water temperature Tw as parameters.

The cooling water temperature Tw is also divided into four stages, for example, −20 ° C. (cryogenic), 0 ° C. (low temperature), 25 ° C. (normal temperature), and 40 ° C. (high temperature). However, it is confirmed and described that the classification of the cooling water temperature Tw into four stages is only an example.

In the control map MP, the larger the amount of PM deposited and the higher the GPF deposition level (to the right in the figure), the higher the lower limit SOC. Further, the lower the cooling water temperature Tw (the higher the temperature), the higher the lower limit SOC. For example, when the GPF deposition level is 0 and the cooling water temperature Tw is 40 ° C., the lower limit SOC is the lowest base value (for example, 20%). The lower limit SOC is the highest (for example, 36%) when the GPF deposition level is 3 and the cooling water temperature Tw is −20 ° C.

In Embodiment 1, the lower limit SOC is raised as the GPF deposition level rises and the filter 30 approaches occlusion. As a result, the output limit of the battery 80 due to the output upper limit power Wout can be weakened, so that even if the output of the engine 10 decreases, the decrease can be more effectively compensated by the output of the battery 80. ..

Further, the lower the cooling water temperature Tw and the more likely PM is to occur, the larger the amount of increase in the lower limit SOC. Then, the vehicle 1 in EV traveling will shift to HV traveling at an early stage. Therefore, when the engine 10 is started and the warm-up of the engine 10 is started, a certain amount of electric power remains in the battery 80. This makes it possible to complete the warm-up of the engine 10 while the output of the battery 80 can satisfy the vehicle required power. Therefore, the generation of PM can be suppressed. In this way, by using a control map that can reflect the temperature of the engine 10 in the lower limit SOC, it is possible to set a more suitable lower limit SOC.

<Control flow>
FIG. 8 is a flowchart showing a battery control processing procedure executed in order to reduce the GPF accumulation amount D in the first embodiment. The flowchart shown in FIG. 8 (and FIG. 17 described later) is, for example, from the main routine (not shown) at predetermined calculation cycles after the system start of the vehicle 1 when the SOC of the battery 80 exceeds the lower limit SOC. Called and executed repeatedly. Each step included in these flowcharts is basically realized by software processing by the ECU 100, but may be realized by hardware processing by an electronic circuit manufactured in the ECU 100. Hereinafter, the step is abbreviated as "S".

With reference to FIGS. 1, 2 and 8, in S101, the ECU 100 determines whether or not the battery 80 can be charged and discharged. For example, when the battery temperature Tb is very low (for example, when the temperature is extremely low), charging / discharging of the battery 80 may be prohibited. Further, as shown in FIG. 6, if the SOC of the battery 80 is excessively low, the discharge of the battery 80 may be prohibited. Although not shown, charging of the battery 80 may be prohibited if the SOC of the battery 80 is excessively high. When such a situation does not exist and the battery 80 is in a state where it can be charged and discharged (YES in S101), the ECU 100 advances the process to S102. If the battery 80 is not in a chargeable / dischargeable state (NO in S101), the process is returned to the main routine and another process (not shown) is executed.

In S102, the ECU 100 calculates the amount of PM deposited on the filter 30 (GPF accumulated amount D). As the GPF deposit amount D increases, the differential pressure (= Pup-Pdw) between the upstream pressure Up and the downstream pressure Pdw of the filter 30 increases. Therefore, the ECU 100 can calculate the current GPF accumulation amount D by acquiring Pup and Pdw from the pressure sensors 31 and 32 and calculating the differential pressure thereof.

In S103, the ECU 100 acquires the cooling water temperature Tw from the cooling water temperature sensor 114. The cooling water temperature Tw is an example of a parameter that can be used for estimating the temperature of the engine 10, and other parameters may be used. For example, in addition to or instead of the cooling water temperature Tw, the temperature of the engine 10 is estimated based on the engine intake air temperature detected by the intake air temperature sensor 112, the outside air temperature Ta detected by the outside air temperature sensor 90, and the like. May be good.

In S104, the ECU 100 raises the lower limit SOC by referring to the control map MP (see FIG. 7). More specifically, the ECU 100 determines the GPF accumulation amount level from the GPF accumulation amount D calculated in S102. Then, the ECU 100 sets the lower limit SOC according to the GPF deposition level and the cooling water temperature Tw acquired in S103, and raises the current lower limit SOC toward the lower limit SOC. As a result, the lower limit SOC can be increased as the GPF deposition level is higher (the larger the GPF deposition amount D is).

As described above, in the first embodiment, the higher the GPF deposition level, the higher the lower limit SOC (see FIG. 4). The engine power Pe decreases as the GPF accumulation level increases, but by raising the lower limit SOC in conjunction with the GPF accumulation level, the timing of switching from EV driving to HV driving can be accelerated. As a result, the engine 10 is started while sufficient power remains in the battery 80, and the limitation of the battery output due to the output upper limit power Wout can be avoided. Therefore, the decrease in engine power Pe can be compensated for by the motor power Pm. Further, the engine 10 can be warmed up to a temperature at which the generation of PM can be suppressed without excessively increasing the engine power Pe. As a result, the amount of PM emitted from the engine 10 can be suppressed. Therefore, according to the first embodiment, it is possible to suppress the deterioration of drivability while appropriately suppressing the blockage of the filter 30.

[Embodiment 2]
In the second embodiment, the engine 10 and the battery 80 are cooperatively controlled in order to appropriately remove the PM accumulated on the filter 30 while preventing the PM from accumulating on the filter 30. Since the overall configuration of the plug-in hybrid vehicle according to the second embodiment is the same as the overall configuration of the vehicle 1 according to the first embodiment (see FIG. 1), the description thereof will not be repeated.

<Suppression control and raising control>
In the vehicle 1, "suppression control", "raising control", and "motoring control" are executed when the engine 10 is driven. As will be described in detail below, the suppression control is a control for reducing the PM emission amount from the engine 10. The raising control and the motoring control are controls for removing PM accumulated on the filter 30 (that is, regenerating the filter 30).

FIG. 9 is a diagram for explaining suppression control. With reference to FIG. 9, the suppression control is a control for reducing the PM emission amount from the engine 10 by suppressing the engine torque Te when the GPF accumulation amount D exceeds the first reference amount REF1. ..

More specifically, when the suppression control is executed, the ECU 100 reduces the fuel injection amount from the injector 17 and controls the ignition timing by the spark plug 18 to the retard side as compared with the time when the suppression control is not executed. By reducing the fuel injection amount, the amount of fuel adhering to the cylinder wall surface (bore wall surface) can be reduced. In addition, by retarding the ignition timing, the thermal efficiency of the engine 10 can be intentionally reduced. Then, the heat loss in the engine 10 increases (that is, the engine 10 warms up quickly), and the temperature of the cylinder wall surface rises. As a result, the fuel adhering to the cylinder wall surface tends to volatilize.

As described above, in the suppression control, the adhesion of fuel to the cylinder wall surface is suppressed by reducing the fuel injection amount, and the volatilization of fuel from the cylinder wall surface is promoted by the retard angle of the ignition timing. As a result, the amount of PM emitted from the engine 10 can be reduced.

When the engine torque Te required to drive the vehicle 1 (for example, steady running at a constant speed) is T0, the ECU 100 executing the deterrence control sets the engine torque Te to a value smaller than T0 by ΔT1. (Te = T0-ΔT1). At the same time, the ECU 100 generates a torque command to the motor generator 42 so that the motor torque increases by the amount of the decrease in the engine torque Te. As a result, a torque (so to speak, an assist torque) that compensates for the insufficient torque ΔT1 is output from the motor generator 42. By compensating for the drop in the driving force of the vehicle 1 with the assist torque, the required driving force according to the user operation (accelerator opening) can be realized. When the suppression control is executed, the electric power for outputting the assist torque to the motor generator 42 is discharged from the battery 80.

In addition, in FIG. 2 and FIG. 9, the configuration in which the injector 17 is a direct injection type has been described as an example. In the direct injection type, the fuel easily adheres to the cylinder wall surface, so there is a great need to remove the adhered fuel, and the effect of suppression control is also high. However, the fuel injection method is not limited to the direct injection type, and may be a port injection type that injects fuel toward the intake port or the intake branch pipe, and the direct injection type and the port injection type are used in combination. It may be a dual injector type.

FIG. 10 is a diagram showing the control in the normal time (when the raising control is not executed) for comparison. FIG. 11 is a diagram for explaining the raising control. With reference to FIGS. 10 and 11, the raising control is to increase the engine torque Te to regenerate the filter 30 when the GPF deposition amount D exceeds the second reference amount REF2 (REF2> REF1) ( In other words, it is a control that reduces the amount of PM deposited in the filter 30 by raising the volume).

More specifically, when the raising control is executed, the ECU 100 adjusts the throttle opening so that the intake amount from the outside of the vehicle increases as compared with the non-execution of the raising control, and adjusts the fuel injection amount from the injector 17. increase. Further, the ECU 100 controls the spark plug 18 so that the optimum ignition timing according to the intake amount, the fuel injection amount, the cooling water temperature Tw, and the like is realized. Then, since the engine output increases, the temperature of the exhaust gas discharged from the engine 10 rises. By raising the temperature of the filter 30 and raising the temperature of the filter 30 to a renewable temperature (for example, 500 ° C to 600 ° C) or higher, the PM deposited on the filter 30 is oxidized by a combustion reaction with nitrogen dioxide (NO ₂ ) or the like. Can be removed.

As described above, in the raising control, the combustion of the fuel in the engine 10 is promoted by controlling the intake amount, the fuel injection amount, the ignition timing and the like. As a result, the amount of PM deposited in the filter 30 can be reduced.

When the engine torque Te required to drive the vehicle 1 (steady running, etc.) is T0, the ECU 100 during the raising control sets the engine torque Te to a value larger than T0 by ΔT2 (Te =). T0 + ΔT2). The increased torque ΔT2 is transmitted to the motor generator 42 via the power split mechanism 51. By allocating an excessive driving force (surplus torque) to the regeneration by the motor generator 42 with respect to the driving force required for the running of the vehicle 1, the required driving force according to the user operation can be realized. When the raising control is executed, the electric power generated by the motor generator 42 is charged to the battery 80 by using the surplus torque.

The motoring control (see FIG. 9) is a control that uses the torque of the motor generator 41 to rotate the crankshaft (not shown) of the engine 10 in a state where combustion is stopped. Air is sucked into the engine 10 as the crankshaft rotates. The oxygen in the sucked air is supplied to the filter 30 without being burned by the engine 10. Therefore, since the combustion state of PM in the filter 30 is improved, the removal of PM accumulated in the filter 30 can be promoted. When the motoring control is executed, the electric power for rotating the crankshaft of the engine 10 is discharged from the battery 80 to the motor generator 41.

The suppression control and the raising control correspond to the "output control" according to the present disclosure. Although the raising control and the motoring control can be combined as the control for regenerating the filter 30, the motoring control is not an essential control in the present disclosure.

<Adjustment of lower limit SOC>
In the second embodiment, the ECU 100 suppresses the blockage of the filter 30 by appropriately using the suppression control and the raising control. As described above, in the suppression control, the electric power stored in the battery 80 is consumed to drive the motor generator 42. On the other hand, in the raising control, the electric power generated by the motor generator 42 using the surplus torque of the engine 10 is stored in the battery 80. Therefore, the length of the period during which the suppression control can be executed (and the amount of torque decrease of the engine 10) and the length of the period during which the raising control can be executed (and the amount of torque increase of the engine 10) are both of the battery 80. Depends on SOC. Therefore, the suppression control and the raising control are executed in association with the adjustment of the lower limit SOC.

FIG. 12 is a conceptual diagram for explaining an example of the adjustment mode of the lower limit SOC according to the GPF accumulation amount D. In FIG. 12, the horizontal axis represents the GPF deposit amount D. The vertical axis represents the lower limit SOC. FIG. 13 is a time chart showing an example of the time transition of the SOC accompanying the adjustment of the lower limit SOC. In FIG. 13, the horizontal axis represents the elapsed time. The vertical axis represents the SOC of the battery 80.

With reference to FIGS. 12 and 13, in this example, as described above, when the GPF deposit amount D is sufficiently small and less than the first reference amount REF1, normal control (normal control) is executed. .. The lower limit SOC in normal control is L0. When the SOC of the battery 80 drops to L0, the vehicle 1 switches the traveling mode from EV traveling to HV traveling, and the engine 10 can be driven (see time t10). By driving the engine 10, the SOC of the battery 80 can be raised to a state higher than the lower limit SOC.

On the other hand, when the GPF deposit amount D increases and becomes equal to or more than the first reference amount REF1 and less than the second reference amount REF2, the condition for executing the suppression control may be satisfied. In the second embodiment, the lower limit SOC is raised from L0 to L1 (L0 <L1) prior to the start of execution of the suppression control (see time t11).

If the SOC of the battery 80 is excessively low, the power required for the motor generator 42 cannot be supplied from the battery 80, and the suppression control may not be effectively executed. By raising the lower limit SOC of the SOC control range from L0 to L1 prior to the start of suppression control, the stored power of the battery 80 increases compared to the normal time, and the amount of power that can be supplied from the battery 80 to the motor generator 42 increases. To increase. This corresponds to preparing the electric power for compensating for the insufficient torque of the engine 10 by the assist torque from the motor generator 42 in the battery 80 in preparation for the execution of the suppression control. As a result, it is possible to prolong the time during which the suppression control can be executed and to increase the torque reduction amount of the engine 10 as compared with the case where the lower limit SOC is maintained at L0. In other words, the suppression control can be executed more effectively.

Further, in this example, when the GPF deposit amount D is further increased and becomes the second reference amount REF2 or more, the condition for executing the raising control may be satisfied. In the second embodiment, the lower limit SOC is lowered from L0 to L2 (L2 <L0) prior to the start of execution of the raising control, contrary to the preparation for execution of the suppression control (see time t12).

If the SOC of the battery 80 is excessively high, there is a possibility that the raising control cannot be effectively executed because the battery 80 does not have a margin for charging the electric power generated by the motor generator 41. By lowering the lower limit SOC of the SOC control range from L0 to L2 prior to the start of raising control, the stored power of the battery 80 is reduced compared to the normal time, and the amount of power that can be charged from the motor generator 41 to the battery 80 is increased. To increase. This corresponds to preparing a free capacity in the battery 80 for charging the generated power of the motor generator 42 due to the surplus torque of the engine 10 in preparation for the execution of the raising control. As a result, it is possible to prolong the time during which the raising control can be executed and to increase the amount of increase in the engine torque Te, as compared with the case where the lower limit SOC is maintained at L0. In other words, the raising control can be executed more effectively.

Note that FIG. 12 shows an example in which suppression control is first executed and then raising control is executed as the GPF deposit amount D increases. However, it is not essential to execute the suppression control and the raising control in this order as the GPF deposit amount D increases. For example, even when the GPF deposit amount D is between the first reference amount REF1 and the second reference amount REF2, the raising control may be appropriately (for example, periodically) executed.

FIG. 14 is a conceptual diagram for explaining an example of a control map used for suppression control. With reference to FIG. 14, the SOC raising map MP1 is used in raising the lower limit SOC prior to the start of suppression control. The SOC pull-up map MP1 is, in this example, a two-dimensional map including the GPF deposition level and the cooling water temperature Tw as parameters.

In the SOC raising map MP1, the larger the amount of PM deposited and the higher the GPF deposition level, the higher the lower limit SOC, L1. Further, the lower the cooling water temperature Tw, the higher the L1. For example, when the GPF deposition level is 0 and the cooling water temperature Tw is 40 ° C., L1 is the lowest base value (as an example, L1 (level 0.40 ° C.) = 20%). When the GPF deposition level is 3 and the cooling water temperature Tw is −20 ° C., L1 is the highest (L1 (level 3, −20 ° C.) = 36%). As described above, the lower the SOC (= L1), the higher the GPF deposition level and the closer the filter 30 is to blockage, and the lower the cooling water temperature Tw and the more likely it is that new PM is deposited on the filter 30. By increasing the amount of pulling up, the effect of suppression control can be further enhanced.

FIG. 15 is a conceptual diagram for explaining an example of a control map used for raising control. With reference to FIG. 15, the SOC reduction map MP2 is used in the reduction of the lower limit SOC prior to the start of the raising control. The SOC pull-down map MP2 is a two-dimensional map including the GPF deposition level and the cooling water temperature Tw as parameters, similar to the SOC pull-up map MP1.

In the SOC reduction map MP2, the larger the amount of PM deposited and the higher the GPF deposition level, the lower the lower limit L2. Further, the lower the cooling water temperature Tw, the lower the L2. For example, when the GPF deposition level is 0 and the cooling water temperature Tw is 40 ° C., L2 is the highest base value (as an example, L2 (level 0.40 ° C.) = 25%). When the GPF deposition level is 3 and the cooling water temperature Tw is −20 ° C., L2 is the lowest (for example, L2 (level 3, −20 ° C.) = 20%). As described above, the lower the SOC (= L2), the higher the GPF deposition level and the closer the filter 30 is to blockage, and the lower the cooling water temperature Tw and the more likely it is that new PM is deposited on the filter 30. By increasing the pulling width of, the effect of raising control can be further enhanced.

In FIGS. 14 and 15, it was explained that the cooling water temperature Tw is used in both the SOC raising map MP1 and the SOC lowering map MP2. However, in the SOC raising map MP1, the engine intake air temperature may be used in place of or in addition to the cooling water temperature Tw. That is, the SOC pull-up map MP1 may be a two-dimensional map including the GPF accumulation level and the engine intake air temperature, or may be a three-dimensional map including the GPF accumulation level, the cooling water temperature Tw, and the engine intake air temperature. ..

Further, in the SOC reduction map MP2, the temperature of the filter 30 may be used in place of or in addition to the cooling water temperature Tw. That is, the SOC reduction map MP2 may be a two-dimensional map including the GPF deposition level and the temperature of the filter 30, or a three-dimensional map including the GPF deposition level, the cooling water temperature Tw, and the temperature of the filter 30. May be good. The temperature of the filter 30 may be directly measured by providing the filter 30 with a temperature sensor, or may be estimated from the outside air temperature Ta or the like.

In this example, any level among the GPF deposition levels divided into a plurality of categories corresponds to the "first reference amount" or "second reference amount" according to the present disclosure. Further, any temperature among the cooling water temperature Tw divided into a plurality of categories corresponds to the "first reference temperature" or the "second reference temperature" according to the present disclosure.

FIG. 16 is a conceptual diagram for explaining another example of the SOC pull-up map MP1. As shown in FIG. 16, the SOC pull-up map MP1 may include the battery temperature Tb as parameters in addition to the GPF deposition level and the cooling water temperature Tw. When the battery temperature Tb is lower than a predetermined temperature (for example, when the temperature is extremely low), it is desirable to suppress the charge / discharge power (input / output) of the battery 80 in order to protect the battery 80. On the contrary, when the battery temperature Tb is higher than the predetermined temperature, the engine output can be adjusted by using the charging / discharging of the battery 80 by increasing the raising width and the lowering width of the lower limit SOC. Therefore, by further considering the battery temperature Tb, it becomes possible to more effectively execute the suppression control while achieving both protection and utilization of the battery 80. Here, the SOC pull-up map MP1 has been described as an example, but the battery temperature Tb can also be included in the parameter for the SOC pull-down map MP2.

<Control flow>
FIG. 17 is a flowchart showing a battery control processing procedure executed in order to reduce the GPF accumulation amount D in the second embodiment. With reference to FIG. 17, in S201, the ECU 100 determines whether or not the battery 80 can be charged and discharged. Since this process is the same as the process of S101 in the first embodiment (see FIG. 8), the description thereof will not be repeated.

In S202, the ECU 100 calculates the amount of PM deposited on the filter 30 (GPF accumulated amount D) in the same manner as the processing of S102 in the first embodiment. Then, the ECU 100 determines whether or not the calculated GPF accumulated amount D is equal to or larger than the first reference amount REF1 (S203). When the GPF accumulated amount D is equal to or larger than the first reference amount REF1 (YES in S203), the ECU 100 advances the process to S204.

When the GPF accumulation amount D is less than the first reference amount REF1 (NO in S203), the ECU 100 considers that it is not necessary to adjust the lower limit SOC for suppression control or raising control, and the ECU 100 performs the subsequent processing. Returns the process to the main routine without executing.

In S204, the ECU 100 determines whether or not the execution condition of the suppression control is satisfied. The ECU 100 can determine, for example, that the execution condition of the suppression control is satisfied when the GPF accumulation amount D is equal to or more than the first reference amount REF1 and less than the second reference amount REF2 (REF1 ≦ D <REF2).

However, the situation in which the suppression control execution condition is satisfied is not limited to this, and for example, the suppression control execution condition is set when the elapsed time from the previous execution time of the suppression control to the present exceeds a predetermined period. It may be established. This makes it possible to periodically execute suppression control regardless of the amount of GPF deposit D. As the execution condition of the suppression control, a condition relating to the GPF accumulation amount D and a condition relating to the elapsed time from the previous execution of the suppression control may be appropriately combined.

When the execution condition of the suppression control is satisfied (YES in S204), the ECU 100 acquires the cooling water temperature Tw from the cooling water temperature sensor 114 (S205). The ECU 100 may acquire the engine intake air temperature in place of or in addition to the cooling water temperature Tw.

In S206, the ECU 100 calculates the lower limit SOC (= L1) from the GPF deposition level determined according to the GPF deposition amount D and the cooling water temperature Tw by referring to the SOC pull-up map MP1 (see FIG. 14). The ECU 100 may calculate the raising width of the lower limit SOC based on the base value. Then, the ECU 100 sets the lower limit SOC to the calculated value. That is, the ECU 100 raises the lower limit SOC from L0 to L1.

After that, the ECU 100 determines whether or not the suppression control start condition is satisfied (S207). Specifically, the ECU 100 can determine that the suppression control start condition is satisfied when the SOC of the battery 80 drops to the lower limit SOC (= L1) set in S206. The ECU 100 may return the process to S205 until the suppression control start condition is satisfied, and update the lower limit SOC to a value corresponding to the latest cooling water temperature Tw.

When the suppression control start condition is satisfied (YES in S207), the ECU 100 starts suppression control (S208). Since the suppression control has been described in detail in FIG. 9, the description here will not be repeated.

In S209, the ECU 100 determines whether or not the end condition of the suppression control is satisfied. For example, when a predetermined time (for example, 10 to 15 minutes) has elapsed since the suppression control was started, the ECU 100 can determine that the suppression control end condition is satisfied.

The ECU 100 returns the process to S208 (NO in S209) until the end condition of the suppression control is satisfied, and continues the suppression control with the lower limit SOC raised. When the suppression control end condition is satisfied (YES in S209), the ECU 100 ends the suppression control, ends the raising of the lower limit SOC, and returns the lower limit SOC to the normal value (= L0) (S210).

When the execution condition of the suppression control is not satisfied in S204 (NO in S204), the ECU 100 advances the process to S211 and determines whether or not the execution condition of the raising control is satisfied. The ECU 100 can determine, for example, that the execution condition of the raising control is satisfied when the GPF accumulation amount D is the second reference amount REF2 or more (REF2 ≦ D). However, the situation in which the raising control execution condition is satisfied is not limited to this, and for example, when the elapsed time from the previous execution time of the raising control to the present exceeds a predetermined period, the raising control execution condition is set. It may be established. This makes it possible to periodically execute the raising control regardless of the amount of GPF deposit D. The execution condition of the raising control may be a combination of the condition relating to the GPF deposit amount D and the condition relating to the elapsed time from the previous execution.

When the execution condition of the raising control is satisfied (YES in S211), the ECU 100 acquires the cooling water temperature Tw from the cooling water temperature sensor 114 (S212). The ECU 100 may estimate the temperature of the engine 10 from the outside air temperature Ta or the like.

In S213, the ECU 100 calculates the lower limit SOC (= L2) from the GPF deposition level and the cooling water temperature Tw by referring to the SOC reduction map MP2 (see FIG. 15). Then, the ECU 100 lowers the lower limit SOC from L0 to L2.

After that, the ECU 100 determines whether or not the raising control start condition is satisfied (S214). Specifically, the ECU 100 can determine that the raising control start condition is satisfied when the SOC of the battery 80 drops to the lower limit SOC (= L2) set in S213. The ECU 100 may return the process to S212 until the raising control start condition is satisfied, and update the lower limit SOC to a value corresponding to the latest cooling water temperature Tw.

When the raising control start condition is satisfied (YES in S214), the ECU 100 starts the raising control (S215). Since the raising control has been described with reference to FIGS. 10 and 11, the description will not be repeated.

In S216, the ECU 100 determines whether or not the end condition of the raising control is satisfied. For example, when the specified time has elapsed since the raising control was started, the ECU 100 can determine that the raising control end condition is satisfied.

The ECU 100 returns the process to S215 (NO in S216) until the end condition of the raising control is satisfied, and continues the raising control with the lower limit SOC raised. When the raising control end condition is satisfied (YES in S216), the ECU 100 ends the raising control, finishes raising the lower limit SOC, and returns the lower limit SOC to the normal value (= L0) (S217). Normally, by returning the lower limit SOC to the value before raising it, it is possible to prevent the deterioration of the fuel efficiency of the vehicle 1.

<Effect of suppression control>
Finally, the effect of suppression control in the second embodiment will be described. In the following, for ease of understanding, it is compared with a comparative example in which suppression control is not executed.

FIG. 18 is a time chart showing the transition of each parameter in the comparative example. FIG. 19 is a time chart showing the transition of each parameter in the second embodiment. In FIGS. 18 and 19, the horizontal axis represents the elapsed time. The vertical axis represents the vehicle speed, the SOC of the battery 80, the discharge power (battery output) from the battery 80, the engine rotation speed Ne, and the cooling water temperature Tw in order from the top.

First, referring to FIG. 18, in the comparative example, the SOC of the battery 80 gradually decreases as the vehicle 1 travels EV, and reaches the lower limit SOC (= L0) at time t90. As a result, the vehicle 1 shifts from EV traveling to HV traveling, and the engine 10 is started. However, it takes some time for the engine 10 to be sufficiently warmed up.

When the SOC of the battery 80 is lowered, the output upper limit power Wout from the battery 80 is suppressed as compared with the case where the SOC of the battery 80 is sufficiently high (see FIG. 6). In this example, the suppression of the output upper limit power Wout starts from the time when the SOC of the battery 80 reaches L0, and the output upper limit power Wout (absolute value) becomes smaller. Since the battery output is limited by the output upper limit power Wout, the power required for the motor generator 42 cannot be supplied from the battery 80.

On the other hand, the vehicle 1 tries to secure a driving force (actual driving force) commensurate with the required driving force according to the user operation from the viewpoint of improving drivability. Therefore, if the battery 80 cannot supply the necessary electric power to the motor generator 42, the engine output may be increased even before the engine 10 has warmed up. Then, the PM emission amount from the engine 10 may increase, and the GPF accumulation amount D may increase.

On the other hand, in the second embodiment, as shown in FIG. 19, the lower limit SOC of the battery 80 is raised from L0 to L1. As a result, the SOC of the battery 80 reaches the lower limit SOC at an earlier timing than that of the comparative example (see time t20). That is, the timing of switching from EV driving to HV driving is earlier. At this point, the SOC of the battery 80 is relatively high, so that the battery output is not limited by the output upper limit power Wout. Then, since it is not necessary to increase the engine output in order to compensate for the limitation of the battery output, the PM emission amount from the engine 10 can be suppressed and the GPF accumulated amount D can be reduced.

As described above, in the second embodiment, the ECU 100 has a temperature related to the amount of PM deposited in the filter 30 (GPF accumulated amount D) and the amount of PM that can be generated from the engine 10 or the amount of PM that can be removed from the filter 30. The lower limit SOC is adjusted according to the index (cooling water temperature Tw, engine intake temperature, outside air temperature Ta, etc.). Then, the ECU 100 executes suppression control when the lower limit SOC is raised, and executes raising control when the lower limit SOC is lowered.

Also in the vehicle 1, regardless of whether suppression control or raising control is executed (or simply without executing suppression control or raising control as in Patent Document 1), the lower limit SOC of the battery 80 is lowered. It is also conceivable to delay the switching timing from EV driving to HV driving due to the decrease in SOC. Then, as compared with the case where the lower limit SOC is not lowered, the PM emission amount can be reduced by the amount that the mileage (EV mileage) in the state where the engine 10 is stopped becomes longer. The control of lowering the lower limit SOC in this way is based on the technical idea that the conditions for the vehicle 1 to start the engine 10 are strict in order to reduce the PM emission amount.

On the other hand, in the second embodiment, the suppression control and the lower limit SOC are combined, and the raising control and the lower limit SOC are combined. More specifically, when the purpose is to reduce the amount of PM that can be generated from the engine 10, the suppression control and the raising of the lower limit SOC are combined, and the switching timing from EV driving to HV driving is intentionally accelerated. Then, since the engine 10 is started while sufficient power remains in the battery 80, further deterioration of SOC can be prevented. As a result, the limitation of the battery output due to the output upper limit power Wout can be avoided, so that the engine 10 can be warmed up to a temperature at which the generation of PM can be suppressed without excessively increasing the engine output. As a result, the PM emission amount from the engine 10 can be suppressed and the GPF accumulation amount D can be reduced.

On the other hand, when the purpose is to increase the amount of PM that can be removed from the filter 30, the raising control and the lowering of the lower limit SOC are combined to delay the switching timing from EV running to HV running. Then, the SOC of the battery 80 is lowered, and the engine 10 can be started after securing a sufficient charge margin for the battery 80. This makes it possible to charge the battery 80 with the electric power generated by the motor generator 41 using the surplus torque from the engine 10 for a longer period of time. As a result, the amount of PM removed from the filter 30 can be increased, and the amount of GPF deposited can be reduced. Therefore, according to the second embodiment, by appropriately combining the suppression control, the raising control, and the adjustment of the lower limit SOC, it is possible to suppress the decrease in drivability while appropriately suppressing the blockage of the filter 30.

The embodiments disclosed this time should be considered to be exemplary and not restrictive in all respects. The scope of the present disclosure is set forth by the claims rather than the description of the embodiments described above, and is intended to include all modifications within the meaning and scope of the claims.

1 vehicle, 10 engine, 11 engine sensor, 111 air flow meter, 112 sensor, 113 throttle opening sensor, 114 cooling water temperature sensor, 115 knock sensor, 116 crank position sensor, 117 air fuel ratio sensor, 12 air cleaner, 13 intake duct, 14 Throttle valve, 15 surge tank, 16 intake manifold, 17 injector, 18 ignition plug, 19 exhaust manifold, 20 catalyst device, 201 first catalyst, 202 second catalyst, 21 catalyst temperature sensor, 22 main muffler, 30 filter, 31,32 pressure sensor, 41,42 motor generator, 51 power split mechanism, 511 sun gear, 512 pinion gear, 513 carrier, 514 ring gear, 52 drive shaft, 53 speed reducer, 54 drive wheel, 60 PCU, 71 inlet, 72 charging relay , 80 battery, 81 battery sensor, 90 outside temperature sensor, 100 ECU, 101 processor, 102 memory.

Claims (14)

It ’s a plug-in hybrid vehicle.
With the engine
A filter that collects particulate matter in the exhaust of the engine,
Power storage device and
An electric drive device configured to be able to output the traveling torque of the plug-in hybrid vehicle using the power discharged from the power storage device and to charge the power storage device with the power generated using the torque of the engine. When,
A control device for controlling the engine and controlling the electric drive device so as to suppress the electric power that can be output from the power storage device when the SOC of the power storage device is lower than a predetermined value is provided.
The control device is
Until the SOC of the power storage device reaches the lower limit SOC of the allowable range, the engine and the electricity so that the plug-in hybrid vehicle runs using the electric power stored in the power storage device without starting the engine. Control the drive,
A plug-in hybrid vehicle in which the lower limit SOC is increased as the amount of particulate matter deposited on the filter is large. The control device is
Prior to starting the engine, the lower limit SOC is adjusted according to the amount of particulate matter deposited on the filter.
The plug-in hybrid vehicle according to claim 1, wherein when the SOC of the power storage device reaches the lower limit SOC and the engine is started, the output control of the engine is executed. The plug-in hybrid vehicle according to claim 2, wherein the control device adjusts the lower limit SOC according to the temperature of the engine in addition to the accumulated amount of the particulate matter. The output control includes suppression control and raising control.
The suppression control is a control for suppressing the torque of the engine and discharging the power storage device by outputting the insufficient torque due to the suppression of the torque from the electric drive device.
The raising control is a control in which the torque of the engine is raised and the surplus torque due to the raising of the torque is input to the electric drive device to charge the power storage device.
The plug-in hybrid vehicle according to claim 2, wherein the control device executes the suppression control when the lower limit SOC is raised, and executes the raising control when the lower limit SOC is lowered. The control device is
With respect to the deposited amount of the particulate matter, it has a first reference amount and a second reference amount larger than the first reference amount.
When the deposited amount of the particulate matter is between the first reference amount and the second reference amount, the lower limit SOC is raised, and when the SOC of the power storage device reaches the lower limit SOC after raising, the suppression is performed. Take control and
4. The raising control is executed when the accumulated amount of the particulate matter exceeds the second reference amount, the lower limit SOC is lowered, and when the SOC of the power storage device reaches the lower limit SOC after the lowering. The plug-in hybrid vehicle described in. Further equipped with a temperature sensor for detecting a temperature related to the temperature of the engine,
The plug-in hybrid vehicle according to claim 4, wherein the control device adjusts the lower limit SOC according to the accumulated amount of the particulate matter and the associated temperature. In the control device, when the deposited amount of the particulate matter exceeds the first reference amount and the related temperature is lower than the first reference temperature, the deposited amount of the particulate matter is the first reference. The plug-in hybrid vehicle according to claim 6, wherein the lower limit SOC is raised more than when the amount is lower than the amount and the related temperature is lower than the first reference temperature. The plug-in hybrid vehicle according to claim 6, wherein the control device increases the amount of increase in the lower limit SOC as the amount of accumulated particulate matter increases and the associated temperature decreases. The plug-in hybrid vehicle according to claim 7 or 8, wherein the temperature sensor detects at least one of the intake air temperature of the engine and the cooling water temperature of the engine as the related temperature. In the control device, when the deposited amount of the particulate matter is higher than the second reference amount and the related temperature is lower than the second reference temperature, the deposited amount of the particulate matter is the second reference amount. The plug-in hybrid vehicle according to claim 6, wherein the lower limit SOC is reduced more than when the amount is lower than the amount and the related temperature is lower than the second reference temperature. When the execution condition of the raising control is satisfied, the control device increases the lower limit SOC reduction width as the amount of the particulate matter deposited increases and the related temperature decreases. The plug-in hybrid vehicle according to claim 6. The plug-in hybrid vehicle according to claim 10 or 11, wherein the temperature sensor detects at least one of the exhaust temperature of the engine and the temperature of the filter as the related temperature. Further equipped with another temperature sensor for detecting the temperature of the power storage device,
When the temperature of the power storage device is higher than the reference temperature, the control device increases the increase and decrease width of the lower limit SOC as compared with the case where the temperature of the power storage device is lower than the reference temperature. The plug-in hybrid vehicle according to any one of claims 1 to 12. It is a control method for plug-in hybrid vehicles.
The plug-in hybrid vehicle is
With the engine
A filter that collects particulate matter in the exhaust of the engine,
Power storage device and
An electric drive device configured to be able to output the traveling torque of the plug-in hybrid vehicle using the power discharged from the power storage device and to charge the power storage device with the power generated using the torque of the engine. And with
The control method is
When the SOC of the power storage device is lower than a predetermined value, a step of suppressing the power that can be output from the power storage device, and
Until the SOC of the power storage device reaches the lower limit SOC of the allowable range, the plug-in hybrid vehicle travels using the electric power stored in the power storage device without starting the engine.
A method for controlling a plug-in hybrid vehicle, comprising a step of increasing the lower limit SOC as the amount of particulate matter deposited on the filter is larger.

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