Control method of hybrid vehicle

Abstract

To enable a filter to be regenerated efficiently even during a short trip.SOLUTION: A CPU 72 executes: processing for obtaining a running pattern of a vehicle before the vehicle starts running; processing for estimating running power that is required in the running pattern; processing for creating an engine output plan for adjusting output of an internal combustion engine 10 in order to perform processing for regenerating a GPF34 during a trip in the running pattern; processing for calculating predicted charging / discharging amounts of a battery 250 in the running pattern; processing for obtaining allowable charge amounts and allowable discharge amounts of the battery 250; processing for correcting the engine output plan to a plan in which output of the engine is set to be lower, when charge amounts indicated in the predicted charge / discharge amounts are larger in comparison with the allowable charge amounts; and processing for correcting the engine output plan to a plan in which the output of the engine is set to be higher, when the discharge amounts indicated in the predicted charge / discharge amounts are larger in comparison with the allowable discharge amounts.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a control method for a hybrid vehicle.

Background Art

[0002] For example, the hybrid vehicle described in Patent Document 1 includes a filter for collecting particulate matter contained in the exhaust gas of an internal combustion engine and a battery. During parking, the filter is regenerated by operating the internal combustion engine or using the battery.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] As methods for regenerating the filter, there are increasing the temperature of the filter using the exhaust heat of the internal combustion engine, supplying oxygen to the filter through fuel cut, and the like. Here, hybrid vehicles tend to have fewer opportunities to operate the internal combustion engine compared to vehicles equipped with only an internal combustion engine. Therefore, in a short trip with a short driving distance or driving time, it may be difficult to efficiently perform filter regeneration.

Means for Solving the Problems

[0005] The control method for a hybrid vehicle that solves the above problems is a control method for a hybrid vehicle including an internal combustion engine and an electric motor as prime movers of the vehicle, a filter that collects particulate matter in exhaust gas, and a battery that is charged using the output of the internal combustion engine and supplies electric power to the electric motor. This control method includes steps of acquiring a driving pattern of the vehicle before starting driving, estimating driving power required in the driving pattern, creating an engine output plan for adjusting the output of the internal combustion engine to perform a regeneration process of the filter during a trip in the driving pattern, calculating an expected charge / discharge amount of the battery in the driving pattern, acquiring an allowable charge amount and an allowable discharge amount of the battery, correcting the engine output plan to be closer to a low output when the charge amount indicated by the expected charge / discharge amount is larger than the allowable charge amount, and correcting the engine output plan to be closer to a high output when the discharge amount indicated by the expected charge / discharge amount is larger than the allowable discharge amount.

Advantages of the Invention

[0006] This control method for a hybrid vehicle can efficiently perform filter regeneration even during a short trip.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

Modes for Carrying Out the Invention

[0008] Hereinafter, an embodiment of the control method for a hybrid vehicle will be described with reference to the drawings. <Configuration of Internal Combustion Engine, Drive System, and Control Device> As shown in FIG. 1, the vehicle 500 is a hybrid vehicle equipped with an internal combustion engine 10 and an electric motor as prime movers. The internal combustion engine 10 includes four cylinders #1 to #4. A throttle valve 14 is provided in the intake passage 12 of the internal combustion engine 10. A port injection valve 16 for injecting fuel into the intake port 12a, which is the downstream portion of the intake passage 12, is provided in the intake port 12a. The air inhaled into the intake passage 12 and the fuel injected from the port injection valve 16 flow into the combustion chamber 20 as the intake valve 18 opens. Fuel is injected into the combustion chamber 20 from an in-cylinder injection valve 22. Further, the air-fuel mixture in the combustion chamber 20 is subjected to combustion by the spark discharge of the spark plug 24. The combustion energy generated at that time is converted into the rotational energy of the output shaft 26.

[0009] The air-fuel mixture subjected to combustion in the combustion chamber 20 is discharged into the exhaust passage 30 as exhaust as the exhaust valve 28 opens. An oxidation catalyst 32 and a gasoline particulate filter (hereinafter referred to as GPF) 34 for collecting particulate matter (hereinafter referred to as PM) in the exhaust are provided in the exhaust passage 30. Note that a three-way catalyst is supported on the GPF 34.

[0010] The output shaft 26 is mechanically connected to the carrier C of the planetary gear mechanism 50 that constitutes a power split device. The rotating shaft 52a of a first motor generator (hereinafter referred to as the first MG) 52, which is an electric motor, is mechanically connected to the sun gear S of the planetary gear mechanism 50. Further, the rotating shaft 54a of a second motor generator (hereinafter referred to as the second MG) 54, which is an electric motor, and the drive wheels 60 are mechanically connected to the ring gear R of the planetary gear mechanism 50. This second MG is mainly used as the prime mover of the vehicle 500.

[0011] The first MG52 and the second MG54 exchange electric power with the battery 250 via the PCU (Power Control Unit) 200. The battery 250 is charged using the output of the internal combustion engine 10 and supplies electric power to the first MG52 and the second MG54. The PCU 200 includes a converter that boosts the DC voltage input from the battery 250 and outputs it, and an inverter that converts the DC voltage boosted by the converter into an AC voltage and outputs it to each of the MG52 and 54. In addition, a socket 300 for charging the battery 250 from an external power supply facility outside the vehicle is connected to the PCU 200.

[0012] The control device 70 controls the internal combustion engine 10, and operates the operation parts of the internal combustion engine 10 such as the throttle valve 14, the port injection valve 16, the in-cylinder injection valve 22, and the spark plug 24 in order to control the torque, the exhaust component ratio, etc. as the control amounts. In addition, the control device 70 controls the first MG52, and operates the inverter via the PCU 200 in order to control the rotational speed which is the control amount thereof. Further, the control device 70 controls the second MG54, and operates the inverter via the PCU 200 in order to control the torque which is the control amount thereof. FIG. 1 shows the respective operation signals MS1 to MS4 of the throttle valve 14, the port injection valve 16, the in-cylinder injection valve 22, and the spark plug 24.

[0013] The control device 70 refers to the intake air amount Ga detected by the air flow meter 80, the output signal Scr of the crank angle sensor 82, and the water temperature THW detected by the water temperature sensor 86. Further, the control device 70 refers to the output signal Sm1 of the first rotation angle sensor 90 that detects the rotation angle of the first MG52 and the output signal Sm2 of the second rotation angle sensor 92 that detects the rotation angle of the second MG54. Further, the control device 70 refers to the accelerator operation amount ACCP which is the depression amount of the accelerator pedal detected by the accelerator sensor 94 and the vehicle speed SP which is the vehicle speed of the vehicle 500 detected by the vehicle speed sensor 95. Further, the control device 70 refers to the outside air temperature THout detected by the outside air temperature sensor 96. Further, a car navigation system 400 is connected to the control device 70. Although not shown, the control device 70 is composed of a plurality of control units such as the control unit of the internal combustion engine 10 and the control unit of the PCU 200.

[0014] The control device 70 calculates the engine rotational speed NE based on the output signal Scr of the crank angle sensor 82. Further, the control device 70 calculates the engine load factor KL based on the engine rotational speed NE and the intake air amount Ga. Here, the engine load factor KL represents the ratio of the current cylinder inflow air amount to the cylinder inflow air amount when the internal combustion engine 10 is in steady operation with the throttle valve 14 fully open at the current engine rotational speed NE. The cylinder inflow air amount is the amount of intake air flowing into each cylinder during the intake stroke.

[0015] Further, the control device 70 acquires the state of the battery 250 detected by sensors or the like, that is, the input current, output current, voltage, temperature, etc. Then, based on the acquired data, the control device 70 calculates the remaining capacity which is the current power storage amount of the battery 250, the current full charge capacity of the battery 250, and the state of charge SOC of the battery 250. The state of charge SOC is a value obtained by dividing the full charge capacity by the remaining capacity.

[0016] The control device 70 includes a CPU 72, a ROM 74, and a peripheral circuit 76, and they are communicable via a communication line 78. Here, the peripheral circuit 76 includes a circuit that generates a clock signal for defining internal operations, a power supply circuit, a reset circuit, and the like. The control device 70 controls the control amount by the CPU 72 executing a program stored in the ROM 74.

[0017] For example, the control device 70 calculates a required output of the vehicle 500 based on the accelerator operation amount ACCP and the vehicle speed SP. Further, the control device 70 controls the engine output PE of the internal combustion engine 10 and the outputs of the first MG 52 and the second MG 54 so as to satisfy the required output of the vehicle 500.

[0018] <Regarding the regeneration of the GPF> The control device 70 calculates a PM deposition amount, which is the amount of PM collected in the GPF 34, based on the engine operating state, the detection values of various sensors, and the like. Then, when the PM deposition amount becomes equal to or greater than a predetermined threshold value, it requests the execution of filter regeneration for burning the PM collected in the GPF 34. And when there is a request for executing filter regeneration, and a predetermined condition is satisfied, the GPF 34 is heated to a high temperature using the exhaust heat of the internal combustion engine 10, and oxygen is supplied to the GPF 34 through fuel cut, whereby the regeneration of the GPF 34 is performed.

[0019] FIG. 2 shows a processing procedure in an example of filter regeneration executed by the control device 70. The processing shown in FIG. 2 is realized by the CPU 72 executing a program stored in the ROM 74. Further, the processing shown in FIG. 2 is executed by the control device 70 when there is a request for executing filter regeneration and before the vehicle 500 starts to run. In the following, the step numbers of each process are represented by numbers with "S" added at the beginning.

[0020] FIG. 3 shows an example of the transition of the engine output and the running power. These engine output and running power will be described later. When starting the process shown in FIG. 2, the CPU 72 acquires the driving pattern of the vehicle 500 before starting the drive (S100). As shown in FIG. 3, the driving pattern is the change in vehicle speed from the expected start of driving in this trip. The CPU 72 acquires the driving pattern from the route information set in the car navigation system 400, the past driving history of the own vehicle, and the like. The driving history of the own vehicle is, for example, the history of repeated driving, and examples include the driving history of commuting or going to school. The CPU 72 determines whether the current trip to start driving is a trip of such repeated driving based on time, day of the week, the departure location of the vehicle, and the like.

[0021] Next, the CPU 72 estimates the driving power (S110). The driving power estimated in S110 is the change in the power required for the vehicle to realize the acquired driving pattern, as shown by the one-dot chain line L1 in FIG. 3. The CPU 72 estimates the driving power based on the driving pattern, the route information of the current trip, the specifications of the own vehicle, and the like.

[0022] Next, the CPU 72 creates an engine output plan (S120). The engine output plan is an engine operation plan for adjusting the engine output, which is the output of the internal combustion engine 10, in order to perform the regeneration process of the GPF 34 during the trip with the acquired driving pattern. The change in the engine output planned by this engine output plan is shown by the solid line L2 in FIG. 3. As shown by this solid line L2, until a predetermined time has elapsed since the start of driving, a warm-up operation for raising the temperature of the GPF 34 by increasing the engine output and raising the temperature of the exhaust gas is planned. Then, when the predetermined time has elapsed since the start of driving, a PM combustion operation for performing PM combustion by reducing the engine output to such an extent that the temperature of the warmed-up GPF 34 can be maintained is planned. The CPU 72 sets the engine output in such an engine output plan based on the outside air temperature THout before starting the drive and the like.

[0023] Next, the CPU 72 calculates the predicted charge-discharge amount CD (S130). The predicted charge-discharge amount CD is the sum of the predicted charge amount and the predicted discharge amount of the battery 250 in the acquired driving pattern. Note that when the predicted charge-discharge amount CD is a positive value, it represents the charge amount of the battery 250, and when it is a negative value, it represents the discharge amount of the battery 250.

[0024] As shown in FIG. 3, when the engine output (solid line L2) exceeds the driving power (dashed-dotted line L1), the battery 250 is charged. Therefore, the CPU 72 calculates the amount of electric power corresponding to the area sandwiched between the engine output and the driving power and where the engine output exceeds the driving power (in FIG. 3, the sum of the areas C1, C2, and C3 corresponds) as the predicted charge amount C. Note that the sign of the predicted charge amount C is positive.

[0025] On the other hand, as shown in FIG. 3, when the engine output (solid line L2) is lower than the driving power (dashed-dotted line L1), the battery 250 is discharged to drive the second MG 54. Therefore, as shown in FIG. 3, the CPU 72 calculates the amount of electric power corresponding to the area sandwiched between the engine output and the driving power and where the engine output is lower than the driving power (in FIG. 3, the area D1 corresponds) as the predicted discharge amount D. Note that the sign of the predicted discharge amount D is negative. Then, the CPU 72 substitutes the sum of the predicted charge amount C and the predicted discharge amount D into the predicted charge-discharge amount CD.

[0026] Next, the CPU 72 acquires the allowable charge amount CP and the allowable discharge amount DP of the battery 250 based on the remaining capacity of the battery 250 (S140). The allowable charge amount CP is a positive value, and the allowable discharge amount DP is a negative value.

[0027] Next, when the predicted charge-discharge amount CD is a positive value, the CPU 72 determines whether the charge amount indicated by the predicted charge-discharge amount CD is greater than the allowable charge amount CP (S150). When it is determined that the charge amount indicated by the predicted charge-discharge amount CD is greater than the allowable charge amount CP (S150: YES), the CPU 72 gradually corrects the engine output plan so as to be closer to the low output (S160). When correcting the engine output plan in this S160, as shown by the two-dot chain line L3 in FIG. 3, the engine output is uniformly reduced. The process of S160 is repeatedly executed until a negative determination is made in the process of S150.

[0028] When a negative determination is made in the process of S150, the CPU 72 performs the process of S170. In the process of S170, when the predicted charge-discharge amount CD is a negative value, the CPU 72 determines whether the discharge amount indicated by the predicted charge-discharge amount CD is greater than the allowable discharge amount DP (S170). In the process of this S170, the CPU 72 determines that the discharge amount indicated by the predicted charge-discharge amount CD is greater than the allowable discharge amount DP when the absolute value of the predicted charge-discharge amount CD is greater than the absolute value of the allowable discharge amount DP. When it is determined that the discharge amount indicated by the predicted charge-discharge amount CD is greater than the allowable discharge amount DP (S170: YES), the CPU 72 gradually corrects the engine output plan so as to be closer to the high output (S180). When correcting the engine output plan in this S180, the engine output is uniformly increased. The process of S180 is repeatedly executed until a negative determination is made in the process of S170.

[0029] When a negative determination is made in the process of S170, the CPU 72 ends this process. Then, the CPU 72 adjusts the engine output after the vehicle 500 starts running according to the engine output plan set at the time when a negative determination is made in the process of S170.

[0030] <Actions and Effects of this Embodiment> (1) The driving pattern of the vehicle 500 is acquired before starting the drive. Then, an engine output plan is created to adjust the output of the internal combustion engine 10 in order to perform the regeneration process of the GPF 34 during the trip in that driving pattern. Therefore, the output adjustment of the internal combustion engine 10 for performing the regeneration process of the GPF 34 is performed in accordance with the driving pattern of the vehicle 500. Accordingly, even in the case of a short trip, the regeneration of the GPF 34 can be efficiently performed.

[0031] (2) When the battery 250 becomes overcharged, for example, the following inconveniences are feared. That is, when the battery 250 is fully charged, warm-up by increasing the engine output cannot be performed. Also, since power regeneration cannot be performed during deceleration, the fuel efficiency deteriorates. Further, when the battery 250 becomes overdischarged, for example, the following inconveniences are feared. That is, the fuel efficiency deteriorates because the engine operation is performed to suppress the shortage of the remaining capacity of the battery 250. In this regard, in the present embodiment, by performing the processes of S130 to S180 above, the engine output plan is corrected according to the charge / discharge state of the battery 250 in the acquired driving pattern. Therefore, it is possible to suppress the occurrence of inconveniences due to overcharging or overdischarging of the battery 250.

[0032] Note that the above embodiment can be implemented with the following modifications. The above embodiment and the following modification examples can be implemented in combination with each other as long as they do not technically conflict with each other.

[0033] · When correcting the engine output plan, the engine output was uniformly increased or decreased. In addition, by increasing or decreasing the engine output in the warm-up operation, the timing of switching from the warm-up operation to the PM combustion operation may be changed. Also, oxygen may be supplied to the GPF 34 by performing fuel cut during the period of performing the PM combustion operation. Further, the engine output plan may be created so as to perform such fuel cut at the timing when a low load of the engine is predicted.

[0034] · After the vehicle 500 starts running, the engine output plan may be corrected according to the charge rate SOC calculated periodically. · The engine output plan may be corrected based on the outside air temperature THout after the vehicle 500 starts running. In this case, even when the outside air temperature varies greatly before and after the vehicle 500 starts running, for example, when the vehicle is started from the garage when the outside air temperature is low, the engine output plan can be created appropriately.

[0035] · The vehicle 500 may be a hybrid vehicle that can be charged from a power supply facility to the battery 250 but does not have equipment for charging the battery 250 from the power supply facility.

[0036] · The GPF 34 is not limited to a filter carrying a three-way catalyst, and may be only a filter. Also, the GPF 34 is not limited to being provided downstream of the oxidation catalyst 32 in the exhaust passage 30. Further, the oxidation catalyst 32 may be replaced with a three-way catalyst that purifies the components contained in the exhaust gas.

Description of Reference Numerals

[0037] 10…Internal combustion engine, 12…Intake passage, 30…Exhaust passage, 32…Oxidation catalyst, 34…Gasoline particulate filter, 50…Planetary gear mechanism, 52…First motor generator, 54…Second motor generator, 60…Drive wheels, 70…Control device, 72…CPU, 74…ROM, 200…PCU, 250…Battery, 400…Car navigation system, 500…Vehicle

Claims

【Claim 1】 A control method for a hybrid vehicle comprising an internal combustion engine and an electric motor as prime movers of the vehicle, a filter for collecting particulate matter in exhaust gas, and a battery that is charged using the output of the internal combustion engine and supplies electric power to the electric motor, the method comprising: obtaining a driving pattern of the vehicle before starting driving; estimating driving power required in the driving pattern; creating an engine output plan for adjusting the output of the internal combustion engine to perform a regeneration process of the filter during a trip in the driving pattern; calculating an expected charge-discharge amount of the battery in the driving pattern; obtaining an allowable charge amount and an allowable discharge amount of the battery; correcting the engine output plan to be closer to a low output when the charge amount indicated by the expected charge-discharge amount is greater than the allowable charge amount; correcting the engine output plan to be closer to a high output when the discharge amount indicated by the expected charge-discharge amount is greater than the allowable discharge amount. A control method for a hybrid vehicle.

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