Vehicle control device

Abstract

To suppress interruption of catalyst warm-up operation.SOLUTION: A vehicle 500 comprises: an internal combustion engine 10 having a catalyst 17 for exhaust emission control in an exhaust passage; a high-voltage battery 300; and a motor generator 30 that generates electric power to be stored in the high-voltage battery 300 by using power of the internal combustion engine 10, and outputs power for traveling by receiving power supply from the high-voltage battery 300. A control device 100 executes warm-up operation execution processing in which when the charging rate of the high-voltage battery 300 is a determination value or more, a first warm-up operation is performed, whereas when the charging rate of the high-voltage battery 300 is less than the determination value, a second warm-up operation in which the output of the internal combustion engine 10 is made higher than the output in the first warm-up operation is performed.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] For example, the control device provided in the hybrid vehicle described in Patent Document 1 selects one of several types of warm-up operation when there is a request to warm up an exhaust purification catalyst provided in the exhaust passage of the internal combustion engine, and performs that warm-up operation. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-78802 Summary of the Invention [Problem to be solved by the invention]

[0004] When warming up the catalyst, the output of the internal combustion engine may be increased to raise the temperature of the exhaust gas. Increasing the output of the internal combustion engine increases the amount of electricity generated by the generator equipped in the hybrid vehicle, which in turn increases the battery's charging rate. As is well known, a battery has an upper limit on its charging rate to prevent overcharging. Therefore, depending on the state of the charging rate when the warm-up operation is started, the charging rate may reach the upper limit during the catalyst warm-up operation, causing the catalyst warm-up operation to be interrupted. [Means for solving the problem]

[0005] A vehicle control device that solves the above problem is applied to a vehicle that includes an internal combustion engine with an exhaust gas purification catalyst in an exhaust passage, a battery, and a generator that uses power from the internal combustion engine to generate electricity to be stored in the battery. This control device executes a warm-up operation execution process that executes a first warm-up operation when the battery's charging rate is equal to or greater than a determination value, and executes a second warm-up operation that increases the output of the internal combustion engine more than the first warm-up operation when the battery's charging rate is less than the determination value.

[0006] According to this configuration, when the battery's charging rate is equal to or higher than the above-mentioned determination value, the first warm-up operation is executed, which has a lower output of the internal combustion engine than the second warm-up operation. Therefore, compared to when the second warm-up operation is executed, the amount of power generated by the generator is less, and it takes longer for the charging rate to reach the upper limit. This ensures the time required for the catalyst warm-up operation. Therefore, it is possible to prevent the catalyst warm-up operation from being interrupted due to the battery's charging rate reaching the upper limit. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a schematic diagram of a vehicle in a first embodiment. [Figure 2] 4 is a flowchart showing the procedure of a warm-up operation execution process in the embodiment; [Figure 3] 10 is a flowchart showing the procedure of a warm-up operation execution process in a second embodiment. [Figure 4] 10 is a flowchart showing a part of a procedure for warm-up operation execution processing in a modified example of the first embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] (First embodiment) A first embodiment of a vehicle control device will be described below with reference to FIGS. <Vehicle configuration> 1, vehicle 500 is a hybrid vehicle equipped with two prime movers, an internal combustion engine 10 and a motor generator 30. Motor generator 30 functions as a generator that uses the power of internal combustion engine 10 to generate electricity to be stored in high-voltage battery 300, and also functions as an electric motor that receives power from high-voltage battery 300 and outputs power for driving.

[0009] The internal combustion engine 10 is equipped with a fuel injection valve 12 that injects fuel directly into the cylinder. The internal combustion engine 10 also has an intake passage 13. The intake passage 13 is provided with an electric throttle valve 14 that adjusts the amount of intake air. The internal combustion engine 10 is also equipped with an exhaust passage 16. The exhaust passage 16 is provided with a catalyst 17 for purifying exhaust gases. The catalyst 17's ability to purify exhaust gases increases when it reaches or exceeds its activation temperature and completes its warm-up. In the combustion chamber of the internal combustion engine 10, a mixture of intake air and fuel injected from the fuel injection valve 12 is combusted, thereby generating engine power.

[0010] The crankshaft 18 of the internal combustion engine 10 is connected to a hydraulic clutch mechanism 20. The clutch mechanism 20 is also connected to an output shaft 41 of the motor generator 30.

[0011] The clutch mechanism 20 is a mechanism that adjusts the amount of torque transmitted between the crankshaft 18 and the output shaft 41 of the motor generator 30. When the clutch mechanism 20 is in an engaged state, the crankshaft 18 is connected to the output shaft 41 of the motor generator 30, whereas when the clutch mechanism 20 is in a released state, the connection between the crankshaft 18 and the output shaft 41 of the motor generator 30 is released.

[0012] A mechanical oil pump 50 driven by the motor generator 30 is provided on the output shaft 41 of the motor generator 30. The vehicle 500 is also provided with an electric oil pump 80.

[0013] The motor generator 30 exchanges power with a high-voltage battery 300 for driving via a PCU (Power Control Unit) 200. An upper limit value SOCmax of the state of charge (SOC) of the high-voltage battery 300 is set, and the charge amount is controlled so that the state of charge (SOC) does not exceed this upper limit value SOCmax.

[0014] PCU 200 includes a boost converter 210, an inverter 220, a DC-DC converter 230, etc. Boost converter 210 boosts and outputs a DC voltage input from high-voltage battery 300. Inverter 220 converts the DC voltage boosted by boost converter 210 into an AC voltage and outputs it to motor generator 30. DC-DC converter 230 reduces the DC voltage of high-voltage battery 300 to a voltage for driving accessories.

[0015] The vehicle 500 is provided with a low-voltage battery 310 that stores the electric power stepped down by the DC-DC converter 230. An output shaft 41 of the motor generator 30 is connected to an input shaft of a torque converter 42 having a lock-up clutch 45. An output shaft of the torque converter 42 is connected to an input shaft of an automatic transmission 48. An output shaft of the automatic transmission 48 is connected to a differential gear 60. Drive wheels 65 of a vehicle 500 are connected to an output shaft of the differential gear 60.

[0016] The vehicle 500 is equipped with a hydraulic pressure adjustment mechanism 90 that uses a mechanical oil pump 50 and an electric oil pump 80 as hydraulic pressure sources. The hydraulic pressure adjustment mechanism 90 is connected to the automatic transmission 48, the lock-up clutch 45, the clutch mechanism 20, and the like as destinations of hydraulic pressure. By controlling the hydraulic pressure supplied from the hydraulic pressure adjustment mechanism 90, the gear shifting operation of the automatic transmission 48, the operation of the lock-up clutch 45, the operation of the clutch mechanism 20, and the like are controlled.

[0017] A control device 100 mounted on the vehicle 500 performs various types of control, such as ignition timing control and fuel injection control of the internal combustion engine 10, control of the motor generator 30, and control of the hydraulic pressure adjustment mechanism 90.

[0018] The control device 100 includes a central processing unit (hereinafter referred to as CPU) 110 and a memory 120 in which control programs and data are stored. Various controls are performed by the CPU 110 executing the programs stored in the memory 120. Although not shown, the control device 100 is made up of multiple control units, such as a control unit for the internal combustion engine and a control unit for the PCU.

[0019] The control device 100 is connected to a crank angle sensor 70 that detects the rotation angle of the crankshaft 18 and a rotation speed sensor 71 that detects the motor rotation speed Nm, which is the rotation speed of the motor generator 30. The control device 100 is also connected to an air flow meter 72 that detects the intake air amount GA of the internal combustion engine 10 and a water temperature sensor 73 that detects the coolant temperature THW, which is the temperature of the coolant for the internal combustion engine 10. The control device 100 is also connected to a throttle sensor 74 that detects the throttle opening TA, which is the opening of the throttle valve 14, and an accelerator position sensor 75 that detects the accelerator operation amount ACCP, which is the operation amount of the accelerator pedal. The control device 100 is also connected to a vehicle speed sensor 76 that detects the vehicle speed SP of the vehicle 500. The control device 100 also recognizes a system startup request of the vehicle 500 based on an input signal Scr from the crank angle sensor 70. The control device 100 calculates the engine rotation speed Ne based on the output signal Scr from the crank angle sensor 70. The control device 100 also calculates the engine load factor KL based on the engine rotation speed Ne and the intake air amount GA. The control device 100 also refers to the charge / discharge current Ib of the high-voltage battery 300 detected by the current sensor 320 and the terminal voltage Vb of the high-voltage battery 300 detected by the voltage sensor 330. The control device 100 then calculates the state of charge SOC of the high-voltage battery 300 based on the charge / discharge current Ib and the terminal voltage Vb.

[0020] The control device 100 is connected to the PCU 200 , and the control device 100 controls the motor generator 30 through the control of the PCU 200 . The control device 100 operates various operating parts of the internal combustion engine 10, such as the throttle valve 14 and the fuel injection valve 12, in order to control the engine output, exhaust component ratio, and other control variables of the internal combustion engine 10 as the control target.

[0021] Furthermore, the control device 100 operates the inverter 220 via the PCU 200 to control the torque, which is the control amount of the motor generator 30 as the controlled object. When the internal combustion engine 10 is used as the prime mover of the vehicle 500, the control device 100 engages the clutch mechanism 20 to transmit the output torque of the internal combustion engine 10 to the automatic transmission 48. In some cases, the control device 100 also operates the motor generator 30 in a power running state to transmit not only the output torque of the internal combustion engine 10 but also the power running torque of the motor generator 30 to the automatic transmission 48. On the other hand, when only the motor generator 30 is used as the prime mover of the vehicle 500, the control device 100 disengages the clutch mechanism 20 to interrupt torque transmission between the internal combustion engine 10 and the automatic transmission 48. Then, the control device 100 operates the motor generator 30 in a power running state to transmit the power running torque of the motor generator 30 to the automatic transmission 48. In this way, when only the motor generator 30 is used as the prime mover of the vehicle 500, the operation of the internal combustion engine 10 is stopped. In this way, intermittent operation is performed during operation of the vehicle 500, in which the internal combustion engine 10 is repeatedly started and stopped.

[0022] <About warm-up operation execution process> When there is a request to warm up the catalyst 17 and predetermined execution permission conditions are met, the control device 100 executes a warm-up operation to promote the warm-up of the catalyst 17. The execution permission conditions include the state of charge (SOC) of the high-voltage battery 300 being less than the above-mentioned upper limit value SOCmax. Note that if the state of charge (SOC) reaches the upper limit value SOCmax during execution of the warm-up operation, the control device 100 stops execution of the warm-up operation.

[0023] The control device 100 of this embodiment selects and executes either a first warm-up operation or a second warm-up operation as the warm-up operation. The first warm-up operation is an operation in which the ignition timing of the internal combustion engine 10 is retarded from the ignition timing that is set when there is no request to warm up the catalyst 17, thereby increasing the temperature of the exhaust gas and promoting a temperature rise of the catalyst 17. When the first warm-up operation is performed, homogeneous combustion is performed.

[0024] The second warm-up operation is an operation in which the ignition timing is set later than in the first warm-up operation, thereby increasing the temperature of the exhaust gas compared to the first warm-up operation and rapidly raising the temperature of the catalyst 17. Note that, in the second warm-up operation, the ignition timing is set later than in the first warm-up operation, which makes the combustion state of the air-fuel mixture more unstable. To prevent this instability in the combustion state, stratified charge combustion is implemented when the second warm-up operation is performed. Furthermore, in the second warm-up operation, the engine is operated with a higher output of the internal combustion engine 10 than in the first warm-up operation. That is, in the second warm-up operation, the opening of the throttle valve 14 is adjusted so that the intake air amount is greater than in the first warm-up operation. In this way, in the second warm-up operation, the engine is operated with a higher output of the internal combustion engine 10 than in the first warm-up operation, which results in a higher exhaust gas temperature than in the first warm-up operation. This also results in a rapid temperature rise of the catalyst 17.

[0025] Here, if the output of the internal combustion engine 10 is increased, the amount of power generated by the motor generator 30 increases, which causes the state of charge (SOC) of the high-voltage battery 300 to rise. As a result, the state of charge (SOC) may reach the upper limit value SOCmax during the second warm-up operation, which may cause the warm-up operation of the catalyst 17 to be interrupted.

[0026] In order to prevent such inconvenience from occurring, the control device 100 executes a warm-up operation execution process shown in FIG. 2 shows the procedure for the warm-up operation execution process, which selects and executes either the first warm-up operation or the second warm-up operation. Note that, hereinafter, step numbers are represented by numbers preceded by "S."

[0027] This warm-up operation execution process is a process that is executed by the control device 100 when starting the internal combustion engine 10 in response to a start request for the internal combustion engine 10. Incidentally, the start request for the internal combustion engine 10 includes an initial start request and an intermittent start request.

[0028] The initial start request is the first start request since the power switch 78 is turned on. The intermittent start request is a start request due to the intermittent operation described above, and examples of when this intermittent start request occurs include the following: That is, when the torque required to run the vehicle 500 cannot be obtained solely from the torque of the motor generator 30 while the internal combustion engine 10 is stopped. Other examples of when an intermittent start request occurs include when a request to charge the high-voltage battery 300 occurs or when a request to charge the low-voltage battery 310 occurs.

[0029] When the process shown in FIG. 2 starts, the control device 100 acquires the cooling water temperature THW at the time of engine start (S100). Next, the control device 100 determines whether the acquired coolant temperature THW is equal to or lower than a threshold value THWref (S110). The magnitude of the threshold value THWref is set so that it can be accurately determined that the catalyst 17 needs to be warmed up based on the coolant temperature THW being equal to or lower than the threshold value THWref.

[0030] When it is determined in the processing of S110 that the cooling water temperature THW is equal to or lower than the threshold value THWref (S110: YES), the control device 100 sets the catalyst warm-up flag Fcw to "ON" (S120). The catalyst warm-up flag Fcw is a flag that is set to "ON" when the processing of S110 makes a positive determination, and its initial value is "OFF." When this catalyst warm-up flag Fcw is "ON," it indicates that there is a request to warm up the catalyst 17, and when the catalyst warm-up flag Fcw is "OFF," it indicates that there is no request to warm up the catalyst 17.

[0031] Next, the control device 100 determines whether the current state of charge SOC is equal to or greater than a reference value SOCref (S130). The reference value SOCref is a value smaller than the upper limit value SOCmax, and is set to the following value in advance. That is, based on the fact that the state of charge SOC is equal to or greater than the reference value SOCref, if the second warm-up operation is performed, it can be determined that the current state of charge SOC is high enough that there is a possibility that the state of charge SOC will reach the upper limit value SOCmax before the warm-up operation is completed.

[0032] If it is determined in the process of S130 that the state of charge SOC is equal to or greater than the reference value SOCref (S130: YES), the control device 100 sets the second warm-up flag Fcw2 to "OFF" (S140). The initial value of the second warm-up flag Fcw2 is "OFF".

[0033] On the other hand, if a negative determination is made in the processing of S130, the control device 100 sets the second warm-up flag Fcw2 to "ON" (S150). After executing the process of S140 or the process of S150, the control device 100 next determines whether the second warm-up flag Fcw2 is "ON" (S160).

[0034] If it is determined in the process of S160 that the second warm-up flag Fcw2 is "ON" (S160: YES), the control device 100 executes the second warm-up operation described above (S170). Note that the second warm-up operation is terminated when the value of the warm-up counter, which increases during the execution of the warm-up operation, reaches a predetermined value.

[0035] On the other hand, if it is determined in the processing of S160 that the second warm-up flag Fcw2 is not "ON" (S160: NO), that is, if the second warm-up flag Fcw2 is "OFF", the control device 100 executes the first warm-up operation described above (S180). Note that the first warm-up operation also ends when the value of the warm-up counter, which increases during the execution of the warm-up operation, reaches a predetermined value.

[0036] If a negative determination is made in the process of S110, or if the process of S170 or the process of S180 is executed, the control device 100 ends this process. <Action and effect> The operation and effects of this embodiment will be described.

[0037] (1) As shown in FIG. 2, when the state of charge SOC of the high-voltage battery 300 is equal to or higher than the reference value SOCref (S130: YES), the second warm-up flag Fcw2 is set to "OFF" (S140), and the first warm-up operation is performed (S180). The first warm-up operation is a warm-up operation in which the output of the internal combustion engine 10 is smaller than that of the second warm-up operation. Therefore, compared to when the second warm-up operation is performed, the amount of power generated by the motor generator 30 is smaller, and the time until the state of charge SOC reaches the upper limit value SOCmax is longer. This ensures the time required for the warm-up operation of the catalyst 17. This prevents the warm-up operation of the catalyst 17 from being interrupted due to the state of charge SOC of the high-voltage battery 300 reaching the upper limit value SOCmax.

[0038] (Second embodiment) Next, a second embodiment of the vehicle control device will be described with reference to FIG. <Regarding the warm-up operation execution process of this embodiment> As shown in Fig. 3, the warm-up operation execution process of this embodiment adds the process of S200 to the warm-up operation execution process described in the first embodiment. The warm-up operation execution process of this embodiment will be described below, focusing on these differences. Note that in Fig. 3, the same steps as those shown in Fig. 2 are assigned the same step numbers.

[0039] 3, when the determination in the process of S160 described above is affirmative, the control device 100 then executes the process of S200. That is, when the second warm-up flag Fcw2 is set to "ON" and the process of S130 determines that the state of charge SOC is less than the upper limit value SOCmax, the control device 100 executes the process of S200.

[0040] In the process of S200, the control device 100 determines whether the vehicle 500 is traveling based on the vehicle speed SP, etc. If it is determined that the vehicle 500 is traveling (S200: YES), the control device 100 executes the process of S170 to perform the second warm-up operation.

[0041] On the other hand, when it is determined in the process of S200 that the vehicle 500 is not running (S200: NOY), that is, when the vehicle 500 is stopped, the control device 100 executes the process of S180 to perform the first warm-up operation.

[0042] If a negative determination is made in the process of S110, or if the process of S170 or the process of S180 is executed, the control device 100 ends this process. <Action and effect> According to this embodiment, in addition to the action and effect of (1) above, the action and effect of (2) described below can also be obtained.

[0043] (2) Because the motor generator 30 does not consume power while the vehicle 500 is stopped, the amount of discharge from the high-voltage battery 300 is smaller than when the vehicle 500 is running. Therefore, the state of charge (SOC) is more likely to increase due to power generation. Therefore, even if the state of charge (SOC) is less than the reference value SOCref, if the second warm-up operation, which increases the amount of power generated, is performed while the vehicle 500 is stopped, the state of charge (SOC) may reach the upper limit value SOCmax. Therefore, in this embodiment, even if it is determined that the state of charge (SOC) is less than the reference value SOCref, the first warm-up operation, which generates less power than the second warm-up operation, is performed while the vehicle 500 is stopped. Therefore, it takes longer for the state of charge (SOC) to reach the upper limit value SOCmax. Therefore, even in this case, it is possible to prevent the warm-up operation of the catalyst 17 from being interrupted due to the state of charge (SOC) of the high-voltage battery 300 reaching the upper limit value SOCmax.

[0044] <Example of change> The above-described embodiments can be modified as follows: The above-described embodiments and the following modifications can be combined with each other within the scope of technical compatibility.

[0045] The reference value NEref described in the first embodiment may be variable. Such variable processing of the reference value NEref can be realized by adding the processes of S300, S310, and S320 shown in FIG. 4 to the warm-up operation execution processing described in the first embodiment.

[0046] 4, after executing the process of S120 shown in FIG. 2, the control device 100 determines whether the vehicle 500 is stopped based on the vehicle speed SP, etc., as the process of S300. If it is determined that the vehicle 500 is stopped (S300: YES), the control device 100 executes a process of substituting a first determination value SOCref1 for the determination value NEref (S310). This first determination value SOCref1 is a preset value that is smaller than a second determination value SOCref2, which will be described later.

[0047] On the other hand, when it is determined in the process of S300 that the vehicle 500 is not stopped (S300: NO), that is, when the vehicle 500 is moving, the control device 100 executes a process of substituting a second determination value SOCref2 for the determination value NEref (S320). This second determination value SOCref2 is a preset value that is smaller than the upper limit value SOCmax and larger than the first determination value SOCref1.

[0048] After executing the process of S310 or the process of S320, the control device 100 then sequentially executes the processes from S130 onwards shown in Fig. 2. When executing the process of S130, it is determined whether the state of charge SOC is equal to or greater than the reference value SOCref set in the process of S310 or the process of S320.

[0049] This modified example provides the following advantages and effects. Specifically, while the vehicle 500 is traveling, the motor generator 30 consumes power, resulting in a greater amount of discharge from the high-voltage battery 300 than while the vehicle is parked. This makes it difficult for the state of charge (SOC) to increase due to power generation. Therefore, even if the determination value SOCref, which is the upper limit of the state of charge (SOC) for selecting the second warm-up operation, is set higher while the vehicle is traveling than while parked, the state of charge (SOC) is unlikely to reach the upper limit SOCmax. Therefore, in this modified example, the determination value SOCref set while the vehicle is traveling is set to a value greater than the determination value SOCref set while the vehicle is parked. Therefore, the second warm-up operation is performed more frequently while the vehicle is traveling. This increases the opportunities for performing so-called rapid warm-up, which rapidly raises the temperature of the catalyst 17 while the vehicle is traveling.

[0050] The process of varying the reference value NEref shown in FIG. 4 may also be applied to the warm-up operation execution process described in the second embodiment. The internal combustion engine 10 is provided with a fuel injection valve for in-cylinder injection that injects fuel directly into the cylinder, but may be provided with a fuel injection valve for port injection that injects fuel into the intake port.

[0051] The vehicle 500 may be equipped with a manual transmission instead of the automatic transmission 48. The vehicle 500 does not have to be equipped with a torque converter 42. Homogeneous combustion was performed when the first warm-up operation was performed, and stratified combustion was performed when the second warm-up operation was performed, but such a change in combustion method is not essential.

[0052] The hybrid system of the vehicle 500 is not limited to the one shown in Fig. 1, and may be any other hybrid system. For example, it may be a so-called series-parallel hybrid system that does not have the clutch mechanism 20 and in which the crankshaft 18 and the motor generator 30 are connected via a power split mechanism.

[0053] The number of motor generators provided in the vehicle 500 can be changed as appropriate. The motor generator 30 functions both as a generator and as an electric motor. Alternatively, the vehicle 500 may be provided with a generator and an electric motor separately.

[0054] The control device 100 includes a CPU 110 and a memory 120, and is not limited to executing software processing. For example, it may include a dedicated hardware circuit (e.g., ASIC) that processes at least part of the software processing executed in the above embodiments. That is, the control device 100 may have any of the following configurations (a) to (c): (a) A processing device that executes all of the above processing in accordance with a program, and a program storage device such as a memory that stores the program; (b) A processing device and program storage device that executes part of the above processing in accordance with a program, and a dedicated hardware circuit that executes the remaining processing; or (c) A dedicated hardware circuit that executes all of the above processing. Here, there may be multiple software processing circuits and dedicated hardware circuits that include a processing device and a program storage device. That is, the above processing may be executed by a processing circuit that includes at least one software processing circuit and one or more dedicated hardware circuits. [Explanation of symbols]

[0055] 10...Internal combustion engine 12...Fuel injection valve 13...Intake passage 14...Throttle valve 16...Exhaust passage 17...Catalyst 18...Crankshaft 20...Clutch mechanism 30...Motor generator 42...Torque converter 45...Lock-up clutch 48...Automatic transmission 60...Differential gear 65...Drive wheels 100...Control device 110...Central processing unit 120...Memory 200…PCU 300...High voltage battery 500...vehicle

Claims

1. A control device applied to a vehicle including an internal combustion engine having an exhaust gas purification catalyst in an exhaust passage, a battery, and a generator that generates electric power to be stored in the battery using power from the internal combustion engine, a warm-up operation execution process that executes a first warm-up operation when the charging rate of the battery is equal to or greater than a determination value, and executes a second warm-up operation that increases the output of the internal combustion engine more than the first warm-up operation when the charging rate is less than the determination value; When the determination value set while the vehicle is stopped is a first determination value and the determination value set while the vehicle is moving is a second determination value, the second determination value is set to a value greater than the first determination value. Vehicle control device.

2. Even if the charging rate is less than the determination value, the first warm-up operation is performed when the vehicle is stopped. The vehicle control device according to claim 1 .

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