Control system for hybrid vehicles

Abstract

To suppress insufficient charge of a battery during travelling.SOLUTION: A control device 100 is applied to a hybrid vehicle that includes an internal combustion engine 10 and a motor generator 30 as motors, charges a high-voltage battery 300 by utilizing output of the internal combustion engine 10 and performs automated driving. The control device 100 executes processing for making an idle rotation speed of the internal combustion engine 10 during travelling of the vehicle with automated driving in operation higher than the idle rotation speed thereof during travelling of the vehicle without automated driving in operation.SELECTED DRAWING: Figure 1

Description

Technical Field

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

Background Art

[0002] For example, the vehicle described in Patent Document 1 is configured to vary the idle speed of the internal combustion engine between when the vehicle is running and when it is stopped.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, a hybrid vehicle is known that includes an internal combustion engine and an electric motor as power sources and charges a battery using the output of the internal combustion engine. In this hybrid vehicle, if the idle rotational speed of the internal combustion engine when the vehicle transitions from a stopped state to a running state is maintained, there is a risk that the vehicle driver will strongly feel the creep force of the vehicle. Therefore, when the vehicle transitions from a stopped state to a running state, the creep force is suppressed by reducing the idle rotational speed of the internal combustion engine. However, when the idle rotational speed of the internal combustion engine is reduced, the output of the internal combustion engine decreases. Therefore, there is a risk that the charge amount of the battery charged using the output of the internal combustion engine will become insufficient during running.

Means for Solving the Problems

[0005] The control device for a hybrid vehicle that solves the above problems is applied to a hybrid vehicle equipped with an internal combustion engine and an electric motor as prime movers, which uses the output of the internal combustion engine to charge the battery and also implements adaptive cruise control. This control device performs a process to make the idle rotation speed of the internal combustion engine during vehicle driving when adaptive cruise control is in operation higher than the idle rotation speed during vehicle driving when adaptive cruise control is not in operation. [Effects of the Invention]

[0006] The control system in this hybrid vehicle can prevent the battery from becoming insufficiently charged while driving. [Brief explanation of the drawing]

[0007] [Figure 1] Figure 1 is a schematic diagram of a vehicle in one embodiment. [Figure 2] Figure 2 is a flowchart showing the procedure of processing performed by the control device of the same embodiment. [Modes for carrying out the invention]

[0008] <Vehicle Configuration> Hereinafter, one embodiment of the control device for a hybrid vehicle will be described with reference to Figures 1 and 2.

[0009] As shown in Figure 1, the vehicle 500 is a hybrid vehicle equipped with two prime movers: a motor-generator 30, which is an electric motor, and an internal combustion engine 10. The motor-generator 30 has two functions: it functions as a generator that generates electricity using the output of the internal combustion engine 10 to store in a high-voltage battery 300, and it functions as an electric motor that receives power from the high-voltage battery 300 and outputs power for driving. The high-voltage battery 300 is a battery that is charged using the output of the internal combustion engine 10.

[0010] The internal combustion engine 10 is equipped with fuel injectors 12 that supply fuel to the cylinders. The intake passage 13 of the internal combustion engine 10 is provided with an electrically operated throttle valve 14 that adjusts the amount of intake air. The exhaust passage 16 of the internal combustion engine 10 is provided with a catalytic converter 17 for purifying exhaust gases. The catalytic converter 17's ability to purify exhaust gases increases when it reaches an activation temperature or higher, after the engine has warmed up. Engine power is obtained when the mixture of intake air and fuel injected from the fuel injectors 12 burns in the combustion chamber of the internal combustion engine 10.

[0011] The crankshaft 18 of the internal combustion engine 10 is connected to the output shaft 41 of the motor generator 30 via a clutch mechanism 20. 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 engaged, the crankshaft 18 and the output shaft 41 of the motor generator 30 are connected, while when it is disengaged, the connection between the crankshaft 18 and the output shaft 41 of the motor generator 30 is released.

[0012] The motor generator 30 exchanges power with the high-voltage battery 300 used for driving via the PCU (Power Control Unit) 200. The PCU200 includes a boost converter 210, an inverter 220, a DC-DC converter 230, and the like. The boost converter 210 boosts the DC voltage input from the high-voltage battery 300 and outputs it. The inverter 220 converts the DC voltage boosted by the boost converter 210 into AC voltage and outputs it to the motor generator 30. The DC-DC converter 230 steps down the DC voltage of the high-voltage battery 300 to a voltage for driving auxiliary equipment. The stepped-down power is stored in the low-voltage battery 310.

[0013] The output shaft 41 of the motor generator 30 is connected to the input shaft of a torque converter 42 having a lock-up clutch 45. The output shaft of the torque converter 42 is connected to the input shaft of an automatic transmission 48. The output shaft of the automatic transmission 48 is connected to a differential gear 60. The output shaft of the differential gear 60 is connected to the drive wheels 65 of the vehicle 500.

[0014] Vehicle 500 is equipped with an autonomous driving system 600. The autonomous driving system 600 includes a CPU, memory that stores control programs and data, and various sensors. The CPU executes the programs stored in memory to perform autonomous driving of vehicle 500. The autonomous driving system 600 can be activated and deactivated by operating buttons or touch panels installed inside the vehicle, for example. The autonomous driving system 600 controls the steering system, braking system, and engine system of vehicle 500. The autonomous driving system 600 also implements adaptive cruise control, a well-known form of autonomous driving. Adaptive cruise control is a control system that automatically accelerates and decelerates the vehicle within a predetermined speed range, for example, to maintain a safe distance from the vehicle in front.

[0015] The autonomous driving system 600 communicates with the control device 100. The control device 100 performs various controls, such as ignition timing control and fuel injection control of the internal combustion engine 10, and control of the motor generator 30.

[0016] The control device 100 includes a CPU 110 and a memory 120 that stores control programs and data. The CPU 110 executes various controls by running the programs stored in the memory 120. Although not shown in the diagram, the control device 100 is composed of multiple control units, such as a control unit for the internal combustion engine and a control unit for the PCU.

[0017] The control device 100 is connected to a crank angle sensor 70 for detecting the rotation angle of the crankshaft 18 and a rotation speed sensor 71 for detecting the motor rotation speed Nm, which is the rotation speed of the motor generator 30. The control device 100 is connected to an air flow meter 72 for detecting the intake air volume GA of the internal combustion engine 10 and a water temperature sensor 73 for detecting the coolant temperature THW, which is the temperature of the coolant of the internal combustion engine 10. The control device 100 is connected to a throttle sensor 74 for detecting the throttle opening TA, which is the opening degree of the throttle valve 14 and an accelerator position sensor 75 for detecting the accelerator pedal operation amount ACCP, which is the amount the accelerator pedal is operated. The control device 100 is connected to a vehicle speed sensor 76 for detecting the vehicle speed SP of the vehicle 500. In addition, the control device 100 is connected to a shift position sensor 77 for detecting the shift position SFT, which is the operating position of the shift lever of the automatic transmission 48 located in the passenger compartment of the vehicle 500. The shift lever has two operating positions: a non-driving position, such as the parking position (P position) or the neutral position (N position), which is selected when the vehicle 500 is not in motion. Additionally, the shift lever has two operating positions, such as the drive position (D position) or the reverse position (R position), which are selected when the vehicle 500 is in motion. The functions of the shift lever may also be provided by buttons or a touch panel. Furthermore, the control device 100 recognizes the system startup request of the vehicle 500 based on the input signal from the power switch 78. The control device 100 also calculates the engine rotation speed NE based on the output signal Scr from the crank angle sensor 70. Finally, the control device 100 calculates the engine load ratio KL based on the engine rotation speed NE and the intake air volume GA.

[0018] 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 each operation unit of the internal combustion engine 10, such as the throttle valve 14 and the fuel injection valve 12, in order to control the control amount of the internal combustion engine 10 as the control target, such as the engine output and the exhaust component ratio. Further, the control device 100 operates the inverter 220 via the PCU 200 in order to control the torque, which is the control amount of the motor generator 30 as the control target.

[0019] When the control device 100 uses the internal combustion engine 10 as the prime mover of the vehicle 500, the clutch mechanism 20 is engaged to transmit the output torque of the internal combustion engine 10 to the automatic transmission 48. Further, in some cases, the motor generator 30 is also made to perform a power running operation, and thus HV running is performed by transmitting 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 the control device 100 uses only the motor generator 30 as the prime mover of the vehicle 500, the clutch mechanism 20 is released to cut off the torque transmission between the internal combustion engine 10 and the automatic transmission 48. Then, by making the motor generator 30 perform a power running operation, the power running torque of the motor generator 30 is transmitted to the automatic transmission 48 to perform EV running. Further, when charging the high-voltage battery 300 using the output of the internal combustion engine 10, the control device 100 engages the clutch mechanism 20 to transmit the output torque of the internal combustion engine 10 to the motor generator 30 and the automatic transmission 48, thereby performing engine running.

[0020] When the accelerator operation amount ACCP is "0" and there is an engine operation request, the control device 100 performs idle operation control of the internal combustion engine 10. In this idle operation control, a target idle rotational speed NEidt is calculated. Then, the engine operation is performed so that the idle rotational speed NEid, which is the engine rotational speed NE during idle operation, coincides with the target idle rotational speed NEidt. Note that examples of the above engine operation request include a charging request for the high-voltage battery 300 and a drive request for an auxiliary machine provided in the internal combustion engine 10.

[0021] <Regarding the setting of the target idle rotational speed> Fig. 2 shows the processing procedure for setting the target idle rotation speed NEidt that is executed when performing idle operation control. The processing shown in Fig. 2 is repeatedly executed at a predetermined cycle when the execution of idle operation control is required. Also, hereinafter, the step numbers are represented by numbers preceded by "S".

[0022] When starting the processing shown in Fig. 2, the control device 100 determines whether or not it is in the middle of automatic driving (S100). And when it is determined that it is in the middle of automatic driving (S100: YES), the control device 100 substitutes the fixed rotation speed NEd for the target idle rotation speed NEidt (S130). The fixed rotation speed NEd is the same value as the third rotation speed NE3 described later. Also, during automatic driving, the fixed rotation speed NEd is substituted as the target idle rotation speed NEidt in both the case of being stopped and the case of the vehicle being in motion.

[0023] When the fixed rotation speed NEd is substituted for the target idle rotation speed NEidt in the processing of S130, the control device 100 performs engine operation so that the idle rotation speed NEid coincides with the fixed rotation speed NEd.

[0024] In the processing of S100, when it is determined that it is not in the middle of automatic driving and not in automatic driving (S100: NO), the control device 100 determines whether or not the current shift position SFT is in the P position or the N position (S110). And when it is determined that the shift position SFT is in the P position or the N position (S110: YES), the control device 100 substitutes the third rotation speed NE3 for the target idle rotation speed NEidt (S140). The third rotation speed NE3 is the rotation speed set when there is a charging requirement for the high-voltage battery 300, and is the fastest rotation speed among the variable idle rotation speeds NEid.

[0025] When the third rotation speed NE3 is substituted for the target idle rotation speed NEidt in the processing of S140, the control device 100 performs engine operation so that the idle rotation speed NEid coincides with the third rotation speed NE3.

[0026] In the process of S110, if it is determined that the shift position SFT is not in the P position or the N position (S110: NO), the control device 100 determines whether the vehicle 500 is in motion based on the vehicle speed SP, etc. (S120). If it is determined that the vehicle is in motion (S120: YES), the control device 100 substitutes the first rotational speed NE1 into the target idle rotational speed NEidt (S150).

[0027] The first rotational speed NE1 is a rotational speed set with consideration to prevent the creep force of the vehicle 500 from becoming excessively strong while it is running, and is the slowest rotational speed among the variable idle rotational speeds NEid. When the first rotational speed NE1 is substituted for the target idle rotational speed NEidt in the process of S150, the control device 100 operates the engine so that the idle rotational speed NEid matches the first rotational speed NE1.

[0028] In the process of S120, if it is determined that the vehicle is not in motion (S120: NO), that is, if the vehicle is stopped, the control device 100 substitutes either the third rotational speed NE3 or the second rotational speed NE2 into the target idle rotational speed NEidt (S160). The second rotational speed NE2 is a default value and is a rotational speed between the first rotational speed NE1 and the third rotational speed NE3 described above.

[0029] If there is a request to charge the high-voltage battery 300, in the process of S160, the control device 100 substitutes the third rotational speed NE3 for the target idle rotational speed NEidt. If there is no request to charge the high-voltage battery 300, in the process of S160, the control device 100 substitutes the second rotational speed NE2 for the target idle rotational speed NEidt.

[0030] When the second rotational speed NE2 is substituted for the target idle rotational speed NEidt by the process in S160, the control device 100 operates the engine so that the idle rotational speed NEid matches the second rotational speed NE2. Also, when the third rotational speed NE3 is substituted for the target idle rotational speed NEidt by the process in S160, the control device 100 operates the engine so that the idle rotational speed NEid matches the third rotational speed NE3. Note that the selection of the third rotational speed NE3 or the second rotational speed NE2 in the process in S160 may be made according to other parameters, such as the shift position SFT.

[0031] Then, when any of the processes S130, S140, S150, and S160 is executed, the control device 100 terminates the execution of this process for the current cycle. <Operation and Effects of This Embodiment> (1) When autonomous driving, including adaptive cruise control, is in operation, the speed of the vehicle 500 is automatically controlled without the driver operating the accelerator, so the driver is less likely to feel the strength of the creep force. In this embodiment, when the vehicle is running in autonomous driving mode, the process in S130 is executed so that the target idle speed NEidt is substituted with the fixed rotation speed NEd. On the other hand, when the vehicle is running in an autonomous driving state, the process in S150 is executed so that the target idle speed NEidt is substituted with the first rotation speed NE1, which is slower than the fixed rotation speed NEd. Therefore, when the vehicle is running in autonomous driving mode, the idle speed NEid of the internal combustion engine 10 is higher than when the vehicle is running in an autonomous driving state. Therefore, insufficient charge of the high-voltage battery 300 during driving can be suppressed.

[0032] (2) This prevents insufficient charge of the high-voltage battery 300, thereby extending the duration of EV driving that utilizes the power stored in the high-voltage battery 300. (3) The process in S130 above is executed while autonomous driving is in progress. Therefore, during autonomous driving, the idle rotation speed NEid is set to the same rotation speed both when the vehicle is stopped and when it is in motion. Consequently, during autonomous driving, the idle rotation speed NEid does not change between when the vehicle is stopped and when it is in motion, thus reducing any discomfort that changes in the idle rotation speed NEid may cause to the vehicle occupants.

[0033] <Example of changes> The above embodiment can be implemented with the following modifications. The above embodiment and the following modifications can be combined with each other to the extent that they do not contradict each other technically.

[0034] In the above embodiment, the idle rotational speed NEid was set to the same rotational speed while the vehicle was stopped and while it was in motion during autonomous driving. Alternatively, the idle rotational speed NEid may be set to different values ​​while the vehicle was stopped and while it was in motion during autonomous driving. In this case as well, effects and benefits other than those described in (3) above can be obtained.

[0035] In the processing of S130, the value of the fixed rotational speed NEd that is substituted into the target idle rotational speed NEidt may be set to a speed that is at least higher than the first rotational speed NE1.

[0036] The idle rotational speed NEid, which is set during autonomous driving, may be set to a higher speed than the idle rotational speed NEid, which is set when autonomous driving is not being performed and the vehicle is stopped. In other words, in the process of S130 shown in Figure 2, a rotational speed faster than the third rotational speed NE3 may be substituted for the target idle rotational speed NEidt. In this case, the idle rotational speed NEid, which is set during autonomous driving, will be higher than the idle rotational speed NEid, which is set when autonomous driving is not being performed and the vehicle is stopped. Therefore, insufficient charge of the high-voltage battery 300 can be more reliably suppressed.

[0037] Vehicle 500 may be a vehicle that implements at least adaptive cruise control as part of autonomous driving. The hybrid system of vehicle 500 is not limited to the one shown in Figure 1; other hybrid systems are also acceptable. For example, it may be a so-called series-parallel hybrid system that does not have a clutch mechanism 20 and in which the crankshaft 18 and motor generator 30 are connected via a power split mechanism.

[0038] The number of motor generators equipped in vehicle 500 can be changed as appropriate. [Explanation of Symbols]

[0039] 10... Internal combustion engine 12…Fuel injector 13…Intake passage 14…Throttle valve 16… Exhaust passage 18... Crankshaft 20...Clutch mechanism 30…Motor Generator 42... Torque converter 48... Automatic transmission 65…Drive wheels 70... Crank angle sensor 71…Rotation speed sensor 75…Accelerator position sensor 76... Vehicle speed sensor 77... Shift position sensor 100...Control device 110…CPU 120...memory 200...PCU 300... High-voltage battery 310... Low-voltage battery 500...vehicles 600…Autonomous driving system

Claims

1. A control device applicable to a hybrid vehicle equipped with an internal combustion engine and an electric motor as prime movers, which uses the output of the internal combustion engine to charge a battery and implement adaptive cruise control, The system executes a process to make the idle speed of the internal combustion engine higher than the idle speed of the vehicle when the adaptive cruise control is not in operation. Control system for hybrid vehicles.

2. The idle speed is set to the same rotational speed while the vehicle is stopped and while the vehicle is in motion, while the adaptive cruise control is in operation. A control device for a hybrid vehicle according to claim 1.

3. The idle speed set while the adaptive cruise control is in operation is higher than the idle speed set when the adaptive cruise control is not in operation and the vehicle is stationary. A control device for a hybrid vehicle according to claim 2.

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