Control device for hybrid electric vehicle

Abstract

The invention relates to a control device for a hybrid electric vehicle. The control device is applied to the hybrid electric vehicle which is provided with an internal combustion engine and a motor generator as prime movers, charges a high-voltage storage battery by using the output of the internal combustion engine, and performs automatic driving. The control device executes a process for increasing the idle speed of the internal combustion engine during a vehicle travel period during a period during which automatic driving is implemented than the idle speed during a vehicle travel period during a period during which automatic driving is not implemented.

Description

Technical Field

[0001] The invention relates to a control device for a hybrid electric vehicle. Background Art

[0002] For example, in a vehicle described in Japanese Patent Application Laid-Open No. 10-115237, the idle speed of the internal combustion engine is different between when the vehicle is running and when the vehicle is stopped. Summary of the invention

[0003] A hybrid electric vehicle is known that has an internal combustion engine and an electric motor as prime movers and uses the output of the internal combustion engine to charge a battery. In this hybrid electric vehicle, if the idle speed of the internal combustion engine is maintained when the vehicle changes from a stopped state to a running state, the vehicle driver may strongly feel the creep force of the vehicle. Therefore, when the vehicle changes from a stopped state to a running state, the creep force is suppressed by reducing the idle speed of the internal combustion engine. However, if the idle speed of the internal combustion engine is reduced, the output of the internal combustion engine decreases. Therefore, the charge amount of the battery that is charged using the output of the internal combustion engine may be insufficient during driving.

[0004] A hybrid electric vehicle control device for solving the above-mentioned problem is applied to a hybrid electric vehicle having an internal combustion engine and an electric motor as prime movers, charging a battery using the output of the internal combustion engine, and implementing adaptive cruise control. The control device performs processing to make the idle speed of the internal combustion engine during vehicle driving during the implementation period of the adaptive cruise control higher than the idle speed during vehicle driving during the non-implementation period of the adaptive cruise control.

[0005] A control device for a hybrid electric vehicle can suppress insufficient charge of a battery during traveling. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Features, advantages and technical and industrial significance of exemplary embodiments of the present invention will be described below with reference to the accompanying drawings, in which like numerals represent like elements, and in which:

[0007] Figure 1 is a schematic diagram of a vehicle in one embodiment;

[0008] Figure 2 It is a flowchart showing the process steps executed by the control device of this embodiment. DETAILED DESCRIPTION

[0009] Vehicle structure

[0010] In the following, regarding one embodiment of a control device for a hybrid electric vehicle, refer to Figure 1 and Figure 2 To explain.

[0011] like Figure 1 As shown, the vehicle 500 is a hybrid electric vehicle equipped with two prime movers, namely, the motor generator 30 as an electric motor and the internal combustion engine 10. The motor generator 30 has a function as a generator that generates electric power stored in the high voltage battery 300 using the output of the internal combustion engine 10, and a function as a motor that receives electric power from the high voltage battery 300 and outputs power for traveling. The high voltage battery 300 is a battery that is charged using the output of the internal combustion engine 10.

[0012] The internal combustion engine 10 is provided with a fuel injection valve 12 for supplying fuel to a cylinder. An electric throttle valve 14 for adjusting the amount of intake air is provided in an intake passage 13 of the internal combustion engine 10. A catalyst 17 for exhaust purification is provided in an exhaust passage 16 of the internal combustion engine 10. When the catalyst 17 is preheated by reaching an activation temperature or higher, the ability to purify exhaust gas increases. In the combustion chamber of the internal combustion engine 10, a mixture of the intake air and the fuel injected from the fuel injection valve 12 is burned, thereby obtaining an internal combustion engine output.

[0013] The crankshaft 18 of the internal combustion engine 10 is connected to an output shaft 41 of the motor generator 30 via a clutch mechanism 20 .

[0014] The clutch mechanism 20 is a mechanism for adjusting the torque transmission amount 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 and the output shaft 41 of the motor generator 30 are connected, and 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.

[0015] The motor generator 30 exchanges electric power with the high voltage battery 300 for traveling via a power control unit (PCU) 200 .

[0016] PCU 200 includes a boost converter 210, an inverter 220, a DC-DC converter 230, and the like. Boost converter 210 boosts the DC voltage input from high voltage battery 300 and outputs the boosted DC voltage. Inverter 220 converts the DC voltage boosted by boost converter 210 into an AC voltage and outputs the AC voltage to motor generator 30. DC-DC converter 230 steps down the DC voltage of high voltage battery 300 into a voltage for driving auxiliary machines. The stepped-down electric power is stored in low voltage battery 310.

[0017] The output shaft 41 of the motor generator 30 is connected to the input shaft of the torque converter 42 having the lock-up clutch 45. The output shaft of the torque converter 42 is connected to the input shaft of the automatic transmission 48. The output shaft of the automatic transmission 48 is connected to the differential 60. The output shaft of the differential 60 is connected to the drive wheels 65 of the vehicle 500.

[0018] The vehicle 500 is provided with an automatic driving system 600. The automatic driving system 600 is provided with a CPU, a memory storing control programs / data, and various sensors. Furthermore, the automatic driving of the vehicle 500 is performed by the CPU executing the program stored in the memory. The automatic driving system 600 performs and releases the automatic driving by operating, for example, buttons and touch panels provided in the vehicle. The automatic driving system 600 controls the steering system of the vehicle 500, the braking system of the vehicle 500, the prime mover system of the vehicle 500, and the like. The automatic driving system 600 implements the well-known adaptive cruise control as one of the automatic driving. The adaptive cruise control is a control such as following driving to maintain a distance between the vehicle and the vehicle in front by automatically accelerating and decelerating the vehicle within a predetermined vehicle speed.

[0019] The automatic 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.

[0020] The control device 100 includes a CPU 110 and a memory 120 storing control programs and data. Various controls are performed by the CPU 110 executing the programs stored in the memory 120. It should be noted that, although not shown, the control device 100 is composed of a plurality of control units such as a control unit for the internal combustion engine and a control unit for the PCU.

[0021] 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 rotation speed of the electric generator 30, that is, the motor rotation speed Nm. The control device 100 is connected to an air flow meter 72 for detecting the intake air amount GA of the internal combustion engine 10, and a water temperature sensor 73 for detecting the temperature of the cooling water of the internal combustion engine 10, that is, the cooling water temperature THW. The control device 100 is connected to a throttle sensor 74 for detecting the opening degree of the throttle valve 14, that is, the throttle opening degree TA, and an accelerator position sensor 75 for detecting the operation amount of the accelerator pedal, that is, the accelerator operation amount ACCP. 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 operation position of the shift lever of the automatic transmission 48 provided in the cabin of the vehicle 500, that is, the shift position SFT. As the operating positions of the shift lever, there are a non-driving position selected when the vehicle 500 is not driving, that is, a parking position (P position) and a neutral position (N position). In addition, as the operating positions of the shift lever, there are a driving position selected when the vehicle 500 is driving, that is, a forward position (D position) and a reverse position (R position). It should be noted that buttons, touch panels, etc. can also have the function of a shift lever. In addition, the control device 100 grasps the starting requirement of the system of the vehicle 500 based on the input signal from the power switch 78. It should be noted that the control device 100 calculates the internal combustion engine speed NE based on the output signal Scr of the crankshaft angle sensor 70. In addition, the control device 100 calculates the internal combustion engine load factor KL based on the internal combustion engine speed NE and the intake air amount GA.

[0022] The above-mentioned PCU 200 is connected to the control device 100 , and the control device 100 controls the motor generator 30 by controlling the PCU 200 .

[0023] 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 control amount of the internal combustion engine 10, i.e., the engine output, the exhaust component ratio, etc. The control device 100 also operates the inverter 220 via the PCU 200 in order to control the control amount of the motor generator 30, i.e., the torque, which is the control amount of the control object.

[0024] When the internal combustion engine 10 is used as the prime mover of the vehicle 500, the control device 100 puts the clutch mechanism 20 into an engaged state to transmit the output torque of the internal combustion engine 10 to the automatic transmission 48. In addition, in some cases, by also performing a power running operation on the motor generator 30, not only the output torque of the internal combustion engine 10 but also the power running torque of the motor generator 30 is transmitted to the automatic transmission 48, thereby performing HV running. On the other hand, when only the motor generator 30 is used as the prime mover of the vehicle 500, the control device 100 puts the clutch mechanism 20 into a released state to cut off the torque transmission between the internal combustion engine 10 and the automatic transmission 48. And, by performing a power running operation on the motor generator 30, the power running torque of the motor generator 30 is transmitted to the automatic transmission 48 to perform EV running. In addition, when the output of the internal combustion engine 10 is used to charge the high voltage battery 300, the control device 100 puts the clutch mechanism 20 into an engaged state to transmit the output torque of the internal combustion engine 10 to the motor generator 30 and the automatic transmission 48, thereby performing internal combustion engine running.

[0025] The control device 100 implements idle operation control of the internal combustion engine 10 when the accelerator operation amount ACCP is "0" and there is an internal combustion engine operation request. In this idle operation control, the target idle speed NEidt is calculated. And the internal combustion engine is operated in a manner that the internal combustion engine speed NE during idle operation, that is, the idle speed NEid, is consistent with the target idle speed NEidt. It should be noted that as the above-mentioned internal combustion engine operation request, for example, a charging request for the high-voltage battery 300, a driving request for an auxiliary machine provided in the internal combustion engine 10, etc. can be cited.

[0026] Setting the target idle speed

[0027] exist Figure 2 In FIG. 1 , the process of setting the target idle speed NEidt executed when the idle operation control is implemented is shown. Figure 2 The processing shown is repeatedly executed at a predetermined cycle when the execution of the idle operation control is requested. In the following, step numbers are represented by numbers with "S" added to the beginning.

[0028] When to start Figure 2After the processing shown, the control device 100 determines whether the automatic driving is in progress (S100). If it is determined that the automatic driving is in progress (S100: Yes), the control device 100 substitutes the fixed speed NEd into the target idle speed NEidt (S130). The fixed speed NEd is the same value as the third speed NE3 described later. In addition, during the automatic driving, the fixed speed NEd is substituted as the target idle speed NEidt regardless of whether the vehicle is parked or traveling.

[0029] When the fixed speed NEd is substituted into the target idle speed NEidt in the process of S130, the control device 100 operates the internal combustion engine so that the idle speed NEid coincides with the fixed speed NEd.

[0030] When it is determined in the process of S100 that the automatic driving is not being implemented or is not being implemented (S100: No), the control device 100 determines whether the current shift position SFT is the P position or the N position (S110). Furthermore, when it is determined that the shift position SFT is the P position or the N position (S110: Yes), the control device 100 substitutes the third speed NE3 into the target idle speed NEidt (S140). The third speed NE3 is a speed set when there is a charge request for the high voltage battery 300, and is the fastest speed among the variable idle speeds NEid.

[0031] When the third speed NE3 is substituted into the target idle speed NEidt in the process of S140, the control device 100 operates the internal combustion engine so that the idle speed NEidt coincides with the third speed NE3.

[0032] When it is determined in the process of S110 that the shift position SFT is not the P position or the N position (S110: No), the control device 100 determines whether the vehicle 500 is running based on the vehicle speed SP and the like (S120). When it is determined that the vehicle 500 is running (S120: Yes), the control device 100 substitutes the first speed NE1 into the target idle speed NEidt (S150).

[0033] The first speed NE1 is set in consideration of preventing the creep force from becoming excessively strong during the running of the vehicle 500, and is the slowest speed among the variable idle speeds NEid. If the first speed NE1 is substituted into the target idle speed NEidt in the process of S150, the control device 100 operates the internal combustion engine so that the idle speed NEid is consistent with the first speed NE1.

[0034] If it is determined in the process of S120 that the vehicle is not traveling (S120: No), that is, if the vehicle is stopped, the control device 100 substitutes one of the third speed NE3 and the second speed NE2 into the target idle speed NEidt (S160). The second speed NE2 is a predetermined value and is a speed between the first speed NE1 and the third speed NE3.

[0035] Furthermore, when there is a charge request for the high voltage battery 300, the control device 100 substitutes the third speed NE3 into the target idle speed NEidt in the process of S160. Furthermore, when there is no charge request for the high voltage battery 300, the control device 100 substitutes the second speed NE2 into the target idle speed NEidt in the process of S160.

[0036] If the second speed NE2 is substituted into the target idle speed NEidt by the process of S160, the control device 100 operates the internal combustion engine in such a manner that the idle speed NEid is consistent with the second speed NE2. In addition, if the third speed NE3 is substituted into the target idle speed NEidt by the process of S160, the control device 100 operates the internal combustion engine in such a manner that the idle speed NEid is consistent with the third speed NE3. It should be noted that the selection of the third speed NE3 or the second speed NE2 in the process of S160 may also be performed based on other parameters, such as the gear position SFT.

[0037] Functions and effects of this embodiment

[0038] Then, when any one of the processes of S130 , S140 , S150 , and S160 is executed, the control device 100 ends the execution of the present process in the current cycle.

[0039] (1) During the implementation of the automatic driving including the adaptive cruise control, the speed of the vehicle 500 is automatically controlled without the vehicle driver operating the accelerator, so the vehicle driver is not easily aware of the strength of the creep force. In this regard, in the present embodiment, during the vehicle driving period during the implementation of the automatic driving, the fixed speed NEd is substituted into the target idle speed NEidt by executing the process of S130. On the other hand, during the vehicle driving period during the non-implementation of the automatic driving, the first speed NE1 which is slower than the fixed speed NEd is substituted into the target idle speed NEidt by executing the process of S150. Therefore, the idle speed NEid of the internal combustion engine 10 becomes higher during the vehicle driving period during the implementation of the automatic driving than during the vehicle driving period during the non-implementation of the automatic driving. Therefore, it is possible to suppress the insufficient charge of the high voltage battery 300 during the driving period.

[0040] (2) Since the shortage of the charge amount of the high voltage battery 300 can be suppressed, the execution time of EV running using the electric power stored in the high voltage battery 300 can be extended.

[0041] (3) During the implementation of the automatic driving, the processing of S130 is performed. Therefore, during the implementation of the automatic driving, the idle speed NEid during the parking period and during the driving period of the vehicle is set to the same speed. Therefore, during the implementation of the automatic driving, the idle speed NEid does not change during the parking period and during the driving period, so that the sense of comfort given to the vehicle passengers by the change of the idle speed NEid can be suppressed.

[0042] Change Example

[0043] It should be noted that the above-mentioned embodiment can be modified and implemented as follows. The above-mentioned embodiment and the following modified examples can be combined and implemented within the scope of no technical contradiction.

[0044] In the above embodiment, the idle speed NEid during the parking period and the vehicle driving period during the implementation of the automatic driving is set to the same speed. In addition, during the implementation of the automatic driving, the idle speed NEid during the parking period and the vehicle driving period may be different. Even in this case, the action and effect other than the above (3) can be obtained.

[0045] As the value of the fixed rotation speed NEd substituted into the target idle rotation speed NEidt in the process of S130 , a speed higher than at least the first rotation speed NE1 may be set.

[0046] The idle speed NEid set during the period of automatic driving may be set to a higher speed than the idle speed NEid set during the parking period when automatic driving is not being executed. Figure 2 In the process of S130 shown in FIG. 1 , a rotation speed faster than the third rotation speed NE3 may be substituted into the target idle speed NEidt. In this case, the idle speed NEid set during the implementation period of the automatic driving is higher than the idle speed NEid set during the parking period in the non-implementation period of the automatic driving. Therefore, the insufficient charge of the high voltage battery 300 can be more reliably suppressed.

[0047] The vehicle 500 may be a vehicle that performs at least adaptive cruise control as autonomous driving.

[0048] The hybrid system of the vehicle 500 is not limited to Figure 1 The hybrid system shown may be another hybrid system, for example, a so-called parallel-type hybrid system in which the clutch mechanism 20 is not provided and the crankshaft 18 and the motor generator 30 are connected via a power split mechanism.

[0049] The number of motor generators included in vehicle 500 can be changed as appropriate.

Claims

1. A control device for a hybrid electric vehicle, applied to a hybrid electric vehicle having an internal combustion engine and an electric motor as prime movers and utilizing the output of the internal combustion engine to charge a battery and implement adaptive cruise control, wherein: The control device executes a process of making the idle speed of the internal combustion engine during vehicle travel in an implementation period of the adaptive cruise control higher than the idle speed during vehicle travel in a non-implementation period of the adaptive cruise control.

2. The control device for a hybrid electric vehicle according to claim 1, The control device sets the idle speed to the same speed during a vehicle stop and during vehicle travel during the execution of the adaptive cruise control.

3. The control device for a hybrid electric vehicle according to claim 2, The idle speed set during the execution period of the adaptive cruise control is higher than the idle speed set during a stop period during which the adaptive cruise control is not executed.

Images