Vehicle control system

Abstract

This makes it possible to reduce the discrepancy between the actual acceleration and the acceleration perceived by the occupants during acceleration control when a hybrid vehicle is in autonomous driving mode and the preceding vehicle disappears. [Solution] The vehicle control device 1 is installed in a hybrid vehicle capable of autonomous driving and includes a determination unit (S1, S3) that determines whether the hybrid vehicle is in autonomous driving mode and acceleration control mode, and a response unit (S5) that sets an upper limit value for the rotational speed of the engine 2 installed in the hybrid vehicle when the determination unit S12 makes a positive determination.

Description

Technical Field

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

Background Art

[0002] For example, Patent Document 1 describes that “in a hybrid vehicle having an engine and a motor as drive sources, a first driving (CS: Charge Sustaining) mode in which the vehicle travels while maintaining the charge amount (SOC: State Of Charge) of a power storage device, and a second driving (CD: Charge Depleting) mode in which the vehicle travels mainly using the stored power without maintaining the SOC are provided”.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In Patent Document 1, in order to maintain the SOC amount even during acceleration, it is necessary to control the engine speed to increase. However, in a hybrid vehicle equipped with a driving support function such as Adaptive Cruise Control (ACC), if the same control as in Patent Document 1 is applied during the ACC, when the preceding vehicle disappears, the actual acceleration during the acceleration control and the acceleration felt by the passenger will deviate greatly, leading to discomfort for the passenger.

[0005] Note that the actual acceleration during the acceleration control when the preceding vehicle disappears during the ACC is about 1 m / s2 or less and is not high, but it is considered that the acceleration felt by the passenger increases as the engine speed increases.

[0006] In view of these circumstances, the present invention aims to provide a vehicle control device that can reduce the discrepancy between the actual acceleration and the acceleration perceived by the occupants during acceleration control when a hybrid vehicle is in autonomous driving mode and the preceding vehicle disappears. [Means for solving the problem]

[0007] The present invention is a vehicle control device to be installed in a hybrid vehicle capable of autonomous driving, and is characterized by including a determination unit that determines whether or not the hybrid vehicle is in autonomous driving mode and acceleration control mode, and a response unit that sets an upper limit value for the rotational speed of the engine installed in the hybrid vehicle when the determination unit makes a positive determination.

[0008] This configuration makes it possible to reduce the discrepancy between the actual acceleration and the acceleration perceived by the occupants during acceleration control when the hybrid vehicle is in autonomous driving mode and the preceding vehicle disappears, thereby reducing discomfort for the occupants. [Effects of the Invention]

[0009] According to the present invention, it is possible to reduce the discrepancy between the actual acceleration and the acceleration perceived by the occupants during acceleration control when a hybrid vehicle is in autonomous driving mode and the preceding vehicle disappears. [Brief explanation of the drawing]

[0010] [Figure 1] (a) is a diagram showing a schematic configuration of one embodiment of the vehicle control device according to the present invention, and (b) is a diagram showing a graph used when setting the upper limit of the engine speed during preceding vehicle non-acceleration control. [Figure 2] This diagram shows a flowchart used to explain the operation of the ACC control unit of the vehicle control system. [Figure 3] This diagram shows a flowchart used to explain the operation of the HEV control unit of the vehicle control system. [Modes for carrying out the invention]

[0011] The best embodiment for carrying out the present invention will be described in detail below with reference to the accompanying drawings.

[0012] Figures 1 to 3 show one embodiment of the present invention. The vehicle control device 1 illustrated in this embodiment is installed, for example, in a hybrid electric vehicle (HEV).

[0013] Although not shown in the diagram, the hybrid vehicle has a configuration based on, for example, FF (front-engine, front-wheel drive) and includes at least an engine 2, a motor 3, a battery 4, an external information input unit 5, a vehicle information input unit 6, etc.

[0014] Engine 2 is a gasoline engine or a diesel engine, etc., and generates the driving force for propulsion.

[0015] Motor 3 is an AC synchronous generator that functions as both a generator and an electric motor. When the accelerator pedal (not shown) is released (zero pedal force), regenerative control is activated, recovering electrical energy and providing regenerative braking force to the vehicle, functioning as a "regenerative brake." Additionally, it functions as an electric motor as needed to generate driving force for propulsion.

[0016] Battery 4 constitutes the main power source of the hybrid vehicle and is connected to motor 3 via an inverter (not shown). The inverter converts DC power from battery 4 into AC power to drive motor 3.

[0017] External information input unit 5 may include radar such as millimeter-wave radar or infrared laser radar, or a stereo camera or monocular camera. Vehicle information input unit 6 may include various sensors that detect information such as driving conditions and accelerator pedal position.

[0018] The vehicle control device 1 consists of an ECU (Electronic Control Unit). Although not shown in detail, this ECU includes a CPU, a ROM, a RAM (also referred to as a memory), a communication I / F, and an input / output I / F that are communicably connected to each other via a bus.

[0019] The vehicle control device 1 at least includes a HEV control unit 7, an ACC control unit 8, etc., and controls the output (driving force) of the engine 2, the output (driving force) of the motor 3, the charge amount (SOC: State Of Charge) of the battery 4, the braking force, etc.

[0020] Although not shown in detail, the braking force is obtained, for example, by a hydraulic brake or an electric brake that generates a frictional braking force, and a regenerative brake that generates a regenerative braking force by the regeneration of the motor 3. The hydraulic brake or the electric brake is configured such that its actuator can be controlled by the vehicle control device 1.

[0021] And the vehicle control device 1 controls the driving mode. As the driving mode, for example, as shown in WO2010 / 143281 (Japanese Patent No. 5229389), there are a first driving (CS: Charge Sustaining) mode in which the vehicle travels while maintaining the charge amount (SOC: State Of Charge) of the battery 4, and a second driving (CD: Charge Depleting) mode in which the vehicle travels mainly using the stored electric power of the battery 4 without maintaining the SOC amount of the battery 4.

[0022] When the battery 4 is charged, the CD mode is set as the default driving mode, and when the SOC amount of the battery 4 decreases to the control target during vehicle travel in the CD mode, the mode is changed from the CD mode to the CS mode.

[0023] Also, the HEV control unit 7 and the ACC control unit 8 of the vehicle control device 1 control, for example, autonomous driving.

[0024] Examples of the aforesaid automatic driving include, for example, a known Adaptive Cruise Control (ACC). This ACC is a function (driving assistance function) that automatically supports the driving of the host vehicle by automatically controlling the driving force and the braking force so as to make the host vehicle travel at a constant speed while maintaining a constant inter-vehicle distance between the host vehicle and the preceding vehicle.

[0025] When the preceding vehicle disappears during the automatic driving of a hybrid vehicle, the vehicle control device 1 switches from the “normal engine / motor optimal drive control mode” to the “motor-priority drive control mode” as acceleration control, and suppresses the increase in the output of the engine 2, that is, the engine speed, so as to suppress the acceleration felt by the passengers. This control will be described in detail based on the flowcharts shown in FIGS. 2 and 3.

[0026] First, the operation of the ACC control unit 8 of the vehicle control device 1 will be described with reference to the flowchart shown in FIG. 2. The ACC control unit 8 starts the flowchart shown in FIG. 2, for example, in accordance with the execution of ACC.

[0027] In step S1, it is determined whether there is no preceding vehicle. If the determination in this step S1 is negative, the “preceding vehicle absent / acceleration control in progress flag” is turned off in step S2, and then the process proceeds to step S6. In this step S6, the required acceleration of ACC is calculated based on information such as the vehicle speed, the set vehicle speed of ACC, and the presence or absence of a preceding vehicle, and then the process ends.

[0028] On the other hand, if the determination in step S1 is affirmative, the process proceeds to step S3. In this step S3, it is determined whether “the vehicle speed < the set vehicle speed of ACC”.

[0029] In this step S3, if the determination is negative, that is, when “the vehicle speed ≥ the set vehicle speed of ACC”, the process proceeds to step S2, while if the determination is affirmative, that is, when “the vehicle speed < the set vehicle speed of ACC”, the process proceeds to step S4.

[0030] In step S4, the "No preceding vehicle, acceleration control in progress" flag is turned ON, and in the following step S5, the upper limit of the ACC's requested engine speed is calculated, and the process proceeds to step S6.

[0031] In step S5, the upper limit of the ACC's requested engine speed is set, for example, based on Figure 1(b). The values ​​in the graph of Figure 1(b) are determined based on values ​​that the occupants do not perceive as being too high for each vehicle speed. These values ​​can be set appropriately through experimentation or simulation.

[0032] Next, the operation of the HEV control unit 7 of the vehicle control device 1 will be explained with reference to the flowchart shown in Figure 3. The HEV control unit 7 starts the flowchart shown in Figure 3 at regular intervals, for example.

[0033] First, in step S11, the required driving force is calculated based on the ACC's requested acceleration, and in step S12, it is determined whether the "No preceding vehicle / Acceleration control in progress flag" is ON or not.

[0034] The "No preceding vehicle / Acceleration control in progress" flag is turned ON when the ACC control unit 8 detects that there is no preceding vehicle and that acceleration control is in progress (see steps S1, S3, and S4 in Figure 2).

[0035] If a negative result is determined in step S12, the optimal driving force for engine 2 and motor 3 according to the SOC amount is calculated in step S13, and then the process proceeds to step S17.

[0036] If the process proceeds to step S17 after step S13, in step S17 the engine 2 and motor 3 are driven based on the driving force calculated in step S13, and then the process ends.

[0037] On the other hand, if a positive determination is made in step S12, then in step S14, it is determined whether or not "SOC amount > lower limit".

[0038] If a negative determination is made in step S14, that is, if "SOC amount ≤ lower limit", then in step S15 the driving force of engine 2 and motor 3 is calculated within the range where the SOC amount does not decrease, and then the process proceeds to step S17.

[0039] If the process proceeds to step S17 after step S15, in step S17 the engine 2 and motor 3 are driven based on the driving force calculated in step S15, and then the process ends.

[0040] On the other hand, if a positive determination is made in step S14, that is, if "SOC amount > lower limit", then in step S16, the driving force to be distributed to engine 2 and motor 3 is calculated based on the upper limit of the ACC's requested engine speed, and then the process proceeds to step S17.

[0041] If the process proceeds to step S17 after step S16, in step S17 the engine 2 and motor 3 are driven based on the driving force calculated in step S16, and then the process ends.

[0042] Incidentally, step S13 corresponds to the "normal engine / motor optimal drive control mode," and steps S15 and S16 correspond to the "motor-prioritized drive control mode."

[0043] As described above, according to embodiments to which the present invention is applied, it becomes possible to reduce the discrepancy between the actual acceleration and the acceleration perceived by the occupants during acceleration control when a preceding vehicle disappears while the hybrid vehicle is in autonomous driving mode, thereby reducing discomfort for the occupants.

[0044] It should be noted that the present invention is not limited to the embodiments described above, and can be modified as appropriate within the scope of the claims and equivalents thereof. For example, the vehicle control device 1 of the present invention can be applied to hybrid vehicles with various configurations. [Industrial applicability]

[0045] The present invention can be suitably used in vehicle control devices. [Explanation of Symbols]

[0046] 1. Vehicle control system 2 engines 3 motors 4 batteries 5. External Information Input Section 6. Vehicle Information Input Section 7 HEV Control Unit 8 ACC Control Unit

Claims

[Claim 1] A vehicle control device installed in a hybrid vehicle capable of autonomous driving, A vehicle control device comprising: a determination unit that determines whether the hybrid vehicle is in autonomous driving mode and acceleration control mode; and a response unit that, if the determination unit determines to be positive, sets an upper limit value for the rotational speed of the engine mounted on the hybrid vehicle.

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