Control device and control method

Abstract

To provide a control device and a control method which suppress a feeling of strangeness from being imparted to a driver.SOLUTION: A control device according to an embodiment controls a vehicle having an engine and a motor as driving sources. The control device comprises a control part. When a travelling mode of the vehicle is an EV mode in which the vehicle travels without driving the engine, the control part starts the engine, when required driving force by the vehicle based on an operation amount of a driver becomes an engine starting threshold or higher, and then shifts the travelling mode to an HV mode in which the vehicle travels using the engine and the motor. When the required driving force becomes less than the engine starting threshold, in a state where the engine is operated for a first predetermined time or less after the required driving force becomes the engine starting threshold or higher, the control part shifts the travelling mode to the EV mode, and notifies a driver that the EV mode is continued to be the travelling mode.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] BACKGROUND ART Conventionally, hybrid vehicles are known in which the engine is driven when the running power reaches or exceeds an engine start threshold (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2011 / 030444 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the hybrid vehicle, the driving power fluctuates depending on the driver's operation of the accelerator pedal, and the engine may be started at a time not intended by the driver, causing the vehicle to run on engine power, which may cause the driver to feel uncomfortable.

[0005] The present invention has been made in view of the above, and has an object to provide a control device and a control method that suppress the sense of discomfort felt by the driver. [Means for solving the problem]

[0006] A control device according to one aspect of the embodiment controls a vehicle using an engine and a motor as drive sources. The control device includes a control unit. When the vehicle's driving mode is in an EV mode in which the vehicle is driven without the engine being driven, and a required driving force of the vehicle based on a driver's operation amount becomes equal to or greater than an engine start threshold, the control unit starts the engine and transitions the driving mode to an HV mode in which the vehicle is driven using the engine and the motor. When the required driving force becomes less than the engine start threshold while the engine operation time is equal to or less than a first predetermined time after the required driving force becomes equal to or greater than the engine start threshold, the control unit switches the driving mode to the EV mode and notifies the driver that the EV mode will continue as the driving mode. [Effects of the Invention]

[0007] According to one aspect of the embodiment, it is possible to suppress the sense of discomfort felt by the driver. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram illustrating a control method according to an embodiment. [Figure 2] FIG. 2 is a diagram illustrating an example of the configuration of the control device according to the embodiment. [Figure 3A] FIG. 3A is a flowchart illustrating the EV mode switching control according to the embodiment. [Figure 3B] FIG. 3B is a flowchart illustrating the EV mode switching control according to the embodiment. [Figure 4] FIG. 4 is a time chart showing an example of the running mode control according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A control device and a control method according to an embodiment will be described in detail below with reference to the accompanying drawings. However, the present invention is not limited to the present embodiment.

[0010] First, a control method according to the embodiment will be described with reference to Fig. 1. Fig. 1 is a schematic diagram illustrating the control method according to the embodiment. The control method according to the embodiment is executed by a control device 10 of a vehicle C shown in Fig. 1.

[0011] The vehicle C is a hybrid vehicle having an engine 1 and a motor 2 as drive sources. The hybrid vehicle has a plurality of driving modes, including an EV mode and an HV mode.

[0012] The EV mode is a mode in which the vehicle C runs without driving the engine 1. The EV mode is a mode in which the motor 2 is used as a driving source.

[0013] The HV mode is a mode in which the engine 1 and the motor 2 are used as drive sources. For example, the HV mode includes a mode in which only the engine 1 is used as a drive source, and a mode in which the engine 1 and the motor 2 are used together as drive sources.

[0014] The HV mode may include an EV priority mode in which the frequency of driving using the motor 2 increases. In the EV priority mode, driving by the engine 1 is suppressed. For example, when the driving mode is the HV mode and the battery's state of charge (SOC) is equal to or lower than a predetermined value, the driving mode is set to an HV mode different from the EV priority mode. When the driving mode is the HV mode and the battery's SOC is higher than a predetermined value, the driving mode is set to the EV priority mode. The EV priority mode may also be set by the driver operating a switch, for example.

[0015] When the driving mode is in EV mode and the required driving force of vehicle C exceeds an engine start threshold, the control device 10 starts the engine 1 and shifts the driving mode from EV mode to HV mode. The required driving force of vehicle C is calculated based on the driver's operation amount, for example, the operation amount of the accelerator pedal. The required driving force of vehicle C increases as the operation amount (depression amount) of the accelerator pedal increases. The control device 10 may start the engine 1 based on the operation amount of the accelerator pedal instead of the required driving force. In other words, the required driving force of vehicle C may include the operation amount of the accelerator pedal. When the driving mode is set based on the operation amount of the accelerator pedal, an engine start threshold corresponding to the operation amount of the accelerator pedal is used. Note that the calculation of the required driving force of vehicle C is not limited to the operation amount of the accelerator pedal. For example, the required driving force of vehicle C may be calculated based on the operation amount of a switch, button, or lever that can change the speed.

[0016] However, even if the required driving force of vehicle C intended by the driver is less than the engine start threshold, the actual required driving force of vehicle C may become greater than or equal to the engine start threshold due to a change in the amount of accelerator pedal operation that is not intended by the driver.

[0017] For example, if the driver does not intend to accelerate vehicle C, but the amount of accelerator pedal operation by the driver increases, the actual required driving force of vehicle C may exceed the engine start threshold.

[0018] In such a case, the required driving force of vehicle C exceeds the engine start threshold, so engine 1 is started, the driving mode is shifted from EV mode to HV mode, and the HV mode is continued. Therefore, even though the driver wants to drive in EV mode, the HV mode is executed, which is a mode different from the driver's intention, and this may cause discomfort to the driver.

[0019] Therefore, the control device 10 according to this embodiment executes the following control method.

[0020] When the driving mode is the EV mode and the required driving force becomes equal to or greater than the engine start threshold, the control device 10 shifts the driving mode from the EV mode to the HV mode (S1). Note that when the required driving force becomes equal to or greater than the engine start threshold, the engine 1 is started.

[0021] The control device 10 shifts the driving mode to EV mode when the required driving force falls below the engine start threshold while the engine operation time is less than or equal to a first predetermined time after the required driving force becomes equal to or greater than the engine start threshold (S2). The first predetermined time is a short period of time that is set in advance and is longer than a second predetermined time required for the engine 1 to transition to a full combustion state. After the second predetermined time, the driver is considered to be aware that the engine 1 has started. The first predetermined time is the reaction time required for the driver to notice that the engine 1 has started and to shift the driving mode from HV mode to EV mode. For example, the first predetermined time is approximately 1.5 seconds. The full combustion state of the engine 1 refers to a state in which combustion is complete and the engine has been successfully started after the start of the internal combustion engine.

[0022] The control device 10 notifies the driver that the EV mode will continue as the driving mode (S3). For example, the control device 10 notifies the driver that the EV mode will continue as the driving mode by displaying on the instrument panel that the EV mode will continue or by turning on a light indicating that the vehicle is driving in the EV mode.

[0023] As a result, the control device 10 prevents the HV mode from being executed unintentionally by the driver. Also, to prevent the driver from mistaking the engine stop immediately after the engine 1 has started for an engine stall, for example, the control device 10 notifies the driver that the EV mode will continue as the driving mode. This makes it possible to prevent the driver from feeling uncomfortable.

[0024] Next, the control device 10 according to the embodiment will be described with reference to Fig. 2. Fig. 2 is a diagram showing an example of the configuration of the control device 10 according to the embodiment.

[0025] The control device 10 controls the vehicle C. The control device 10 controls the engine 1 and the motor 2 in accordance with the amount of accelerator pedal operation, and drives the vehicle C with a driving force corresponding to the amount of accelerator pedal operation. The control device 10 includes a memory unit 20 and a control unit 21.

[0026] The storage unit 20 is realized by, for example, a semiconductor memory element such as a random access memory (RAM) or a flash memory, or a storage device such as a hard disk or an optical disk.

[0027] The control unit 21 is a controller, and is realized by, for example, a CPU (Central Processing Unit), MPU (Micro Processing Unit), ASIC (Application Specific Integrated Circuit), FPGA (Field Programmable Gate Array), etc., by executing various programs (corresponding to an example of an information processing program) stored in a memory device inside the control device 10 using a memory area such as RAM as a working area.

[0028] The control unit 21 includes an acquisition unit 22, a calculation unit 23, a measurement unit 24, a determination unit 25, a switching unit 26, and a notification unit 27. The acquisition unit 22, the calculation unit 23, the measurement unit 24, the determination unit 25, the switching unit 26, and the notification unit 27 are not limited to this, and may be configured as an integrated unit or may be configured as separate units.

[0029] The acquisition unit 22 acquires a signal relating to the amount of operation of the accelerator pedal from the accelerator pedal sensor 30. The calculation unit 23 calculates the required driving force of the vehicle C based on the amount of operation of the accelerator pedal.

[0030] When the required driving force becomes equal to or greater than the engine start threshold, the measurement unit 24 measures the engine operation time since the required driving force became equal to or greater than the engine start threshold. When the required driving force becomes less than the engine start threshold, the measurement unit 24 resets the engine operation time at a predetermined timing. For example, the measurement unit 24 resets the engine operation time after determining that the engine operation time is equal to or less than a first predetermined time. The measurement unit 24 resets the engine operation time after determining whether the engine operation time is less than a second predetermined time.

[0031] Determination unit 25 determines whether the current driving mode is EV mode. Determination unit 25 determines whether the required driving force is equal to or greater than the engine start threshold. When the required driving force becomes equal to or greater than the engine start threshold, the driving mode is switched from EV mode to HV mode, and the required driving force becomes less than the engine start threshold, determination unit 25 determines whether the engine operating time in HV mode is equal to or less than a first predetermined time. Furthermore, when the required driving force becomes equal to or greater than the engine start threshold, the driving mode is switched from EV mode to HV mode, and the required driving force becomes less than the engine start threshold, determination unit 25 determines whether the engine operating time in HV mode is less than a second predetermined time.

[0032] The switching unit 26 switches the driving mode between the EV mode and the HV mode. Specifically, when the current driving mode is the EV mode and the required driving force becomes equal to or greater than the engine start threshold, the switching unit 26 shifts the driving mode from the EV mode to the HV mode.

[0033] The switching unit 26 transitions the driving mode from the HV mode to the EV mode when the required driving force becomes equal to or greater than the engine start threshold and the driving mode is transitioned from the EV mode to the HV mode, and then when the required driving force becomes less than the engine start threshold and the engine operating time is equal to or less than a first predetermined time.

[0034] When the engine operation time is equal to or longer than the second predetermined time and equal to or shorter than the first predetermined time, the switching unit 26 executes stop control of the engine 1. When the engine operation time is shorter than the second predetermined time, the switching unit 26 halts start control of the engine 1 and prevents the engine 1 from transitioning to a complete combustion state.

[0035] When the driving mode is shifted from the EV mode to the HV mode, the switching unit 26 starts the engine 1. When the driving mode is shifted from the HV mode to the EV mode, the switching unit 26 stops the engine 1.

[0036] The notification unit 27 notifies the driver that the EV mode will continue as the driving mode when the required driving force becomes equal to or greater than the engine start threshold, the driving mode is shifted from the EV mode to the HV mode, and the required driving force becomes less than the engine start threshold while the engine operating time is equal to or greater than the second predetermined time and equal to or less than the first predetermined time, and the driving mode is shifted from the HV mode to the EV mode. For example, the notification unit 27 displays on the instrument panel that the EV mode will continue. Note that the notification unit 27 may notify the driver that the EV mode will continue as the driving mode by voice.

[0037] The notification unit 27 does not issue a notification when the required driving force becomes equal to or greater than the engine start threshold, the driving mode is shifted from EV mode to HV mode, the engine operating time is less than a second predetermined time, the required driving force becomes less than the engine start threshold, and the driving mode is shifted from HV mode to EV mode.

[0038] Next, the EV mode switching control according to this embodiment will be described with reference to the flowcharts of Figures 3A and 3B. Figures 3A and 3B are flowcharts illustrating the EV mode switching control according to this embodiment.

[0039] The control device 10 determines whether the current driving mode is the EV mode (S100). If the current driving mode is not the EV mode (S100: No), that is, if the driving mode is the HV mode, the control device 10 ends this processing.

[0040] If the current driving mode is the EV mode (S100: Yes), the control device 10 acquires the accelerator pedal operation amount (S101), and calculates the required driving force based on the accelerator pedal operation amount (S102).

[0041] The control device 10 determines whether the required driving force is equal to or greater than the engine start threshold (S103). If the required driving force is less than the engine start threshold (S103: No), the control device 10 ends this processing. The driving mode is maintained in the EV mode.

[0042] If the required driving force is equal to or greater than the engine start threshold (S103: Yes), the control device 10 switches the driving mode to the HV mode (S104). That is, if the driving mode is the EV mode and the required driving force is equal to or greater than the engine start threshold, the control device 10 shifts the driving mode from the EV mode to the HV mode.

[0043] Following S104, the control device 10 measures the engine operation time after the requested driving force becomes equal to or greater than the engine start threshold (S105).

[0044] The control device 10 acquires the accelerator pedal operation amount (S106). The control device 10 calculates the required driving force based on the accelerator pedal operation amount (S107). The control device 10 calculates the required driving force in the HV mode.

[0045] The control device 10 determines whether the required driving force is less than the engine start threshold (S108). Specifically, the control device 10 determines whether the required driving force is less than the engine start threshold after the required driving force becomes equal to or greater than the engine start threshold and the driving mode changes to the HV mode.

[0046] If the required driving force is equal to or greater than the engine start threshold (S108: No), the control device 10 returns to step S105 and repeats the above process. That is, if the driving mode is the HV mode and the required driving force is equal to or greater than the engine start threshold, the control device 10 continues measuring the engine operating time in the HV mode.

[0047] If the requested driving force is less than the engine start threshold in S108 (S108: Yes), the control device 10 determines whether the engine operating time is equal to or less than a first predetermined time (S109).

[0048] If the engine operation time is longer than the first predetermined time (S109: No), the control device 10 ends this processing. If the engine operation time is longer than the first predetermined time, the driving mode is maintained in the HV mode. Note that if it is determined that the engine operation time is longer than the first predetermined time, the engine operation time is reset.

[0049] If the engine operation time is equal to or shorter than the first predetermined time (S109: Yes), the control device 10 switches the driving mode to the EV mode (S110). That is, after the required driving force becomes equal to or greater than the engine start threshold and the driving mode becomes the HV mode, if the required driving force becomes less than the engine start threshold within a short period of time during which the engine operation time is equal to or shorter than the first predetermined time, the control device 10 switches the driving mode back to the EV mode and continues the EV mode.

[0050] The control device 10 determines whether the engine operation time is less than the second predetermined time (S111). If the engine operation time is equal to or greater than the second predetermined time (S111: No), the control device 10 notifies the driver that the driving mode will continue in the EV mode (S112).

[0051] If the engine operation time is less than the second predetermined time (S111: Yes), the control device 10 ends this processing. If the engine operation time is less than the second predetermined time, the control device 10 ends this processing without notifying that the driving mode will continue in EV mode. Note that after the determination in step S111, the engine operation time is reset.

[0052] If the engine operation time is less than the second predetermined time, the driving mode is shifted from HV mode to EV mode before the engine 1 transitions to a full combustion state, so it is difficult for the driver to notice that the driving mode has been changed from EV mode to HV mode and then from HV mode to EV mode. Therefore, the control device 10 ends the processing without notifying the driver that the driving mode has been shifted to EV mode.

[0053] Next, an example of the driving mode control according to the embodiment will be described with reference to Fig. 4. Fig. 4 is a time chart showing an example of the driving mode control according to the embodiment. Here, it is assumed that the vehicle C is driving in EV mode, the driver intends to maintain a constant amount of accelerator pedal operation, and the required driving force intended by the driver is constant.

[0054] Although the driver's desired driving force is constant, the actual desired driving force varies depending on the driver's slight change in accelerator pedal pressure.

[0055] At time t1, the requested driving force increases against the driver's will and exceeds the engine start threshold, causing the driving mode to shift from EV mode to HV mode. Also, since the requested driving force has exceeded the engine start threshold, engine 1 starts and the engine rotation speed increases.

[0056] When the requested driving force falls below the engine start threshold at time t2, when the engine operation time is equal to or longer than the second predetermined time and equal to or shorter than the first predetermined time, the driving mode is shifted from HV mode to EV mode. Because the engine operation time is equal to or longer than the second predetermined time and equal to or shorter than the first predetermined time, the driving mode is shifted from HV mode to EV mode, and a notification is issued that EV mode will be maintained.

[0057] The control device 10 controls a vehicle C using an engine 1 and a motor 2 as drive sources. The control device 10 includes a control unit 21. When the driving mode of the vehicle C is an EV mode in which the vehicle C is driven without the engine 1 being driven, and the requested driving force of the vehicle C based on the amount of operation of the accelerator pedal reaches or exceeds an engine start threshold, the control unit 21 starts the engine 1 and shifts the driving mode to an HV mode in which the vehicle C is driven using the engine 1 and the motor 2. If the engine operating time after the requested driving force reaches or exceeds the engine start threshold is less than a first predetermined time and the requested driving force falls below the engine start threshold, the control unit 21 switches the driving mode to the EV mode, and if the engine operating time is greater than or equal to a second predetermined time, the control unit 21 notifies the driver that the EV mode will continue as the driving mode.

[0058] As a result, when the required driving force temporarily becomes equal to or greater than the engine start threshold against the driver's intention, the control device 10 can switch the driving mode to the EV mode and continue driving in the EV mode. Therefore, the control device 10 can drive the vehicle C in a driving mode that corresponds to the driver's intention, and can prevent the driver from feeling uncomfortable. Furthermore, the control device 10 can increase the frequency of driving in the EV mode, and can reduce fuel consumption by the engine 1. Furthermore, for example, when the vehicle C is driving in a residential area, the control device 10 can reduce noise caused by the operation of the engine 1.

[0059] Furthermore, the control device 10 can make the driver aware that the EV mode will continue by notifying the driver that the EV mode will continue as the driving mode. Therefore, the control device 10 can prevent the driver from feeling uncomfortable when the driving mode is switched from the EV mode to the HV mode and then from the HV mode to the EV mode in a short period of time.

[0060] If the engine operating time is less than a second predetermined time, which is shorter than the first predetermined time, the control unit 21 stops the start control of the engine 1 and does not issue a notification. The second predetermined time is the time required for the engine 1 to transition to a complete combustion state.

[0061] As a result, if the required driving force falls below the engine start threshold before the engine 1 transitions to a full combustion state, the control device 10 can suppress fuel consumption by the engine 1 by halting the start of the engine 1. Furthermore, since the driver does not feel the engine 1 starting, the control device 10 does not notify the driver that the driving mode will continue in the EV mode, thereby suppressing the provision of unnecessary information to the driver and suppressing any sense of discomfort to the driver.

[0062] When the requested driving force falls below the engine start threshold while the engine operation time is equal to or longer than the second predetermined time and equal to or shorter than the first predetermined time, the control unit 21 executes stop control of the engine 1 and issues a notification.

[0063] As a result, when the engine 1 transitions to a full combustion state and the required driving force becomes less than the engine start threshold immediately after the engine 1 transitions to the full combustion state, the control device 10 notifies the driver that the EV mode will continue as the driving mode. Therefore, the control device 10 notifies the driver that the stop of the engine 1 is not due to, for example, an engine stall, and can prevent the driver from feeling uncomfortable.

[0064] As a modified example, the control device 10 according to the modified example may shift the driving mode to the EV-priority mode when the required driving force becomes equal to or greater than the engine start threshold and the driving mode changes to the HV mode, and then when the required driving force becomes less than the engine start threshold and the engine operating time is equal to or less than a third predetermined time and is longer than the first predetermined time. The third predetermined time is longer than the first predetermined time. For example, the third predetermined time is about 5 seconds.

[0065] As a result, immediately after the required driving force becomes equal to or greater than the engine start threshold, the control device 10 can suppress running by the engine 1 and suppress fuel consumption by the engine 1. Furthermore, for example, when the vehicle C runs in a residential area, the control device 10 can suppress noise caused by the operation of the engine 1.

[0066] Further advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described above. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents. [Explanation of symbols]

[0067] 1 engine 2 motors 10 Control device 21 Control section 22 Acquisition Department 23 Calculation section 24 Measurement section 25 Judgment section 26 Switching section 27. Information Department C vehicle

Claims

1. A control device that controls a vehicle driven by an engine and a motor, a control unit that, when a driving mode of the vehicle is an EV mode in which the vehicle is driven without the engine being driven, starts the engine and transitions the driving mode to an HV mode in which the vehicle is driven using the engine and the motor when a required driving force of the vehicle based on an operation amount of a driver becomes equal to or greater than an engine start threshold; When the required driving force becomes equal to or greater than the engine start threshold and the vehicle's driving mode transitions from the EV mode to the HV mode, and the engine operating time is equal to or less than a first predetermined time and the required driving force becomes less than the engine start threshold, the control unit stops the engine by returning the driving mode to the EV mode and notifies the driver that the engine stop is not due to an engine stall.

2. The control device according to claim 1 , wherein the control unit halts the engine start control and does not issue the notification when the engine operation time is less than a second predetermined time that is shorter than the first predetermined time.

3. 3. The control device according to claim 2, wherein the second predetermined time is a time required for the engine to transition to a complete combustion state.

4. 4. The control device according to claim 2, wherein the control unit executes engine stop control and issues the notification when the engine operation time is equal to or longer than the second predetermined time and the required driving force becomes less than the engine start threshold when the engine operation time is equal to or shorter than the first predetermined time.

5. The control device according to any one of claims 1 to 4, wherein the control unit, when the engine operation time is equal to or shorter than a third predetermined time that is longer than the first predetermined time, transitions the driving mode to a mode in the HV mode in which EV driving is prioritized.

6. A control device for controlling a vehicle driven by an engine and a motor, The vehicle has, as driving modes, an EV mode in which the vehicle is driven without the engine being driven, and an HV mode in which, when a required driving force of the vehicle based on an operation amount of a driver becomes equal to or greater than an engine start threshold, the engine is started and the vehicle is driven using the engine and the motor, When the required driving force becomes equal to or greater than the engine start threshold, causing the vehicle's driving mode to transition from the EV mode to the HV mode, and the required driving force becomes less than the engine start threshold before the engine transitions to a full combustion state, the control device stops engine start control.

7. A control method performed by a control device that controls a vehicle driven by an engine and a motor, a transition step of starting the engine and transitioning the driving mode to an HV mode in which the vehicle is driven using the engine and the motor when a required driving force of the vehicle becomes equal to or greater than an engine start threshold value when the driving mode of the vehicle is an EV mode in which the vehicle is driven without the engine being driven, The transition process includes a control method in which, when the required driving force becomes equal to or greater than the engine start threshold and the vehicle's driving mode transitions from the EV mode to the HV mode, and when the engine operating time is equal to or less than a first predetermined time and the required driving force becomes less than the engine start threshold, the driving mode is returned to the EV mode to stop the engine, and an alert is issued that the engine stop is not due to an engine stall.

8. A control method performed by a control device that controls a vehicle driven by an engine and a motor, comprising: The vehicle has, as driving modes, an EV mode in which the vehicle is driven without the engine being driven, and an HV mode in which, when a required driving force of the vehicle based on an operation amount of a driver becomes equal to or greater than an engine start threshold, the engine is started and the vehicle is driven using the engine and the motor, a control method for stopping engine start control when the required driving force becomes equal to or greater than the engine start threshold, causing the vehicle's driving mode to transition from the EV mode to the HV mode, and when the required driving force becomes less than the engine start threshold before the engine transitions to a full combustion state.

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