Hybrid vehicle control device

Abstract

To provide a control device of a hybrid vehicle that enables a series-type hybrid vehicle to suppress deterioration in responsiveness to an acceleration request.SOLUTION: A control device is a control device of a hybrid vehicle which is equipped with an internal combustion engine, an electric motor for power generation that can perform power running for starting the internal combustion engine and regenerative running for converting motive power of the internal combustion engine to electric power, an electric motor for driving that supplies driving wheels with driving force for running, and a battery. The control device, when a target value of the driving force is equal to or more than an upper limit value of driving force that can be generated only by electric power stored in the battery, makes the electric motor for power generation perform regenerative running, and supplies the electric motor for driving with electric power generated by the electric motor for power generation and electric power outputted from the battery, and when detecting predetermined operation from which acceleration of the hybrid vehicle is predicted, makes the electric motor for power generation perform power running to start the internal combustion engine, no matter whether the target value is equal to or more than the upper limit value or not.SELECTED DRAWING: Figure 5

Description

[Technical Field]

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

[0002] For example, a series hybrid system includes an engine, a generator motor that generates electricity using engine power, a drive motor that generates driving force for traveling, and a battery that stores the power supplied to the drive motor. The battery may be a lithium-ion battery or the like.

[0003] In a hybrid vehicle equipped with such a hybrid system, when the output required of the drive motor is smaller than the output of the battery, the drive motor is driven by electric power from the battery, and drive force is transmitted from the drive motor to the drive wheels. On the other hand, when the output required of the drive motor exceeds the output of the battery, engine power is converted into electric power by a generator motor, and the converted electric power is used to drive the drive motor, and drive force is transmitted from the drive motor to the drive wheels. Furthermore, when the hybrid vehicle decelerates, the drive motor operates in regenerative mode, converting the power transmitted from the drive wheels to the drive motor into electric power. At this time, the drive motor acts as resistance to the driving system, and this resistance acts as braking force (regenerative braking force) that brakes the hybrid vehicle. Furthermore, the electric power generated by the drive motor is stored in the battery and used to drive the drive motor. This improves the fuel efficiency of the hybrid vehicle.

[0004] As such a hybrid vehicle, for example, a technique has been disclosed in which engine start control is performed based on a required value of generated power for a generator motor (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-103563 Summary of the Invention [Problem to be solved by the invention]

[0006] In a series hybrid vehicle, even if the drive motor's torque is high when starting, the drive motor's rotational speed is low, allowing the vehicle to run with low drive motor output. As the drive motor's rotational speed increases, the drive motor's output increases. Therefore, even if the accelerator pedal is pressed deeply, i.e., a certain acceleration request is made, the engine is started only after the drive motor's rotational speed (vehicle speed) has increased to a certain level. In other words, when the target value for the drive motor's driving force is equal to or greater than the upper limit of the drive force that can be generated using only the power stored in the battery, the generator motor is operated in regenerative mode, and the power generated by the generator motor and the power output from the battery are supplied to the drive motor. However, since the increase in drive motor output depends on the rate at which the drive motor's rotational speed increases, if the drive motor's rotational speed increases more than expected, for example, when going downhill, if the engine is started after the vehicle speed has increased to a certain level (i.e., power is used by the generator motor), the power available to the drive motor during the increase in drive motor rotational speed is limited, and it may not be possible to achieve acceleration in response to the acceleration request.

[0007] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a control device for a hybrid vehicle that can suppress deterioration in responsiveness to acceleration requests in a series hybrid vehicle. [Means for solving the problem]

[0008] In order to solve the above-mentioned problems and achieve the object, a control device according to the present invention is a control device for a hybrid vehicle including an internal combustion engine, a generator motor capable of power running to start the internal combustion engine and regenerative running to convert the power of the internal combustion engine into electric power, a drive motor that supplies drive power for traveling to drive wheels, and a battery electrically connected to the generator motor and the drive motor, and when a target value of the drive power is equal to or greater than an upper limit value of drive power that can be generated using only electric power stored in the battery, the generator motor is operated in regenerative running, and electric power generated by the generator motor and electric power output from the battery are supplied to the drive motor, and the hybrid vehicle Driving range, and Detects accelerator operation with an opening greater than the threshold. If this is the case, regardless of whether the target value is equal to or greater than the upper limit value, The generator motor is operated in power running to start the internal combustion engine, and after the internal combustion engine is started, the rotation of the drive motor is in the forward direction, which is the rotation when the hybrid vehicle travels in the forward direction, and when the drive motor is in power running operation, Before exceeding the battery's output limit The generator motor is operated in regenerative mode, and the electric power generated by the regenerative mode is supplied to the battery. do .

[0009] With this configuration, when the control device detects a predetermined operation that predicts acceleration of the hybrid vehicle, the control device powers the generator motor and starts the internal combustion engine regardless of whether the target value is equal to or greater than the upper limit. Therefore, even if the target value of the driving force is less than the upper limit of the driving force that can be generated using only the electric power stored in the battery, the internal combustion engine can be started in advance when acceleration of the hybrid vehicle is predicted. Therefore, deterioration of responsiveness to acceleration requests can be suppressed.

[0010] In the control device, for example, the predetermined operation is an accelerator operation in which the accelerator opening is equal to or greater than a threshold value.

[0011] With this configuration, when the accelerator pedal is operated to a position equal to or greater than the threshold, the internal combustion engine can be started in advance if acceleration of the hybrid vehicle is predicted, even if the target value of the driving force is less than the upper limit of the driving force that can be generated using only the electric power stored in the battery, thereby preventing a deterioration in responsiveness to an acceleration request. [Effects of the Invention]

[0012] According to the present invention, deterioration in responsiveness to an acceleration request can be suppressed in a series hybrid vehicle. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a diagram showing an example of a configuration of a main part of a hybrid vehicle according to an embodiment. [Figure 2] FIG. 2 is a time chart showing an example of the flow of control operations when the accelerator opening degree is less than a threshold value in the hybrid vehicle according to this embodiment. [Figure 3] FIG. 3 is a flowchart showing an example of the flow of control operations in response to accelerator operation when the accelerator opening is less than a threshold value in the hybrid vehicle according to this embodiment. [Figure 4] FIG. 4 is a time chart showing an example of the flow of control operations when the accelerator opening is equal to or greater than a threshold value in the hybrid vehicle according to this embodiment. [Figure 5] FIG. 5 is a flowchart showing an example of the flow of control operations including the case where the accelerator opening is equal to or greater than a threshold value in the hybrid vehicle according to this embodiment. [Figure 6] FIG. 6 is a time chart showing an example of the flow of control operations when the accelerator opening is equal to or greater than a threshold value in a hybrid vehicle according to a comparative example of the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, embodiments of a control device and a hybrid vehicle according to the present invention will be described in detail with reference to Figures 1 to 6. Furthermore, the present invention is not limited to the following embodiments, and the components in the following embodiments include those that would be easily conceived by a person skilled in the art, those that are substantially the same, and those that are within the scope of what is called equivalents. Furthermore, various omissions, substitutions, modifications, and combinations of the components can be made without departing from the spirit of the following embodiments.

[0015] (Hybrid vehicle configuration) 1 is a diagram showing an example of a main configuration of a hybrid vehicle according to an embodiment, and the main configuration of a hybrid vehicle 1 according to this embodiment will be described with reference to FIG.

[0016] The hybrid vehicle 1 is a vehicle equipped with a series hybrid system 2. The hybrid vehicle 1 also includes drive wheels 17, an ECU (Electronic Control Unit) 31, an accelerator sensor 32, and a vehicle speed sensor 33. The ECU 31 is an example of a control device.

[0017] The hybrid system 2 includes an engine 11, a generator motor (MG1) 12 (electric motor for generating electricity), a drive motor (MG2) 13 (electric motor for driving electricity), a battery 14, and a PCU (Power Control Unit) 15. The generator motor 12 is an example of an electric motor for generating electricity, and the drive motor 13 is an example of an electric motor for driving electricity.

[0018] The engine 11 is an internal combustion engine such as a gasoline engine.

[0019] The generator motor 12 is, for example, a permanent magnet synchronous motor for converting the power of the engine 11 into electric power. The rotating shaft of the generator motor 12 is mechanically connected to the crankshaft of the engine 11 via a gear (not shown). For example, an engine output gear is supported on the crankshaft of the engine 11 so as not to rotate relative thereto, and a motor gear is supported on the rotating shaft of the generator motor 12 so as not to rotate relative thereto, and the engine output gear and the motor gear are meshed.

[0020] The drive motor 13 is a permanent magnet synchronous motor for transmitting power to drive wheels 17. A rotary shaft of the drive motor 13 is connected to a drive train 16 for driving and rotating the drive wheels 17. The drive train 16 includes a differential gear, and the power of the drive motor 13 is transmitted to the differential gear, and then distributed and transmitted from the differential gear to drive wheels 17 consisting of left and right front wheels or rear wheels. This causes the left and right drive wheels 17 to rotate, and the hybrid vehicle 1 moves forward or backward.

[0021] The battery 14 is an assembled battery made up of a combination of multiple secondary batteries (e.g., lithium ion batteries). The battery 14 outputs DC power. The battery 14 is electrically connected to the generator motor 12 and the drive motor 13, and can exchange power with the generator motor 12 and the drive motor 13.

[0022] The PCU 15 is a unit for controlling the driving of the generator motor 12 and the drive motor 13. The PCU 15 includes a first inverter 21, a second inverter 22, and a converter .

[0023] The first inverter 21 is an inverter device that converts DC power from the converter 23 into AC power, or converts AC power generated by the generator motor 12 into DC power. The second inverter 22 is an inverter device that converts DC power from the converter 23 into AC power, or converts AC power generated by regenerative operation of the drive motor 13 into DC power. The converter 23 is a device that boosts the DC power output from the battery 14, or reduces the DC power output from the first inverter 21 or the second inverter 22.

[0024] When starting the engine 11, the DC power output from the battery 14 is boosted by the converter 23, the boosted DC power is converted to AC power by the first inverter 21, and the converted AC power is supplied to the generator motor 12. This causes the generator motor 12 to perform power running, and the engine 11 is motored (cranked) by the generator motor 12. When the rotation speed of the crankshaft of the engine 11 has increased to the rotation speed required for starting due to motoring, the ignition plug of the engine 11 is sparked, and the engine 11 starts.

[0025] When the hybrid vehicle 1 is traveling, the drive motor 13 is operated in a power running mode, and the drive motor 13 generates power.

[0026] When the hybrid vehicle 1 is running, if the output required of the drive motor 13 is smaller than the output of the battery 14, the hybrid vehicle 1 runs in EV (Electric Vehicle) mode. That is, in EV running, the engine 11 is stopped, no power is generated by the generator motor 12, and the drive motor 13 is driven by power supplied from the battery 14 via the converter 23 and the second inverter 22.

[0027] On the other hand, when the output required of the drive motor 13 exceeds the output of the battery 14 while the hybrid vehicle 1 is running, the hybrid vehicle 1 runs as an HV (Hybrid Vehicle). That is, during HV running, the engine 11 is in operation and the generator motor 12 is operated to generate electricity (regeneratively), so that the power of the engine 11 is converted into AC power by the generator motor 12. The AC power from the generator motor 12 is then converted into DC power by the first inverter 21, and the DC power is converted into AC power by the second inverter 22. The AC power is supplied to the drive motor 13, thereby driving the drive motor 13.

[0028] When the hybrid vehicle 1 decelerates, the drive motor 13 undergoes regenerative operation, and power transmitted from the drive wheels 17 to the drive motor 13 is converted into AC power. At this time, the drive motor 13 acts as a resistor in the drivetrain 16, and this resistance acts as a braking force (regenerative braking force) that brakes the hybrid vehicle 1. At this time, in the PCU 15, the AC power supplied from the drive motor 13 to the second inverter 22 is converted into DC power by the second inverter 22, and the DC power is stepped down by the converter 23. The stepped-down DC power is then supplied to the battery 14, thereby charging the battery 14.

[0029] The ECU 31 is a control device that controls the hybrid system 2. An accelerator sensor 32 and a vehicle speed sensor 33 are connected to the ECU 31. The ECU 31 can detect accelerator operation and accelerator opening from a detection signal from the accelerator sensor 32. The accelerator opening is the ratio of the current operation amount to the maximum operation amount of the accelerator pedal, and can be obtained from the detection signal from the accelerator sensor 32. The ECU 31 also obtains the frequency of the detection signal (pulse signal) from the detection signal output from the vehicle speed sensor 33 and converts the frequency into vehicle speed. The ECU 31 controls the acceleration of the hybrid vehicle 1 by controlling the regenerative operation and power running operation of the generator motor 12 and the drive motor 13 in response to an acceleration request. The acceleration request is, for example, an accelerator pedal depression operation (accelerator operation).

[0030] The accelerator sensor 32 is a sensor that outputs a detection signal corresponding to the amount of operation of the accelerator pedal (accelerator opening) operated by the driver's foot.

[0031] The vehicle speed sensor 33 is a sensor that outputs, as a detection signal, a pulse signal synchronized with the rotation of a rotating body that rotates as the hybrid vehicle 1 travels.

[0032] The hybrid vehicle 1 is equipped with a plurality of ECUs including an ECU 31. Each ECU has a microcontroller unit (microcomputer), which incorporates, for example, a central processing unit (CPU), a nonvolatile memory such as a flash memory, and a volatile memory such as a dynamic random access memory (DRAM). The plurality of ECUs are connected to enable bidirectional communication using the controller area network (CAN) communication protocol. Each ECU is connected to various sensors required for control, and receives detection signals from the connected sensors. In addition to the detection signals received from the various sensors, each ECU also receives information required for control from other ECUs.

[0033] (Control operation when accelerator opening is below threshold) Fig. 2 is a time chart showing an example of the flow of control operations when the accelerator opening degree is less than a threshold value in a hybrid vehicle according to this embodiment. Fig. 3 is a flowchart showing an example of the flow of control operations when the accelerator opening degree is less than a threshold value in a hybrid vehicle according to this embodiment. With reference to Figs. 2 and 3, the control operations when the accelerator pedal is operated in hybrid vehicle 1 according to this embodiment will be described.

[0034] First, with reference to FIG. 2, an outline of the flow of control operations when the accelerator opening degree is less than a threshold value in the hybrid vehicle 1 will be described.

[0035] As shown in Fig. 2, when the driver first operates the accelerator pedal, the DC power output from the battery 14 begins to increase, the DC power is boosted by the converter 23 and converted to AC power by the second inverter 22, and the AC power drives the drive motor (MG2) 13 to rotate, causing the torque to begin to increase. As the torque of the drive motor 13 increases, the rotation speed of the drive motor 13 increases, the rotation speed of the drive wheels 17 increases, and the vehicle speed of the hybrid vehicle 1 increases. In other words, at this stage, the output of the battery 14 contributes to the powering operation of the drive motor 13, the engine 11 does not start, and the hybrid vehicle 1 runs in EV mode ("(1) MG2 = Battery" shown in Fig. 2).

[0036] Next, when the DC power output from the battery 14 exceeds a predetermined threshold value Th, the portion of the DC power exceeding the threshold value Th is converted to AC power by the first inverter 21, and the AC power powers the generator motor (MG1) 12 to power running, thereby starting the engine 11. Then, the rotational drive torque of the generator motor 12 increases the rotation speed of the engine 11. That is, at this stage, the output of the battery 14 contributes to the power running of the generator motor 12 and the power running of the drive motor 13 ("(2) MG2 = battery - MG1" shown in FIG. 2). In other words, the power running of the drive motor 13 is contributed by the output of the battery 14 minus the power used for power running of the generator motor 12 as the engine 11 starts and the rotation speed increases, so that the power available to the drive motor 13 is limited.

[0037] Then, when the rotation speed of the engine 11 reaches or exceeds a predetermined rotation speed, the generator motor 12 switches to regenerative operation, and the power of the engine 11 is converted to AC power by the generator motor 12. The AC power from the generator motor 12 is then converted to DC power by the first inverter 21, and the DC power is converted to AC power by the second inverter 22, and the AC power is supplied to the drive motor 13. That is, at this stage, the output of the battery 14 and the power generated by the regenerative operation of the generator motor 12 contribute to the power running operation of the drive motor 13, and the hybrid vehicle 1 accelerates by HV running ("(3) MG2 = battery + MG1" shown in FIG. 2).

[0038] Next, with reference to FIG. 3, the flow of control operations when the accelerator pedal is operated in the hybrid vehicle 1 will be described in detail.

[0039] <Step S11> First, the ECU 31 calculates a target torque from the accelerator opening detected by the accelerator sensor 32 and the rotation speed of the drive motor (MG2) 13. Then, the process proceeds to step S12.

[0040] <Step S12> The ECU 31 determines whether the target output, which is the product of the calculated target torque and the rotation speed, is equal to or greater than a predetermined value. The target output is a target value for the driving force of the drive motor 13, which supplies the driving force for traveling to the drive wheels 17. The predetermined value is the upper limit of the driving force that can be generated when the target output (target value) of the drive motor 13 is generated using only the electric power stored in the battery 14. If the target output is equal to or greater than the predetermined value (step S12: Yes), the process proceeds to step S13. If the target output is less than the predetermined value (step S12: No), the process proceeds to step S15.

[0041] <Step S13> The ECU 31 powers the generator motor (MG1) 12 using part of the DC power output from the battery 14, and starts the engine 11. If the engine 11 has already started, this step is skipped. Then, the process proceeds to step S14.

[0042] <Step S14> When the rotation speed of the engine 11 reaches a predetermined rotation speed, the ECU 31 switches the generator motor 12 to regenerative operation and causes the generator motor 12 to convert the power of the engine 11 into AC power. The ECU 31 then converts the AC power from the generator motor 12 into DC power using the first inverter 21, converts the DC power into AC power using the second inverter 22, and supplies the AC power to the drive motor 13. As a result, the output of the battery 14 and the power generated by the regenerative operation of the generator motor 12 contribute to the power running operation of the drive motor 13, and the hybrid vehicle 1 accelerates by HV running. Then, the process returns to step S11.

[0043] <Step S15> The ECU 31 converts the DC power output from the battery 14 and boosted by the converter 23 into AC power using the second inverter 22, and powers the drive motor (MG2) 13. As the torque of the drive motor 13 increases, the rotation speed of the drive motor 13 increases, the rotation speed of the drive wheels 17 increases, and the vehicle speed of the hybrid vehicle 1 increases. This causes the hybrid vehicle 1 to perform EV running. In this case, the drive motor (MG2) 13 operates only using the power output from the battery 14. Then, the process returns to step S11.

[0044] As described above, in the hybrid vehicle 1, when the target output, which is the target value of the driving force of the drive motor 13, is equal to or greater than the upper limit of the driving force that can be generated using only the power stored in the battery, the generator motor 12 is operated in regenerative mode, and the power generated by the generator motor 12 and the power output from the battery 14 are supplied to the drive motor 13. On the other hand, when the target output, which is the target value of the driving force of the drive motor 13, is less than the upper limit of the driving force that can be generated using only the power stored in the battery 14, the engine is not started, i.e., the generator motor 12 does not operate in regenerative mode, and only the power output from the battery 14 is supplied to the drive motor 13. However, since the increase in the output of the drive motor 13 depends on the degree of increase in the rotation speed of the drive motor 13, if the degree of increase in the rotation speed of the drive motor 13 becomes greater than expected, for example, when going downhill, if the engine 11 is started after the vehicle speed has increased to a certain extent (i.e., power is used by the generator motor 12), the power available to the drive motor 13 while the rotation speed of the drive motor 13 is increasing will be limited, and it may not be possible to achieve acceleration in accordance with the acceleration request, depending on the acceleration request.

[0045] To meet this demand, in the hybrid vehicle 1 according to this embodiment, when the ECU 31 detects a predetermined operation that predicts acceleration of the hybrid vehicle 1, it causes the generator motor 12 to operate in power running mode and starts the engine 11, regardless of whether the target output (target value) of the drive motor 13 is equal to or greater than an upper limit. The predetermined operation is an accelerator operation that causes the accelerator opening to be equal to or greater than a threshold value. The control operation of the ECU 31 will be described in detail below.

[0046] (Control operation when accelerator opening is above threshold) Fig. 4 is a time chart showing an example of the flow of control operations when the accelerator opening degree is equal to or greater than a threshold value in a hybrid vehicle according to this embodiment. Fig. 5 is a flowchart showing an example of the flow of control operations including when the accelerator opening degree is equal to or greater than a threshold value in a hybrid vehicle according to this embodiment. With reference to Figs. 4 and 5, the control operations when the accelerator opening degree is equal to or greater than a threshold value in a hybrid vehicle 1 according to this embodiment will be described. Note that Fig. 4 shows an example when the hybrid vehicle 1 starts moving downhill.

[0047] First, with reference to FIG. 4, an outline of the flow of control operations when the accelerator opening is equal to or greater than a threshold will be described.

[0048] As shown in Fig. 4, first, when an accelerator opening degree equal to or greater than a threshold is detected, DC power from the battery 14 is boosted by the converter 23 and converted to AC power by the second inverter 22. The AC power drives the drive motor (MG2) 13 to rotate, and the rotation speed and torque begin to increase. The torque (driving force) of the drive motor 13 then drives the drive wheels 17 to rotate, and the hybrid vehicle 1 starts moving. At the same time, the DC power from the battery 14 is boosted by the converter 23 and converted to AC power by the first inverter 21. The AC power drives the generator motor (MG1) 12 to rotate, and the torque begins to increase. The engine 11 then starts due to the torque of the generator motor 12 to rotate, and the rotation speed increases.

[0049] Next, when the rotation speed of the engine 11 reaches a predetermined rotation speed, the generator motor 12 switches to regenerative operation, and the power of the engine 11 is converted to AC power by the generator motor 12. The AC power from the generator motor 12 is then converted to DC power by the first inverter 21, and the DC power is converted to AC power by the second inverter 22, and the AC power is supplied to the drive motor 13. In other words, the output of the battery 14 and the power generated by the regenerative operation of the generator motor 12 contribute to the power running operation of the drive motor 13, and the hybrid vehicle 1 starts running in HV running mode.

[0050] In the above case, the total amount of power supplied from the battery 14 to the generator motor (MG1) 12 and the drive motor (MG2) 13, i.e., the total battery output, does not exceed the battery output limit value. This is because the earlier start of the engine 11 also earlier causes the generator motor 12 to switch from power running to regenerative running, i.e., the timing at which power generation starts, to be earlier, and the power supplied from the generator motor 12 to the drive motor 13 also increases earlier.

[0051] Next, with reference to FIG. 5, the flow of control operations when the accelerator opening degree is equal to or greater than a threshold value in the hybrid vehicle 1 will be described in detail.

[0052] <Step S31> ECU 31 determines whether the selector lever is in the drive range and the accelerator opening is equal to or greater than a threshold. The drive range includes D range and R range. The accelerator opening threshold is, for example, 20% to 30%, but is not limited to this. If the selector lever is in the drive range and the accelerator opening is equal to or greater than the threshold (step S31: Yes), the process proceeds to step S32. On the other hand, if the selector lever is not in the drive range or the accelerator opening is less than the threshold (step S31: No), the process proceeds to step S36.

[0053] <Step S32> The ECU 31 converts the DC power output from the battery 14 and boosted by the converter 23 into AC power using the first inverter 21, and uses the AC power to power the generator motor (MG1) 12 and start the engine 11.

[0054] <Step S33> If the rotation of the drive motor (MG2) 13 is reverse (negative) rather than forward (No in step S33), the process proceeds to step S34, and if the rotation of the drive motor (MG2) 13 is forward (Yes in step S33), the process proceeds to step S35. Note that the forward rotation of the drive motor (MG2) 13 refers to the rotation direction of the drive motor 13 when the hybrid vehicle 1 is traveling in the forward direction. The reverse (negative) rotation of the drive motor (MG2) 13 refers to rotation in the opposite direction to the forward rotation, and occurs, for example, when the hybrid vehicle 1 temporarily backs up (slides downhill) when starting on a slope.

[0055] <Step S34> When the rotation of the drive motor (MG2) 13 is reversed, the drive motor (MG2) 13 is in regenerative operation. Therefore, the ECU 31 converts the DC power output from the battery 14 and boosted by the converter 23 into AC power using the first inverter 21, and powers the generator motor (MG1) 12 using the AC power. That is, the engine 11 is put into motoring mode. This prevents the amount of electricity stored in the battery 14 from exceeding its discharge limit. In addition, in this case, the engine 11 is not stopped, but fuel is simply cut off, so the responsiveness when switching the state of the engine 11 from motoring to firing is improved compared to when the engine 11 is stopped. Note that the process of S34, i.e., the process of putting the engine 11 into motoring mode after starting it, may be performed, for example, when the amount of electricity stored in the battery 14 is equal to or greater than a threshold. Then, the process returns to step S31. The amount of electricity stored can be expressed, for example, by SOC (State of Charge).

[0056] <Step S35> When the drive motor (MG2) 13 is rotating in the forward direction, the drive motor (MG2) 13 is in power running, so the ECU 31 switches the generator motor 12 to regenerative operation and causes the generator motor 12 to convert the power of the engine 11 into AC power. That is, the ECU 31 sets the state of the engine 11 to firing. Then, the ECU 31 causes the first inverter 21 to convert the AC power into DC power, and the converter 23 to step down the DC power, supplying it to the battery 14 for charging. This prevents the amount of electricity stored in the battery 14 from exceeding its discharge limit. Then, the process returns to step S31.

[0057] <Steps S36 to S40> The processes in steps S36 to S40 are the same as the processes in steps S11 to S15 shown in FIG. 3 above.

[0058] FIG. 6 is a time chart showing an example of the flow of control operations when the accelerator opening is equal to or greater than a threshold value in a hybrid vehicle according to a comparative example of the embodiment. FIG. 6 shows an example of the hybrid vehicle 1 starting on a downhill slope. As shown in FIG. 6, in the comparative example, even if the accelerator opening is equal to or greater than a threshold value, the generator motor 12 is not operated in regenerative mode until the target output (target value) of the driving force of the drive motor 13 reaches or exceeds the upper limit of the driving force that can be generated using only the electric power stored in the battery 14. In this case, the output of the drive motor 13 increases, causing the output of the battery 14 (battery output) to exceed the limit value, so it is necessary to limit the output of the drive motor 13. This is because limiting the electric power to the generator motor 12 would make it impossible to start the engine 11.

[0059] (Effects of the embodiment) As described above, in this embodiment, the ECU 31 (control device) is the ECU 31 of the hybrid vehicle 1. The hybrid vehicle 1 includes an engine 11 (internal combustion engine), a generator motor 12 (electric generator motor) capable of power running to start the engine 11 and regenerative running to convert the power of the engine 11 into electric power, a drive motor 13 (electric drive motor) that supplies driving power for traveling to drive wheels 17, and a battery 14 electrically connected to the generator motor 12 and the drive motor 13. When the target value of driving power is equal to or greater than the upper limit of driving power that can be generated using only the electric power stored in the battery 14, the ECU 31 causes the generator motor 12 to perform regenerative operation, and supplies the electric power generated by the generator motor 12 and the electric power output from the battery 14 to the drive motor 13. When the ECU 31 detects a predetermined operation that predicts acceleration of the hybrid vehicle 1, the ECU 31 causes the generator motor 12 to perform power running to start the engine 11, regardless of whether the target value is equal to or greater than the upper limit.

[0060] According to this configuration, when the ECU 31 detects a predetermined operation that predicts acceleration of the hybrid vehicle 1, it powers the generator motor 12 and starts the engine 11 regardless of whether the target value is equal to or greater than the upper limit. Therefore, even if the target value of the driving force is less than the upper limit of the driving force that can be generated using only the electric power stored in the battery 14, the engine 11 can be started in advance when acceleration of the hybrid vehicle 1 is predicted. This prevents deterioration in responsiveness to an acceleration request. Also, it prevents a decrease in the output of the drive motor 13 that accompanies the start of the engine 11. This allows smooth acceleration of the hybrid vehicle 1. Furthermore, because the engine 11 has already started during acceleration of the hybrid vehicle 1, it is easy to control the SOC of the battery 14 even while the acceleration request is continuing.

[0061] Furthermore, in the ECU 31, for example, the predetermined operation is an accelerator operation in which the accelerator opening is equal to or greater than a threshold value.

[0062] With this configuration, when the accelerator is operated so that the accelerator opening is equal to or greater than the threshold, the engine 11 can be started in advance if acceleration of the hybrid vehicle 1 is predicted, even if the target value of the driving force is less than the upper limit of the driving force that can be generated using only the electric power stored in the battery 14. This makes it possible to prevent deterioration in responsiveness to an acceleration request.

[0063] In the above embodiment, an accelerator operation in which the accelerator opening is equal to or greater than a threshold value is exemplified as a predetermined operation that predicts acceleration of the hybrid vehicle 1. However, the present invention is not limited to this. For example, the predetermined operation may be an operation to switch the driving mode to a sports mode, a downshift operation, or the like. [Explanation of symbols]

[0064] 1... hybrid vehicle, 11... engine (internal combustion engine), 12... generator motor (electric motor for generating electricity), 13... drive motor (electric motor for driving), 14... battery, 17... drive wheels, 31... ECU (control device).

Claims

[Claim 1] A control device for a hybrid vehicle including an internal combustion engine, a generator motor capable of power running to start the internal combustion engine and regenerative running to convert the power of the internal combustion engine into electric power, a drive motor that supplies drive force to drive wheels for traveling, and a battery electrically connected to the generator motor and the drive motor, When the target value of the driving force is equal to or greater than an upper limit of the driving force that can be generated using only the electric power stored in the battery, the generator motor is operated in a regenerative manner, and the electric power generated by the generator motor and the electric power output from the battery are supplied to the driving motor; When the hybrid vehicle is in a driving range and an accelerator operation in which an accelerator opening degree is equal to or greater than a threshold value is detected, the generator motor is caused to perform a power running operation to start the internal combustion engine, regardless of whether the target value is equal to or greater than the upper limit value. A control device that, after the internal combustion engine is started, when the rotation of the drive motor is in the forward direction, which is the rotation when the hybrid vehicle is traveling in the forward direction, and the drive motor is in power running operation, causes the generator motor to operate in regenerative mode before the output limit value of the battery is exceeded, and supplies the power generated by the regenerative operation to the battery.

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