JP7215328B2 - hybrid vehicle - Google Patents

Description

The present disclosure relates to hybrid vehicles.

Japanese Patent Laying-Open No. 2015-58924 (Patent Document 1) discloses a hybrid vehicle including an internal combustion engine having a supercharger, a motor generator, and a planetary gear mechanism. An internal combustion engine, a motor generator, and an output shaft are connected to the planetary gear mechanism. In this hybrid vehicle, the operating point (rotational speed and torque) of the internal combustion engine is changed according to the state of the vehicle.

JP 2015-58924 A

The operating point of the internal combustion engine is set, for example, as the intersection of the required engine power and the equal power line and the predetermined engine operating line. As the operation line, for example, a fuel consumption line used when giving priority to fuel consumption and a power line used when giving priority to the output of the internal combustion engine may be set. In this case, for example, when the driver depresses the accelerator pedal to request acceleration, the operating line used to determine the operating point shifts from the fuel efficiency line to the power line.

In a hybrid vehicle equipped with an internal combustion engine with a supercharger, there are cases where the divergence between the fuel consumption line and the power line becomes large. Since the operating point of the internal combustion engine is near the supercharging line where supercharging starts, the fuel efficiency is improved. This is because the power line is set near the maximum torque line of the engine.

If the divergence between the fuel consumption line and the power line is large, a situation may occur in which the rotation speed (rotational speed) of the internal combustion engine decreases when the operation line shifts from the fuel consumption line to the power line in response to the acceleration request. The driver may feel uncomfortable with the fact that the rotation speed of the internal combustion engine decreases even though the accelerator pedal is depressed to request acceleration.

The present disclosure has been made in order to solve the above problems, and the object thereof is to provide a hybrid vehicle equipped with a supercharged internal combustion engine, in which the driver is provided with a It is to reduce the sense of incongruity given.

(1) A hybrid vehicle according to this disclosure controls an internal combustion engine having a supercharger, a rotating electrical machine, a planetary gear mechanism to which the internal combustion engine, the rotating electrical machine, and an output shaft are connected, and the internal combustion engine and the rotating electrical machine. and a control device configured to: When there is a request to increase the output of the internal combustion engine, the control device sets a lower limit rotation speed based on the rotation speed of the internal combustion engine when the request to increase the output is received, and the rotation speed of the internal combustion engine reaches the lower limit rotation speed. Determine the operating point of the internal combustion engine so as not to fall below the number.

According to the above configuration, when there is a request to increase the output of the internal combustion engine, the lower limit rotation speed of the internal combustion engine is set based on the rotation speed of the internal combustion engine when the request to increase the output is received. Then, the operating point of the internal combustion engine is determined so that the rotational speed of the internal combustion engine does not fall below the lower limit rotational speed. By appropriately setting the lower limit rotation speed, it is possible to reduce the sense of discomfort given to the driver even if the rotation speed of the internal combustion engine changes.

(2) In one embodiment, the lower limit speed is equal to or higher than the speed of the internal combustion engine when the request for increasing the output is made.

By setting the lower limit rotation speed in this manner, the rotation speed of the internal combustion engine does not fall below the rotation speed of the internal combustion engine when the request for increasing the output is made. In other words, since the engine speed does not decrease in response to the driver's acceleration request, it is possible to reduce the driver's sense of discomfort.

(3) In one embodiment, when the output increase is requested, the control device further sets the upper limit engine speed based on the engine speed at which the output increase is requested. do. Then, the control device determines the operating point of the internal combustion engine so that the rotation speed of the internal combustion engine does not fall below the lower limit rotation speed and does not exceed the upper limit rotation speed.

If you try to increase the speed of the internal combustion engine, the torque generated by the internal combustion engine at the beginning of acceleration due to the effects of the inertia torque required to increase the speed of the internal combustion engine and the response delay of the boost pressure of the supercharger. response delay may occur. Therefore, if the upper limit speed is set so that the speed of the internal combustion engine does not exceed the upper limit speed, it is possible to suppress the delay in the response of the torque generated by the internal combustion engine at the initial stage of acceleration. As a result, deterioration of drivability can be suppressed.

Advantageous Effects of Invention According to the present disclosure, in a hybrid vehicle having a supercharged internal combustion engine, it is possible to reduce discomfort given to the driver when the operating line shifts from the fuel economy line to the power line.

1 is an overall configuration diagram showing an example of a hybrid vehicle according to Embodiment 1; FIG. It is a figure which shows the structural example of an engine. 2 is a block diagram showing an example of the configuration of a control device for the hybrid vehicle shown in FIG. 1; FIG. FIG. 2 is a diagram for explaining operating points of an engine; FIG. 4 is a flowchart showing a procedure of processing for determining operating points of the engine, first MG, and second MG of the hybrid vehicle according to the embodiment; 4 is a flow chart showing a procedure of processing for determining an operating point of an engine; FIG. 11 is a flow chart showing a procedure of processing for determining an operating point of an engine according to a modification; FIG.

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. The same or corresponding parts in the drawings are denoted by the same reference numerals, and the description thereof will not be repeated.

<Overall composition>
FIG. 1 is an overall configuration diagram showing an example of a hybrid vehicle according to Embodiment 1. FIG. Referring to FIG. 1, this hybrid vehicle (hereinafter also simply referred to as "vehicle") 10 includes an engine 13, a first motor generator (hereinafter also referred to as "first MG (motor generator)") 14, and a second motor. A generator (hereinafter also referred to as “second MG”) 15 and a planetary gear mechanism 20 are provided.

Both the first MG 14 and the second MG 15 have a function as a motor that outputs torque when supplied with drive power, and a function as a generator that generates generated power when torque is applied. AC rotary electric machines are used as first MG 14 and second MG 15 . AC rotary electric machines include, for example, permanent magnet type synchronous motors having a rotor in which permanent magnets are embedded.

Both the first MG 14 and the second MG 15 are electrically connected to the battery 18 via a PCU (Power Control Unit) 81 . PCU 81 includes a first inverter 16 that exchanges power with first MG 14 , a second inverter 17 that exchanges power with second MG 15 , and a converter 83 .

Converter 83 transfers electric power between battery 18 and first inverter 16 and second inverter 17 . Converter 83 is configured, for example, to boost the electric power of battery 18 and supply it to first inverter 16 or second inverter 17 . Alternatively, converter 83 is configured to step down the power supplied from first inverter 16 or second inverter 17 and supply it to battery 18 .

First inverter 16 is configured to convert DC power from converter 83 into AC power and supply the AC power to first MG 14 . Alternatively, first inverter 16 is configured to convert AC power from first MG 14 into DC power and supply the DC power to converter 83 .

Second inverter 17 is configured to convert DC power from converter 83 into AC power and supply the AC power to second MG 15 . Alternatively, second inverter 17 is configured to convert AC power from second MG 15 into DC power and supply the DC power to converter 83 .

That is, PCU 81 uses power generated in first MG 14 or second MG 15 to charge battery 18 or uses power of battery 18 to drive first MG 14 or second MG 15 .

The battery 18 is mounted on the vehicle 10 as a driving power source (that is, a power source) for the vehicle 10 . The battery 18 includes a plurality of stacked batteries. The battery is, for example, a secondary battery such as a nickel-metal hydride battery or a lithium-ion battery. Further, the battery may be a battery having a liquid electrolyte between the positive electrode and the negative electrode, or a battery having a solid electrolyte (all-solid battery). The battery 18 may be a rechargeable DC power supply, and a large-capacity capacitor may also be used.

Engine 13 and first MG 14 are connected to planetary gear mechanism 20 . The planetary gear mechanism 20 divides and transmits the output torque of the engine 13 to the first MG 14 and the output gear 21 . The planetary gear mechanism 20 has, for example, a single pinion type planetary gear mechanism, and is arranged on the same axis line Cnt as the output shaft 22 of the engine 13 .

The planetary gear mechanism 20 includes a sun gear S, a ring gear R arranged coaxially with the sun gear S, a pinion gear P meshing with the sun gear S and the ring gear R, and a carrier C holding the pinion gear P rotatably and revolvingly. An output shaft 22 of the engine 13 is connected to the carrier C. As shown in FIG. A rotor shaft 23 of the first MG 14 is connected to the sun gear S. Ring gear R is connected to output gear 21 .

The carrier C to which the output torque of the engine 13 is transmitted functions as an input element, the ring gear R which outputs torque to the output gear 21 functions as an output element, and the sun gear S connected to the rotor shaft 23 of the first MG 14 functions as a reaction element. . That is, the planetary gear mechanism 20 divides the output of the engine 13 between the first MG 14 side and the output gear 21 side. The first MG 14 is controlled to output torque corresponding to the output torque of the engine 13 .

The countershaft 25 is arranged parallel to the axis Cnt. A driven gear 26 meshing with the output gear 21 is provided on the countershaft 25 . A drive gear 27 is further provided on the countershaft 25 , and the drive gear 27 meshes with a ring gear 29 of a differential gear 28 . A drive gear 31 provided on a rotor shaft 30 of the second MG 15 meshes with the driven gear 26 . Therefore, the output torque of second MG 15 is added to the torque output from output gear 21 at driven gear 26 . The torque thus synthesized is transmitted to the drive wheels 24 via drive shafts 32 and 33 extending left and right from the differential gear 28 . A driving force is generated in the vehicle 10 by transmitting the driving torque to the driving wheels 24 .

<Engine configuration>
FIG. 2 is a diagram showing a configuration example of the engine 13. As shown in FIG. Referring to FIG. 2, engine 13 is, for example, an in-line four-cylinder spark ignition internal combustion engine having a supercharger 47 . As shown in FIG. 2, the engine 13 includes, for example, an engine body 40 formed by aligning four cylinders 40a, 40b, 40c, and 40d in one direction.

One end of an intake port and one end of an exhaust port formed in the engine body 40 are connected to the cylinders 40a, 40b, 40c and 40d, respectively. One end of the intake port is opened and closed by two intake valves 43 provided for each of the cylinders 40a, 40b, 40c and 40d. One end of the exhaust port is opened and closed by two exhaust valves 44 provided for each of the cylinders 40a, 40b, 40c and 40d. The other end of each intake port of cylinders 40 a , 40 b , 40 c , 40 d is connected to intake manifold 46 . The other end of each exhaust port of cylinders 40 a , 40 b , 40 c , 40 d is connected to exhaust manifold 52 .

Engine 13 according to Embodiment 1 is, for example, a direct injection engine, in which fuel is injected into each of cylinders 40a, 40b, 40c, and 40d by a fuel injection device (not shown) provided at the top of each cylinder. be jetted. A mixture of fuel and intake air in the cylinders 40a, 40b, 40c and 40d is ignited by spark plugs 45 provided in each of the cylinders 40a, 40b, 40c and 40d.

2 shows the intake valve 43, the exhaust valve 44 and the ignition plug 45 provided in the cylinder 40a, and the intake valve 43, the exhaust valve 44 and the ignition plug 45 provided in the other cylinders 40b, 40c and 40d. The plug 45 is omitted.

The engine 13 is provided with a supercharger 47 that supercharges intake air using exhaust energy. The supercharger 47 includes a compressor 48 and a turbine 53 .

One end of the intake passage 41 is connected to the intake manifold 46 . The other end of intake passage 41 is connected to an intake port. A compressor 48 is provided at a predetermined position in the intake passage 41 . An air flow meter 50 is provided between the other end (intake port) of the intake passage 41 and the compressor 48 to output a signal corresponding to the flow rate of the air flowing through the intake passage 41 . An intercooler 51 for cooling the intake air pressurized by the compressor 48 is arranged in the intake passage 41 provided downstream of the compressor 48 . A throttle valve 49 is provided between the intercooler 51 and the intake manifold 46 to adjust the flow rate of the intake air flowing through the intake passage 41 .

One end of the exhaust passage 42 is connected to the exhaust manifold 52 . The other end of exhaust passage 42 is connected to a muffler (not shown). A turbine 53 is provided at a predetermined position in the exhaust passage 42 . The exhaust passage 42 also includes a bypass passage 54 that bypasses the exhaust upstream of the turbine 53 to the downstream of the turbine 53, and a waste gate valve 55 that is provided in the bypass passage and can adjust the flow rate of the exhaust guided to the turbine 53. and are provided. Therefore, by controlling the opening of the waste gate valve 55, the flow rate of the exhaust gas flowing into the turbine 53, that is, the supercharging pressure of the intake air is adjusted. Exhaust gas passing through the turbine 53 or the wastegate valve 55 is purified by a start catalytic converter 56 and an aftertreatment device 57 provided at predetermined positions in the exhaust passage 42 before being released to the atmosphere. Start catalytic converter 56 and aftertreatment device 57 include, for example, a three-way catalyst.

The engine 13 is provided with an EGR (Exhaust Gas Recirculation) device 58 for causing exhaust gas to flow into the intake passage 41 . The EGR device 58 has an EGR passage 59 , an EGR valve 60 and an EGR cooler 61 . The EGR passage 59 extracts part of the exhaust gas from the exhaust passage 42 as EGR gas and guides it to the intake passage 41 . The EGR valve 60 adjusts the flow rate of EGR gas flowing through the EGR passage 59 . The EGR cooler 61 cools the EGR gas flowing through the EGR passage 59 . The EGR passage 59 connects between the portion of the exhaust passage 42 between the starter catalytic converter 56 and the aftertreatment device 57 and the portion of the intake passage 41 between the compressor 48 and the air flow meter 50 .

<Configuration of control device>
FIG. 3 is a block diagram showing an example of the configuration of the control device 11 of the hybrid vehicle 10 shown in FIG. 1. As shown in FIG. Referring to FIG. 3, control device 11 includes an HV (Hybrid Vehicle)-ECU (Electronic Control Unit) 62, an MG-ECU 63, and an engine ECU 64. As shown in FIG.

HV-ECU 62 is a control device for cooperatively controlling engine 13 , first MG 14 and second MG 15 . MG-ECU 63 is a control device for controlling the operation of PCU 81 . The engine ECU 64 is a control device for controlling the operation of the engine 13 .

The HV-ECU 62, the MG-ECU 63, and the engine ECU 64 each include an input/output device for exchanging signals with various connected sensors and other ECUs, a memory for storing various control programs and maps, and a control unit. It comprises a central processing unit (CPU) for executing programs, a counter for timekeeping, and the like.

The HV-ECU 62 includes a vehicle speed sensor 66, an accelerator opening sensor 67, a first MG rotational speed sensor 68, a second MG rotational speed sensor 69, an engine rotational speed sensor 70, a turbine rotational speed sensor 71, and a supercharger sensor. A pressure sensor 72, a battery monitoring unit 73, a first MG temperature sensor 74, a second MG temperature sensor 75, a first INV temperature sensor 76, a second INV temperature sensor 77, a catalyst temperature sensor 78, and a turbine temperature sensor 79. are connected to each other.

A vehicle speed sensor 66 detects the speed of the vehicle 10 (vehicle speed). The accelerator opening sensor 67 detects the depression amount (accelerator opening) of the accelerator pedal by the driver. A first MG rotation speed sensor 68 detects the rotation speed of the first MG 14 . A second MG rotation speed sensor 69 detects the rotation speed of the second MG 15 . The engine rotation speed sensor 70 detects the rotation speed of the engine 13 (hereinafter also referred to as "engine rotation speed") Ne. A turbine rotation speed sensor 71 detects the rotation speed of the turbine 53 of the supercharger 47 . A boost pressure sensor 72 detects the boost pressure of the engine 13 . A first MG temperature sensor 74 detects the internal temperature of the first MG 14, for example the temperature associated with the coils and magnets. A second MG temperature sensor 75 detects the internal temperature of the second MG 15, for example the temperature associated with the coils and magnets. A first INV temperature sensor 76 senses the temperature of the first inverter 16, eg, the temperature associated with the switching elements. A second INV temperature sensor 77 detects the temperature of the second inverter 17, eg, the temperature associated with the switching element. A catalyst temperature sensor 78 detects the temperature of the aftertreatment device 57 . A turbine temperature sensor 79 detects the temperature of the turbine 53 . Various sensors output signals indicating the detection results to HV-ECU 62 .

Battery monitoring unit 73 acquires a state of charge (SOC), which is the ratio of the remaining charge amount to the full charge capacity of battery 18 , and outputs a signal indicating the acquired SOC to HV-ECU 62 .

Battery monitoring unit 73 includes, for example, sensors that detect the current, voltage and temperature of battery 18 . The battery monitoring unit 73 obtains the SOC by calculating the SOC using the detected current, voltage and temperature of the battery 18 .

As a method for calculating the SOC, various known methods such as a method based on current value integration (coulomb counting) or a method based on estimation of an open circuit voltage (OCV: Open Circuit Voltage) can be employed.

<Vehicle control>
The vehicle 10 sets the running mode to an HV running mode using the engine 13 and the second MG 15 as power sources, and an EV running mode in which the engine 13 is stopped and the second MG 15 is driven by the electric power of the battery 18 to run. Or switching is possible. Mode setting and switching are performed by the HV-ECU 62 . The EV driving mode is a mode selected, for example, in a low-load driving range in which the vehicle speed is low and the required driving force is small. The HV driving mode is a mode selected in a high-load driving range in which the vehicle speed is high and the required driving force is large. do.

In the HV running mode, when the torque output from the engine 13 is transmitted to the driving wheels 24, the reaction force is applied to the planetary gear mechanism 20 by the first MG14. Therefore, the sun gear S functions as a reaction force element. That is, in order to cause the output torque of the engine 13 to act on the drive wheels 24 , the first MG 14 is controlled to output the reaction torque with respect to the output torque of the engine 13 . In this case, regenerative control can be executed to cause the first MG 14 to function as a generator.

Coordinated control of the engine 13, the first MG 14, and the second MG 15 during operation of the vehicle 10 will be described below.

The HV-ECU 62 calculates the required driving force based on the accelerator opening determined by the depression amount of the accelerator pedal. HV-ECU 62 calculates the required running power of vehicle 10 based on the calculated required driving force, vehicle speed, and the like. The HV-ECU 62 calculates the required system power by adding the required charging/discharging power of the battery 18 to the required traveling power. Note that the required charging/discharging power of the battery 18 is set according to the SOC of the battery 18, for example.

HV-ECU 62 determines whether operation of engine 13 is required according to the calculated required system power. HV-ECU 62 determines that operation of engine 13 is required, for example, when the required system power exceeds a threshold. The HV-ECU 62 sets the HV running mode to the running mode when the operation of the engine 13 is requested. The HV-ECU 62 sets the EV driving mode as the driving mode when the operation of the engine 13 is not requested.

The HV-ECU 62 calculates a required power for the engine 13 (hereinafter also referred to as "required engine power") when the operation of the engine 13 is requested (that is, when the HV traveling mode is set). . HV-ECU 62, for example, calculates the required system power as the required engine power. HV-ECU 62 outputs the calculated required engine power to engine ECU 64 as an engine operating state command.

Engine ECU 64 performs various controls on each part of engine 13 such as throttle valve 49 , spark plug 45 , wastegate valve 55 and EGR valve 60 based on the engine operating state command input from HV-ECU 62 .

The HV-ECU 62 also uses the calculated required engine power to set the operating point of the engine 13 in the coordinate system defined by the engine speed Ne and the engine torque Te. The HV-ECU 62 sets, for example, the intersection of the required engine power and the equal output equal power line and a predetermined action line in the coordinate system as the operating point of the engine 13 . Note that the predetermined operation line indicates the trajectory of change in engine torque with respect to change in engine speed Ne in the coordinate system. In the present embodiment, as will be described later, a power line used when giving priority to the output of the engine 13 and a fuel consumption line used when giving priority to fuel consumption are predetermined as operation lines.

The HV-ECU 62 sets the engine speed Ne corresponding to the set operating point of the engine 13 as the target engine speed Net.

When the target engine speed Net is set, the HV-ECU 62 sets the torque command value for the first MG 14 to bring the current engine speed Ne to the target engine speed Net. HV-ECU 62 sets the torque command value for first MG 14, for example, by feedback control based on the difference between current engine speed Ne and target engine speed Net.

The HV-ECU 62 calculates the transmission amount of the engine torque Te to the drive wheels 24 from the set torque command value of the first MG 14 (hereinafter also referred to as "engine direct torque Tep"), and calculates the amount of engine torque Te to satisfy the required driving force. A torque command value for the second MG 15 is set. HV-ECU 62 outputs the set torque command values of first MG 14 and second MG 15 to MG-ECU 63 as a first MG torque command and a second MG torque command, respectively.

Based on the first MG torque command and the second MG torque command input from the HV-ECU 62, the MG-ECU 63 calculates a current value and its frequency corresponding to the torque generated in the first MG 14 and the second MG 15, and calculates the calculated current value and A signal containing that frequency is output to the PCU 81 .

Further, when the accelerator pedal is depressed and the engine torque Te exceeds the supercharging line (broken line L3 in FIG. 4), the HV-ECU 62 requests supercharging by the supercharger 47, and the engine torque Te increases. request an increase in boost pressure according to The request for supercharging and the request for increasing the supercharging pressure are notified to the engine ECU 64 . The engine ECU 64 fully opens the waste gate valve 55 in an NA (Natural Aspiration) region where the engine torque Te is below the supercharging line. As a result, the exhaust gas flows through the bypass passage 54 without being introduced into the turbine 53 of the supercharger 47, so supercharging by the supercharger 47 is not performed. On the other hand, the engine ECU 64 operates the fully open waste gate valve 55 in the closing direction in the supercharging region where the engine torque Te exceeds the supercharging line. As a result, the turbine 53 of the supercharger 47 is rotated by the exhaust energy, and supercharging by the supercharger 47 is performed. By adjusting the opening of the waste gate valve 55 , it is possible to adjust the flow rate of the exhaust gas flowing into the turbine 53 of the supercharger 47 and adjust the supercharging pressure of the intake air through the compressor 48 .

Each of HV-ECU 62, MG-ECU 63 and engine ECU 64 incorporates a CPU and a memory (not shown) as described above. In FIG. 3, the configuration in which the HV-ECU 62, the MG-ECU 63 and the engine ECU 64 are separated is described as an example, but these may be integrated into one ECU.

<Engine operating point>
FIG. 4 is a diagram for explaining the operating points of the engine 13. As shown in FIG. In FIG. 4, the vertical axis indicates the engine torque Te, and the horizontal axis indicates the engine speed Ne. In FIG. 4, the operating point of the engine 13 is determined by the engine torque Te and the engine speed Ne.

Referring to FIG. 4 , each of solid line L1 and solid line L2 is an operating line of engine 13 . The engine 13 is normally controlled such that an operating point determined by the engine torque Te and the engine speed Ne moves on a preset operating line (solid line L1 or solid line L2). A solid line L1 indicates the maximum torque that the engine 13 can output, and is set as a power line that is used when an increase in the output of the engine 13 is requested. A solid line L2 is set as a fuel efficiency line that is used when priority is given to fuel efficiency. For example, which of the power line L1 and the fuel consumption line L2 is used is determined depending on the accelerator pedal depression amount (accelerator opening). For example, the power line L1 is used when the accelerator opening is equal to or greater than a predetermined opening, and the fuel efficiency line L2 is used when the accelerator opening is less than the predetermined opening. A power button for switching the operation line may be provided inside the vehicle. In this case, when the driver presses the power button, the operating line switches from the fuel consumption line L2 to the power line L1. When the power button is not pressed, the operating line is set to the fuel efficiency line L2.

A dashed line L3 indicates a line (supercharging line) where supercharging by the supercharger 47 is started. Each of dashed line L4 and dashed line L5 is an equal power line corresponding to the required engine power. A dashed line L4 indicates an equal power line corresponding to a required engine power smaller than that of the dashed line L5.

Here, in the hybrid vehicle 10 including the engine 13 with the turbocharger 47, there are cases where the divergence between the power line L1 and the fuel consumption line L2 becomes large. Since the fuel efficiency is improved when the operating point of the engine 13 is near the supercharging line L3, the fuel efficiency line L2 is set near the supercharging line L3. This is because the power line L1 is set on the maximum torque line of (or near the maximum torque line).

If the divergence between the power line L1 and the fuel consumption line L2 is large, when the operation line shifts from the fuel consumption line L2 to the power line L1 in response to an acceleration request (that is, a request to increase the output of the engine 13), the rotation speed of the engine 13 increases. A declining situation can arise. A specific example will be described with reference to FIG.

It is assumed that the intersection (engine speed Ne1, engine torque Te1) of the fuel efficiency line L2 and the constant power line L4 is determined as the operating point E1 of the engine 13 . In this case, when the driver depresses the accelerator and the accelerator opening reaches or exceeds a predetermined opening, the operating line shifts from the fuel efficiency line L2 to the power line L1. At this time, if the constant power line corresponding to the required engine power is the constant power line L5, the intersection of the power line L1 and the constant power line L5 (engine speed Ne2 (<Ne1), engine torque Te2 (> Te1)) is determined as the operating point E2 of the engine 13 after movement. By moving the operating point of the engine 13 from the operating point E1 to the operating point E2, it becomes possible to output engine power corresponding to the required engine power.

However, as can be recognized from FIG. 4, when the operating point of the engine 13 is moved from the operating point E1 to the operating point E2, the rotation speed of the engine 13 decreases from Ne1 to Ne2 (<Ne1). The driver may feel uncomfortable with the fact that the rotation speed of the engine 13 decreases even though the accelerator pedal is pressed to request acceleration.

Therefore, in the vehicle 10 according to the present embodiment, when the operation line shifts from the fuel consumption line L2 to the power line L1, the HV-ECU 62 determines the engine speed after the shift based on the engine speed Ne before the shift. Set the lower limit number of revolutions, which is the lower limit of the number of revolutions. In other words, the HV-ECU 62 sets the lower limit rotation speed based on the engine rotation speed Ne at the time when the request for the increase in the output is received when there is a request for an increase in the output of the engine 13 by a predetermined amount or more. The case where there is a request to increase the output of the engine 13 by a predetermined amount or more is, for example, when the accelerator opening becomes a predetermined opening or more, or when the power button is pressed.

The lower limit rotation speed is set, for example, to the engine rotation speed Ne at the time when an increase in output is requested. HV-ECU 62, for example, determines the operating point of engine 13 to be operating point E3 (engine speed Ne1, engine torque Te3 (>Te1)). This makes it possible to output the engine power corresponding to the required engine power while maintaining the engine speed so that the engine speed does not drop below the engine speed Ne1 at the operating point E1. . As a result, the engine speed does not decrease in response to the driver's acceleration request, so that the sense of discomfort given to the driver can be reduced.

It should be noted that the lower limit engine speed may be set to a engine speed that is smaller than the engine speed at the time when the output increase is requested by a threshold engine speed. The threshold engine speed is set to a value that does not make the driver feel uncomfortable even if the engine speed decreases by the threshold engine speed. The threshold rotation speed is set, for example, in consideration of the specifications of the vehicle 10, more specifically, the specifications of the engine 13, vibrations of the engine 13 transmitted to the interior of the vehicle, engine sounds transmitted to the interior of the vehicle, and the like.

When there is a request for an increase in output, by reducing the engine speed by the threshold speed, the efficiency of charging air to each cylinder of the engine 13 increases and the pressure of each cylinder increases, so the torque generated by the engine 13 rises. As a result, it is possible to reduce the response delay of the torque generated by the engine 13 at the initial stage of acceleration.

<Processing Executed by Control Device>
FIG. 5 is a flowchart showing a procedure of processing for determining operating points of engine 13, first MG 14, and second MG 15 of hybrid vehicle 10 according to the present embodiment. The processing shown in this flowchart is repeatedly executed in the HV-ECU 62 at predetermined intervals. Each step (hereinafter abbreviated as "S") shown in FIG. (Electric circuit).

Referring to FIG. 5, HV-ECU 62 acquires information indicating the state of the vehicle (for example, accelerator opening, selected shift range, and vehicle speed) (S1). Then, the HV-ECU 62 extracts the required driving force (torque ) is calculated (S2).

Next, the HV-ECU 62 multiplies the calculated required driving force by the vehicle speed and adds a predetermined power loss to calculate the required running power of the vehicle 10 (step S3).

The HV-ECU 62 determines the amount of charging/discharging required of the battery 18 (hereinafter also referred to as the "requested amount of charging/discharging"), and adds the required amount of charging/discharging (the charging side is a positive value) to the required traveling power calculated in S3. is added to calculate the required system power of the vehicle 10 (S4). The HV-ECU 62 increases the required charge/discharge amount on the positive side as the SOC of the battery 18 is low, and can set the required charge/discharge amount to a negative value when the SOC of the battery 18 is high.

Next, HV-ECU 62 determines whether to operate or stop engine 13 based on the calculated required system power and required traveling power (S5). For example, when the required system power is greater than the first threshold, HV-ECU 62 determines to operate engine 13 . Also, when the required running power is greater than the second threshold, the HV-ECU 62 determines to operate the engine 13 . When the required system power is equal to or less than the first threshold and the required running power is equal to or less than the second threshold, the HV-ECU 62 determines to stop the engine 13 .

When determining to operate the engine 13, the HV-ECU 62 sets the HV driving mode as the driving mode of the vehicle 10. FIG. When the HV driving mode is set as the driving mode of the vehicle 10, the HV-ECU 62 executes the process of shifting to S6. When it is determined to stop the engine 13, the HV-ECU 62 sets the EV running mode as the running mode of the vehicle . In the EV running mode, a motor torque calculation process (not shown) is executed to calculate the torque of the second MG 15 based on the required driving force.

In the HV running mode, the HV-ECU 62 calculates the required engine power Pe of the engine 13 from the required system power calculated in S4 (S6). The required engine power Pe is calculated by performing various corrections and restrictions on the required system power. The requested engine power Pe corresponds to an engine operating state command for the engine 13 and is transmitted from the HV-ECU 62 to the engine ECU 64 .

The HV-ECU 62 then determines the operating point of the engine 13 (S7). FIG. 6 is a flow chart showing the procedure for determining the operating point of the engine 13. As shown in FIG.

Referring to FIG. 6, HV-ECU 62 determines whether or not there is a request to increase the output of engine 13 (S71). Specifically, HV-ECU 62 determines whether required engine power Pe calculated in S6 (FIG. 5) is greater than current engine power Pec by a predetermined amount or more. Note that the determination in S71 may be made based on whether or not the power button is pressed.

When required engine power Pe is not greater than current engine power Pec by a predetermined amount or more (NO in S71), HV-ECU 62 selects fuel efficiency line L2 as the operating line (S72). When the fuel efficiency line L2 is selected as the operation line, the HV-ECU 62 determines the intersection of the fuel efficiency line L2 and the equal power line corresponding to the required engine power Pe as the operating point of the engine 13 (S73).

On the other hand, when requested engine power Pe is greater than current engine power Pec by a predetermined value or more (YES in S71), HV-ECU 62 selects power line L1 as the operating line (S74).

When the power line L1 is selected as the operating line, the HV-ECU 62 determines whether the operating line is a transition from the fuel efficiency line L2 to the power line L1 (S75). In other words, it is determined whether or not the operation line shifts from the fuel efficiency line L2 to the power line L1 by selecting the power line L1 as the operation line this time. In other words, it is determined whether or not the fuel efficiency line L2 was selected as the operation line by the previous execution of the processing of this flowchart.

When it is determined that the operation line does not correspond to the case where the fuel consumption line L2 shifts to the power line L1 (NO in S75), the HV-ECU 62 determines the intersection of the power line L1 and the equal power line corresponding to the required engine power Pe. It is determined as the operating point of the engine 13 (S76). A case that does not apply to the case where the operation line shifts from the fuel efficiency line L2 to the power line L1 is, for example, the case where the power line L1 was selected as the operation line even by the previous execution of the processing of this flowchart.

If it is determined that the operating line corresponds to the case where the fuel economy line L2 shifts to the power line L1 (YES in S75), the HV-ECU 62 sets the lower limit engine speed of the engine 13 based on the current engine speed (S77 ). HV-ECU 62, for example, sets the current engine speed as the lower limit speed. Note that the HV-ECU 62 may set the lower limit engine speed to a engine speed lower than the current engine speed by a threshold engine speed.

Then, the HV-ECU 62 determines an operating point so that the engine speed does not fall below the lower limit speed (S78).

After determining the operating point of the engine 13 in S73, S76 or S78, the HV-ECU 62 sets the engine speed determined by the determined operating point as the target engine speed (S79).

Returning to FIG. 5, the HV-ECU 62 uses the target engine speed to calculate the torque Tg to be generated in the first MG 14 (S8). The torque Tg generated by the first MG 14 is calculated so that the operating point of the engine 13 becomes the target operating point. HV-ECU 62 can obtain torque Tg from the target engine speed according to a formula including the planetary gear ratio of planetary gear mechanism 20, for example. Torque Tg calculated here is transmitted from HV-ECU 62 to MG-ECU 63 as a torque command for first MG 14 .

Next, HV-ECU 62 calculates engine direct torque Tep using torque Tg (S9). When the engine torque Te is input to the carrier C of the planetary gear mechanism 20, the ring gear R of the planetary gear mechanism 20 outputs the engine direct torque Tep. HV-ECU 62 can obtain engine direct torque Tep from engine torque Te (or torque Tg) according to a formula including the planetary gear ratio of planetary gear mechanism 20, for example.

HV-ECU 62 calculates torque Tm to be generated in second MG 15 using the required driving force and engine direct torque Tep. The torque Tm generated by the second MG 15 is calculated so that the required driving force is output to the drive wheels 24 . The HV-ECU 62 can calculate, for example, by subtracting the engine direct torque Tep from the required driving force converted on the output shaft. Torque Tm calculated here is output to MG-ECU 63 as a torque command to second MG 15 .

As described above, in the vehicle 10 according to the present embodiment, when the operation line shifts from the fuel efficiency line L2 to the power line L1 due to a request to increase the output of the engine 13, the engine speed Ne is set to the lower limit speed. number is set. Then, the operating point of the engine 13 is determined so that the engine speed Ne does not fall below the lower limit speed. By appropriately setting the lower limit engine speed, it is possible to prevent the engine speed Ne from decreasing, or to reduce the engine speed Ne to such an extent that the driver does not feel discomfort. Therefore, it is possible to reduce the sense of discomfort given to the driver.

(Modification)
In addition to the lower limit rotation speed, the upper limit rotation speed may be set based on the engine rotation speed Ne at the time when an increase in output is requested. In the modified example, an example in which the upper limit rotation speed is set in addition to the lower limit rotation speed will be described.

In the modified example, when the operation line shifts from the fuel efficiency line L2 to the power line L1, the HV-ECU 62 adjusts the engine speed after the shift based on the engine speed Ne before the shift in addition to the lower limit speed. Set the upper limit rotation speed that is the upper limit of the number. In other words, when there is a request to increase the output of the engine 13 by a predetermined amount or more, the HV-ECU 62 sets the lower limit rotation speed and the upper limit rotation speed based on the engine rotation speed Ne at the time when the output increase is requested. do. That is, the engine speed Ne after the shift is determined to be between the lower limit speed and the upper limit speed.

The reason for setting the upper limit rotation speed is as follows. If an attempt is made to increase the engine speed Ne when there is a request for an increase in the output of the engine 13, the inertia torque required to increase the engine speed Ne and the response delay of the supercharging pressure of the supercharger 47 will occur. , there is a possibility that the response delay of the torque generated by the engine 13 may occur in the initial stage of acceleration. As a result, there is a possibility that the feeling of acceleration expected by the driver cannot be obtained at the initial stage of acceleration. Therefore, by setting the upper limit rotation speed so that the rotation speed of the engine 13 does not exceed the upper limit rotation speed, it is possible to suppress the response delay of the torque generated by the engine 13 at the initial stage of acceleration. As a result, deterioration of drivability can be suppressed.

FIG. 7 is a flowchart showing the procedure of processing for determining the operating point of the engine 13 according to the modification. The processing of the flowchart of FIG. 7 is obtained by adding S81 to the processing of the flowchart of FIG. 6 and replacing S78 with S83. Other processes are the same as those in the flowchart of FIG. 6, and therefore will not be described repeatedly.

In the case where the operation line shifts from the fuel consumption line L2 to the power line L1, the HV-ECU 62 sets the lower limit rotation speed of the engine 13 (S77), and then adjusts the engine 13 based on the current engine rotation speed. Set the upper limit rotation speed of . The upper limit speed is set, for example, in consideration of the inertia torque required to increase the engine speed and the response delay of the boost pressure of the supercharger 47 .

The HV-ECU 62 determines the operating point so that the engine speed does not fall below the lower limit speed and does not exceed the upper limit speed (S83). The HV-ECU 62 sets the engine speed determined by the determined operating point as the target engine speed (S79).

If an attempt is made to increase the engine speed Ne, the torque generated by the engine 13 at the initial stage of acceleration will decrease due to the influence of the inertia torque required to increase the engine speed Ne and the response delay of the boost pressure of the supercharger 47. Response delay may occur, but the response delay of the torque generated by the engine 13 at the initial stage of acceleration is suppressed by setting the upper limit rotation speed based on the engine rotation speed Ne at the time when the output increase is requested. be able to. That is, by setting the upper limit number of revolutions, it is possible to suppress deterioration in drivability.

The embodiments disclosed this time should be considered as examples and not restrictive in all respects. The scope of the present disclosure is indicated by the scope of claims rather than the description of the above-described embodiments, and is intended to include all modifications within the scope and meaning equivalent to the scope of the claims.

10 hybrid vehicle, 11 control device, 13 engine, 14 first MG, 15 second MG, 16 first inverter, 17 second inverter, 18 battery, 20 planetary gear mechanism, 21 output gear, 22 output shaft, 23, 30 rotor shaft , 24 drive wheel, 25 countershaft, 26 driven gear, 27, 31 drive gear, 28 differential gear, 29 ring gear, 32, 33 drive shaft, 40 engine body, 40a, 40b, 40c, 40d cylinder, 41 intake passage, 42 exhaust passage, 43 intake valve, 44 exhaust valve, 45 spark plug, 46 intake manifold, 47 supercharger, 48 compressor, 49 throttle valve, 50 air flow meter, 51 intercooler, 52 exhaust manifold, 53 turbine, 54 bypass passage, 55 waste gate valve, 56 start catalytic converter, 57 aftertreatment device, 58 EGR device, 59 EGR passage, 60 EGR valve, 61 EGR cooler, 66 vehicle speed sensor, 67 accelerator opening sensor, 68 first MG rotation speed sensor, 69 second MG rotational speed sensor, 70 engine rotational speed sensor, 71 turbine rotational speed sensor, 72 boost pressure sensor, 73 battery monitoring unit, 74 first MG temperature sensor, 75 second MG temperature sensor, 76 first INV temperature sensor, 77 second INV temperature sensor , 78 catalyst temperature sensor, 79 turbine temperature sensor, 81 PCU, 83 converter, C carrier, P pinion gear, R ring gear, S sun gear.

Claims (2)

an internal combustion engine having a supercharger;
a rotating electric machine;
a planetary gear mechanism to which the internal combustion engine, the rotating electrical machine, and an output shaft are connected;
a control device configured to control the internal combustion engine and the rotating electrical machine;
When there is a request to increase the output of the internal combustion engine, the control device
setting a lower limit rotation speed based on the rotation speed of the internal combustion engine when the output increase is requested;
determining an operating point of the internal combustion engine so that the rotational speed of the internal combustion engine does not fall below the lower limit rotational speed ;
The hybrid vehicle , wherein the lower limit rotation speed is set to a rotation speed that is smaller by a threshold rotation speed than the rotation speed of the internal combustion engine when the output increase is requested . When there is a request to increase the output, the control device
further setting an upper limit rotation speed based on the rotation speed of the internal combustion engine when the output increase is requested;
2. The hybrid vehicle according to claim 1 , wherein the operating point of said internal combustion engine is determined so that the rotational speed of said internal combustion engine does not fall below said lower limit rotational speed and does not exceed said upper limit rotational speed.

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