阅读说明：本技术 混合动力车辆和控制混合动力车辆的方法 (Hybrid vehicle and method of controlling hybrid vehicle ) 是由 米泽幸一 吉嵜聪 前田治 安藤大吾 浅见良和 板垣宪治 尾山俊介 牟田浩一郎 于 2020-03-10 设计创作，主要内容包括：本发明涉及混合动力车辆和控制混合动力车辆的方法。HV-ECU执行如下的处理,所述处理包括：计算要求的系统功率(S100),在已经发出发动机启动要求时(S102中为“是”)计算要求的发动机功率(S104),获取涡轮温度(S106),当涡轮温度等于或低于阈值Ta时(S108中为“是”)在预定运行线上设定运行点(S110),当涡轮温度高于阈值Ta时(S108中为“否”)将沿着等功率线高预定值的较高转速侧上的位置设定为运行点(S112),进行发动机控制(S114),并且进行MG控制(S116)。(The invention relates to a hybrid vehicle and a method of controlling the hybrid vehicle. The HV-ECU executes processing including: calculating a required system power (S100), calculating a required engine power (S104) when an engine start request has been issued (yes in S102), acquiring a turbine temperature (S106), setting an operating point on a predetermined operating line (S110) when the turbine temperature is equal to or lower than a threshold Ta (yes in S108), setting a position on a higher rotation speed side higher by a predetermined value along an equal power line as an operating point (S112) when the turbine temperature is higher than the threshold Ta (no in S108), performing engine control (S114), and performing MG control (S116).)

1. A hybrid vehicle comprising:

an engine comprising a turbocharger;

a motor generator that generates electricity by using power of the engine;

a power splitter that splits power output from the engine into power to be transmitted to the motor generator and power to be transmitted to drive wheels;

an acquisition device that acquires a temperature of the turbocharger; and

a controller that controls the engine and the motor generator based on the temperature of the turbocharger, wherein:

the controller sets a position on a predetermined operation line that outputs a required engine power of the engine as an operation point when the temperature of the turbocharger does not exceed a threshold value, sets the predetermined operation line on a coordinate plane of an engine torque and an engine speed,

when the temperature of the turbocharger exceeds the threshold, the controller sets, as the operating point, a position that changes from a position set on the predetermined operation line toward a higher rotation speed side along a line of constant power of the engine power, and

the controller controls the engine and the motor generator to operate the engine at the set operating point.

2. The hybrid vehicle according to claim 1, wherein:

the controller sets the operating point to increase the rotation speed of the engine as the temperature of the turbocharger becomes higher.

3. The hybrid vehicle according to claim 1 or 2, wherein:

when the engine speed corresponding to the position changed toward the higher rotation speed side exceeds an upper limit value, the controller sets, as the operation point, a position changed toward a lower torque side with the rotation speed of the engine equal from a position set on the predetermined operation line.

4. A hybrid vehicle comprising:

an engine comprising a turbocharger;

a first motor generator that generates electricity by using power of the engine;

a power splitter that splits power output from the engine into power to be transmitted to the first motor generator and power to be transmitted to drive wheels;

a second motor generator that transmits power to the drive wheel;

an acquisition device that acquires a temperature of the turbocharger; and

a controller that controls the engine, the first motor generator, and the second motor generator based on the temperature of the turbocharger, wherein:

the controller sets a position on a predetermined operation line that outputs a required engine power of the engine as an operation point when the temperature of the turbocharger does not exceed a threshold value, sets the predetermined operation line on a coordinate plane of an engine torque and an engine speed,

the controller sets, as the operation point, a position that changes from a position set on the predetermined operation line toward a lower torque side with the engine speed equal when the temperature of the turbocharger exceeds the threshold,

the controller controls the engine and the first motor generator to operate the engine at the set operating point, and

the controller compensates for an insufficiency of the driving force corresponding to a decrease in the engine torque from a position set on the predetermined operation line to the operation point by using the second motor generator.

5. A method of controlling a hybrid vehicle, the hybrid vehicle comprising: an engine comprising a turbocharger; a motor generator that generates electricity by using power of the engine; and a power splitter that splits power output from the engine into power to be transmitted to the motor generator and power to be transmitted to drive wheels, the method comprising:

acquiring the temperature of the turbocharger;

setting a position on a predetermined operation line that outputs a required engine power of the engine as an operation point when the temperature of the turbocharger does not exceed a threshold value, the predetermined operation line being set on a coordinate plane of an engine torque and an engine speed;

setting, as the operation point, a position that changes from a position set on the predetermined operation line toward a higher rotation speed side along an equal power line of the engine power when the temperature of the turbocharger exceeds the threshold; and

the engine and the motor generator are controlled to operate the engine at the set operating point.

6. A method of controlling a hybrid vehicle, the hybrid vehicle comprising: an engine comprising a turbocharger; a first motor generator that generates electricity by using power of the engine; a power splitter that splits power output from the engine into power to be transmitted to the first motor generator and power to be transmitted to drive wheels; and a second motor generator that transmits power to the drive wheel, the method comprising:

acquiring the temperature of the turbocharger;

setting a position on a predetermined operation line that outputs a required engine power of the engine as an operation point when the temperature of the turbocharger does not exceed a threshold value, the predetermined operation line being set on a coordinate plane of an engine torque and an engine speed;

setting, as the operation point, a position that changes from a position set on the predetermined operation line toward a lower torque side with the engine rotation speed being equal, when the temperature of the turbocharger exceeds the threshold;

controlling the engine and the first motor generator to operate the engine at the set operating point; and

the shortage of the driving force corresponding to the decrease of the engine torque from the position set on the predetermined operation line to the operation point is compensated for by using the second motor generator.

Technical Field

The present disclosure relates to control of a hybrid vehicle including an electric motor and an engine including a turbocharger as drive sources.

Background

There has conventionally been known a hybrid vehicle that includes an electric motor and an engine as drive sources, includes an electric power storage that is charged with power of the engine, and runs with the power of the engine. Some engines mounted on such hybrid vehicles include a turbocharger.

For example, japanese patent laid-open No. 2015-58924 discloses a hybrid vehicle that includes an electric motor and an engine that includes a turbocharger.

Disclosure of Invention

However, in the above-described hybrid vehicle, the temperature of the exhaust gas may increase due to the start of the engine, particularly in a high engine torque region, and components constituting the turbocharger (such as a turbine through which the exhaust gas flows) are heated. Thus, depending on the temperature of the component, the engine may not operate as desired in order to protect the component. Therefore, the electric power storage cannot be sufficiently charged or cannot generate the driving force required by the vehicle, which may result in poor drivability of the vehicle.

An object of the present disclosure is to provide a hybrid vehicle that achieves suppression of deterioration of drivability while suppressing overheating of a turbocharger, and a method of controlling the hybrid vehicle.

A hybrid vehicle according to an aspect of the present disclosure includes: an engine comprising a turbocharger; a motor generator that generates electricity by using power of an engine; a power splitter that splits power output from the engine into power to be transmitted to the motor generator and power to be transmitted to drive wheels; an acquisition device that acquires a temperature of a turbocharger; and a controller that controls the engine and the motor generator based on a temperature of the turbocharger. When the temperature of the turbocharger does not exceed the threshold, the controller sets a position on a predetermined operation line that outputs a required engine power of the engine as an operation point, and sets the predetermined operation line on a coordinate plane of the engine torque and the engine speed. When the temperature of the turbocharger exceeds a threshold value, the controller sets, as an operating point, a position that changes from a position set on a predetermined operating line toward a higher rotation speed side along an equipower line of the engine power. The controller controls the engine and the motor generator to operate the engine at the set operating point.

Therefore, when the temperature of the turbocharger exceeds the threshold value and the high temperature state is set, the position at which the engine power requested from the output on the predetermined operation line is changed to the higher rotation speed side along the isopower line is set as the operation point. Therefore, the engine speed increases and the engine torque decreases as compared with the example in which the position on the predetermined operation line is set as the operation point. Therefore, the temperature increase of the exhaust gas can be suppressed, and therefore the temperature increase of the turbocharger can be suppressed. Therefore, the required engine power is output while suppressing overheating of the turbocharger, and therefore deterioration of the drivability of the vehicle can be suppressed.

In one embodiment, the controller sets an operating point to increase a rotational speed of the engine as the temperature of the turbocharger becomes higher.

Therefore, as the temperature of the turbocharger increases, the engine speed increases and the engine torque decreases. Therefore, the temperature increase of the exhaust gas can be suppressed, and therefore the temperature increase of the turbocharger can be suppressed.

Further, in one embodiment, when the engine speed corresponding to the position changed toward the higher rotation speed side exceeds the upper limit value, the controller sets, as the operation point, a position changed toward the lower torque side with the rotation speed of the engine equal from a position set on the predetermined operation line.

Therefore, the engine torque is reduced while suppressing the engine speed from exceeding the upper limit value. Therefore, the temperature increase of the exhaust gas can be suppressed, and therefore the temperature increase of the turbocharger can be suppressed.

A hybrid vehicle according to another aspect of the present disclosure includes: an engine comprising a turbocharger; a first motor generator that generates electricity by using power of an engine; a power splitter that splits power output from the engine into power to be transmitted to the first motor generator and power to be transmitted to drive wheels; a second motor generator that transmits power to a drive wheel; an acquisition device that acquires a temperature of a turbocharger; and a controller that controls the engine, the first motor generator, and the second motor generator based on a temperature of the turbocharger. When the temperature of the turbocharger does not exceed the threshold, the controller sets a position on a predetermined operation line that outputs a required engine power of the engine as an operation point, and sets the predetermined operation line on a coordinate plane of the engine torque and the engine speed. When the temperature of the turbocharger exceeds a threshold value, the controller sets, as an operating point, a position that changes from a position set on a predetermined operating line toward a lower torque side with the engine speed equal. The controller controls the engine and the first motor generator to operate the engine at the set operating point. The controller compensates for a shortage of the driving force corresponding to a decrease in the engine torque from a position set on the predetermined operation line to the operation point by using the second motor generator.

Therefore, when the temperature of the turbocharger exceeds the threshold value and a high temperature state is set, the engine torque is reduced. Therefore, the temperature increase of the exhaust gas can be suppressed, and therefore the temperature increase of the turbocharger can be suppressed. Therefore, while suppressing overheating of the turbocharger, it is possible to suppress deterioration of drivability of the vehicle by compensating for the shortage of the driving force of the second motor generator.

A method of controlling a hybrid vehicle according to still another aspect of the present disclosure is a method of controlling a hybrid vehicle including: an engine comprising a turbocharger; a motor generator that generates electricity by using power of an engine; and a power splitter that splits power output from the engine into power to be transmitted to the motor generator and power to be transmitted to the drive wheels. The method comprises the following steps: acquiring the temperature of the turbocharger; setting a position on a predetermined operation line that outputs a required engine power of the engine as an operation point when the temperature of the turbocharger does not exceed a threshold value, and setting the predetermined operation line on a coordinate plane of an engine torque and an engine speed; setting, as an operation point, a position that changes from a position set on a predetermined operation line toward a higher rotation speed side along an equipower line of engine power when a temperature of the turbocharger exceeds a threshold; and controlling the engine and the motor generator to operate the engine at the set operating point.

A method of controlling a hybrid vehicle according to still another aspect of the present disclosure is a method of controlling a hybrid vehicle including: an engine comprising a turbocharger; a first motor generator that generates electricity by using power of an engine; a power splitter that splits power output from the engine into power to be transmitted to the first motor generator and power to be transmitted to drive wheels; and a second motor generator that transmits power to the drive wheels. The method comprises the following steps: acquiring the temperature of the turbocharger; setting a position on a predetermined operation line that outputs a required engine power of the engine as an operation point when the temperature of the turbocharger does not exceed a threshold value, and setting the predetermined operation line on a coordinate plane of an engine torque and an engine speed; setting, as an operation point, a position that changes from a position set on a predetermined operation line toward a lower torque side with an equal engine speed when a temperature of the turbocharger exceeds a threshold value; controlling the engine and the first motor generator to operate the engine at the set operating point; and compensating for a shortage of the driving force corresponding to a decrease in the engine torque from a position set on the predetermined operation line to the operation point by using the second motor generator.

The foregoing and other objects, features, aspects and advantages of the present disclosure will become more apparent from the following detailed description of the present disclosure when considered in conjunction with the accompanying drawings.

Drawings

Fig. 1 is a diagram showing an exemplary configuration of a drive system of a hybrid vehicle.

Fig. 2 is a diagram showing an exemplary configuration of an engine including a turbocharger.

Fig. 3 is a block diagram showing an exemplary configuration of the controller.

Fig. 4 is a flowchart showing an exemplary process executed by the HV-ECU.

Fig. 5 is a diagram for explaining an exemplary operation of the HV-ECU.

Fig. 6 is a flowchart showing an exemplary process performed by the HV-ECU in one modification.

Fig. 7 is a diagram for explaining an exemplary operation of the HV-ECU in the modification.

Fig. 8 is a flowchart showing exemplary processing executed by the HV-ECU in the second embodiment.

Fig. 9 is a diagram for explaining an exemplary operation of the HV-ECU in the second embodiment.

Detailed Description

Embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. The same or corresponding elements in the drawings have the same reference numerals assigned thereto, and the description thereof will not be repeated.

< first embodiment >

< drive System for hybrid vehicle >

Fig. 1 is a diagram showing an exemplary configuration of a drive system of a hybrid vehicle (hereinafter simply referred to as a vehicle) 10. As shown in fig. 1, a vehicle 10 includes a controller 11 as a drive system, and an engine 13, a first motor generator (hereinafter, referred to as a first MG)14, and a second motor generator (hereinafter, referred to as a second MG)15, which serve as power sources for running. The engine 13 includes a turbocharger 47. The first MG 14 and the second MG15 each perform a function of a motor that outputs torque by being supplied with driving electric power and a function of a generator that generates electric power by being supplied with torque. For the first MG 14 and the second MG15, an Alternating Current (AC) rotating electric machine is employed. The alternating-current rotary electric machine includes, for example, a permanent magnet synchronous motor including a rotor in which permanent magnets are embedded.

The first MG 14 and the second MG15 are electrically connected to the battery 18 with a Power Control Unit (PCU)81 interposed between the first MG 14 and the second MG15 and the battery 18. The PCU 81 includes: a first inverter 16 that supplies electric power to the first MG 14 and receives electric power from the first MG 14; a second inverter 17 that supplies electric power to the second MG15 and receives electric power from the second MG 15; a battery 18; and a converter 83, the converter 83 supplying power to the first inverter 16 and the second inverter 17 and receiving power from the first inverter 16 and the second inverter 17.

For example, the converter 83 may up-convert the electric power from the battery 18 and supply the up-converted electric power to the first inverter 16 or the second inverter 17. Alternatively, the converter 83 may down-convert the electric power supplied from the first inverter 16 or the second inverter 17 and supply the down-converted electric power to the battery 18.

The first inverter 16 may convert Direct Current (DC) power from the converter 83 into alternating current power, and supply the alternating current power to the first MG 14. Alternatively, the first inverter 16 may convert the alternating-current power from the first MG 14 into direct-current power, and supply the direct-current power to the converter 83.

The second inverter 17 may convert the direct-current power from the converter 83 into alternating-current power, and supply the alternating-current power to the second MG 15. Alternatively, the second inverter 17 may convert the alternating-current power from the second MG15 into direct-current power, and supply the direct-current power to the converter 83.

The PCU 81 charges the battery 18 with electric power generated by the first MG 14 or the second MG15, or drives the first MG 14 or the second MG15 with electric power from the battery 18.

The battery 18 includes, for example, a lithium-ion secondary battery or a nickel metal hydride secondary battery. The lithium ion secondary battery is a secondary battery using lithium as a charge carrier, and may include not only a general lithium ion secondary battery including a liquid electrolyte but also a so-called all-solid-state battery including a solid electrolyte. The battery 18 should be only an at least rechargeable power storage, and an electric double layer capacitor may be used instead of the secondary battery, for example.

The engine 13 and the first MG 14 are coupled to the planetary gear mechanism 20. The planetary gear mechanism 20 transmits the drive torque output from the engine 13 by dividing the drive torque into the drive torque of the first MG 14 and the drive torque of the output gear 21, and represents an exemplary power splitter in the embodiment of the present disclosure. The planetary gear mechanism 20 includes a single pinion planetary gear mechanism, and is arranged on an axis Cnt coaxial with an 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; pinions P that mesh with the sun gear S and the ring gear R; and a carrier C that rotatably and rotatably holds the pinion P. The output shaft 22 is coupled to the carrier C. The rotor shaft 23 of the first MG 14 is coupled to the sun gear S. The ring gear R is coupled to the output gear 21. The output gear 21 represents one of output elements for transmitting the driving torque to the driving wheels 24.

In the planetary gear mechanism 20, the drive torque output from the engine 13 is transmitted to the carrier C, which serves as an input element, the ring gear R that outputs the drive torque to the output gear 21 serves as an output element, and the sun gear S coupled to the rotor shaft 23 serves as a reaction force element. The planetary gear mechanism 20 divides the power output from the engine 13 into the power on the first MG 14 side and the power on the output gear 21 side. The first MG 14 is controlled to output torque in accordance with the engine speed.

The secondary shaft 25 is arranged parallel to the axis Cnt. The counter shaft 25 is attached to a driven gear 26 that meshes with the output gear 21. A drive gear 27 is attached to the counter shaft 25, and the drive gear 27 meshes with a ring gear 29 in a differential gear 28 representing a final reduction gear. A drive gear 31 attached to a rotor shaft 30 in the second MG15 meshes with the driven gear 26. Therefore, the drive torque output from the second MG15 is added to the drive torque output from the output gear 21 in a part of the driven gear 26. The driving torque thus combined is transmitted to the driving wheel 24 through the driving shaft 32 and the driving shaft 33 extending laterally from the differential gear 28. When the driving torque is transmitted to the driving wheels 24, a driving force is generated in the vehicle 10.

A mechanical oil pump (which is hereinafter referred to as MOP)36 is provided coaxially with the output shaft 22. The MOP36 delivers lubricating oil having a cooling function, for example, to the planetary gear mechanism 20, the first MG 14, the second MG15, and the differential gear 28. The vehicle 10 also includes an electric oil pump (which is hereinafter referred to as EOP) 38. When the engine 13 is stopped, the EOP38 is driven by electric power supplied from the battery 18 and delivers lubricating oil to the planetary gear mechanism 20, the first MG 14, the second MG15, and the differential gear 28 in the same or similar manner as the MOP 36.

< construction of Engine >

Fig. 2 is a diagram showing an exemplary configuration of the engine 13 including the turbocharger 47. The engine 13 is, for example, an in-line four-cylinder spark ignition internal combustion engine. As shown in fig. 2, the engine 13 includes, for example, an engine main body 40, and the engine main body 40 is formed with four cylinders 40a, 40b, 40c, and 40d aligned 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 40 d. One end of the intake port is opened and closed by two intake valves 43 provided in each of the cylinders 40a, 40b, 40c, and 40d, and one end of the exhaust port is opened and closed by two exhaust valves 44 provided in each of the cylinders 40a, 40b, 40c, and 40 d. The other ends of the intake ports of the cylinders 40a, 40b, 40c, and 40d are connected to an intake manifold 46. The other ends of the exhaust ports of the cylinders 40a, 40b, 40c, and 40d are connected to an exhaust manifold 52.

In the present embodiment, the engine 13 is, for example, a direct injection engine, and fuel is injected into each of the cylinders 40a, 40b, 40c, and 40d through a fuel injector (not shown) provided at the top of each cylinder. The air-fuel mixture of the fuel and the intake air in the cylinders 40a, 40b, 40c, and 40d is ignited by the ignition plug 45 provided in each of the cylinders 40a, 40b, 40c, and 40 d.

Fig. 2 shows the intake valve 43, the exhaust valve 44, and the ignition plug 45 provided in the cylinder 40a, and does not show the intake valve 43, the exhaust valve 44, and the ignition plug 45 provided in the other cylinders 40b, 40c, and 40 d.

The engine 13 is provided with a turbocharger 47, and the turbocharger 47 intensifies the intake air by using the energy of exhaust gas. The turbocharger 47 includes a compressor 48 and a turbine 53.

The intake passage 41 has one end connected to an intake manifold 46 and the other end connected to an intake port. The compressor 48 is provided at a prescribed 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, and the air flow meter 50 outputs a signal to the controller 11 in accordance with the flow rate of air flowing through the intake passage 41. An intercooler 51 that cools the intake air pressurized by the compressor 48 is provided in the intake passage 41 provided downstream of the compressor 48. An intake throttle valve (throttle valve) 49 is provided between the intercooler 51 and one end of the intake passage 41, and the intake throttle valve 49 is capable of adjusting the flow rate of intake air flowing through the intake passage 41.

The exhaust passage 42 has one end connected to the exhaust manifold 52 and the other end connected to a muffler (not shown). The turbine 53 is provided at a prescribed position in the exhaust passage 42. In the exhaust passage 42, a bypass passage 54 is provided, the bypass passage 54 bypassing the exhaust gas upstream of the turbine 53 to a portion downstream of the turbine 53, and a wastegate valve 55 is provided, the wastegate valve 55 being provided in the bypass passage and being capable of adjusting the flow rate of the exhaust gas guided to the turbine 53. Therefore, the flow rate of the exhaust gas flowing into the turbine 53, that is, the supercharging pressure of the intake air is adjusted by controlling the position of the wastegate valve 55. The exhaust gas passing through the turbine 53 or the wastegate valve 55 is purified by a startup converter 56 and an aftertreatment device 57 provided at predetermined positions in the exhaust passage 42, and then discharged to the atmosphere. The aftertreatment device 57 contains, for example, a three-way catalyst.

The engine 13 is provided with an Exhaust Gas Recirculation (EGR) device 58, and the EGR device 58 causes exhaust gas to flow into the intake passage 41. The EGR device 58 includes an EGR passage 59, an EGR valve 60, and an EGR cooler 61. The EGR passage 59 allows some exhaust gas to be taken out as EGR gas from the exhaust passage 42, and guides the EGR gas 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 a portion of the exhaust passage 42 between the start-up converter 56 and the aftertreatment device 57 to a portion of the intake passage 41 between the compressor 48 and the airflow meter 50.

< construction of controller >

Fig. 3 is a block diagram showing an exemplary configuration of the controller 11. As shown in fig. 3, the controller 11 includes a Hybrid Vehicle (HV) -Electronic Control Unit (ECU)62, an MG-ECU 63, and an engine ECU 64.

The HV-ECU62 is a controller that coordinately controls the engine 13, the first MG 14, and the second MG 15. The MG-ECU 63 is a controller that controls the operation of the PCU 81. The engine ECU 64 is a controller that controls the operation of the engine 13.

The HV-ECU62, the MG-ECU 63, and the engine ECU 64 each include: input and output devices that supply signals to and receive signals from various sensors and other ECUs connected thereto; a memory for storing various control programs or maps (including a Read Only Memory (ROM) and a Random Access Memory (RAM)); a Central Processing Unit (CPU) that executes a control program; and a timer that times.

A vehicle speed sensor 66, an accelerator position 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, a boost 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 the HV-ECU 62.

The vehicle speed sensor 66 detects the speed of the vehicle 10 (vehicle speed). The accelerator position sensor 67 detects the depression amount of the accelerator pedal (accelerator position). The first MG rotation speed sensor 68 detects the rotation speed of the first MG 14. The second MG rotation speed sensor 69 detects the rotation speed of the second MG 15. The engine speed sensor 70 detects the rotational speed of the output shaft 22 of the engine 13 (engine speed). The turbine rotation speed sensor 71 detects the rotation speed of the turbine 53 of the turbocharger 47. The boost pressure sensor 72 detects the boost pressure of the engine 13. The first MG temperature sensor 74 detects an internal temperature of the first MG 14, such as a temperature associated with a coil or a magnet. The second MG temperature sensor 75 detects the internal temperature of the second MG15, such as the temperature associated with a coil or a magnet. The first INV temperature sensor 76 detects a temperature of the first inverter 16, for example, a temperature associated with the switching elements. The second INV temperature sensor 77 detects a temperature of the second inverter 17, for example, a temperature related to the switching element. The catalyst temperature sensor 78 detects the temperature of the aftertreatment device 57. The turbine temperature sensor 79 detects the temperature of the turbine 53. Various sensors output signals indicating the detection results to the HV-ECU 62.

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

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

As a method of calculating the SOC, various known methods such as a method by accumulating a current value (coulomb counting) or a method by estimating an Open Circuit Voltage (OCV) can be employed.

< control relating to travel of vehicle >

The vehicle 10 configured as above may be set or switched to a travel mode such as a Hybrid (HV) travel mode in which the engine 13 and the second MG15 serve as power sources and an Electric (EV) travel mode in which the vehicle travels with the engine 13 kept stopped and the second MG15 driven by electric power stored in the battery 18. Setting and switching to each mode are performed by the HV-ECU 62. The HV-ECU62 controls the engine 13, the first MG 14, and the second MG15 based on the set or switched running mode.

The EV running mode is selected, for example, in a low-load operation region where the vehicle speed is low and the required driving force is low, and refers to a running mode in which the operation of the engine 13 is stopped and the second MG15 outputs the driving force.

The HV running mode is selected in a high-load operation region where the vehicle speed is high and the required driving force is high, and refers to a running mode where the output total torque of the driving torque of the engine 13 and the driving torque of the second MG15 is zero.

In the HV travel mode, the first MG 14 applies a reaction force to the planetary gear mechanism 20 while transmitting the drive torque output from the engine 13 to the drive wheels 24. Therefore, the sun gear S functions as a reaction force element. In other words, in order to apply the engine torque to the drive wheels 24, the first MG 14 is controlled to output a reaction torque against the engine torque. In this case, the regeneration control in which the first MG 14 functions as a generator may be performed.

Control of coordinately controlling the engine 13, the first MG 14, and the second MG15 while the vehicle 10 is running will be described below.

The HV-ECU62 calculates the required driving force based on the accelerator position determined by the depression amount of the accelerator pedal. The HV-ECU62 calculates the required running power of the vehicle 10 based on the calculated required driving force and the vehicle speed. The HV-ECU62 calculates a value resulting from adding the required charge and discharge power of the battery 18 to the required running power as the required system power.

The HV-ECU62 determines whether or not the start of the engine 13 has been requested based on the calculated required system power. For example, when the required system power exceeds a threshold, the HV-ECU62 determines that the start of the engine 13 has been requested. When the start of the engine 13 is requested, the HV-ECU62 sets the HV running mode to the running mode. When the starting of the engine 13 is not required, the HV-ECU62 sets the EV running mode to the running mode.

When starting of the engine 13 has been requested (i.e., when the HV travel mode is set), the HV-ECU62 calculates a requested power of the engine 13 (which is hereinafter referred to as requested engine power). For example, the HV-ECU62 calculates the required system power as the required engine power. For example, when the required system power exceeds the upper limit value of the required engine power, the HV-ECU62 calculates the upper limit value of the required engine power as the required engine power. The HV-ECU62 outputs the calculated required engine power to the engine ECU 64 as an engine operating state command.

The engine ECU 64 sends a control signal C2 based on the engine operating state command input from the HV-ECU62, and controls various components of the engine 13, such as the intake throttle valve 49, the ignition plug 45, the wastegate valve 55, and the EGR valve 60, in various ways.

The HV-ECU62 sets an operating point of the engine 13 in a coordinate system defined by the engine speed and the engine torque based on the calculated required engine power. The HV-ECU62 sets, for example, an intersection between a line of equal power, which is equal in output to the required engine power in the coordinate system, and a predetermined operation line as an operation point of the engine 13.

The predetermined operation line indicates a locus of variation in engine torque with variation in engine speed in the coordinate system, and is set by, for example, experimentally adapting the locus of variation in engine torque with high fuel efficiency.

The HV-ECU62 sets the engine speed corresponding to the set operating point to the target engine speed.

When the target engine speed is set, the HV-ECU62 sets a torque command value for the first MG 14 to set the current engine speed to the target engine speed. The HV-ECU62 sets the torque command value of the first MG 14 by feedback control, for example, based on the difference between the current engine speed and the target engine speed.

The HV-ECU62 calculates the engine torque to be transmitted to the drive wheels 24 based on the set torque command value for the first MG 14, and sets the torque command value for the second MG15 so as to satisfy the required driving force. The HV-ECU62 outputs the set torque command values for the first MG 14 and the second MG15 to the MG-ECU 63 as a first MG torque command and a second MG torque command.

The MG-ECU 63 calculates a current value corresponding to the torque generated by the first MG 14 and the second MG15 and the frequency thereof based on the first MG torque command and the second MG torque command input from the HV-ECU62, and outputs a control signal C1 including the calculated current value and the frequency thereof to the PCU 81.

The HV-ECU62 also sends a control signal C3 to the EOP38 based on the operating conditions including the running mode, and controls the driving of the EOP 38.

For example, the HV-ECU62 may request an increase in boost pressure when the accelerator position exceeds a threshold value for activating the turbocharger 47, when the required engine power exceeds a threshold value, and when the engine torque corresponding to a set operating point exceeds a threshold value.

Although fig. 3 shows a configuration in which the HV-ECU62, the MG-ECU 63, and the engine ECU 64 are separately provided by way of example, these ECUs may be integrated into a single ECU.

< relation between turbocharger temperature and vehicle travel control >

In the vehicle 10 including the turbocharger 47 configured as above, the temperature of the exhaust gas is increased due to the operation of the engine, particularly, due to the operation of the engine in the high engine torque region, and the components constituting the turbocharger 47, such as the turbine 53 through which the exhaust gas flows, are heated. This is because as the supercharging pressure increases, the combustion energy increases and the heat generation amount increases. Therefore, depending on the temperature of the components, the engine 13 may not operate as desired in order to protect the components. Therefore, the battery 18 cannot be sufficiently charged, or cannot generate the required driving force of the vehicle 10, which may result in poor drivability of the vehicle 10.

In the present embodiment, it is assumed that the HV-ECU62 operates as follows. Specifically, when the temperature of the turbocharger 47 is lower than the threshold value, the HV-ECU62 sets, as an operating point, a position on a predetermined operating line set on a coordinate plane of the engine torque and the engine speed, which outputs the required engine power of the engine 13. When the temperature of the turbocharger 47 exceeds the threshold value, the HV-ECU62 sets, as an operation point, a position that changes from a position set on a predetermined operation line to a higher rotation speed side along an equipower line of the required engine power.

By so doing, when the temperature of the turbocharger 47 exceeds the threshold value and the high temperature state is set, a position at which the position of the engine power required from the output on the predetermined operation line changes to the higher rotation speed side along the equal power line is set as the operation point. Therefore, the engine speed increases and the engine torque decreases as compared with the example in which the position on the predetermined operation line is set as the operation point. Therefore, the temperature increase of the exhaust gas can be suppressed, and therefore the temperature increase of the turbocharger 47 can be suppressed. Therefore, the required engine power is output while suppressing overheating of the turbocharger 47, and deterioration of the drivability of the vehicle 10 can be suppressed.

< processing performed with respect to the HV-ECU62 >

The processing executed by the HV-ECU62 will be described below with reference to FIG. 4. Fig. 4 is a flowchart showing exemplary processing executed by the HV-ECU 62.

In step (step denoted as S below) 100, the HV-ECU62 calculates the required system power.

In S102, the HV-ECU62 determines whether a request to start the engine 13 has been issued. When it is determined that a request to start the engine 13 has been issued (yes in S102), the processing proceeds to S104.

In S104, the HV-ECU62 calculates the required engine power. The HV-ECU62 calculates the required system power as the required engine power, for example.

Since the method of calculating the required system power, the method of determining issuance of the request to start the engine 13, and the method of calculating the required engine power are as described above, detailed descriptions thereof will not be repeated.

In S106, the HV-ECU62 acquires the temperature of the turbocharger 47 (which is hereinafter referred to as turbine temperature). The HV-ECU62 may acquire, for example, the turbine temperature detected by the turbine temperature sensor 79 as the turbine temperature. Alternatively, the HV-ECU62 may calculate an estimated value of the turbine temperature based on the intake air amount, the injected fuel amount, the engine speed, the boost pressure, or the history of changes thereof, and acquire the calculated estimated value as the turbine temperature.

In S108, the HV-ECU62 determines whether the turbine temperature is equal to or less than a threshold Ta. The threshold Ta is a temperature threshold for determining whether the turbocharger 47 is overheated, and is set in advance (for example, the minimum value of the temperatures that the components can withstand) through experiments or based on the temperatures that the components constituting the turbocharger 47 (for example, the components constituting the compressor 48, the turbine 53, the wastegate valve 55, or the components constituting the shaft such as the coupling the compressor 48 and the turbine 53 to each other) can withstand.

The HV-ECU62 may set the threshold Ta, for example, by correcting a value (initial value) set in advance based on a deterioration state of the usage time of the turbocharger 47 (for example, the total operating time of the engine 13 or the total duration of the boost pressure equal to or higher than the threshold) or a load history (for example, the total rotation speed of the turbocharger 47). Alternatively, for example, when the degree of degradation is equal to or greater than a threshold value, the HV-ECU62 may set a threshold value Ta that is lower than the value set under the brand-new condition (initial value) or the value that decreases as the degree of degradation increases. When it is determined that the turbine temperature is equal to or less than the threshold Ta (yes in S108), the processing proceeds to S110.

In S110, the HV-ECU62 sets an operation point on a predetermined operation line. Specifically, the HV-ECU62 sets the intersection between the isopower line of the required engine power and the predetermined operation line as the operation point. Since the isopower line and the predetermined operation line are as described above, detailed description thereof will not be repeated. When the turbine temperature is higher than the threshold Ta (no in S108), the process proceeds to S112.

In S112, the HV-ECU62 sets, as the operating point, a position shifted by a predetermined value toward the higher rotation speed side with equal output from the position of the intersection between the equal power line of the required engine power and the predetermined operation line. The predetermined value is set to at least suppress an increase in the turbine temperature. The predetermined value may be set, for example, to an engine speed for setting an engine torque at which the boost pressure is equal to or lower than the threshold value. The predetermined value may be set according to the position of the intersection between the isopower line of the required engine power and the predetermined operation line.

In S114, the HV-ECU62 executes engine control. Specifically, the HV-ECU62 generates an engine operating state command so that the required engine power is output. The HV-ECU62 outputs a signal indicating the generated engine operating state command to the engine ECU 64. Although the engine control is performed in S114 after the operating point is set in S110 or S112 in the description of the present embodiment, the engine control should be performed only after the required engine power is calculated at least in S104, and the engine control may be performed before the operating point is set. When it is determined that the request to start the engine 13 has not been issued (no in S102), the processing proceeds to S116.

In S116, the HV-ECU62 executes MG control. Specifically, the HV-ECU62 sets the engine speed corresponding to the set operating point to the target engine speed. The HV-ECU62 generates a torque command value for the first MG 14 as a first MG torque command so that the engine speed reaches the set target engine speed. The HV-ECU62 outputs the generated first MG torque command to the MG-ECU 63.

The HV-ECU62 calculates the engine torque to be transmitted to the drive wheels 24 based on the torque command value of the first MG 14, and generates the torque command value of the second MG15 as a second MG command so as to satisfy the required driving force (i.e., so as to generate a driving force corresponding to the difference between the driving force corresponding to the engine torque to be transmitted to the drive wheels 24 and the required driving force). The HV-ECU62 outputs the generated second MG torque command to the MG-ECU 63. When the request to start the engine 13 has not been issued, the HV-ECU62 sets the torque command value of the second MG15 as the second MG torque command so that the requested driving force is generated only by the second MG 15.

< exemplary operation with respect to HV-ECU62 >

The operation of the HV-ECU62 according to the present embodiment based on the above-described structure and flowchart will be described with reference to FIG. 5. Fig. 5 is a diagram for explaining an exemplary operation of the HV-ECU 62. The ordinate in fig. 5 represents the engine torque. The abscissa in fig. 5 represents the engine speed. Fig. 5 shows a predetermined operation line LN1 (solid line). Fig. 5 shows an equal power line (dashed line) of the (exemplary) demanded engine power LN 2. For ease of description, it is assumed that the required system power is constant.

When the required system power is calculated (S100), and when it is determined that a start request of the engine 13 has been issued because the calculated required system power has exceeded the threshold (yes in S102), the required engine power is calculated (S104), and the turbine temperature is acquired (S106).

When it is determined that the acquired turbine temperature is equal to or lower than the threshold Ta (yes in S108), an intersection a of a predetermined operation line (LN 1 in fig. 5) and a line of equal power of the required engine power (LN 2 in fig. 5) is set as an operation point (S110). Specifically, an intersection a where the engine rotational speed reaches Ne (0) and the engine torque reaches Tq (1) in a coordinate plane of the engine torque and the engine rotational speed is set as an operation point.

Then, engine control is executed based on the required engine power (S114), and MG control is executed when the first MG torque command is generated (S116) such that the engine rotational speed reaches Ne (0) set as the target engine rotational speed, and the second MG torque command is generated such that the required driving force and the engine torque are generated and transmitted to the drive wheels 24.

When the operating state of the engine 13 in the high engine torque region continues, the exhaust gas temperature increases and the turbine temperature increases. Therefore, when it is determined that the acquired turbine temperature is higher than the threshold Ta (no in S108), a point B on the higher rotation speed side along the equal power line (LN 2 in fig. 5) higher than the intersection a on the predetermined operation line is set as an operation point (S112). In other words, a point B where the engine rotational speed reaches Ne (1) higher than Ne (0) by a predetermined value and the engine torque reaches Tq (0) in the coordinate plane of the engine torque and the engine rotational speed is set as the operating point.

Then, engine control is executed based on the required engine power (S114), and MG control is executed based on the set operating point (S116).

When the point B is set as the operation point, the engine torque output from the engine 13 is lower than when the intersection a is set as the operation point. Since the increase in the exhaust gas temperature is thus suppressed, the temperature increase of the turbocharger 47 is suppressed.

< function and Effect >

As described above, according to the hybrid vehicle in the embodiment, when the turbine temperature exceeds the threshold Ta and the high temperature state is set, the position at which the position of the engine power required from the output on the predetermined operation line changes toward the higher rotation speed side along the equal power line is set as the operation point. Therefore, the engine speed increases and the engine torque decreases as compared with the example in which the position on the predetermined operation line is set as the operation point. Therefore, the boost pressure of the turbocharger 47 is reduced, and therefore an increase in the exhaust gas temperature of the engine 13 can be suppressed. Therefore, the required engine power is output while suppressing overheating of the turbocharger, and deterioration of the drivability of the vehicle can be suppressed. Therefore, it is possible to suppress overheating of the turbocharger and suppress a decrease in drivability of the hybrid vehicle, and it is possible to provide a method of controlling the hybrid vehicle.

< modifications relating to the first embodiment >

A modification of the first embodiment will be described below.

In the above-described embodiment, when the turbine temperature exceeds the threshold Ta, the position on the higher rotation speed side higher by the predetermined value along the isopower line is set as the operation point. However, when the turbine temperature exceeds the threshold Ta, for example, the operating point may be set such that the degree of increase in the engine speed increases with the position on the predetermined operating line defined as the reference as the turbine temperature increases. By so doing, as the turbine temperature increases, the engine speed increases and the engine torque decreases. Therefore, the temperature rise of the turbocharger 47 can be suppressed.

Although the intake throttle valve 49 is described as being disposed between the intercooler 51 and the intake manifold 46 in the above embodiment, it may be disposed, for example, in the intake passage 41 between the compressor 48 and the airflow meter 50.

In the above-described embodiment, when the turbine temperature exceeds the threshold Ta, the position on the higher rotation speed side higher by the predetermined value along the isopower line is set as the operation point. For example, when the engine speed exceeds the upper limit value by setting a position on the higher rotation speed side higher by a predetermined value along the contour as the operation point, a position that is changed from the position set on the predetermined operation line to the lower torque side with the engine speeds equal may be set as the operation point.

The processing executed by the HV-ECU62 in this modification will be described below with reference to FIG. 6. Fig. 6 is a flowchart showing an exemplary process performed by the HV-ECU62 in the modification.

The processes in S100, S102, S104, S106, S108, S110, S114, and S116 in the flowchart of fig. 6 are similar to the processes in S100, S102, S104, S106, S108, S110, S114, and S116 in the flowchart of fig. 4, except for the following. Therefore, a detailed description of such processing will not be repeated.

When it is determined in S108 that the turbine temperature is higher than the threshold Ta (no in S108), the processing proceeds to S200.

In S200, the HV-ECU62 calculates a value obtained by adding a predetermined amount to the engine speed corresponding to a position on the predetermined operation line (i.e., an intersection between the predetermined operation line and an equal power line of the required engine power).

In S202, it is determined whether or not the value calculated in S200 exceeds the upper limit rotation speed. The upper limit rotation speed is predetermined, and it may be an upper limit value of the engine rotation speed set to the specification of the engine 13, an upper limit value of the engine rotation speed set to prevent the first MG 14 from entering the overspeed state, an upper limit value of the engine rotation speed set to prevent the pinion gear P from entering the overspeed state, or a minimum value of the upper limit values of the above various engine rotation speeds. When it is determined that the value calculated in S200 exceeds the upper limit rotation speed (yes in S202), the process proceeds to S204.

In S204, the HV-ECU62 sets, as the operation point, a position that changes from a position on the predetermined operation line toward the lower torque side with the engine rotation speed equal. The HV-ECU62 sets, as an operating point, a position where, for example, the engine torque is lower by a predetermined value than the intersection between a predetermined operating line and an equal-power line of the required engine power. The predetermined value is set to at least suppress an increase in the turbine temperature. For example, a predetermined value may be set to achieve an engine torque at which the boost pressure is equal to or less than the threshold value. Alternatively, the predetermined value may be set according to the position of the intersection between the equal power line of the required engine power and the predetermined operation line. When it is determined that the value calculated in S200 does not exceed the upper limit value (no in S202), the processing proceeds to S206.

In S206, the HV-ECU62 sets, as the operation point, a position shifted by a predetermined value toward the higher rotation speed side from the intersection between the equal power line of the required engine power and the predetermined operation line in the case where the outputs are equal. Since the specific processing is similar to that in S112 in fig. 4, detailed description thereof will not be repeated.

The operation of the HV-ECU62 in this modification will be described below with reference to FIG. 7. Fig. 7 is a diagram for explaining an operation example of the HV-ECU62 in the modification. The ordinate in fig. 7 represents the engine torque. The abscissa in fig. 7 represents the engine speed. LN1 and LN2 in fig. 7 are similar to LN1 and LN2, respectively, in fig. 5, showing the predetermined operating line and the equal power line of the (exemplary) demanded engine power. Fig. 7 assumes, for example, Ne (2) as the upper limit rotation speed.

When the required system power is calculated (S100), and when it is determined that a start request of the engine 13 has been issued because the calculated required system power has exceeded the threshold (yes in S102), the required engine power is calculated (S104), and the turbine temperature is acquired (S106).

When it is determined that the acquired turbine temperature is higher than the threshold Ta (no in S108), a value resulting from adding a predetermined amount to the engine speed corresponding to the intersection a on a predetermined operation line (e.g., Ne (1)) is calculated (S200).

Since the calculated value exceeds the upper limit rotation speed Ne (2) (yes in S202), a point C on the lower torque side lower than the intersection a on the predetermined operation line with the engine rotation speed equal is set as the operation point (S204). In other words, a point C, on the coordinate plane of the engine torque and the engine rotational speed, at which the engine rotational speed reaches Ne (0) and the engine torque reaches Tq (0) lower than Tq (1) by a predetermined value, is set as the operating point.

Then, engine control is executed based on the required engine power (S114), and MG control is executed based on the set operating point (S116).

When the point C is set as the operation point, the engine torque output from the engine 13 is lower than when the intersection a is set as the operation point. Since the increase in the exhaust gas temperature is thus suppressed, the temperature increase of the turbocharger 47 is suppressed. Therefore, while suppressing the engine speed from exceeding the upper limit speed, the temperature increase of the turbocharger 47 can be suppressed.

When a value obtained by adding a predetermined amount to the engine speed corresponding to the intersection between the predetermined operation line and the equal power line of the required engine power is equal to or less than the upper limit speed Ne (2) (at S202), the operation point is set on the higher rotation speed side along the equal power line (LN 2 of fig. 5) than the intersection of the predetermined operation line (S112).

The above-described modifications may be implemented in whole or in part in appropriate combinations thereof.

< second embodiment >

A hybrid vehicle according to a second embodiment will be described below. The vehicle 10 according to the present embodiment is partially different from the vehicle 10 according to the first embodiment described above in the processing performed by the HV-ECU 62. In other respects, the features of the vehicle 10 according to the present embodiment are the same as those of the vehicle 10 according to the first embodiment described above, and those features have the same reference numerals. These features also have the same function, and thus a detailed description thereof will not be repeated.

In the present embodiment, it is assumed that the HV-ECU62 operates as follows. Specifically, when the turbine temperature does not exceed the threshold Ta, the HV-ECU62 sets, as an operating point, a position on a predetermined operating line set on a coordinate plane of the engine torque and the engine speed at which the required engine power of the engine 13 is output. When the turbine temperature exceeds the threshold value Ta, the HV-ECU62 sets, as an operation point, a position that changes from a position set on a predetermined operation line toward a lower torque side with the engine rotation speed equal. The HV-ECU62 compensates for the shortage of the driving force corresponding to the decrease in the engine torque from the position set on the predetermined operation line to the operation point by using the second MG 15.

The processing executed by the HV-ECU62 in this embodiment will be described below with reference to FIG. 8. Fig. 8 is a flowchart showing exemplary processing executed by the HV-ECU62 in the second embodiment.

The processes in S100, S102, S104, S106, S108, S110, S114, and S116 in the flowchart of fig. 8 are similar to the processes in S100, S102, S104, S106, S108, S110, S114, and S116 in the flowchart of fig. 4, except for the following. Therefore, a detailed description of such processing will not be repeated.

When it is determined in S108 that the turbine temperature is higher than the threshold Ta (no in S108), the processing proceeds to S300.

In S300, the HV-ECU62 sets, as an operation point, a position that changes from a position on a predetermined operation line toward a lower torque side with the engine rotation speed equal. The HV-ECU62 sets, as an operating point, a position where, for example, the engine torque is lower by a predetermined value than the intersection between a predetermined operating line and an equal-power line of the required engine power. The predetermined value is set at least to suppress an increase in the turbine temperature. For example, a predetermined value may be set to achieve an engine torque at which the boost pressure is equal to or less than the threshold value. Alternatively, the predetermined value may be set according to the position of the intersection between the equal power line of the required engine power and the predetermined operation line.

The operation of the HV-ECU62 in this embodiment will be described below with reference to FIG. 9. Fig. 9 is a diagram for explaining an operation example of the HV-ECU62 in the second embodiment. The ordinate in fig. 9 represents the engine torque. The abscissa in fig. 9 represents the engine speed. LN1 and LN2 in fig. 9 are similar to LN1 and LN2, respectively, in fig. 5, showing the constant power lines of the predetermined operating line and the (exemplary) demanded engine power.

When the required system power is calculated (S100) and when it is determined that a start request of the engine 13 has been issued because the calculated required system power has exceeded the threshold (yes in S102), the required engine power is calculated (S104), and the turbine temperature is acquired (S106).

When it is determined that the acquired turbine temperature is higher than the threshold Ta (no in S108), a point C on the lower torque side lower than an intersection a between the required engine power and the predetermined operation line with the engine rotation speed equal is set as an operation point (S300). In other words, a point C at which the engine rotational speed reaches Ne (0) and the engine torque reaches Tq (0) lower than Tq (1) by a predetermined value in the coordinate plane of the engine torque and the engine rotational speed is set as the operating point.

Then, engine control is executed based on the required engine power (S114), and MG control is executed based on the set operating point (S116). In the MG control, the engine torque transmitted to the drive wheels 24 and the torque of the second MG15 result in generation of the required driving force.

When the point C is set as the operation point, the engine torque output from the engine 13 is lower than when the intersection a is set as the operation point. Since the increase in the exhaust gas temperature is thus suppressed, the temperature increase of the turbocharger 47 is suppressed. Further, the shortage of the driving force corresponding to the decrease in the engine torque is compensated for by the second MG 15. Therefore, deterioration of drivability can be suppressed. Therefore, it is possible to provide a hybrid vehicle that suppresses overheating of the turbocharger and suppresses deterioration of drivability, and a method of controlling the hybrid vehicle.

< modification relating to the second embodiment >

Next, a modification of the second embodiment will be described.

In the above-described embodiment, when the turbine temperature exceeds the threshold Ta, the position on the lower torque side lower than the intersection between the predetermined operation line and the equal power line of the required engine power with the engine rotation speed equal is set as the operation point. However, for example, when the turbine temperature exceeds the threshold Ta, the operating point may be set such that the decrease in the engine torque with the position on the predetermined operating line defined as the reference increases as the turbine temperature increases. By so doing, as the turbine temperature increases, the engine torque decreases, so it is possible to suppress the temperature increase of the turbocharger 47.

Although the intake throttle valve 49 is described as being disposed between the intercooler 51 and the intake manifold 46 in the above embodiment, the throttle valve 49 may be disposed, for example, in the intake passage 41 between the compressor 48 and the airflow meter 50.

While embodiments of the present invention have been described, it is to be understood that the embodiments disclosed herein are illustrative and not restrictive in every respect. The scope of the invention is defined by the terms of the claims, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.