CN112389409A

CN112389409A - Hybrid vehicle

Info

Publication number: CN112389409A
Application number: CN202010684850.3A
Authority: CN
Inventors: 牟田浩一郎
Original assignee: Toyota Motor Corp
Current assignee: Toyota Motor Corp
Priority date: 2019-07-30
Filing date: 2020-07-16
Publication date: 2021-02-23
Also published as: JP2021020631A

Abstract

A hybrid vehicle is provided with: an engine; a first MG; a planetary gear mechanism including a carrier connected to an output shaft of the engine, a sun gear connected to a rotor shaft of the first MG, and a ring gear connected to a drive shaft that transmits power to drive wheels, and including a pinion gear; and an HV-ECU controlling the engine and the first MG. When determining that a predetermined condition that the first MG or the pinion gear is expected to exceed the upper limit rotation speed is satisfied (yes in step S111 and step S112), the HV-ECU executes specific control for controlling the engine and the first MG so as not to exceed the upper limit rotation speed (step S113 to step S115). The first MG or the pinion gear can be made not to exceed the upper limit rotation speed.

Description

Hybrid vehicle

Technical Field

The present disclosure relates to a hybrid vehicle, and more particularly, to a hybrid vehicle including a planetary gear mechanism.

Background

Japanese patent application laid-open No. 2013-230794 discloses a hybrid vehicle including a rotating electric machine in addition to an internal combustion engine for generating a driving force for traveling.

Disclosure of Invention

The hybrid system disclosed in japanese patent application laid-open No. 2013-230794 is of a parallel system, and can output the driving forces of the internal combustion engine and the rotating electric machine together. However, in the hybrid system disclosed in japanese patent application laid-open No. 2013-230794, a series operation cannot be performed in which the driving force of the internal combustion engine is used for power generation and only the driving force of the rotating electric machine based on the generated power is output.

In a split-flow type hybrid system such as a hybrid system including a planetary gear mechanism, the hybrid system can operate while switching between the parallel connection type and the series connection type. The planetary gear mechanism includes a first element (for example, a carrier) connected to an output shaft of the internal combustion engine, a second element (for example, a sun gear) connected to a rotating shaft of the rotating electric machine, and a third element (for example, a ring gear) connected to a drive shaft that transmits power to drive wheels, and includes a specific gear (for example, a pinion gear).

However, in a hybrid system including a planetary gear mechanism, when a brake pedal is operated from a state in which the rotation speed of an internal combustion engine is high and a drive shaft is rapidly decelerated, a rotating electric machine or a specific gear may be abnormally rotated at a high speed.

The present disclosure has been made to solve the above-described problems, and an object thereof is to provide a hybrid vehicle capable of preventing a rotating electric machine or a specific gear from exceeding an upper limit rotation speed.

The disclosed hybrid vehicle is provided with: an internal combustion engine; a first rotating electrical machine; and a planetary gear mechanism including a specific gear, the planetary gear mechanism including a first element connected to an output shaft of the internal combustion engine, a second element connected to a rotating shaft of the first rotating electric machine, and a third element connected to a drive shaft that transmits power to a drive wheel; and a control device that controls the internal combustion engine and the first rotating electric machine. The control device executes a specific control for controlling the internal combustion engine and the first rotating electric machine so as not to exceed the upper limit rotation speed, when a predetermined condition that the first rotating electric machine or the specific gear is expected to exceed the upper limit rotation speed is satisfied.

With this configuration, when it is expected that the first rotating electric machine or the specific gear will exceed the upper limit rotation speed, the upper limit rotation speed can be prevented from being exceeded. As a result, it is possible to provide the hybrid vehicle capable of making the first rotating electrical machine or the specific gear not to exceed the upper limit rotation speed.

Preferably, as the specific control, the control device executes a control of reducing the upper limit rotation speed when the predetermined condition is satisfied, as compared with a case where the predetermined condition is not satisfied.

According to such a configuration, when the predetermined condition is satisfied, the internal combustion engine and the first rotating electric machine are controlled by decreasing the upper limit rotation speed. As a result, the first rotating electric machine or the specific gear can be made difficult to exceed the upper limit rotation speed.

Preferably, the planetary gear mechanism includes a carrier as the first element, a sun gear as the second element, a ring gear as the third element, and a plurality of pinion gears as the specific gears.

According to such a configuration, in the hybrid vehicle including the planetary gear mechanism including the carrier, the sun gear, the ring gear, and the pinion gear, the first rotating electrical machine or the specific gear can be made not to exceed the upper limit rotation speed.

Preferably, the predetermined condition is a condition that the rotation speed of the internal combustion engine exceeds a rotation speed predetermined in accordance with the rotation speed of the drive shaft and the drive shaft is decelerating at an acceleration equal to or higher than a predetermined acceleration.

According to this configuration, when the rotation speed of the internal combustion engine exceeds the rotation speed predetermined in accordance with the rotation speed of the drive shaft and the drive shaft is decelerating at an acceleration equal to or higher than a predetermined acceleration, the first rotating electric machine or the specific gear can be made not to exceed the upper limit rotation speed.

Preferably, the hybrid vehicle further includes an operation unit that operates a brake device that brakes the drive shaft. The predetermined condition is that the rotation speed of the internal combustion engine exceeds a rotation speed predetermined in accordance with the rotation speed of the drive shaft and the operation unit is being operated.

According to this configuration, when the rotation speed of the internal combustion engine exceeds the rotation speed predetermined in accordance with the rotation speed of the drive shaft and the operation unit of the brake device is being operated, the first rotating electrical machine or the specific gear can be made not to exceed the upper limit rotation speed.

Preferably, as the specific control, the control device executes a control for increasing a feedback gain in the rotational speed control of the first rotating electric machine when the predetermined condition is satisfied, as compared with a case where the predetermined condition is not satisfied.

According to such a configuration, when the predetermined condition is satisfied, the feedback gain of the rotation speed control of the first rotating electric machine is increased to control the internal combustion engine and the first rotating electric machine. As a result, the first rotating electric machine or the specific gear can be made difficult to exceed the upper limit rotation speed.

Preferably, the control device executes, as the specific control, control of stopping supply of the fuel to the internal combustion engine.

According to such a configuration, when the predetermined condition is satisfied, the supply of the fuel to the internal combustion engine is stopped. As a result, the first rotating electric machine or the specific gear can be made difficult to exceed the upper limit rotation speed.

Preferably, the hybrid vehicle further includes a power storage device capable of storing electric power generated by the first rotating electric machine and supplying the stored electric power to the first rotating electric machine. The control device controls the internal combustion engine and the first rotating electric machine so that a power value charged to the power storage device does not exceed a charging power limit value, controls the internal combustion engine to operate at an idle speed when the power value charged to the power storage device is within a range from a value obtained by adding a first predetermined value to the charging power limit value to a value obtained by adding a second predetermined value larger than the first predetermined value to the charging power limit value, and stops the supply of fuel to the internal combustion engine when the power value charged to the power storage device exceeds a value obtained by adding a second predetermined value to the charging power limit value.

With this configuration, it is possible to make it difficult for the electric power value charged to the power storage device to exceed the charging electric power limit value.

Preferably, the hybrid vehicle further includes a second rotating electric machine connected to the drive shaft. The control device controls the internal combustion engine, the first rotating electric machine, and the second rotating electric machine so that a drive torque on a positive vehicle speed side is generated at a negative vehicle speed at which it is expected that the first rotating electric machine or the specific gear will exceed the upper limit rotation speed, when the shift position is the reverse shift position.

According to such a structure, the first rotating electrical machine or the specific gear can be made not to exceed the upper limit rotation speed at the negative vehicle speed.

The above and other objects, features, aspects and advantages of the present invention will become apparent from the following detailed description of the present invention which is to be read in connection with the accompanying drawings.

Drawings

Fig. 1 is a diagram illustrating an example of a configuration of a drive system of a hybrid vehicle according to an embodiment of the present disclosure.

Fig. 2 is a block diagram showing an example of the configuration of the control unit.

Fig. 3 is a first alignment chart showing a relationship between the rotation speed and the torque of the engine, the first MG, and the output element.

Fig. 4 is a second alignment chart showing a relationship between the rotation speed and the torque of the engine, the first MG, and the output element.

Fig. 5 is a third line diagram showing the relationship between the rotation speed and the torque of the engine, the first MG, and the output element.

Fig. 6 is a flowchart showing an example of basic calculation processing for determining the operating points of the engine, the first MG, and the second MG.

Fig. 7 is a diagram showing the relationship between the ring gear rotation speed and the engine rotation speed.

Fig. 8 is an alignment chart showing a relationship among the rotation speeds of the engine, the first MG, and the output element in a case where the over-rotation prevention process is not executed.

Fig. 9 is a flowchart showing the flow of the over-rotation prevention processing.

Fig. 10 is an alignment chart showing a relationship among the rotation speeds of the engine, the first MG, and the output element when the over-rotation prevention process is executed.

Fig. 11 is a diagram showing a driving force map at the time of reverse before the change.

Fig. 12 is a diagram showing the driving force map at the time of reverse after the change.

Fig. 13 is a flowchart showing the flow of the Win time processing.

Fig. 14 is a diagram for explaining control based on Win excess time processing.

Detailed Description

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

< drive System for hybrid vehicle >

Fig. 1 is a diagram illustrating an example of a configuration of a drive system of a hybrid vehicle (hereinafter, simply referred to as a "vehicle") 10 according to an embodiment of the present disclosure. As shown in fig. 1, a vehicle 10 includes a control unit 11, and an engine 13, a first motor generator (hereinafter, referred to as "first MG") 14, and a second motor generator (hereinafter, referred to as "second MG") 15 as drive systems, which are power sources for traveling.

Each of the first MG14 and the second MG15 has a function as a motor that outputs torque by receiving supply of drive power and a function as a generator that generates generated power by receiving supply of torque. As the first MG14 and the second MG15, an ac rotary electric machine is used. The ac rotating electrical machine is, for example, a permanent magnet type synchronous motor or an induction motor including a rotor in which a permanent magnet is embedded.

Both the first MG14 and the second MG15 are electrically connected to the battery 18 via a PCU (Power Control Unit) 81. The PCU81 includes a first inverter 16 that exchanges electric power with the first MG14, a second inverter 17 that exchanges electric power with the second MG15, a battery 18, and a converter 83 that exchanges electric power with the first inverter 16 and the second inverter 17.

The converter 83 is configured to be able to boost the electric power of the battery 18 and supply the boosted electric power to the first inverter 16 or the second inverter 17, for example. Alternatively, the converter 83 is configured to be able to step down the electric power supplied from the first inverter 16 or the second inverter 17 and supply the electric power to the battery 18.

The first inverter 16 is configured to be able to convert dc power from the converter 83 into ac power and supply the ac power to the first MG 14. Alternatively, first inverter 16 is configured to be able to convert ac power from first MG14 into dc power and supply the dc power to converter 83.

The second inverter 17 is configured to be able to convert dc power from the converter 83 into ac power and supply the ac power to the second MG 15. Alternatively, the second inverter 17 is configured to be able to convert ac power from the second MG15 into dc power and supply the dc power to the converter 83.

The battery 18 is a rechargeable power storage element. The battery 18 is configured to include a storage element such as a secondary battery including a lithium ion battery or a nickel hydrogen battery, or an electric double layer capacitor. The lithium ion secondary battery is a secondary battery using lithium as a charge carrier, and may include a so-called all-solid-state battery using a solid electrolyte, in addition to a general lithium ion secondary battery in which an electrolyte is a liquid.

The battery 18 can receive and store the electric power generated by the first MG14 by the first inverter 16, and can supply the stored electric power to the second MG15 by the second inverter 17. The battery 18 may be configured to receive and store electric power generated by the second MG15 during deceleration of the vehicle or the like by the second inverter 17, and to supply the stored electric power to the first MG14 by the first inverter 16 during startup of the engine 13 or the like.

That is, the PCU81 charges the battery 18 using the electric power generated in the first MG14 or the second MG15, or drives the first MG14 or the second MG15 using the electric power of the battery 18.

The battery 18 is set with a charge power limit value Win that is an allowable value of electric power to be charged into the battery 18 and a discharge power limit value Wout that is an allowable value of electric power to be discharged from the battery 18. Win and Wout are set small in order to suppress deterioration of the battery 18 due to rapid Charge and discharge (high rate Charge and discharge), that is, high rate deterioration, as the State of Charge (SOC) that is the ratio of the remaining Charge amount to the full Charge capacity of the battery 18 becomes lower and becomes smaller as the battery 18 becomes lower in temperature. The controller 11 controls charging and discharging so that the charge power and the discharge power of the battery 18 do not exceed Win and Wout, respectively.

The engine 13 and the first MG14 are coupled to the planetary gear mechanism 20. The planetary gear mechanism 20 divides and transmits the drive torque output by the engine 13 to the first MG14 and the output gear 21. The planetary gear mechanism 20 has a single-pinion type planetary gear mechanism, and is disposed on the same axis Cnt as the output shaft 22 of the engine 13.

The planetary gear mechanism 20 includes a sun gear S, a ring gear R disposed coaxially with the sun gear S, pinion gears P meshing with the sun gear S and the ring gear R, and a carrier C holding the pinion gears P so as to be rotatable and revolvable. The output shaft 22 of the engine 13 is coupled to the carrier C. The rotor shaft 23 of the first MG14 is coupled to the sun gear S. The ring gear R is coupled to the output gear 21.

The carrier C that receives transmission of the output torque of the engine 13 functions as an input element, the ring gear R that outputs torque to the output gear 21 functions as an output element, and the sun gear S connected to the rotor shaft 23 functions as a reaction force element. That is, the planetary gear mechanism 20 divides the output of the engine 13 to the first MG14 side and the output gear 21 side. The first MG14 is controlled to output a torque corresponding to the output torque of the engine 13.

The counter shaft 25 is arranged parallel to the axis Cnt. The counter shaft 25 is mounted on a driven gear 26 that meshes with the output gear 21. Further, 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 as a final reduction gear. The driven gear 26 is meshed with the drive gear 31 attached to the rotor shaft 30 of the second MG 15. Therefore, the output torque of the second MG15 is superimposed at the driven gear 26 to the torque output from the output gear 21. The torque thus combined is transmitted to the drive wheels 24 via the

drive shafts

32 and 33 extending from the differential gear 28 to the left and right. By transmitting torque to the drive wheels 24, a driving force is generated in the vehicle 10.

< construction of control section >

Fig. 2 is a block diagram showing an example of the configuration of the control unit 11. As shown in fig. 2, control unit 11 includes HV (Hybrid Vehicle) -ECU (Electronic control unit) 62, MG-ECU63, and engine ECU 64.

The HV-ECU62 is a control device for cooperatively controlling the engine 13, the first MG14, and the second MG 15. The MG-ECU63 is a control device for controlling the operation of the PCU 81. The engine ECU64 is a control device for controlling the operation of the engine 13.

Each of HV-ECU62, MG-ECU63, and engine ECU64 is configured to include an input/output device that transmits and receives signals to and from various sensors and other ECUs connected thereto, a storage device (including a ROM (Read only Memory), a RAM (Random Access Memory), and the like) that stores various control programs, maps, and the like, a Central processing unit (CPU (Central processing unit)) that executes the control programs, a counter for counting time, and the like.

The HV-ECU62 is connected with a vehicle speed sensor 66, an accelerator opening degree sensor 67, a first MG rotation speed sensor 68, a second MG rotation speed sensor 69, an engine rotation speed sensor 70, 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 shift position sensor 78, and a brake pedal sensor 71, respectively.

The vehicle speed sensor 66 detects the speed of the vehicle 10 (vehicle speed). The accelerator opening sensor 67 detects a depression amount of an accelerator pedal (accelerator opening). 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 first MG temperature sensor 74 detects an internal temperature (e.g., a temperature associated with a coil or a magnet) of the first MG 14. The second MG temperature sensor 75 detects an internal temperature (e.g., a temperature associated with a coil, a magnet) of the second MG 15. The first INV temperature sensor 76 detects a temperature of the first inverter 16 (e.g., a temperature associated with the switching element). A second INV temperature sensor 77 detects a temperature of second inverter 17 (e.g., a temperature associated with the switching element). The shift position sensor 78 detects an operation position (shift position) of a shift lever of the vehicle 10, and outputs the detection result to the HV-ECU 62. The brake pedal sensor 71 detects the amount of operation of the brake pedal 72 by the driver of the vehicle 10, and outputs the detection result to the HV-ECU 62. Various sensors output signals indicating the detection results to the HV-ECU 62.

The battery monitoring unit 73 acquires the SOC of the battery 18, 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 obtains the SOC by calculating the SOC using the detected current, voltage, and temperature of the battery 18. As a method of calculating the SOC, various known methods such as a method based on current value integration (coulomb count) or a method based on estimation of Open Circuit Voltage (OCV) can be used.

< traveling control of vehicle >

The vehicle 10 having the above configuration can be set or switched to a travel mode such as a Hybrid (HV) travel mode in which the engine 13 and the second MG15 are used as power sources, and an Electric (EV) travel mode in which the vehicle travels by driving the second MG15 with electric power stored in the battery 18 while the engine 13 is stopped. The setting and switching of the modes are performed by the HV-ECU 62. The HV-ECU62 controls the engine 13, the first MG14, and the second MG15 based on the set or switched running mode.

The EV running mode is a mode selected, for example, in a low-load operating region where the vehicle speed is low and the required driving force is small, and is 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 a mode selected in a high load operating region where the vehicle speed is high and the required driving force is large, and is a running mode in which a torque obtained by adding the driving torque of the engine 13 and the driving torque of the second MG15 is output.

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

The cooperative control of the engine 13, the first MG14, and the second MG15 during the operation of the vehicle 10 will be described below.

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

The HV-ECU62 determines whether or not the operation of the engine 13 is required based on the calculated required system power. The HV-ECU62 determines that the operation of the engine 13 is required, for example, when the required system power exceeds a threshold value. In the case where the operation of the engine 13 is requested, the HV-ECU62 sets the HV travel mode to the travel mode. The HV-ECU62 sets the EV running mode to the running mode without requiring the operation of the engine 13.

When the operation of the engine 13 is requested (that is, when the HV travel mode is set), the HV-ECU62 calculates the required power for the engine 13 (hereinafter, referred to as required engine power). The HV-ECU62 calculates the required system power as the required engine power, for example. Note that, for example, in the case where 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 ECU64 as an engine operating state command.

The engine ECU64 performs various controls of various portions of the engine 13 such as the intake throttle Valve 49, the ignition plug 45, and the VVT (Variable Valve Timing) mechanism 46 based on an engine operating state command input from the HV-ECU 62.

The VVT mechanism 46 is a mechanism capable of changing at least 1 of the valve opening period, the opening/closing timing, and the lift amount of at least one of the intake valve and the exhaust valve of the engine 13 in accordance with a command from the engine ECU64, and in this embodiment, at least the opening/closing timing of the intake valve can be changed.

The HV-ECU62 uses the calculated required engine power to set the operating point of the engine 13 in a coordinate system defined by the engine speed and the engine torque. The HV-ECU62 sets, for example, in the coordinate system, the intersection with the isopower line that requests the output of the engine power and the like and the predetermined operation line as the operation point of the engine 13.

The predetermined operation line indicates a change locus of the engine torque with respect to a change in the engine speed in the coordinate system, and for example, the change locus of the engine torque with high fuel efficiency is adapted and set by an experiment or the like.

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

After the target engine speed is set, the HV-ECU62 sets the torque command value of the first MG14 for bringing the current engine speed to the target engine speed. The HV-ECU62 sets the torque command value of the first MG14, for example, by feedback control based on the difference between the current engine speed and the target engine speed.

The HV-ECU62 calculates the amount of transmission of engine torque to the drive wheels 24 based on the set torque command value of the first MG14, and sets the torque command value of the second MG15 so as to satisfy the required driving force. The HV-ECU62 outputs the set torque command values for the first MG14 and the second MG15 to the MG-ECU63 as a first MG torque command and a second MG torque command, respectively.

The MG-ECU63 calculates a current value and a frequency thereof corresponding to the torque to be generated by the first MG14 and the second MG15 based on the first MG torque command and the second MG torque command input from the HV-ECU62, and outputs a signal including the calculated current value and the frequency thereof to the PCU 81.

In fig. 2, the configuration divided into HV-ECU62, MG-ECU63, and engine ECU64 is described as an example, but 1 ECU may be used in combination.

Fig. 3 to 5 are first to third line graphs showing relationships between the rotation speed and the torque of engine 13, first MG14, and the output element, respectively. Fig. 3 is an alignment chart showing the relationship between the rotation speed and the torque of each element before the operating point of the engine 13 is changed. Fig. 4 is an alignment chart showing the relationship between the rotation speed and the torque of each element when the rotation speed Ne of the engine 13 is increased from the state shown in fig. 3. Fig. 5 is an alignment chart showing the relationship between the rotation speed and the torque of each element when the torque Te of the engine 13 is increased from the state shown in fig. 3.

In each of fig. 3 to 5, the output element is a ring gear R connected to the counter shaft 25 (fig. 1). The positions on the vertical axis indicate the rotation speeds of the respective elements (the engine 13, the first MG14, and the second MG15), and the intervals on the vertical axis indicate the gear ratio of the planetary gear mechanism 20. "Te" represents the torque of the engine 13, and "Tg" represents the torque of the first MG 14. "Tep" represents a straight-running torque of the engine 13, and "Tm 1" represents a torque obtained by converting the torque Tm of the second MG15 to the output element. The sum of Tep and Tm1 corresponds to the torque output to the drive shaft (counter shaft 25). The upward arrow indicates positive torque, the downward arrow indicates negative torque, and the length of the arrow indicates the magnitude of the torque.

Referring to fig. 3 and 4, the broken line in fig. 4 shows the relationship before the rotation speed Ne is increased, and corresponds to the line shown in fig. 3. Since the relationship between the torque Te of the engine 13 and the torque Tg of the first MG14 is uniquely determined by the gear ratio of the planetary gear mechanism 20, the rotation speed Ne of the engine 13 can be increased while maintaining the driving torque by controlling the first MG14 so as to increase the rotation speed of the first MG14 while maintaining the torque Tg of the first MG 14.

Referring to fig. 3 and 5, by controlling the engine 13 so as to increase the output (power) of the engine 13, the torque Te of the engine 13 can be increased. At this time, by increasing the torque Tg of the first MG14 so as not to increase the rotation speed of the first MG14, the torque Te of the engine 13 can be increased while maintaining the rotation speed Ne of the engine 13. Since the engine straight-running torque Tep increases as the torque Te increases, the torque of the drive shaft can be maintained by controlling the second MG15 so as to decrease the torque Tm 1.

When the torque Te of the engine 13 is increased, the torque Tg of the first MG14 is increased, and therefore the generated power of the first MG14 is increased. At this time, if the charging of the battery 18 is not restricted, the increased generated power can be charged into the battery 18.

On the other hand, although not particularly shown, the torque Te of the engine 13 can be reduced by controlling the engine 13 so as to reduce the output (power) of the engine 13. At this time, by decreasing the torque Tg of the first MG14 so as not to decrease the rotation speed of the first MG14, the torque Te of the engine 13 can be decreased while maintaining the rotation speed Ne of the engine 13. In this case, the torque Tg of the first MG14 decreases, and therefore the generated power of the first MG14 decreases. At this time, if the discharge of the battery 18 is not limited, the amount of power generation decrease of the first MG14 can be compensated for by increasing the discharge of the battery 18.

< description of basic calculation processing of operating Point >

Fig. 6 is a flowchart showing an example of basic calculation processing for determining the operating points of the engine 13, the first MG14, and the second MG 15. The series of processes shown in this flowchart is repeatedly executed in the HV-ECU62 at every prescribed cycle.

Referring to fig. 6, the HV-ECU62 acquires information such as the accelerator opening, the selected gear, and the vehicle speed (step S10). The accelerator opening is detected by an accelerator opening sensor 67. The shift position is detected by a shift position sensor 78. The vehicle speed is detected by a vehicle speed sensor 66. Instead of the vehicle speed, the rotation speeds of the drive shaft and the ring gear R may be used.

Next, the HV-ECU62 calculates the required driving force (torque) from the information acquired in step S10 using a driving force map prepared in advance for each gear position and indicating the relationship among the required driving force, the accelerator opening degree, and the vehicle speed (step S15). The HV-ECU62 multiplies the calculated required driving force by the vehicle speed, and adds a predetermined loss power to calculate the running power of the vehicle (step S20).

Next, when there is a request for charge/discharge (power) from the battery 18, the HV-ECU62 calculates a value obtained by adding the charge/discharge request (setting charge to a positive value) to the calculated traveling power as the system power (step S25). For example, the charge/discharge request may be a positive value that is larger as the SOC of the battery 18 is lower, or a negative value when the SOC is higher.

Subsequently, the HV-ECU62 determines the operation/stop of the engine 13 based on the calculated system power and the calculated running power (step S30). For example, when the system power is larger than the first threshold value or the running power is larger than the second threshold value, it is determined that the engine 13 is operated.

If a decision is made that the engine 13 is to be operated, the HV-ECU62 executes the processing (HV travel mode) after step S35. Although not particularly shown, when it is determined that the engine 13 is stopped (EV running mode), the torque Tm of the second MG15 is calculated based on the required driving force.

During operation of the engine 13 (in the HV travel mode), the HV-ECU62 calculates the power Pe of the engine 13 from the system power calculated in step S25 (step S35). The power Pe is calculated by performing various corrections, restrictions, and the like on the system power. The power Pe of the engine 13 calculated here is output to the engine ECU64 as a power command for the engine 13.

Next, the HV-ECU62 calculates the rotation speed Ne of the engine 13 (target engine rotation speed) (step S40). In this embodiment, as described above, the rotation speed Ne is calculated so that the operating point of the engine 13 is on the recommended operating line. Specifically, the relationship between the power Pe and the rotation speed Ne on the recommended operating line at the operating point of the engine 13 is prepared in advance as a map or the like, and the rotation speed Ne is calculated from the power Pe calculated in step S35 using the map. When the rotation speed Ne is determined, the torque Te of the engine 13 (target engine torque) is also determined. Thereby, the operating point of the engine 13 is determined.

Next, the HV-ECU62 calculates the torque Tg of the first MG14 (step S45). The torque Te of the engine 13 can be estimated from the rotation speed Ne of the engine 13, and the relationship between the torque Te and the torque Tg is uniquely determined by the gear ratio of the planetary gear mechanism 20, so that the torque Tg can be calculated from the rotation speed Ne. The torque Tg calculated here is output to the MG-ECU63 as a torque command of the first MG 14.

Further, the HV-ECU62 calculates the engine straight running torque Tep (step S50). Since the relationship between the engine straight-running torque Tep and the torque Te (or the torque Tg) is uniquely determined by the gear ratio of the planetary gear mechanism 20, the engine straight-running torque Tep can be calculated from the calculated torque Te or torque Tg.

And finally, the HV-ECU62 calculates the torque Tm of the second MG15 (step S50). The torque Tm is determined so as to realize the required driving force (torque) calculated in step S15, and can be calculated by subtracting the engine running torque Tep from the required driving force converted to the output shaft. The torque Tm calculated here is output to the MG-ECU63 as a torque command of the second MG 15.

As described above, the operating point of the engine 13 and the operating points of the first MG14 and the second MG15 are calculated.

[ prevention of over-rotation of the first MG14 or the pinion gear P ]

In the drive system of the hybrid vehicle including the planetary gear mechanism 20 as described above, when the brake pedal 72 is operated from a state in which the rotation speed of the engine 13 is high, and the output gear 21, which is the drive shaft of the planetary gear mechanism 20 that transmits power to the drive wheels 24, is rapidly decelerated, there is a possibility that the first MG14 or the pinion gear P abnormally rotates at a high speed.

Then, the HV-ECU62 of the vehicle 10 of the present disclosure controls the engine 13 and the first MG14 so as not to exceed the upper limit rotation speed when it is expected that the predetermined condition that the first MG14 or the pinion gear P would exceed the upper limit rotation speed is satisfied. Therefore, when it is expected that first MG14 or pinion gear P will exceed the upper limit rotation speed, the upper limit rotation speed can be prevented from being exceeded. As a result, first MG14 or pinion gear P can be made not to exceed the upper limit rotation speed.

The control in this embodiment will be described below. Fig. 7 is a diagram showing the relationship between the ring gear rotation speed and the engine rotation speed. Referring to fig. 7, the ring gear rotation speed is the rotation speed of the ring gear R of the planetary gear mechanism 20. The rotational speed of the engine 13 is equal to the rotational speed of the carrier C of the planetary gear mechanism 20.

The line L1 is a line indicating the upper limit rotational speed in the design of the engine 13. The line L2 is a line indicating the relationship between the ring gear rotation speed and the engine rotation speed when the first MG14 has the design upper limit rotation speed. Line L3 is a line indicating the relationship between the ring gear rotation speed and the engine rotation speed when pinion gear P has reached the design upper limit rotation speed. The line L4 is a line indicating the relationship between the ring gear rotation speed and the engine rotation speed when the first MG14 has the design lower limit rotation speed. Line L5 is a line indicating the relationship between the ring gear rotation speed and the engine rotation speed when pinion gear P has the design lower limit rotation speed. The line L6 is a line indicating the design upper limit rotation speed of the ring gear R.

The hatched portion indicates the over-rotation attention area. The over-rotation attention region is a region in which the first MG14 or the pinion gear P may be over-rotated when the ring gear R is rapidly decelerated when the operating point is included in the region. The line L7 is a line indicating the lower limit of the over-rotation attention area. For example, it is considered that the rotational speed of the ring gear R is rapidly decelerated by operating the brake pedal 72 in the state of the operating point P1, and moves to the operating point P2. In such a case, the operating point P2 exceeds the line L2 and the line L3, and therefore the rotation speed of the first MG14 and the pinion gear P exceeds the upper limit rotation speed.

Fig. 8 is an alignment chart showing the relationship among the rotation speeds of the engine 13, the first MG14, and the output element (ring gear R) in the case where the over-rotation prevention process is not executed. Referring to fig. 8, the broken line indicates before rapid deceleration of the rotation speed of the ring gear R. The solid line indicates after the rapid deceleration of the rotation speed of the ring gear R. When the rotation speed of the ring gear R is suddenly reduced by sudden braking due to an operation of the brake pedal 72 or the like, the rotation speed of the carrier C is hard to change immediately because the inertia of the engine 13 to which the carrier C is connected is large, and the rotation speed of the sun gear S to which the first MG14 is connected is suddenly increased.

Fig. 9 is a flowchart showing the flow of the over-rotation prevention processing. This over-rotation prevention processing is repeatedly executed by the HV-ECU62 at every predetermined cycle. Referring to fig. 9, HV-ECU62 determines whether or not rotation speed Ne of engine 13 is equal to or greater than the line of the lower limit of the over-rotation caution region indicated by line L7 in fig. 7 (step S111). When determining that the rotation speed Ne is not equal to or greater than the over-rotation attention line (no in step S111), the HV-ECU62 advances the process to step S121.

On the other hand, when determining that the rotation speed Ne is equal to or greater than the over-rotation attention line (yes in step S111), the HV-ECU62 determines whether the brake pedal 72 is operated, based on whether or not the detection signal is received from the brake pedal sensor 71 (step S112). If it is determined that the brake pedal 72 is not operated (no in step S112), the HV-ECU62 advances the executed process to step S121.

On the other hand, if it is determined that the brake pedal 72 is operated (yes in step S112), the HV-ECU62 starts execution of fuel cut control for stopping fuel injection in the engine 13 (step S113). This causes the engine brake to rapidly reduce the rotation speed of the engine 13.

Fig. 10 is an alignment chart showing a relationship among the rotation speeds of the engine 13, the first MG14, and the output element (ring gear R) when the over-rotation prevention process is executed. Referring to fig. 10, the dotted line indicates the rapid deceleration of the rotation speed of the ring gear R in the case where the over-rotation prevention process is not executed as indicated by the solid line in fig. 8. The solid line indicates after the rapid deceleration of the rotation speed of the ring gear R in the case where the over-rotation prevention process is executed. Even if the rotation speed of the ring gear R is suddenly reduced by sudden braking due to operation of the brake pedal 72 or the like, the rotation speed of the engine 13 is also suddenly reduced by the fuel cut control, so the rotation speed of the carrier C is also reduced, and the rotation speed of the sun gear S to which the first MG14 is connected is also reduced.

When the over-rotation prevention process is executed, the difference in the rotation speeds between the sun gear S and the carrier C is smaller than that in the case where the over-rotation prevention process is not executed, and therefore the rotation speed of the pinion P is reduced.

Returning to fig. 9, the HV-ECU62 lowers the upper limit rotation speed used in the control of the rotation speed of the first MG14 and the pinion gear P (step S114). Accordingly, since the engine 13 and the first MG14 are controlled in accordance with the reduced upper limit rotation speed of the first MG14 and the pinion gear P, it is possible to make it difficult to exceed the original design upper limit rotation speed of the first MG14 and the pinion gear P.

The HV-ECU62 increases the feedback gain of the feedback control of the first MG14 from the original value (step S115).

In the hybrid vehicle, the engine 13 is controlled by the generated torque of the first MG 14. The engine 13 outputs a target torque calculated based on the rotation speed and the required engine power. Therefore, the control torque of the first MG14 is uniquely determined according to the power and the rotation speed. The control torque of the first MG14 is used as a feedforward term. However, since there are variations in environment, fuel, and hardware, the engine 13 does not necessarily output the same torque in accordance with the same required engine power and rotation speed.

If the above-described feedforward term is used to cope with the variation in the output torque of the engine 13, a phenomenon such as reverse rotation or over rotation of the engine 13 may occur. Therefore, feedback control of the rotation speed based on the generated torque of the first MG14 is performed using the deviation of the actual rotation speed of the engine 13 from the target rotation speed.

For example, the feedback term is calculated by adding the proportional term to the integral term. The target rotation speed of the first MG14 is calculated from the target rotation speed of the engine 13. The proportional term is calculated by a proportional gain that multiplies the deviation of the target rotation speed from the actual rotation speed of the first MG14 by the feedback gain. The integral term is calculated by multiplying a value obtained by adding the previous deviation and the present deviation by an integral gain of the feedback gain.

In step S115, the proportional gain Kp1 and the integral gain Ki1 of the feedback gain are changed to large values Kp2 and Ki2, respectively. The proportional gain Kp1 and the integral gain Ki1 are determined at the time of design as values at which the rotation speed of the first MG14 converges rapidly and stably toward the target rotation speed. In addition, the proportional gain Kp2 and the integral gain Ki2 are determined at the time of design as the following values: when the rotation speed Ne is equal to or higher than the over-rotation attention line and the brake pedal 72 is operated, not only does the rotation speed of the first MG14 converge quickly and stably toward the target rotation speed, but also the rotation speeds of the first MG14 and the pinion gear P do not exceed the upper limit rotation speed.

When it is determined that the rotation speed Ne of the engine 13 is not equal to or greater than the over-rotation attention line (no in step S111), when it is determined that the brake pedal 72 is not operated (no in step S112), and after step S115, the HV-ECU62 determines whether the rotation speed Ne of the engine 13 is equal to or greater than the line of the lower limit of the over-rotation attention area indicated by the line L7 in fig. 7 (step S121). When it is determined that the rotation speed Ne is equal to or greater than the over-rotation attention line (yes in step S121), the HV-ECU62 determines whether the brake pedal 72 is operated (step S122). If it is determined that the brake pedal 72 is being operated (yes at step S122), the HV-ECU62 returns the executed process to the process of calling out the source of the over-rotation prevention process.

On the other hand, when it is determined that the rotation speed Ne is not equal to or greater than the over-rotation attention line (no in step S121) and when it is determined that the brake pedal 72 is not operated (no in step S122), the HV-ECU62 ends the fuel cut control started in step S113 (step S123), returns the upper limit rotation speed of the first MG14 and the pinion gear P, which have been decreased in step S114, to the original value (step S124), and returns the feedback gain of the feedback control of the first MG14, which has been increased in step S115, to the original value (step S125). After that, the HV-ECU62 returns the executed process to the process of calling out the source of the over-rotation prevention process.

[ prevention of over-rotation on the negative side of the first MG14 or pinion gear P ]

In the drive system of the vehicle 10 including the planetary gear mechanism 20 as described above, the upper and lower limit rotation speeds are set for the pinion gear P, the first MG14, and the second MG15, depending on hardware requirements. Since the rotation speed of the second MG15 is proportional to the vehicle speed, it can be limited to the upper limit vehicle speed in order to prevent over-rotation. However, the rotation speeds of the first MG14 and the pinion gear P change depending on the rotation speed of the engine 13 and the vehicle speed (the rotation speed of the second MG15) at this time, and therefore sufficient attention is required for the over-rotation.

In particular, when the vehicle speed is high (that is, the number of revolutions of the ring gear R is large), if the engine 13 is stopped, the difference between the number of revolutions of the ring gear R and the carrier C (engine 13) becomes large, and the number of revolutions of the pinion gears P becomes excessive on the negative side.

Then, the HV-ECU62 of the vehicle 10 of the present disclosure controls the engine 13 so as to start the engine 13 when the rotation speed of the engine 13 at which the first MG14 or the pinion gear P has the lower limit rotation speed exceeds 0. Preferably, the engine 13 and the first MG14 are controlled so that the target rotation speed of the engine 13 is equal to or higher than the rotation speed of the engine 13 at which the first MG14 or the pinion gear P has the lower limit rotation speed. Thus, when there is a possibility that the first MG14 or the pinion gear P exceeds the lower limit rotation speed, the engine 13 can be started so that the first MG14 or the pinion gear P does not exceed the lower limit rotation speed.

[ prevention of over-rotation of the first MG14 or the pinion gear P when the vehicle is moving backward ]

In particular, when the engine 13 is generating torque and the second MG15 is rotating negatively (i.e., at a negative vehicle speed) during the backward movement of the vehicle 10, the rotation speed of the first MG14 or the pinion gear P is likely to be high.

Then, the HV-ECU62 of the vehicle 10 of the present disclosure controls the engine 13 so as to forcibly stop the engine 13 when the first MG14 or the pinion gear P at a certain vehicle speed is the rotation speed of the engine 13 at which the rotation speed is excessively high. Thus, when there is a possibility that the first MG14 or the pinion gear P exceeds the upper limit rotation speed, the engine 13 can be stopped so that the first MG14 or the pinion gear P does not exceed the upper limit rotation speed.

If the vehicle speed further increases to the negative side, first MG14 or pinion gear P is over-rotated even when engine 13 is not generating torque.

Then, the HV-ECU62 of the vehicle 10 of the present disclosure controls the engine 13, the first MG14, and the second MG15 so that a driving torque on the positive vehicle speed side is generated at a negative vehicle speed at which it is expected that the first MG14 or the pinion gear P will exceed the upper limit rotation speed when the shift position is detected by the shift position sensor 78 as the reverse gear. This can suppress an increase in vehicle speed to the negative side. As a result, the rotation speed of first MG14 or pinion gear P can be prevented from becoming excessive.

Fig. 11 is a diagram showing a driving force map at the time of reverse before the change. Fig. 12 is a diagram showing the driving force map at the time of reverse after the change. Referring to fig. 11 and 12, in the drive force map, the required torque Tpa in the case where the rotation speed Np of the ring gear R is lowest after the change is a positive value regardless of the accelerator opening degree, as compared to before the change. Thus, when the vehicle speed during reverse increases to such an extent that the rotation speed Np of the ring gear R becomes the minimum, the required torque Tpa becomes a positive value, and a torque in the forward direction of the vehicle 10 is applied to the ring gear R. Thus, the vehicle speed in the reverse direction can be prevented from further increasing.

[ prevention of excess of charging power limit value Win at engine braking ]

In a vehicle other than a hybrid vehicle, the vehicle is decelerated by engine braking with the accelerator off during running. In the vehicle 10 that is a hybrid vehicle as described above, the engine 13, the first MG14, and the second MG15 are also controlled so as to generate a negative driving force with the accelerator off in order to obtain the same operability. In this case, basically, the second MG15 is operated as a generator to generate a torque for decelerating the vehicle 10. At this time, regenerative electric power of the second MG15 is generated and charged in the battery 18.

Therefore, when the regenerative electric power is limited by the charge electric power limit value Win of the battery 18, torque for decelerating the vehicle 10 cannot be generated. The deceleration torque at the accelerator off is not suitable for the situation of the charging power limit value Win, and therefore some countermeasure is required. In order to cope with this, in the vehicle 10 which is a hybrid vehicle, the kinetic energy of the vehicle 10 is consumed by the drag which rotates the engine 13 by the external force without burning the fuel in the engine 13. In this way, in the vehicle 10 that is a hybrid vehicle, both deceleration by engine braking and prevention of exceeding of the charging power limit value Win are achieved.

When charging power limit value Win is small, the rotation speed of engine 13 is increased to increase the energy consumed by the motoring, but there is an upper limit to the rotation speeds of engine 13, first MG14, and pinion gear P. Therefore, there is a limit to the number of revolutions of the engine 13 that can be increased. Further, by increasing the rotation speed of the engine 13, there is a possibility that engine Noise different from normal causes discomfort from the viewpoint of NV (Noise, Vibration).

Then, the HV-ECU62 of the vehicle 10 according to the present disclosure sets the predetermined flag to the activated state when the rotation speed of the engine 13 becomes equal to or higher than the first predetermined rotation speed, and outputs an engine brake increase request to the engine ECU64 when the predetermined flag is in the activated state and the engine brake equal to or higher than the predetermined torque is required. The engine ECU64 controls the VVT mechanism 46 to advance the opening/closing timing of the intake valve in accordance with an engine brake increase request from the HV-ECU 62.

The magnitude of the engine brake (i.e., the energy consumed by the engine 13) is determined by the losses per unit cycle (or per unit revolution) and the rotational speed of the engine 13. Thus, in the case where a large engine brake is required, the loss per cycle is increased or the rotation speed of the engine 13 is increased. However, if the rotation speed of the engine 13 is increased, NV has an influence. In addition, there is an allowable upper limit rotation speed of the engine 13. Therefore, in this embodiment, the VVT mechanism 46 is controlled to advance the opening/closing timing of the intake valve so as to increase the loss per cycle. As a result, the pump loss of the engine 13 increases and the compression work increases as compared with the case where the advance is not made, and the engine brake can be strengthened. As a result, the regenerative electric power of second MG15 (or first MG) can be reduced, and therefore the regenerative electric power can be made less likely to exceed charging electric power limit value Win.

[ prevention of excess of charging power limit value Win at sudden deceleration ]

In the vehicle 10, which is a hybrid vehicle, command values of the outputs of the first MG14, the second MG15, and the engine 13 are determined so as not to exceed the charge electric power limit value Win and the discharge electric power limit value Wout of the battery 18, on the assumption that a part of the output of the engine 13 is converted into electric power by the first MG14 and the electric power is consumed by the second MG 15.

However, if the power consumption in the second MG15 is suddenly reduced by the operation of the TRC (TRaction Control), sudden deceleration, or the like, the charging power to the battery 18 may exceed the charging power limit value Win and become overcharged. Here, the TRC is the following control: when a sensor senses the idling of the drive wheels at the time of starting or accelerating on a slippery road surface, optimal values of the brake hydraulic pressure of each wheel, the target drive force of the vehicle, and the like are automatically set, and the optimal drive force is ensured.

Then, the HV-ECU62 controls the engine 13 so as to forcibly cut off the fuel injected into the engine 13 when a significant overcharge occurs (for example, when the actual charge power exceeds a value obtained by adding the first predetermined power value to the charge power limit value Win). Thereby, the generated electric power of the first MG14 is reduced, and therefore it is possible to make it difficult to exceed the charging electric power limit value Win.

In this case, the HV-ECU62 controls the engine 13 so as to end the forced cutoff of the fuel injected into the engine 13 when the actual charge power becomes lower than the value obtained by adding the second predetermined power value (< the first predetermined power value) to the charge power limit value Win.

Further, the control may be performed as described below. Fig. 13 is a flowchart showing the flow of the Win time processing. This Win excess processing is repeatedly executed by the HV-ECU62 every predetermined cycle.

Referring to fig. 13, HV-ECU62 determines whether or not the actual charging electric power is equal to or greater than the value obtained by adding third predetermined electric power value a to charging electric power limit value Win and less than the value obtained by adding fourth predetermined electric power value B to charging electric power limit value Win (step S131). If it is determined that the actual charging electric power is equal to or greater than the value obtained by adding a to charging electric power limit value Win and smaller than the value obtained by adding B to charging electric power limit value Win (yes at step S131), HV-ECU62 controls engine 13 to be switched to autonomous operation (step S132). Autonomous operation refers to operation of the engine 13 at idle speed. The idle rotation speed is a rotation speed at which the engine 13 can stably continue to rotate because the power generated by itself by the combustion of the fuel exceeds the resistance to rotation such as friction, and is usually adjusted to a minimum rotation speed at which the engine can stably continue to rotate.

When it is determined that the actual charging electric power is not equal to or greater than the value obtained by adding a to charging electric power limit value Win or not less than the value obtained by adding B to charging electric power limit value Win (no at step S131), and after step S132, HV-ECU62 determines whether or not the actual charging electric power is equal to or greater than the value obtained by adding a fourth predetermined electric power value B to charging electric power limit value Win (step S133). When it is determined that the actual charging power is equal to or greater than the value obtained by adding B to the charging power limit value Win (yes in step S133), the HV-ECU62 starts control of the engine 13 in which the fuel injected into the engine 13 is forcibly cut off (step S134).

When determining that the actual charging electric power is not equal to or greater than the value obtained by adding B to charging electric power limit value Win (no in step S133), and after step S134, HV-ECU62 determines whether or not the actual charging electric power is less than the value obtained by adding third predetermined electric power value a to charging electric power limit value Win (step S135). If it is determined that the actual charge power becomes smaller than the value obtained by adding a to the charge power limit value Win (yes in step S135), the HV-ECU62 returns the control of the engine 13 to the control of the autonomous operation after the switch in step S132 or the normal control before the fuel cut control started in step S134 (step S136).

Upon determining that the actual charging electric power does not become smaller than the value obtained by adding a to charging electric power limit value Win (no in step S135), and after step S136, the HV-ECU62 returns the executed process to the process of calling out the source of the process when Win exceeds.

Fig. 14 is a diagram for explaining control based on Win excess time processing. Referring to fig. 14, in the Win excess time process shown in fig. 13, as shown in steps S133 and S134, when the actual charging electric power exceeds a value obtained by adding a fourth predetermined electric power value B to the charging electric power limit value Win, the fuel cut control of the engine 13 is executed. As shown in steps S131 and S132, when the actual charging electric power exceeds the value obtained by adding the third predetermined electric power value a to the charging electric power limit value Win and the actual charging electric power is lower than the value obtained by adding the fourth predetermined electric power value B to the charging electric power limit value Win, control is executed to switch the engine 13 to the autonomous operation. When the actual charging electric power becomes lower than the value obtained by adding the third predetermined electric power value a to the charging electric power limit value Win as shown in steps S135 and S136, the control of the engine 13 is returned to the normal control.

[ modified examples ]

(1) In the above-described embodiment, as shown in steps S111 and S112 of fig. 9, the predetermined condition that the rotation speed of the first MG14 or the pinion gear P is expected to exceed the upper limit rotation speed is set as a condition that the rotation speed Ne of the engine 13 is equal to or more than the over-rotation attention line and the brake pedal 72 is operated.

However, the predetermined condition under which the rotation speed of the first MG14 or the pinion gear P is expected to exceed the upper limit rotation speed may be other conditions as long as the condition under which it is detected that the rotation speed of the first MG14 or the pinion gear P is expected to exceed the upper limit rotation speed.

For example, the predetermined condition may be a condition that the rotation speed Ne of the engine 13 is equal to or higher than the over-rotation attention line and the rotation speed of a predetermined element (for example, the output gear 21, the driven gear 26, the counter shaft 25, the drive gears 27, 31, the ring gear 29, the differential gear 28, the

drive shafts

32, 33, the rotor shaft 30, or the like) between the drive wheels 24 and the planetary gear mechanism 20 is decelerating at an acceleration equal to or higher than a predetermined acceleration. The predetermined acceleration may be the minimum detectable value as long as it indicates the acceleration at which the brake pedal 72 is being operated. The rotation speed of the predetermined element is detected by a rotation speed sensor.

(2) In the above embodiment, the carrier C of the planetary gear mechanism 20 is connected to the engine 13, the sun gear S is connected to the first MG14, and the ring gear R is connected to the drive shaft. However, the present invention is not limited to this, and devices connected to the respective elements of the planetary gear mechanism 20 may be different.

[ conclusion ]

(1) As shown in fig. 1 and 2, the vehicle 10 includes: an engine 13; a first MG 14; a planetary gear mechanism 20 including a first element (for example, a carrier C) connected to an output shaft of the engine 13, a second element (for example, a sun gear S) connected to a rotor shaft 23 of the first MG14, and a third element (for example, a ring gear R) connected to a drive shaft (for example, an output gear 21, a driven gear 26, a counter shaft 25, and the like) that transmits power to the drive wheels 24, and including a specific gear (for example, a pinion gear P); and an HV-ECU62 that controls the engine 13 and the first MG 14. As shown in fig. 9, when the HV-ECU62 determines in steps S111 and S112 that the predetermined condition that the first MG14 or the specific gear is expected to exceed the upper limit rotation speed is satisfied, the HV-ECU62 executes specific control for controlling the engine 13 and the first MG14 so as not to exceed the upper limit rotation speed in steps S113 to S115.

Thus, when it is expected that first MG14 or the specific gear will exceed the upper limit rotation speed, the upper limit rotation speed can be prevented from being exceeded. As a result, first MG14 or the specific gear can be made not to exceed the upper limit rotation speed.

(2) As the specifying control, the HV-ECU62 executes, when the predetermined condition is satisfied, control for reducing the upper limit rotation speed as compared with the case where the predetermined condition is not satisfied, as shown in step S114 in fig. 9.

Thus, when the predetermined condition is satisfied, the upper limit rotation speed is reduced to control the engine 13 and the first MG 14. As a result, first MG14 or the specific gear can be made hard to exceed the upper limit rotation speed.

(3) As shown in fig. 1, the planetary gear mechanism 20 includes a carrier C as a first element, a sun gear S as a second element, a ring gear R as a third element, and a plurality of pinion gears P as specific gears.

Thus, in the vehicle 10 including the planetary gear mechanism 20 including the carrier C, the sun gear S, the ring gear R, and the pinion gears P, the first MG14 or the pinion gears P can be made not to exceed the upper limit rotation speed.

(4) As shown in steps S111 and S112 and the modified example of fig. 9, the predetermined condition is that the rotation speed of the engine 13 exceeds a rotation speed predetermined in accordance with the rotation speed of the drive shaft and the drive shaft is decelerating at an acceleration equal to or higher than a predetermined acceleration.

Thus, when the rotation speed of the engine 13 exceeds the rotation speed predetermined in accordance with the rotation speed of the drive shaft and the drive shaft is decelerating at an acceleration equal to or higher than a predetermined acceleration, the first MG14 or the specific gear can be made not to exceed the upper limit rotation speed.

(5) As shown in fig. 2, the vehicle 10 further includes a brake pedal 72 that operates a brake for braking the drive shaft. As shown in steps S111 and S112 of fig. 9, the predetermined condition is that the rotational speed of the engine 13 exceeds a rotational speed predetermined in accordance with the rotational speed of the drive shaft and the brake pedal 72 is being operated.

Thus, when the rotational speed of the engine 13 exceeds the rotational speed predetermined in accordance with the rotational speed of the drive shaft and the brake pedal 72 is being operated, the first MG14 or the specific gear can be made not to exceed the upper limit rotational speed.

(6) As the specific control, the HV-ECU62 executes, when the predetermined condition is satisfied, control for increasing the feedback gain of the rotation speed control of the first MG14 as compared to when the predetermined condition is not satisfied, as shown in step S115 of fig. 9.

Thus, when the predetermined condition is satisfied, the feedback gain of the rotation speed control of the first MG14 is increased to control the engine 13 and the first MG 14. As a result, first MG14 or the specific gear can be made hard to exceed the upper limit rotation speed.

(7) As the specific control, the HV-ECU62 executes control of stopping the supply of fuel to the engine 13, as shown in step S113 of fig. 9.

Thus, when the predetermined condition is satisfied, the supply of the fuel to the engine 13 is stopped. As a result, first MG14 or the specific gear can be made hard to exceed the upper limit rotation speed.

(8) As shown in fig. 1 and 2, the vehicle 10 further includes a battery 18 capable of storing electric power generated by the first MG14 and supplying the stored electric power to the first MG 14. As shown in fig. 13 and 14, the HV-ECU62 controls the engine 13 and the first MG14 so that the electric power value charged into the battery 18 does not exceed the charging electric power limit value Win, and when it is determined in step S131 that the electric power value charged into the battery 18 is within a range from a value obtained by adding the third predetermined electric power value a to the charging electric power limit value Win to a value obtained by adding the fourth predetermined electric power value B, which is larger than the third predetermined electric power value a, to the charging electric power limit value Win, it is controlled so that the engine 13 is operated at an idle speed in step S132, and when it is determined in step S133 that the electric power value charged into the battery 18 exceeds a value obtained by adding the fourth predetermined electric power value B to the charging electric power limit value Win, the supply of fuel to the engine 13 is stopped in step S134.

This makes it possible to make it difficult for the electric power value charged into the battery 18 to exceed the charging electric power limit value Win.

(9) As shown in fig. 1 and 2, vehicle 10 further includes a second MG15 connected to the drive shaft. As shown in fig. 12, the HV-ECU62 controls the engine 13, the first MG14, and the second MG15 so that a driving torque on the positive vehicle speed side is generated at a negative vehicle speed at which it is expected that the first MG14 or the specific gear will exceed the upper limit rotation speed when the shift position is the reverse position.

Thereby, the first MG14 or the specific gear can be made not to exceed the upper limit rotation speed at the negative vehicle speed.

The embodiments disclosed herein are also intended to be implemented in appropriate combinations.

While the embodiments of the present invention have been described, the embodiments disclosed herein are to be considered in all respects as illustrative and not restrictive. The scope of the present invention is indicated by the claims, and all changes that come within the meaning and range of equivalency of the claims are intended to be embraced therein.

Claims

1. A hybrid vehicle is provided with:

an internal combustion engine;

a first rotating electrical machine;

a planetary gear mechanism including a specific gear, the planetary gear mechanism including a first element connected to an output shaft of the internal combustion engine, a second element connected to a rotating shaft of the first rotating electric machine, and a third element connected to a drive shaft that transmits power to a drive wheel; and

a control device that controls the internal combustion engine and the first rotating electric machine,

the control device executes a specific control for controlling the internal combustion engine and the first rotating electric machine so as not to exceed an upper limit rotation speed, when a predetermined condition that the first rotating electric machine or the specific gear is expected to exceed the upper limit rotation speed is satisfied.

2. The hybrid vehicle according to claim 1,

as the specific control, the control device executes control for reducing the upper limit rotation speed when the predetermined condition is satisfied, as compared with a case where the predetermined condition is not satisfied.

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

the planetary gear mechanism includes a carrier as the first element, a sun gear as the second element, a ring gear as the third element, and a plurality of pinion gears as the specific gear.

4. The hybrid vehicle according to any one of claims 1 to 3,

the predetermined condition is a condition that the rotation speed of the internal combustion engine exceeds a rotation speed predetermined in accordance with the rotation speed of the drive shaft and the drive shaft is decelerating at an acceleration equal to or higher than a predetermined acceleration.

5. The hybrid vehicle according to any one of claims 1 to 4,

further comprises an operation unit for operating a brake device for braking the drive shaft,

the predetermined condition is a condition that the rotation speed of the internal combustion engine exceeds a rotation speed predetermined in correspondence with the rotation speed of the drive shaft and the operation portion is being operated.

6. The hybrid vehicle according to any one of claims 1 to 5,

as the specific control, the control device executes control for increasing a feedback gain in the rotational speed control of the first rotating electric machine when the predetermined condition is satisfied, as compared with a case where the predetermined condition is not satisfied.

7. The hybrid vehicle according to any one of claims 1 to 5,

as the specific control, the control device executes control of stopping supply of fuel to the internal combustion engine.

8. The hybrid vehicle according to any one of claims 1 to 7,

further comprises a power storage device capable of storing electric power generated by the first rotating electric machine and supplying the stored electric power to the first rotating electric machine,

the control device controls the internal combustion engine and the first rotating electric machine with a target that a value of electric power charged to the power storage device does not exceed a charging electric power limit value,

the control device controls the internal combustion engine to operate at an idle rotation speed when the electric power value charged to the power storage device is within a range from a value obtained by adding a first predetermined value to the charging electric power limit value to a value obtained by adding a second predetermined value larger than the first predetermined value to the charging electric power limit value,

the control device stops the supply of fuel to the internal combustion engine when the electric power value charged to the power storage device exceeds a value obtained by adding the second predetermined value to the charging electric power limit value.

9. The hybrid vehicle according to any one of claims 1 to 8,

further comprises a second rotating electric machine connected to the drive shaft,

the control device controls the internal combustion engine, the first rotating electric machine, and the second rotating electric machine so that a drive torque on a positive vehicle speed side is generated at a negative vehicle speed at which it is expected that the first rotating electric machine or the specific gear will exceed the upper limit rotation speed, when the shift position is a reverse shift position.