Controller and control method for hybrid vehicle

Abstract

Controller (200) for a hybrid vehicle, the hybrid vehicle comprising: a power distribution integration mechanism (40) comprising a ring gear (42) configured to work in a toothed manner with a driven gear (62), a sun gear (41) configured to rotate at a center of the ring gear (42), a planetary gear (43) located between the sun gear (41) and the ring gear (42) and configured to orbit the sun gear (41), and a planetary gear carrier (44) configured to rotate while the planetary gear (43) orbits; an internal combustion engine (10) comprising an output shaft (14) coupled to the planetary gear carrier (44); a first motor generator (71) arranged to operate in a toothed manner with the sun gear (41); a second motor generator (72) configured to operate in a toothed manner with the ring gear (42); a battery (77) connected to the first motor generator (71) and the second motor generator (72); and a battery controller (400) configured to calculate a state of charge (SOC) of the battery (77), an upper input limit (Win) of the battery (77), and an upper output limit (Wout) of the battery (77) using a voltage (VB) in the battery (77), a temperature (TB) of the battery (77), and a ratio of electric power in the first and second motor generators (71, 72), wherein the controller (200) comprises: an execution device (200a, 200b) configured to control the first motor generator (71) and the second motor generator (72) such that the electric power input to the battery (77) does not exceed the upper input limit value (Win) and an electric power output from the battery (77) does not exceed the upper output limit value (Wout), wherein the execution device (200a, 200b) is configured: controlling the engine (10) and the first motor generator (71) such that the engine speed (Ne) approaches a target engine speed, the target engine speed being set using a requested driving force; controlling the second motor generator (72) such that the requested driving force is achieved by power transmitted from the ring gear (42) to the driven wheel (62); performing a start to rotate the output shaft (14) using the first motor generator (71) in a state where a combustion operation of the internal combustion engine (10) is stopped, thereby causing a braking force generated by friction of the internal combustion engine (10) to act on the driven wheel (62); and to execute a valve opening limiting process that limits an increase in a throttle opening degree according to the upper input limit value (Win) when an increase request regarding the throttle opening degree is issued that is not based on an operation requesting a change in the braking force performed by the driver during the execution of the cranking.

Description

Background1. Area

[0001] The present invention relates to a controller and a control method for a hybrid vehicle. 2. Description of the state of the art

[0002] JP 2016-164026 A discloses a hybrid vehicle in which a first motor generator, a second motor generator, and an internal combustion engine are interconnected by a power distribution integration mechanism. The first motor generator, the second motor generator, and the internal combustion engine cooperate to adjust the torque transmitted to the driven wheels. In this hybrid vehicle, a battery is charged and discharged depending on the ratio of electric power in the first and second motor generators, that is, depending on the relationship between the electric power generated by one of the motor generators and the electric power consumed by the other motor generator. Regarding the prior art, reference is also made to JP 2010-125936 A, DE 10 2019 109 057 A1, and DE 10 2020 122 021 A1.

[0003] The above-described document discloses that when the accelerator operation is deactivated, the controller for the hybrid vehicle executes a cranking operation to drive an output shaft of the internal combustion engine whose combustion operation is stopped using the first motor generator. Executing the cranking operation causes a braking force generated by engine friction to act on the driven wheels.

[0004] If the throttle opening degree is changed by executing cranking while the engine friction generated by the braking force acts on the driven wheels, the magnitude of the engine friction changes, causing the braking force to change. To limit such a change in braking force, it is necessary to control the braking force generated by the second motor generator so that the sum of the braking force generated by the engine friction and the braking force generated by the second motor generator remains unchanged. However, under some battery conditions, when the second motor generator is used to limit a change in braking force, the input and output of electric power to and from the battery may exceed an allowable range.

[0005] Based on the prior art, the object is therefore to provide a technology that can prevent the problems described above. This object is achieved by the features of the independent claims; advantageous developments are the subject of the subclaims. Summary

[0006] This summary serves to introduce a selection of concepts in a simplified form, which are described in more detail in the detailed description below. This summary is not intended to identify the key features or essential characteristics of the subject matter of the application, nor should it be used as an aid in determining the scope of protection of the subject matter of the application.

[0007] One aspect of the present invention provides a controller for a hybrid vehicle. The hybrid vehicle includes a power distribution integration mechanism including a ring gear configured to mesh with a driven gear, a sun gear configured to rotate at a center of the ring gear, a planetary gear located between the sun gear and the ring gear and configured to orbit the sun gear, and a planetary gear carrier configured to rotate while the planetary gear orbits.The hybrid vehicle also includes an internal combustion engine having an output shaft coupled to the planetary gear carrier, a first motor generator configured to operate in a meshed manner with the sun gear, a second motor generator configured to operate in a meshed manner with the ring gear, and a battery connected to the first motor generator and the second motor generator. The hybrid vehicle further includes a battery controller configured to calculate a state of charge of the battery, an upper input limit of the battery, and an upper output limit of the battery using a voltage in the battery, a temperature of the battery, and a ratio of electrical power in the first and second motor generators.The controller includes an execution device configured to control the first motor generator and the second motor generator such that the electric power input to the battery does not exceed the upper input limit and the electric power output from the battery does not exceed the upper output limit. The execution device is configured to control the engine and the first motor generator such that an engine speed approaches a target engine speed, the target engine speed being set using a requested driving force, and to control the second motor generator such that the requested driving force is achieved by power transmitted from the ring gear to the driven wheel.The execution device is also configured to execute cranking using the first motor generator in a state where a combustion operation of the internal combustion engine is stopped to rotate the output shaft, thereby causing a braking force generated by friction of the internal combustion engine to act on the driven wheel. The execution device is further configured to execute a valve opening limiting process that limits an increase in a throttle opening degree according to the input upper limit value when an increase request for the throttle opening degree is issued that is not based on an operation requesting a change in the braking force performed by a driver during the execution of the cranking.

[0008] Another aspect of the present application provides a control method for a hybrid vehicle. The method includes calculating a battery state of charge, a battery upper input limit, and a battery upper output limit using a voltage in a battery, a battery temperature, and a ratio of electric power in the first and second motor generators; controlling the first motor generator and the second motor generator such that the electric power input to the battery does not exceed the upper input limit and the electric power output from the battery does not exceed the upper output limit; controlling the engine and the first motor generator such that an engine speed approaches a target engine speed, the target engine speed being set using a requested driving force;to control the second motor generator such that the requested driving force is achieved by the power transmitted from the ring gear to the driven wheel, to execute cranking using the first motor generator in a state where an internal combustion engine operation is stopped, to rotate the output shaft, thereby causing a braking force generated by friction of the engine to act on the driven wheel, and to execute a valve opening limiting process that limits an increase in a throttle opening degree according to the upper input limit value once an increase request regarding the throttle opening degree is issued, which is not based on an operation requesting a change in the braking force performed by a driver during the execution of the cranking.

[0009] Other features and aspects will become apparent from the following detailed description, drawings and claims. Short description of the drawing Fig. 1 is a schematic diagram showing the configuration of a hybrid vehicle including a hybrid ECU according to an embodiment. Fig. 2 is a graph showing a relationship between the vehicle speed of each virtual shift position and the engine speed. Fig. 3 is a diagram showing the selector device connected to the shift ECU. Fig. Figure 4 is a nomogram showing engine braking in the hybrid vehicle. Fig. Figure 5 is a graph showing the relationship between engine speed and engine friction torque. Fig. 6 is a nomogram showing an increase in the charge amount when the throttle opening degree is increased during low-speed rotation. Fig. Figure 7 is a nomogram showing an increase in the discharge amount when the throttle opening degree is increased during high-speed rotation. Fig. 8 is a flowchart illustrating a series of processes executed when an increase request for the throttle opening degree is issued in a state where engine braking is applied by performing cranking. Fig. 9 is a flowchart showing a series of processes executed by the hybrid ECU according to a modification.

[0010] In the drawing and the detailed description, like reference numerals refer to the same elements. The drawing may not be to scale, and the relative size, proportions, and representation of elements in the drawing may be exaggerated for clarity, illustration, and simplicity. Detailed description

[0011] A controller and a control method for a hybrid vehicle according to an embodiment will now be described with reference to the Fig. 1 to 8 described.

[0012] Fig. 1 shows schematically the configuration of the hybrid vehicle. As in Fig. 1, the hybrid vehicle includes an internal combustion engine 10, a power distribution integration mechanism 40 connected to a crankshaft 14 serving as an output shaft of the internal combustion engine 10, and first and second motor generators 71, 72 connected to the power distribution integration mechanism 40. The hybrid vehicle further includes a transmission 90 providing four shift positions, each of the shift positions having a different gear ratio.

[0013] The power distribution integration mechanism 40 is a planetary gear mechanism including a sun gear 41, which is an externally toothed gear, and a ring gear 42, which is an internally toothed gear. The sun gear 41 is located at the center of the ring gear 42. Planetary gears 43, which mesh with the sun gear 41 and the ring gear 42, are arranged between the sun gear 41 and the ring gear 42. The planetary gears 43 are supported by a planetary gear carrier 44 such that the planetary gears 43 can rotate and orbit the sun gear 41. The first motor generator 71 is coupled to the sun gear 41. That is, the first motor generator 71 operates in a meshed manner with the sun gear 41.

[0014] The crankshaft 14 is coupled to the planetary gear carrier 44. A ring gear shaft 45 and the second motor generator 72 are connected to the ring gear 42. Thus, the second motor generator 72, which is coupled to the ring gear 42, operates in a toothed manner with the ring gear 42. The ring gear shaft 45 is connected to an input shaft of the transmission 90.

[0015] The transmission 90 is a planetary gear-type stepped transmission. The transmission 90 creates four shift positions, from a first gear having the largest gear ratio to a fourth gear having the smallest gear ratio, by selectively engaging engagement devices. The output shaft of the transmission 90 is coupled to driven wheels 62 via a differential 61. The transmission 90 enters a neutral state in which no shift position is established (i.e., a state in which power transmission is blocked) by disengaging all engagement devices.

[0016] The first motor generator 71 exchanges electrical power with a battery 77 via a first inverter 75. The second motor generator 72 exchanges electrical power with the battery 77 via a second inverter 76.

[0017] When the torque from the engine 10 is input to the planetary gear carrier 44 of the power distribution integration mechanism 40, the torque is distributed to the sun gear 41 and the ring gear 42. Rotating the first motor generator 71 by the torque distributed to the sun gear 41 allows the first motor generator 71 to function as a generator.

[0018] In the case where the first motor generator 71 is caused to function as an electric motor, the torque from the first motor generator 71 is input to the first sun gear 41. The torque of the first motor generator 71 input to the first sun gear 41 is distributed to the planetary gear carrier 44 and the first ring gear 42. Then, when the torque of the first motor generator 71 is input to the crankshaft 14 via the planetary gear carrier 44, the crankshaft 14 is rotated. Rotating the crankshaft 14 by causing the first motor generator 71 to function as an electric motor in this manner is called cranking.

[0019] The torque of the internal combustion engine 10, which is distributed to the ring gear 42, and the torque of the first motor generator 71 are input to the driven wheels 62 via the ring gear shaft 45, the transmission 90 and the differential 61.

[0020] When the hybrid vehicle is decelerated, causing the second motor generator 72 to function as a generator causes regenerative braking force corresponding to the power generation amount of the second motor generator 72 to be generated in the hybrid vehicle. Causing the second motor generator 72 to function as an electric motor causes the output torque of the second motor generator 72 to be input to the driven wheels 62 via the ring gear shaft 45, the transmission 90, and the differential 61.

[0021] The power of the engine 10 is input to the transmission 90 via the power distribution integration mechanism 40. Further, after an engine speed Ne is changed by the transmission 90 and reduced by the differential 61, the power of the engine 10 is supplied to the driven wheels 62. A rotational speed Nr of the ring gear 42 is reduced by the deceleration ratio obtained by multiplying a deceleration ratio of the differential 61 and a gear ratio corresponding to the shift position established in the transmission 90. The rotational speeds of the driven wheels 62 are reduced in this way.

[0022] Controlling the first motor generator 71 and the second motor generator 72 allows the rotational speed Nr of the ring gear 42 to be differentiated independently of the engine rotational speed Ne. That is, the deceleration ratio between the engine rotational speed Ne and the rotational speed Nr of the ring gear 42 can be continuously changed. Thus, in the hybrid vehicle, the overall deceleration ratio (the ratio between the engine rotational speed Ne and the rotational speeds of the driven wheels 62) can be continuously changed.

[0023] In the hybrid vehicle, the engine speed Ne is controlled by the cranking performed by the first motor generator 71. Specifically, in the same way as when the deceleration ratio between the engine speed Ne and the rotational speed Nr of the ring gear 42 is a fixed value, a gear-changing behavior like that of a vehicle with a stepped transmission is achieved by changing the engine speed Ne. That is, in the same way as when the total deceleration ratio from the engine 10 to the driven wheels 62 is determined for each shift position, the engine speed Ne can be changed in proportion to a vehicle speed SP.

[0024] Fig. 2 shows ten virtual shift positions from a first gear to a tenth gear in the hybrid vehicle. The ten virtual shift positions are achieved by combining four shift positions in the transmission 90 and deceleration ratio switching performed by controlling the engine speed Ne by the first motor generator 71.

[0025] Specifically, the first motor generator 71 controls the engine speed Ne such that a first gear of the transmission 90 is divided into three virtual shift positions from the first gear to the third gear. Further, the first motor generator 71 controls the engine speed Ne such that a second gear of the transmission 90 is divided into three virtual shift positions from the fourth gear to the sixth gear. Further, the first motor generator 71 controls the engine speed Ne such that a third gear of the transmission 90 is divided into three virtual shift positions from the seventh gear to the ninth gear. Then, a fourth gear of the transmission 90 establishes a tenth gear in the virtual shift position.

[0026] As in Fig. 1, an intake passage 15 of the internal combustion engine 10 is formed with a throttle valve 16 that adjusts the flow rate of intake air flowing through the intake passage 15. The exhaust gas produced by the combustion of a fuel-air mixture in the combustion chamber of the internal combustion engine 10 is discharged to an exhaust passage 21. The exhaust passage 21 includes a three-way catalyst 22. On the downstream side of the three-way catalyst 22 in the exhaust passage 21, a filter 23 is formed to trap particulates contained in exhaust gas. On the downstream side of the filter 23 in the exhaust passage 21, a downstream catalyst 24 is formed. The downstream catalyst 24 is similar to the three-way catalyst 22.

[0027] The internal combustion engine 10 is controlled by an engine ECU 100. An air flow sensor 81 that detects an intake air amount GA, a water temperature sensor 82 that detects a coolant temperature THW, which is a temperature of coolant in the internal combustion engine 10, and a crank angle sensor 85 that detects the rotation angle of the crankshaft 14 are connected to the engine ECU 100. The engine ECU 100 receives output signals from these sensors. Furthermore, a first air-fuel ratio sensor 83 and a second air-fuel ratio sensor 84 are connected to the engine ECU 100. The first air-fuel ratio sensor 83 is arranged in the exhaust passage 21 on the upstream side of the three-way catalyst 22 to output a signal corresponding to the oxygen concentration of exhaust gas.The second air-fuel ratio sensor 84 is arranged in the exhaust passage 21 between the three-way catalyst 22 and the filter 23 to output a signal corresponding to the oxygen concentration of exhaust gas. The engine ECU 100 also receives output signals from these air-fuel ratio sensors. The signal output from the first air-fuel ratio sensor 83 is used to detect an upstream air-fuel ratio Afu, which is the air-fuel ratio of the exhaust gas on the upstream side of the three-way catalyst 22. Further, the signal output from the second air-fuel ratio sensor 84 is used to detect a downstream air-fuel ratio Afd, which is the air-fuel ratio of the exhaust gas on the downstream side of the three-way catalyst 22. A temperature sensor 89 is connected to the engine ECU 100.The temperature sensor 89 is arranged in the exhaust pipe 21 between the three-way catalyst 22 and the filter 23 to detect a catalyst outlet gas temperature THe, which is the temperature of exhaust gas after passing through the three-way catalyst 22.

[0028] The engine ECU 100 calculates the engine speed Ne using an output signal Scr of the crank angle sensor 38. The engine ECU 100 uses the catalyst outlet gas temperature THe and various engine operating conditions, such as an intake air amount GA and the engine speed Ne, to calculate a catalyst temperature Tsc, which is the temperature of the three-way catalyst 22, and a filter temperature Tf, which is the temperature of the filter 23. Further, the engine ECU 100 uses, for example, the engine speed Ne, the intake air amount GA, and the filter temperature Tf, to calculate a PM deposition amount Ps, which is the amount of particulate matter deposited in the filter 23.

[0029] In addition to the engine ECU 100, which performs various types of controls for the engine 10 as described above, the hybrid vehicle includes an electric motor ECU 300 and a hybrid ECU 200. The electric motor ECU 300 performs various types of controls for the first motor generator 71 and the second motor generator 72. The hybrid ECU 200 centrally controls various ECUs including the engine ECU 100 and the electric motor ECU 300. The hybrid ECU 200 is the controller for the hybrid vehicle.

[0030] The hybrid ECU 200 is a microprocessor including a CPU 200a. In addition to the CPU 200a, the hybrid ECU 200 includes a ROM 200b that stores a program and a RAM 200c that temporarily stores data. In the hybrid ECU 200, the CPU 200a reads and executes the program stored in the ROM 200b, thereby performing various types of control. That is, in the hybrid ECU 200, the CPU 200a and the ROM 200b correspond to an execution device. An accelerator position sensor 86 and a brake position sensor 80 are connected to the hybrid ECU 200. The accelerator position sensor 86 detects an accelerator operation amount Acc, which is the amount for the accelerator pedal depressed by a driver. The brake position sensor 80 detects a brake position Bp, which is the depression amount of the brake pedal. Further, a vehicle speed sensor 87 and a power switch 88 are connected to the hybrid ECU 200.The vehicle speed sensor 87 detects the vehicle speed SP, which is the traveling speed of the hybrid vehicle. The hybrid ECU 200 receives output signals from these sensors and the switch. The power switch 88 is used to activate the hybrid vehicle system. When the power switch 88 is turned on, the hybrid vehicle enters a drivable state.

[0031] The hybrid vehicle also includes a battery ECU 400 that monitors the condition of the battery 77 and a shift ECU 500 that controls the transmission 90. The engine ECU 100, the electric motor ECU 300, the battery ECU 400, and the shift ECU 500 are communicatively connected to the hybrid ECU 200.

[0032] The battery ECU 400, which serves as a battery controller, is connected to the battery 77. The battery ECU 400 monitors a current IB in the battery 77, a voltage VB in the battery 77, and a temperature TB of the battery 77. The battery ECU 400 uses the current IB, the voltage VB, and the temperature TB to calculate the state of charge SOC of the battery 77 and to calculate an upper input limit value Win and an upper output limit value Wout of the battery 77.

[0033] Specifically, the battery ECU 400 calculates the state of charge SOC using an integration value of the current IB. The battery ECU 400 uses the calculated state of charge SOC and the temperature TB to calculate the input upper limit value Win, which is a maximum allowable electric power with which the battery 77 can be charged, and the output upper limit value Wout, which is the maximum allowable electric power that can be discharged from the battery 77. The input upper limit value Win is represented by 0 or a negative value. As the absolute value of the input upper limit value Win increases, it is allowable to charge a larger amount of electric power into the battery 77. The output upper limit value Wout is represented by 0 or a positive value. As the absolute value of the output upper limit value Wout increases, it is allowable to output a larger amount of electric power from the battery 77.

[0034] In the hybrid vehicle, the electric power generated by one of the motor generators can be consumed by the other motor generator. Thus, the battery 77 is charged or discharged when the electric power generated by one of the motor generators is excess or insufficient compared to the electric power consumed by the other motor generator. If the electric power ratio in the first motor generator 71 and the second motor generator 72 is balanced, the battery 77 is not charged or discharged. The electric power ratio in the first and second motor generators refers to the relationship between the electric power generated by one of the motor generators and the electric power consumed by the other motor generator.When the electric power ratio of the first motor generator 71 and the second motor generator 72 is balanced, it means that the electric power generated by one of the motor generators is substantially equal to the electric power consumed by the other motor generator. The electric power ratio of the first and second motor generators 71, 72 affects the current IB, the voltage VB, and the temperature TB of the battery 77. Thus, the electric power ratio of the first and second motor generators 71, 72 is also a parameter used to calculate the upper input limit Win and the upper output limit Wout.

[0035] The electric motor ECU 300 is connected to the first inverter 75 and the second inverter 76. The electric motor ECU 300 controls the amount of electric power supplied from the battery 77 to the first motor generator 71 and the second motor generator 72, and the amount of electric power supplied from the first motor generator 71 and the second motor generator 72 to the battery 77 (i.e., charge amount).

[0036] A selector 95 is connected to the shift ECU 500. When the selector 95 is operated by the driver, it outputs a signal requesting a change in the shift range. In the hybrid vehicle, when the selector 95 is operated, a signal output from the selector 95 is transmitted through the selector 95 to the hybrid ECU 200. Further, the shift ECU 500 operates the transmission 90 using a signal output from the selector 95 and a signal output from the hybrid ECU 200. Thus, the hybrid vehicle includes a shift-by-wire system that operates the transmission 90 by converting an operating input to the selector 95 into an electrical signal and transmitting the electrical signal to the hybrid ECU 200.

[0037] As in Fig. As shown in Figure 3, the selector device 95 includes a shift lever 96 operated by the driver, and an upshift paddle 51 and a downshift paddle 52 arranged on a steering wheel 50. The shift lever 96 is operated in conjunction with a shift gate 97. Shift positions, each associated with different shift ranges, are set for the shift gate 97.

[0038] In particular, as in Fig. 3, a P position corresponding to a parking range, an R position corresponding to a reverse range, an N position corresponding to a neutral range, a D position corresponding to a drive range, and an M position corresponding to a manual range are set for the shift gate 97. In Fig. 3 the dashed line shows the shift lever 96 in the N position.

[0039] The selector 95 outputs a signal corresponding to the position of the shift lever 96 to the shift ECU 500. When the shift lever 96 is operated to the D position, the selector 95 issues a request to the shift ECU 500 to change the shift range to the drive range. The drive range is a shift range selected to propel the hybrid vehicle. When the shift range is the drive range, the hybrid ECU 200 controls the engine 10, the first motor generator 71, the second motor generator 72, and the transmission 90 so that the driving force acting in the propelling direction of the hybrid vehicle is transmitted to the driven wheels 62. When the shift range is the drive range, the hybrid ECU 200 sets the control mode of the hybrid vehicle to an automatic transmission mode.In the automatic transmission mode, continuous speed-changing control is performed that continuously changes the overall deceleration ratio to control the engine 10, the first motor generator 71, the second motor generator 72, and the transmission 90 so as to utilize fuel and power with optimum efficiency.

[0040] When the shift lever 96 is moved to the M position, the selector 95 outputs a request to the shift ECU 500 to change the shift range to the manual range. The manual range is a shift range selected to propel the hybrid vehicle. Accordingly, when the shift range is the manual range, the hybrid ECU 200 controls the engine 10, the first motor generator 71, the second motor generator 72, and the transmission 90 so that the driving force acting in the propelling direction of the hybrid vehicle is transmitted to the driven wheels 62. When the shift range is the manual range, the hybrid ECU 200 sets the control mode of the hybrid vehicle to a manual transmission mode.

[0041] As in Fig. 3, a plus position and a minus position are arranged at the front and rear of the M position, respectively. The shift lever 96 is operated to the plus position to request an upshift. The shift lever 96 is operated to the minus position to request a downshift. The M position is a neutral position located midway between the plus position and the minus position. When an operating force at the plus position or the minus position is released, the shift lever 96 returns to the M position.

[0042] When the shift lever 96 is moved from the M position to the plus position or the minus position, the virtual shift position is shifted up or down by the hybrid ECU 200. Specifically, whenever the shift lever 96 is moved to the plus position, the virtual shift position is shifted up by one. Whenever the shift lever 96 is moved to the minus position, the virtual shift position is shifted down by one.

[0043] As in Fig. 3, the steering wheel 50 includes the upshift paddle 51 and the downshift paddle 52. In the hybrid vehicle, the upshift paddle 51 and the downshift paddle 52 are also part of the selector 95. Thus, the virtual shift position can also be changed by operating the upshift paddle 51 or the downshift paddle 52. Specifically, when the control mode is set to the manual transmission mode by operating the shift lever 96 to the M position, the virtual shift position is shifted up by one whenever the upshift paddle 51 is pulled. The virtual shift position is shifted down by one whenever the downshift paddle 52 is pulled.

[0044] Thus, in the manual transmission mode, the virtual shift position is changed by the driver performing a virtual shift position change operation. That is, in the manual transmission mode, the overall deceleration ratio corresponding to the selected virtual shift position is maintained. Furthermore, according to Fig. 2, a shift position fixing control is executed to change the engine speed Ne according to the vehicle speed SP at a rate of change corresponding to the virtual shift position. That is, the CPU 200a of the hybrid ECU 200 executes the shift position fixing control in the manual transmission mode.

[0045] The virtual shift position is changed by the hybrid ECU 200 with reference to a command from the shift ECU 500 to change the virtual shift position. As described above, in the hybrid vehicle, four shift positions in the transmission 90 are divided into ten virtual shift positions by controlling the first motor generator 71. Thus, when the virtual shift position is changed, the shift position can also be changed by the shift ECU 500 that operates the transmission 90.

[0046] When the shift lever 96 is operated to the R position, the selector 95 outputs a request to the shift ECU 500 to change the shift range to the reverse range. The reverse range is a shift range in which the driving force generated by the engine 10 is transmitted to the driven wheels 62 as driving force acting in a direction in which the hybrid vehicle moves backward. When the shift range is the reverse range, the hybrid ECU 200 controls the second motor generator 72 and the transmission 90 such that the driving force acting in the reverse movement direction of the hybrid vehicle is transmitted to the driven wheels 62. Consequently, the torque of the second motor generator 72 causes the hybrid vehicle to move backward.

[0047] When the shift lever 96 is operated to the N position, the selector 95 outputs a request to the shift ECU 500 to change the shift range to the neutral range. The neutral range is a shift range selected for towing the hybrid vehicle or causing the hybrid vehicle to coast. The neutral range is a shift range for blocking the transmission of driving power between the engine 10 and the driven wheels 62. When the shift range is in the neutral range, the hybrid ECU 200 controls the transmission 90 via the shift ECU 500 such that the driving power generated by the engine 10 is not transmitted to the driven wheels 62. Specifically, the shift ECU 500 outputs a command to the transmission 90 to release all engagement devices of the transmission 90.to disengage the clutch and block the transmission of the drive force through the transmission 90 such that the drive force of the internal combustion engine 10 is not transmitted to the driven wheels 62. That is, the neutral range is a non-driven range that prevents the drive force of the internal combustion engine 10 from being transmitted to the driven wheels 62.

[0048] When the shift lever 96 is moved to the P position, the selector 95 outputs a request to the shift ECU 500 to change the shift range to the parking range. The parking range is a shift range selected to keep the hybrid vehicle stopped after parking. When the shift range is the parking range, the hybrid ECU 200 disengages all engagement devices of the transmission 90 in the same manner as in the neutral range and blocks the transmission of drive power through the transmission 90. Further, in the parking range, the hybrid ECU 200 activates a parking lock, which limits the rotation of the output shaft of the transmission 90, thereby keeping the hybrid vehicle stopped.

[0049] As described above, the engine ECU 100, the electric motor ECU 300, the battery ECU 400, and the shift ECU 500 are communicatively connected to the hybrid ECU 200. The hybrid ECU 200 receives information regarding the selected virtual shift position and the shift position in the transmission 90 from the shift ECU 500. The hybrid ECU 200 receives the state of charge SOC, the input upper limit value Win, and the output upper limit value Wout of the battery 77 from the battery ECU 400. The engine ECU 100 controls the engine 10 with a control signal from the hybrid ECU 200 and transmits signals from various sensors and data indicative of the operating state of the engine 10 to the hybrid ECU 200.

[0050] The hybrid ECU 200 uses the accelerator operation amount Acc and the vehicle speed SP to calculate a requested driving force required for the hybrid vehicle. The hybrid ECU 200 uses the state of charge SOC to calculate the total power in consideration of the power required to generate electric power. Using the total power, the hybrid ECU 200 controls the engine 10, the first motor generator 71, and the second motor generator 72 so as to obtain the required driving force and achieve a requested charging power. To prevent the battery 77 from deteriorating, the CPU 200a of the hybrid ECU 200 controls the first motor generator 71 and the second motor generator 72 within a range where the input and output of the battery 77 are not greater than the upper input limit value Win and the upper output limit value Wout.

[0051] The CPU 200a controls the engine 10 and the first motor generator 71 such that the engine speed Ne approaches a target engine speed set using the requested driving force. Furthermore, the CPU 200a controls the second motor generator 72 such that the requested driving force is achieved by the power transmitted from the ring gear 42 of the power distribution integration mechanism 40 to the driven wheels 62.

[0052] In the internal combustion engine 10, the requested driving force when the accelerator operation is deactivated may be a negative value, and the combustion of a fuel-air mixture in the cylinders may be suspended by the rotation of the crankshaft 14. The period during which the combustion of a fuel-air mixture in the cylinders is suspended during the rotation of the crankshaft 14 is referred to as the combustion suspended period. In contrast to the combustion suspended period during which the combustion of a fuel-air mixture in the cylinders is suspended, the period during which a fuel-air mixture is combusted in the cylinders is referred to as the combustion operation period.

[0053] When the shift range is the drive range and the requested driving force is a negative value due to the disabling of the accelerator operation, the hybrid ECU 200 causes the second motor generator 72 to perform regenerative braking in a state where the combustion operation of the engine 10 is stopped. In this case, a rotation speed Nm1 of the first motor generator 71 and the engine rotation speed Ne are zero, and braking torque that generates electric power is produced by the second motor generator 72. The hybrid ECU 200 controls the second motor generator 72 via the electric motor ECU 300 to produce a braking force corresponding to the requested driving force.

[0054] As described above, when the shift range is the manual range, the hybrid ECU 200 controls the first motor generator 71 so that the engine speed Ne changes according to the vehicle speed SP. Thus, the hybrid ECU 200 drives the crankshaft 14 using the first motor generator 71 via the motor ECU 300, thereby performing cranking. In order to rotate the crankshaft 14 of the engine 10 in which the combustion operation is not performed, the crankshaft 14 must be rotated against the friction of the engine 10. To perform cranking, the torque generated by the friction of the engine 10 acts on the ring gear shaft 45. Then, the torque generated by the friction produces a braking force in the ring gear shaft 45. That is, when cranking is performed, engine braking is performed.Changing the virtual shift position changes the magnitude of the braking force produced by engine braking.

[0055] That is, as indicated by the dashed arrows in Fig. As shown in Figure 2, at the same vehicle speed SP, the engine speed Ne is higher in sixth gear than in fifth gear, and higher in fifth gear than in fourth gear. In other words, as the virtual shift position decreases, the engine speed Ne increases. Therefore, as the selected virtual shift position decreases, the engine speed Ne increases, thereby increasing the torque generated by friction and increasing the braking force generated by engine braking.

[0056] Fig. 4 is a nomogram showing the relationship between the rotational speeds in each rotating element of the power distribution integration mechanism 40 when engine braking is applied in this manner. Fig. 4, the S-axis on the left side represents the rotational speed of the sun gear 41 (the rotational speed Nm1 of the first motor generator 71), the C-axis represents the rotational speed of the planetary gear carrier 44 (the engine rotational speed Ne), and the R-axis represents a rotational speed Nm2 of the second motor generator 72 (the rotational speed Nr of the ring gear 42).

[0057] When cranking is performed so that the crankshaft 14 is rotated by the first motor generator 71, a negative torque produced by the friction of the internal combustion engine 10 acts on the crankshaft 14, as indicated by the open arrow pointing downward on the C-axis in Fig. 4. As indicated by the empty arrow pointing downwards on the R-axis in Fig. 4, the torque generated by the frictional forces causes a negative torque to act on the ring gear shaft 45. Since the ring gear shaft 45 is connected to the driven wheels 62 via the transmission 90 and the differential 61, the negative torque acting on the ring gear shaft 45 acts on the driven wheels 62 as a braking force produced by engine braking.

[0058] If the virtual shift position is changed to a lower one, the rotational speed Nm1 of the first motor generator 71 increases until the engine rotational speed Ne takes a value corresponding to the changed virtual shift position, as shown by the dashed arrow in Fig. 4. Consequently, the engine speed Ne increases as shown by the dashed line in Fig. 4, and the magnitude of the torque produced by the friction of the internal combustion engine 10 increases, as shown by the open, downward arrow on the C-axis. This increases the magnitude of the negative torque acting on the ring gear shaft 45, as shown by the open, dashed arrow on the R-axis, thereby increasing the braking force generated by engine braking. Thus, the magnitude of the braking force in the manual range during a fuel cut produced by disabling the accelerator application can be selectively changed by changing the virtual shift position.

[0059] During the combustion-suspended period, the piston in each cylinder of the internal combustion engine 10 reciprocates in synchronization with the rotation of the crankshaft 14. Thus, the air drawn into each cylinder through the intake pipe 15 is expelled to the exhaust pipe 21 without being burned.

[0060] During the combustion stop period, in addition to a fuel cut that stops fuel supply, a fuel suction process may be performed to inject fuel, expel the fuel from each cylinder without burning the fuel, and suck the fuel into the three-way catalyst 22.

[0061] When the fuel intake process is performed, the fuel flows with air through the exhaust pipe 21 and is then sucked into the three-way catalyst 22. If the temperature of the three-way catalyst 22 is greater than or equal to an activation temperature and a sufficient amount of oxygen is present in the three-way catalyst 22 to combust the fuel, the fuel combusts in the three-way catalyst 22. As the fuel combusts in the three-way catalyst 22, the temperature of the three-way catalyst 22 rises, so that a high-temperature gas flows into the filter 23, thereby increasing the temperature of the filter 23. When the temperature of the filter 23 becomes equal to or greater than the ignition point temperature of particulates in a state where oxygen is supplied to the filter 23, the particulates trapped in the filter 23 are burned and eliminated, thereby regenerating the filter 23.

[0062] Thus, during a fuel cut-off, while executing a filter regeneration process that regenerates the filter 23, the hybrid ECU 200 performs a cranking operation with the throttle valve 16 open, so that oxygen continues to be supplied to the filter 23 even during the fuel cut-off. Continued supply of oxygen in this manner causes particulate matter to continue to combust even during the fuel cut-off, and quickly completes the filter regeneration.

[0063] Opening the throttle valve 16 during cranking changes the magnitude of a negative torque produced by the friction of the engine 10. In the hybrid vehicle, the friction of the engine 10 produces a negative torque in a state where cranking is performed. Fig. Figure 5 shows the relationship between the magnitude of such negative torque and the engine speed Ne. This relationship was obtained from the result of an experiment in which a measurement was performed with a changed throttle opening degree. In the following description, the torque acting on the crankshaft 14 due to the friction of the engine 10 is referred to as engine friction torque, and the braking torque acting on the ring gear shaft 45 due to the engine friction torque is referred to as engine braking torque.

[0064] In Fig. 5, the rectangular symbols indicate the result of the measurement taken with the throttle valve 16 closed. The triangular symbols indicate the result of the measurement taken in a state where the throttle valve 16 is inadvertently opened as a result of the flow of intake air produced by cranking rather than by driving the throttle valve 16 (i.e., the same state as when engine braking is applied in the manual range). The circular symbols indicate the result of the measurement taken with the throttle valve 16 fully open. Fig. 5 shows the absolute value of the motor friction torque, which is a negative value. This means that the motor friction torque increases, as well as the positions of the symbols in Fig. 5 higher.

[0065] As in Fig. 5, all measurement results show that the absolute value of the engine braking torque (i.e., the magnitude of the engine braking torque) increases as the engine speed Ne increases. As shown in Fig. However, as shown in Figure 5, the solid line connecting the triangular symbols showing the result of the case where the throttle valve 16 opens unintentionally and the solid line connecting the circular symbols showing the result of the case where the throttle valve 16 is fully open intersect at a certain point. This indicates that the direction in which the engine friction torque changes when the throttle valve 16 is opened reverses at a certain rotational speed Nth, which is a value of the engine rotational speed Ne at the intersection point of the solid lines.

[0066] In particular, Fig. 5 the solid line connecting the triangular symbols indicating the result of the case where the throttle valve 16 opens unintentionally, above the solid line connecting the circular symbols showing the result of the case where the throttle valve 16 is fully opened when the engine speed Ne is less than the predetermined speed Nth. That is, the graph in Fig. 5 shows that when the engine speed Ne is lower than the predetermined speed Nth, the engine friction torque is reduced by opening the throttle valve 16.

[0067] In Fig. 5, the solid line connecting the triangular symbols indicating the result of the case where the throttle valve 16 opens unintentionally is located below the solid line connecting the circular symbols indicating the result of the case where the throttle valve 16 is fully opened when the engine speed Ne is greater than the predetermined speed Nth. That is, the graph in Fig. 5 shows that when the engine speed Ne is greater than the predetermined speed Nth, the engine friction torque is increased by opening the throttle valve 16.

[0068] When performing the filter regeneration process as described above is requested, the opening of the throttle valve 16 may be requested during cranking to issue an increase request for the throttle opening degree. Changes in the braking force due to such an increase request for the throttle opening degree must be limited when applying the braking force produced by the engine friction torque to the driven wheels 62 by manipulating the engine speed Ne to obtain the overall deceleration ratio corresponding to the virtual shift position selected by the driver with the manual range selected.That is, such an increase in the throttle opening degree request is not based on the operation for requesting a change in the braking force performed by the driver, such as a virtual shift position change operation, an accelerator operation, or a brake operation performed by the driver. Therefore, the driver is annoyed when the braking force changes according to such an increase in the throttle opening degree request.

[0069] To limit such a change in braking force, the CPU 200a of the hybrid ECU 200 operates the first motor generator 71 to limit a change in the engine speed Ne caused by a change in the engine friction torque, and increases or decreases the regenerative braking torque by the second motor generator 72 to limit a change in braking force.

[0070] With reference to Fig. 6 and Fig. 7 the control for limiting a change in the braking force is now described in detail. Fig. 6 is a nomogram showing the control performed when the engine speed Ne is lower than the predetermined speed Nth and the engine friction torque decreases while the throttle valve 16 opens. Fig. 7 is a nomogram illustrating the control performed when the engine speed Ne is greater than the predetermined speed Nth and the engine friction torque increases while the throttle valve 16 opens.

[0071] In the Fig. 6 and Fig. 7, the shaded arrow pointing downwards at the R-axis represents a total braking torque acting on the ring gear shaft 45. The total braking torque is the sum of the motor braking torque acting on the ring gear shaft 45 and the regenerative braking torque generated by the second motor generator 72. In the Fig. 6 and Fig. 7, the torque produced before the throttle valve 16 opens is shown by the solid line blank arrow, and the torque produced after the throttle valve 16 opens is shown by the dashed line blank arrow.

[0072] As in Fig. 6, when the throttle valve 16 opens, the engine friction torque decreases as shown on the C-axis in the case where the engine speed Ne is low. In order to limit a change in the engine speed Ne, the CPU 200a of the hybrid ECU 200 outputs a signal to the motor ECU 300 that decreases a positive torque (i.e., a drive torque) in the first motor generator 71 by an amount corresponding to a decrease in the engine friction torque, as shown on the S-axis. Further, as the engine friction torque decreases, the engine braking torque decreases as shown on the R-axis. Thus, the CPU 200a of the hybrid ECU 200 outputs a signal to the motor ECU 300 that increases a negative torque (i.e., a regenerative braking torque) in the second motor generator 72 by an amount corresponding to a decrease in the engine braking torque.

[0073] As in Fig. As shown in Figure 7, when the throttle valve 16 opens, the engine friction torque increases as shown on the C-axis in the case where the engine speed Ne is high. In order to limit a change in the engine speed Ne, the CPU 200a of the hybrid ECU 200 outputs a signal to the motor ECU 300 that increases the drive torque in the first motor generator 71 by an amount corresponding to an increase in the engine friction torque, as shown on the S-axis. Furthermore, the engine braking torque increases as shown on the R-axis as the engine friction torque increases. Therefore, the CPU 200a of the hybrid ECU 200 outputs a signal to the motor ECU 300 that decreases the regenerative braking torque in the second motor generator 72 by an amount corresponding to an increase in the engine braking torque.

[0074] The first motor generator 71 and the second motor generator 72 are controlled as described above. In this control, limiting changes in the engine speed Ne and the braking force changes the electric power ratio in the first and second motor generators 71, 72 and changes the manner of inputting and outputting electric power to and from the battery 77.

[0075] In particular, as in Fig. As shown in Figure 6, when the motor friction torque decreases, the positive torque in the first motor generator 71 increases, whereas the negative torque in the second motor generator 72 decreases. Thus, the input and output of electric power in the battery 77 change such that the output from the battery 77 increases and the input to the battery 77 decreases.

[0076] If, however, as in Fig. As shown in Figure 7, the motor friction torque increases, the positive torque in the first motor generator 71 is decreased, whereas the negative torque in the second motor generator 72 is increased. Thus, the input and output of electric power in the battery 77 change such that the output from the battery 77 decreases and the input to the battery 77 increases.

[0077] As described above, the CPU 200a of the hybrid ECU 200 controls the first motor generator 71 and the second motor generator 72 in the range where the input and output of the battery 77 are not greater than the upper input limit value Win and the upper output limit value Wout. Accordingly, in some magnitudes of the upper input limit value Win and the upper output limit value Wout, it is not possible to limit changes in the engine speed Ne and the braking force by controlling the first motor generator 71 and the second motor generator 72 as described with reference to Fig. 6 and Fig. 7 described.

[0078] Therefore, in the hybrid ECU 200, in a case where the increase request regarding the throttle opening degree is outputted when cranking is performed to apply engine braking, a valve opening limiting process is executed to limit an increase in the throttle opening degree corresponding to the magnitude of the upper input limit value Win and the upper output limit value Wout.

[0079] With reference to Fig. 8 the valve opening limitation process is now described. Fig. Figure 8 is a flowchart showing a series of processes in a sequence for the valve opening limiting process.

[0080] The processing is executed by the CPU 200a of the hybrid ECU 200 upon outputting the increase request regarding the throttle opening degree, which is not based on the operation for requesting a change in the braking force performed by the driver in a state where the shift range is the manual range and the engine braking torque is generated by cranking.

[0081] As in Fig. 8, at the start of the flow, the CPU 200a first determines whether the engine speed Ne is greater than the predetermined speed Nth in the process of step S100. If it is determined in step S100 that the engine speed Ne is greater than the predetermined speed Nth (step S100: YES), the CPU 200a proceeds the process to step S200.

[0082] In the process of step S200, the CPU 200a determines whether the upper output limit value Wout is smaller than a threshold value Xout. The threshold value Xout is used to determine whether the valve opening limiting process needs to be executed. The threshold value Xout is set to a magnitude that allows the determination that the output from the battery 77 does not exceed the upper output limit value Wout even if the valve opening limiting process is not executed when the upper output limit value Wout is greater than or equal to the threshold value Xout, using the result of a preliminary experiment.

[0083] If it is determined in the process of step S200 that the output upper limit value Wout is smaller than the threshold value Xout (step S200: YES), the CPU 200a proceeds to step S210. In the process of S210, the CPU 200a calculates an upper limit value THout of the throttle opening corresponding to the upper limit value Wout of the output. The upper limit value THout of the throttle opening is the upper limit value of the throttle opening, which is set so that the output from the battery 77 does not exceed the upper limit value Wout of the output. Referring to a calculation map stored in the ROM 200b, the CPU 200a uses the upper limit value Wout of the output and the engine speed Ne to calculate the upper limit value THout of the throttle opening. The calculation map is created from the result of an experiment performed in advance.

[0084] The upper opening degree limit value THout, which is calculated with reference to the calculation map, decreases as the upper output limit value Wout decreases. Furthermore, the upper opening degree limit value THout, which is calculated with reference to the calculation map, decreases as the engine speed Ne increases. The upper opening degree limit value THout thus decreases with the engine speed Ne increasing because the amount of engine friction torque increased by the opening of the throttle valve 16 increases with the engine speed Ne increasing in the case where the engine speed Ne is greater than the predetermined speed Nth, as shown in Fig. 5 shown.

[0085] When the upper limit opening degree value THout is calculated in step S210, the CPU 200a proceeds to step S220. In the process of step S220, the CPU 200a determines whether an opening degree command value, which is a command value of the opening degree of the throttle valve 16, is greater than the upper limit opening degree value THout.

[0086] If it is determined in step S220 that the opening degree command value is greater than the upper limit value THout (step S220: YES), the CPU 200a proceeds the process to step S230. In the process of step S230, the CPU 200a updates the opening degree command value to a value equivalent to the upper limit value THout. Then, the CPU 200a proceeds the process to step S400. In the process of step S400, the CPU 200a outputs the opening degree command value to the engine ECU 100. If it is determined in the process of step S220 that the opening degree command value is equal to or less than the upper limit value THout (step S220: NO), the CPU 200a proceeds the process to step S400 without executing the process of step S230. When the opening degree command value is output in this way, the CPU 200a terminates the process.

[0087] After receiving the opening degree command value output from the hybrid ECU 200, the engine ECU 100 changes the throttle opening degree according to the opening degree command value. That is, the processes from step S210 to step S230 correspond to a second valve opening limiting process that limits an increase in the throttle opening degree by setting the upper limit opening value THout calculated according to the output upper limit value Wout and the engine speed Ne, and by implementing upper limit protection so that the opening degree command value does not exceed the upper limit opening value THout.

[0088] Thus, the hybrid ECU 200 executes the second valve opening limiting process as a valve opening limiting process to limit an increase in the throttle opening degree using the upper limit value THout calculated according to the upper output limit value Wout when the engine speed Ne is greater than the predetermined speed Nth. If it is determined in the process of step S200 that the upper output limit value Wout is equal to or greater than the threshold value Xout (step S200: NO), the valve opening limiting process does not need to be executed. In this case, the CPU 200a therefore proceeds the process to step S400 to output the opening degree command value without executing the processes from step S210 to step S230.

[0089] When it is determined in step S100 that the engine speed Ne is equal to or less than the predetermined speed Nth (step S100: NO), that is, when the engine friction torque decreases with increasing throttle opening degree, the CPU 200a proceeds the process to step S300.

[0090] In the process of step S300, the CPU 200a determines whether the upper input limit value Win is equal to or greater than a threshold value Xin. The upper input limit value Win and the threshold value Xin are both negative values. Therefore, if the upper input limit value Win is equal to or greater than the threshold value Xin, the magnitude of the input to the battery 77 does not exceed the magnitude of the input specified by the threshold value Xin. The threshold value Xin is used to determine whether the valve opening limiting process needs to be executed. The threshold value Xin is set to a magnitude that allows the determination that the magnitude of the input to the battery 77 does not exceed the upper input limit value Win, even if the valve opening limiting process is not executed when the upper input limit value Win is smaller than the threshold value Xin, using the result of a preliminary experiment.

[0091] If it is determined in the process of step S300 that the input upper limit value Win is equal to or greater than the threshold value Xin (step S300: YES), the CPU 200a proceeds to step S310. In the process of S310, the CPU 200a calculates an upper limit value THin of the throttle opening corresponding to the upper limit value Win of the input. The upper limit value THin of the throttle opening is set so that the magnitude of the input to the battery 77 does not exceed the upper limit value Win of the input. Referring to a calculation map stored in the ROM 200b, the CPU 200a uses the upper limit value Win of the input and the engine speed Ne to calculate the upper limit value THin of the throttle opening. The calculation map is created from the result of an experiment conducted in advance.

[0092] The upper limit opening degree value THin calculated with reference to the calculation map decreases with increasing input upper limit value Win (i.e., as the absolute value of the upper limit input value Win decreases and the magnitude of a permissible input decreases). Furthermore, the upper limit opening degree value THin calculated with reference to the calculation map decreases with decreasing engine speed Ne. The upper limit opening degree value THin thus decreases with decreasing engine speed Ne because the amount of engine friction torque that decreases due to the opening of the throttle valve 16 becomes larger with decreasing engine speed Ne in the case where the engine speed Ne is lower than the predetermined speed Nth, as shown in Fig. 5 shown.

[0093] When the upper limit value THin of the opening degree is calculated in step S310, the CPU 200a proceeds to step S320. In the process of step S320, the CPU 200a determines whether the opening degree command value, which is a command value of the opening degree of the throttle valve 16, is greater than the upper limit value THin of the opening degree.

[0094] If it is determined in step S320 that the opening degree command value is greater than the upper opening degree limit value THout (step S320: YES), the CPU 200a proceeds to step S330. In the process from step S330, the CPU 200a updates the opening degree command value to a value equivalent to the upper opening degree limit value THin. Then, the CPU 200a proceeds to step S400.

[0095] If it is determined in the process of step S320 that the opening degree command value is equal to or less than the upper opening degree limit value THin (step S320: NO), the CPU 200a proceeds to step S400 without executing the process of step S330. When the opening degree command value is output in this way, the CPU 200a ends the process.

[0096] After receiving the opening degree command value output from the hybrid ECU 200, the engine ECU 100 changes the throttle opening degree according to the opening degree command value. That is, the processes from step S310 to step S330 correspond to a first valve opening limiting process that limits an increase in the throttle opening degree by setting the upper limit opening value THin calculated according to the input upper limit value Win and the engine speed Ne, and by implementing upper limit protection so that the opening degree command value does not exceed the upper limit opening value THout.

[0097] Thus, the hybrid ECU 200 executes the first valve opening limiting process as a valve opening limiting process to limit an increase in the throttle opening degree using the upper opening degree limit value THin calculated according to the upper input limit value Win when the engine speed Ne is equal to or less than the predetermined speed Nth. If it is determined in the process of step S300 that the upper input limit value Win is equal to or less than the threshold value Xin (step S300: NO), the valve opening limiting process does not need to be executed. In this case, the CPU 200a therefore proceeds the process to step S400 to output the opening degree command value without executing the processes from step S310 to step S330.

[0098] Now, the operation of the present embodiment will be described.

[0099] An increase in the throttle opening degree reduces the flow resistance of air in the intake pipe 15. Therefore, when the engine speed Ne is low, an increase in the throttle opening degree during cranking reduces the friction of the engine 10. When an increase in the throttle opening degree reduces the friction of the engine 10, the friction of the engine 10 generates a smaller braking force. Therefore, to maintain the braking force, the regenerative braking force generated by the second motor generator 72 must be increased. In this case, the electric power input to the battery 77 increases. Therefore, to prevent overcharging, the increase in the throttle opening degree must simply be limited so that the input electric power does not exceed the upper input limit Win.

[0100] When the engine speed Ne is equal to or less than the predetermined speed Nth, the first valve opening limiting process is executed in the engine ECU 100 to limit the throttle opening degree according to the input upper limit value Win.

[0101] When the engine speed Ne becomes higher than the predetermined speed Nth, the direction in which the friction of the engine 10 changes due to an increase in the throttle opening degree is reversed. When the engine speed Ne is higher than the predetermined speed Nth, an increase in the throttle opening degree increases the friction of the engine 10.

[0102] Therefore, when the engine speed Ne is greater than the predetermined speed Nth, the second valve opening limiting process is executed in the engine ECU 100 to limit an increase in the throttle opening degree according to the upper output limit Wout. That is, if an increase in the throttle opening degree increases the friction of the engine 10, the regenerative braking force generated by the second motor generator 72 needs to be reduced. In this case, the electric power output from the braking force is likely to increase. Therefore, to prevent overdischarge, the increase in the throttle opening degree simply needs to be limited so that the output electric power does not exceed the upper output limit Wout.

[0103] Therefore, in the engine ECU 100, when the engine speed Ne is greater than the predetermined speed Nth, the throttle opening degree is limited according to the output upper limit value Wout.

[0104] The advantages of the embodiment will now be described. (1) The first valve opening limiting process prevents the occurrence of overboosting resulting from an increase in the throttle opening degree. (2) Furthermore, the second valve opening limiting process prevents the occurrence of over-discharge resulting from an increase in the throttle opening degree. (3) The magnitude of a change in friction of the engine 10 resulting from a change in the throttle opening degree differs depending on the engine speed Ne. In the above-described configuration, the first valve opening limiting process is executed to limit the throttle opening degree according to the engine speed Ne and the input upper limit value Win. The engine speed Ne correlates with the magnitude of a change in friction of the engine 10. The engine speed Ne also correlates with the amount of input electric power, which increases as the throttle opening degree increases.Accordingly, overcharging caused when the throttle opening degree becomes larger than the upper limit opening degree THin is prevented by setting the upper limit opening degree THin, which is the upper limit of the throttle opening degree, according to the input upper limit value Win and the engine speed Ne, and limiting the throttle opening degree such that the throttle opening degree is within the range of less than or equal to the upper limit opening degree THin. (4) In the configuration described above, the second valve opening limiting process is executed to limit the throttle opening degree according to the engine speed Ne and the output upper limit value Wout. Accordingly, over-discharge caused when the throttle opening degree becomes larger than the upper opening degree limit value THout is prevented by setting the upper opening degree limit value THout, which is the upper limit value of the throttle opening degree, according to the upper output limit value Wout and the engine speed Ne, and limiting the throttle opening degree such that the throttle opening degree is within the range of less than or equal to the upper opening degree limit value THout.

[0105] The present embodiment may be modified as described below. The present embodiment and the following modifications may be combined as long as they remain technically compatible with each other.

[0106] In the above-described embodiment, the upper limit opening degree THout is calculated according to the upper output limit Wout and the engine speed Ne, and the upper limit opening degree THin is calculated according to the upper input limit Win and the engine speed Ne. The upper limit opening degrees do not need to be calculated in this way. Instead of calculating the upper limit opening degree THout according to the upper output limit Wout, the upper limit opening degree THout may be calculated, for example, according to an output available capacity Eout calculated using the upper limit opening degree THout. The output available capacity Eout is calculated as a value obtained by subtracting the difference in the electric power ratio of the first and second motor generators 71, 72 from the upper limit output Wout.That is, the output available capacity Eout is a value indicating the magnitude of the output electric power until the upper output limit Wout is reached. The difference in the electric power ratio of the first and second motor generators 71, 72 is a value obtained by subtracting the value of electric power generated by the second motor generator 72 from the value of electric power consumed by the first motor generator 71. When the value of electric power generated by the second motor generator 72 is greater than the value of electric power consumed by the first motor generator 71, the difference in the electric power ratio is a negative value.Furthermore, instead of calculating the upper opening degree limit value THin according to the input upper limit value Win, the upper opening degree limit value THin may be calculated according to an input available capacity Ein calculated using the upper opening degree limit value THin. The input available capacity Ein is calculated as a difference obtained by subtracting the difference in the electric power ratio of the first and second motor generators 71, 72 from the upper input limit value Win.

[0107] That is, the input available capacity Ein is a value that indicates the magnitude of the input electrical power until the upper input limit Win is reached.

[0108] Fig. 9 shows an example of a process executed by the hybrid ECU that executes the valve opening restriction process using the output available capacity Eout and the input available capacity Ein. Fig. 9 can be replaced by the process described with reference to Fig. 8 described process. Processes of the process in Fig. 9, which, with reference to Fig. 8 are identical or similar are designated by identical or similar reference symbols.

[0109] As in Fig. 9, at the start of the flow, the CPU of the hybrid ECU executes the process of step S100. Then, in the process of step S100, the CPU determines whether the engine speed Ne is greater than the predetermined speed Nth. If it is determined in step S100 that the engine speed Ne is greater than the predetermined speed Nth (step S100: YES), the CPU of the hybrid ECU proceeds the process to step S500.

[0110] In the process of step S500, the CPU determines whether the output available capacity Eout is less than a threshold value Yout. The threshold value Yout is used to determine whether the valve opening limiting process needs to be executed. The threshold value Yout is set, using the result of a preliminary experiment, to a magnitude that allows the determination that the output from the battery 77 does not exceed the upper output limit value Wout even if the valve opening limiting process is not executed when the output available capacity Eout is greater than or equal to the threshold value Yout.

[0111] If it is determined in the process of step S500 that the output available capacity Eout is less than the threshold value Yout (step S500: YES), the CPU proceeds to step S510. In the process of S510, the CPU calculates the upper limit opening degree THout according to the output available capacity Eout. Referring to a calculation map stored in the ROM, the CPU uses the output available capacity Eout and the engine speed Ne to calculate the upper limit opening degree THout. The calculation map is created from the result of a preliminary experiment.

[0112] The upper limit opening degree THout, calculated with reference to the calculation map, decreases as the output available capacity Eout decreases. Furthermore, the upper limit opening degree THout, calculated with reference to the calculation map, decreases as the engine speed Ne increases.

[0113] When the upper limit opening degree value THout is calculated, in step S510, the CPU proceeds the process to step S520. In the process of step S520, the CPU determines whether the opening degree command value, which is a command value of the opening degree of the throttle valve 16, is greater than the upper limit opening degree value THout.

[0114] If it is determined in step S520 that the opening degree command value is greater than the upper limit opening degree value THout (step S520: YES), the CPU proceeds the process to step S530. In the process of step S530, the CPU updates the opening degree command value to a value equivalent to the upper limit opening degree value THout. Then, the CPU proceeds the process to step S400. If it is determined in the process of step S520 that the opening degree command value is less than or equal to the upper limit opening degree value THout (step S520: NO), the CPU proceeds the process to step S400 without executing the process of step S530. When the opening degree command value is output in this way, the CPU ends the process.

[0115] In the flow, the processes from step S510 to step S530 correspond to the second valve opening limiting process that limits an increase in the throttle opening degree by setting the upper limit opening degree value THout calculated according to the output available capacity Eout and the engine speed Ne, and by implementing an upper limit protection so that the opening degree command value does not exceed the upper limit opening degree value THout.

[0116] Thus, the hybrid ECU executes the second valve opening limiting process as a valve opening limiting process to limit an increase in the throttle opening degree using the upper limit value THout calculated according to the output available capacity Eout when the engine speed Ne is greater than the predetermined speed Nth. If it is determined in the process of step S500 that the output available capacity Eout is equal to or greater than the threshold value Yout (step S500: NO), the valve opening limiting process does not need to be executed. In this case, the CPU therefore proceeds the process to step S400 to output the opening degree command value without executing the processes from step S510 to step S530.

[0117] When it is determined in step S100 that the engine speed Ne is equal to or less than the predetermined speed Nth (step S100: NO), that is, when the engine friction torque decreases with increasing throttle opening degree, the CPU proceeds the process to step S600.

[0118] In the process of step S600, the CPU determines whether the input available capacity Ein is equal to or greater than a threshold value Yin. The input available capacity Ein and the threshold value Yin are both negative values. Consequently, if the input available capacity Ein is equal to or greater than the threshold value Yin, the input magnitude to the battery 77 does not exceed the input magnitude specified by the threshold value Yin. The threshold value Yin is used to determine whether the valve opening limiting process needs to be executed.The threshold value Yin is set to a magnitude that allows the determination that the input to the battery 77 does not exceed the input available capacity Ein even if the valve opening limiting process is not executed when the input available capacity Ein is smaller than the threshold value Yin, using the result of a preliminary experiment.

[0119] If it is determined in the process of step S600 that the input available capacity Ein is equal to or greater than the threshold value Xin (step S600: YES), the CPU proceeds to step S610. In the process of S610, the CPU calculates the upper limit opening degree THin according to the input available capacity Ein. The upper limit opening degree THin is the upper limit of the throttle opening degree, which is set such that the magnitude of the input to the battery 77 does not exceed the input available capacity Ein. Referring to a calculation map stored in the ROM, the CPU uses the input available capacity Ein and the engine speed Ne to calculate the upper limit opening degree THin. The calculation map is created from the result of an experiment conducted in advance.

[0120] The upper limit value of the opening degree THin calculated with reference to the calculation map decreases with increasing input available capacity Ein (that is, the absolute value of the input available capacity Ein decreases and the magnitude of excess force that can be input decreases). Furthermore, the upper limit value of the opening degree THin calculated with reference to the calculation map decreases with decreasing engine speed Ne.

[0121] When the upper limit value THin of the opening degree is calculated in step S610, the CPU proceeds to step S620. In the process of step S620, the CPU determines whether the opening degree command value, which is a command value of the opening degree of the throttle valve 16, is greater than the upper limit value THin of the opening degree.

[0122] If it is determined in step S620 that the opening degree command value is greater than the upper opening degree limit value THin (step S620: YES), the CPU proceeds to step S630. In the process from step S630, the CPU updates the opening degree command value to a value equivalent to the upper opening degree limit value THin. Then, the CPU proceeds to step S400.

[0123] If it is determined in the process of step S620 that the opening degree command value is equal to or less than the upper opening degree limit value THin (step S620: NO), the CPU proceeds to step S400 without executing the process of step S630. When the opening degree command value is output in this way, the CPU terminates the process.

[0124] That is, the processes from step S610 to step S630 correspond to the first valve opening limiting process that limits an increase in the throttle opening degree by setting the upper limit opening degree value THin calculated according to the input available capacity Ein and the engine speed Ne, and by implementing an upper limit protection such that the opening degree command value does not exceed the upper limit opening degree value THout.

[0125] Thus, the hybrid ECU executes the first valve opening limiting process as a valve opening limiting process to limit an increase in the throttle opening degree using the upper limit value THin calculated according to the input available capacity Ein when the engine speed Ne is equal to or less than the predetermined speed Nth. If it is determined in the process of step S600 that the input available capacity Ein is equal to or less than the threshold value Yin (step S600: NO), the valve opening limiting process does not need to be executed. In this case, the CPU therefore proceeds the process to step S400 to output the opening degree command value without executing the processes from step S610 to step S630.

[0126] The use of such a configuration provides the following advantages (5) and (6) in addition to the advantages (1) and (2) described above. (5) The magnitude of input electric power until the upper input limit value Win (ie, the input available capacity Ein) is reached is calculated using the ratio of electric power in the first and second motor generators 71, 72 and the upper input limit value Win. In other words, the input available capacity Ein is calculated using the upper input limit value Win, the value of electric power consumed by the first motor generator 71, and the value of electric power generated by the second motor generator 72. Setting the upper opening degree limit value THin (ie,The throttle opening degree upper limit value (THin) calculated in this way sets the throttle opening degree upper limit value (THin) more closely based on actual conditions than setting the throttle opening degree upper limit value (THin) based only on the input throttle opening degree upper limit value (Win) and the engine speed (Ne). (6) The magnitude of output electric power until the upper output limit Wout (ie, the output available capacity Eout) is reached is calculated using the ratio of electric power in the first and second motor generators 71, 72 and the upper output limit Wout. In other words, the output available capacity Eout is calculated using the upper output limit Wout, the value of electric power consumed by the first motor generator 71, and the value of electric power generated by the second motor generator 72.Setting the upper limit opening degree THout based on the output available capacity Eout calculated in this way sets the upper limit opening degree THout more based on actual conditions than when the upper limit opening degree THout is set based only on the output upper limit Wout and the engine speed Ne.

[0127] As with reference to Fig. 5, in the embodiment described above, the direction in which the engine friction torque changes due to an increase in the throttle opening degree when the engine speed Ne is greater than the predetermined speed Nth is opposite to that when the engine speed Ne is lower than the predetermined speed Nth. Depending on the specification of the engine or the manner in which the engine is used, such a reversal does not occur in the direction in which the engine friction torque changes due to an increase in the throttle opening degree.Even in the same type as the internal combustion engine 10 of the above-described embodiment, for example, the direction in which the engine friction torque changes due to an increase in the throttle opening degree is not reversed due to the running state of the internal combustion engine when the region of a rotation speed higher than the predetermined rotation speed Nth is not used in the vehicle.

[0128] If the direction in which the engine friction torque changes due to an increase in the throttle opening degree does not reverse, it is not necessary to use the first valve opening limiting process that prevents overcharging and the second valve opening limiting process that prevents overdischarging selectively depending on the engine speed Ne.

[0129] Consequently, the process of step S100 and the processes of step S200 to step S230 described with reference to Fig. 8 may be omitted, and the processes from step S300 to step S330 and the process from step S400 may be executed as a valve opening limiting process.

[0130] In the same way, the process of step S100 and the processes of step S500 to step S530 described with reference to Fig. 9 may be omitted, and the processes from step S600 to step S630 and the process from step S400 may be executed as a valve opening limiting process.

[0131] That is, the second valve opening limiting process that prevents over-discharge does not necessarily need to be implemented.

[0132] In the above-described embodiment, when the shift lever 96 is in the M position and the shift range is in the manual range, the control mode of the hybrid vehicle switches to the manual transmission mode, enabling the driver to change the virtual shift position by operating the selector 95. Switching the control mode from the manual transmission mode, which allows the driver to change the virtual shift position by operating the selector 95, can be performed by operating the shift lever 96 as described above. For example, when the shift lever 96 is in the D position and the shift range is the drive range, the control mode can be switched to the manual transmission mode by operating the upshift paddle 51 or the downshift paddle 52.Alternatively, an additional switch may be provided that is used to switch the control mode to the manual transmission mode. In this case, the control mode is switched to the manual transmission mode when the switch is operated.

[0133] In the above-described embodiment, the manual transmission mode is used to change the virtual shift position sequentially, and selects a specific shift position by operating the upshift paddle 51, operating the downshift paddle 52, operating the shift lever 96 to the plus position, or operating the shift lever 96 to the minus position. The control to achieve a change in the virtual shift position to change the braking force caused by engine braking does not need to be performed in this way.The control to achieve a change in the virtual shift position to change the braking force caused by engine braking can be performed, for example, even by a virtual shift position upper limit selection control selected by operating the selector 95, even in an automatic speed changing control that automatically selects the virtual shift position basically by using the vehicle speed SP, the accelerator operation amount Acc, and the like.

[0134] That is, the configuration that may have the same problem as the above-described embodiment is not limited to the hybrid vehicle that executes the manual transmission mode as in the above-described embodiment. The configuration that eliminates the problem by performing the same valve opening limiting process as in the embodiment described with reference to Fig. 8 and Fig. 9 is therefore not limited to the hybrid vehicle that executes the same manual transmission mode as in the embodiment described above.

[0135] In the embodiment described above, the gate-type selector 95 is used to guide the shift lever 96 with the gate 97. Such a selector 95 does not need to be included in the hybrid vehicle capable of performing the same valve opening limiting process as the embodiment described above. For example, the selector may include a shift knob, each corresponding to a shift range. In this case, the shift knob is operated to select the shift range. Alternatively, the selector may include an additional switch used to select the parking range while including the shift lever 96 and the gate 97. Another option is that the selector may be a rotary knob type in which the shift range is selected by rotating a knob to a position corresponding to each shift position arranged around the knob.

[0136] The device operated to request a change in the virtual shift position may be changed. For example, the shift gate 97 does not need to include the plus position and the minus position. Even in this case, the virtual shift position can be changed by operating the upshift paddle 51 or the downshift paddle 52. Alternatively, a configuration may be adopted in which the plus position and the minus position are formed in the shift gate 97, and the upshift paddle 51 and the downshift paddle 52 are not formed in the shift gate 97. In this case, the virtual shift position can be changed by operating the shift lever 96. Without such a configuration, the device only needs to accept an operation requesting a change in the virtual shift position.

[0137] In the automatic transmission mode, the virtual shift position may be changed according to the vehicle speed SP and the accelerator operation amount Acc through virtual shift position control, as in the automatic speed-changing control for the vehicle including the automatic transmission. In such a case, the same problem as in the above-described embodiment may occur when the accelerator operation is disabled in the automatic transmission mode. To solve such a problem, the same solution as in the above-described embodiment may be applied to the automatic transmission mode.

[0138] The transmission 90, which is capable of providing four shift positions, is described as one transmission in the embodiment described above. Instead, a transmission that provides a smaller or larger number of shift positions may be used. Furthermore, the number of virtual shift positions and the manner in which the virtual shift position is assigned, each corresponding to a shift position of a transmission, may be changed. As a further option, a transmission capable of providing multiple shift positions need not be used. For example, a speed-reducing mechanism with a fixed gear ratio may be used.

[0139] The hybrid vehicle does not need to include a transmission. Even in a configuration where the shift position is not changed by a transmission, the virtual shift position can be changed by controlling the first motor generator 71.

[0140] In the hybrid vehicle, multiple virtual shift positions do not need to be selected. For example, the total deceleration ratio can be controlled to be fixed at a constant value when an engine braking model is selected using a selector to apply engine braking. In a hybrid vehicle with such a configuration, the same problem as in the above-described embodiment may occur. Therefore, the same solution as in the above-described embodiment can be adopted.

[0141] Instead of performing control to fix the overall deceleration ratio, engine braking may be applied by performing cranking that maintains the engine speed at a constant value when the accelerator operation is disabled. Even in a case where an increase request regarding the throttle opening degree is issued when engine braking is applied by such control, the same problem as in the above-described embodiment may occur. Therefore, the same solution as in the above-described embodiment can be applied to a hybrid vehicle for which such control is performed.

[0142] If overcharging or overdischarging can be prevented, the way in which an increase in the throttle opening degree is limited in the valve opening limitation process may be changed. For example, an increase in the throttle opening degree does not need to be limited by calculating the upper limit value. Instead, the opening degree command value may be uniformly lowered by determining, when the increase request regarding the throttle opening degree is issued, whether an increase in the opening degree should be limited according to the upper input limit value Win or the upper output limit value Wout. Specifically, such a limitation is achieved, for example, by multiplying the opening degree command value by a coefficient that is greater than 0 and less than 1.

[0143] When the upper input limit value Win is greater than or equal to a threshold value and the magnitude of electric power that can be input to the battery 77 is low, the throttle opening degree may be prohibited from being increased. Further, when the upper output limit value Wout is less than or equal to a threshold value and the magnitude of electric power that can be output from the battery 77 is low, the throttle opening degree may be prohibited from being increased.

[0144] In the hybrid vehicle of the above-described embodiment, the controller for the hybrid vehicle is the hybrid ECU 200, and the engine ECU 100, the electric motor ECU 300, the battery ECU 400, and the shift ECU 500 are also formed. Instead, the controller for the hybrid vehicle may be a single controller that includes the function of one of these ECUs, a plurality of these ECUs, or all of these ECUs.

[0145] The execution device is not limited to the device that includes the CPU 200a and the ROM 200b and executes software processing. A dedicated hardware circuit (such as an ASIC) may be configured to execute at least part of the processes executed in the above-described embodiment through hardware processing.That is, the execution device only needs to be a circuit comprising one of the following configurations (a) to (c): (a) a circuit comprising a processor that executes all of the above-described processes according to programs, and a program storage device such as a ROM that stores the programs; (b) a circuit comprising a processor and a program storage device that execute part of the above-described processes according to the programs, and a dedicated hardware circuit that executes the remaining processes; and (c) a circuit comprising a dedicated hardware circuit that executes all of the above-described processes. One or more software execution devices comprising a processor and a program storage device and one or more dedicated hardware circuits may be formed.

Claims

[1] Controller (200) for a hybrid vehicle, the hybrid vehicle comprising: a power distribution integration mechanism (40) comprising a ring gear (42) configured to work in a toothed manner with a driven gear (62), a sun gear (41) configured to rotate at a center of the ring gear (42), a planetary gear (43) located between the sun gear (41) and the ring gear (42) and configured to orbit the sun gear (41), and a planetary gear carrier (44) configured to rotate while the planetary gear (43) orbits; an internal combustion engine (10) comprising an output shaft (14) coupled to the planetary gear carrier (44); a first motor generator (71) arranged to operate in a toothed manner with the sun gear (41); a second motor generator (72) configured to operate in a toothed manner with the ring gear (42); a battery (77) connected to the first motor generator (71) and the second motor generator (72); and a battery controller (400) configured to calculate a state of charge (SOC) of the battery (77), an upper input limit (Win) of the battery (77), and an upper output limit (Wout) of the battery (77) using a voltage (VB) in the battery (77), a temperature (TB) of the battery (77), and a ratio of electric power in the first and second motor generators (71, 72), wherein the controller (200) comprises: an execution device (200a, 200b) configured to control the first motor generator (71) and the second motor generator (72) such that the electric power input to the battery (77) does not exceed the upper input limit value (Win) and an electric power output from the battery (77) does not exceed the upper output limit value (Wout), wherein the execution device (200a, 200b) is configured: controlling the engine (10) and the first motor generator (71) such that the engine speed (Ne) approaches a target engine speed, the target engine speed being set using a requested driving force; controlling the second motor generator (72) such that the requested driving force is achieved by power transmitted from the ring gear (42) to the driven wheel (62); performing a start to rotate the output shaft (14) using the first motor generator (71) in a state where a combustion operation of the internal combustion engine (10) is stopped, thereby causing a braking force generated by friction of the internal combustion engine (10) to act on the driven wheel (62); and to execute a valve opening limiting process that limits an increase in a throttle opening degree according to the upper input limit value (Win) when an increase request regarding the throttle opening degree is issued that is not based on an operation requesting a change in the braking force performed by the driver during the execution of the cranking. [2] Controller (200) according to claim 1, wherein the execution device (200a, 200b) is arranged to execute a shift position fixing control that fixes a total deceleration ratio at a value corresponding to a shift position selected by the driver, and changes the engine speed (Ne) according to a vehicle speed, wherein the total deceleration ratio is a ratio of the engine speed (Ne) and a speed of the driven wheel (62), and the braking force change request operation performed by the driver includes a shift position change operation, an accelerator operation, and a brake operation performed by the driver during execution of the shift position fixing control. [3] The controller (200) according to claim 1, wherein the execution device (200a, 200b) is configured to: set an upper limit value (THin) of the throttle opening degree using the upper input limit value (Win) and the engine speed (Ne); and to limit the throttle opening degree to a range that is less than or equal to the upper limit value (THin). [4] The controller (200) according to claim 1, wherein the execution device (200a, 200b) is configured to: calculate an input available capacity (Ein) of the battery (77) using the ratio of electric power in the first and second motor generators (71, 72) and the input upper limit value (Win); set an upper limit value (THin) of the throttle opening degree using the input available capacity (Ein) and the engine speed (Ne); and to limit the throttle opening degree to a range that is less than or equal to the upper limit value (THin). [5] Controller (200) according to claim 1, wherein the internal combustion engine (10) is arranged such that the friction of the internal combustion engine (10) is reduced by increasing the throttle opening degree when the internal combustion engine speed (Ne) is lower than a predetermined speed (Nth) and the friction of the internal combustion engine (10) is increased by increasing the throttle opening degree when the internal combustion engine speed (Ne) is higher than the predetermined speed (Nth), the valve opening limiting process is a first valve opening limiting process, and the execution device (200a, 200b) is arranged, upon outputting the increase request regarding the degree of throttle opening, which is not based on the operation performed by the driver to request a change in the braking force during the execution of the starting: to execute a second valve opening limiting process that limits an increase in the throttle opening degree according to the upper output limit value (Wout) when the engine speed (Ne) is higher than the predetermined speed (Nth); and to execute the first valve opening limiting process when the engine speed (Ne) is less than or equal to the predetermined speed (Nth). [6] The controller (200) according to claim 5, wherein the execution device (200a, 200b) is configured, in the second valve opening limiting process: set an upper limit value (THout) of the throttle opening degree using the upper output limit value (Wout) and the engine speed (Ne); and to limit the throttle opening degree to a range that is less than or equal to the upper limit value (THout). [7] The controller (200) according to claim 5, wherein the execution device (200a, 200b) is configured to: calculate an output available capacity (Eout) of the battery (77) using the ratio of electric power in the first and second motor generators (71, 72) and the upper output limit value (Wout); set an upper limit value (THout) of the throttle opening degree using the output available capacity (Eout) and the engine speed (Ne); and to limit the throttle opening degree to a range that is less than or equal to the upper limit value (THout). [8] A control method for a hybrid vehicle, the hybrid vehicle comprising: a power distribution integration mechanism (40) comprising a ring gear (42) configured to work in a toothed manner with a driven gear (62), a sun gear (41) configured to rotate at a center of the ring gear (42), a planetary gear (43) located between the sun gear (41) and the ring gear (42) and configured to orbit the sun gear (41), and a planetary gear carrier (44) configured to rotate while the planetary gear (43) orbits; an internal combustion engine (10) comprising an output shaft (14) coupled to the planetary gear carrier (44); a first motor generator (71) arranged to operate in a toothed manner with the sun gear (41); a second motor generator (72) configured to operate in a toothed manner with the ring gear (42); and a battery (77) connected to the first motor generator (71) and the second motor generator (72), the method comprising: calculate a state of charge (SOC) of the battery (77), an upper input limit (Win) of the battery (77), and an upper output limit (Wout) of the battery (77) using a voltage (VB) in a battery (77), a temperature (TB) of the battery (77), and a ratio of electric power in the first and second motor generators (71, 72); controlling the first motor generator (71) and the second motor generator (72) such that the electric power input to the battery (77) does not exceed the upper input limit (Win) and an electric power output from the battery (77) does not exceed the upper output limit (Wout); controlling the engine (10) and the first motor generator (71) such that the engine speed (Ne) approaches a target engine speed, the target engine speed being set using a requested driving force; controlling the second motor generator (72) such that the requested driving force is achieved by the power transmitted from the ring gear (42) to the driven wheel (62); to perform a start-up to rotate the output shaft (14) using the first motor generator (71) in a state in which a combustion operation of the internal combustion engine (10) is stopped, thereby causing a braking force generated by friction of the internal combustion engine (10) to act on the driven wheel (62); and to execute a valve opening limiting process that limits an increase in a throttle opening degree according to the upper input limit value (Win) when an increase request regarding the throttle opening degree is issued that is not based on an operation requesting a change in the braking force performed by a driver during the execution of the cranking.

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