Hybrid vehicle control device

Abstract

To make both suppression of discomfort which an occupant feels and quick completion of starting of an engine compatible when starting the engine.SOLUTION: A control device 100 is applied to a hybrid vehicle equipped with an engine 10, a motor generator 30 and a clutch 20. A CPU 101 of the control device 100 executes a first starting process for starting combustion of the engine 10, after increasing a rotation speed of the engine up to a rotation speed of a motor by engaging the clutch 20, when starting the engine 10 under the situation where an increment of required torque value is less than an increment determination value. The CPU 101 executes a second starting process for starting combustion of the engine 10 before the rotation speed of the engine reaches the rotation speed of the motor, when a crank shaft 18 of the engine 10 starts rotating by engaging the clutch 20, in order to start the engine 10 under the situation where the increment of the required torque value is above the increment determination value.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] Patent Document 1 discloses a control device that is applied to a hybrid vehicle that has an engine and a motor generator as power sources, and a clutch disposed between the engine and the motor generator. When starting the engine, the control device engages the clutch to connect the crankshaft of the engine and the drive shaft of the motor generator. This makes it possible to rotate the crankshaft by driving the motor generator. Then, the control device starts combustion in the engine after starting the rotation of the crankshaft by driving the motor generator. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-25985 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the case where combustion in the engine is started after the crankshaft starts to rotate by driving the motor generator as described above, an advance in the timing at which combustion starts allows the engine to be started earlier, but vibrations associated with engine start are likely to occur. On the other hand, a delay in the timing at which combustion starts makes it difficult for vibrations associated with engine start to occur, but the completion of engine start is delayed. [Means for solving the problem]

[0005] A hybrid vehicle control device for solving the above problem is applied to a hybrid vehicle that includes an engine having a crankshaft and a motor generator having a drive shaft as a power source of the vehicle, and a clutch is disposed between the crankshaft and the drive shaft. This hybrid vehicle control device includes an execution device that controls the engine, the motor generator, and the clutch. When the execution device starts the engine under a condition in which an increase amount of a torque request value that is a torque request value for the power source is less than an increase amount determination value, the execution device executes a first start process that increases the engine speed, which is the rotation speed of the crankshaft, to the motor speed, which is the rotation speed of the drive shaft, by engaging the clutch, and then starts combustion in the engine. When the execution device starts the engine under a condition in which an increase amount of the torque request value is equal to or greater than the increase amount determination value, when the crankshaft starts to rotate by engaging the clutch, the execution device executes a second start process that starts combustion in the engine before the engine speed reaches the motor speed.

[0006] The greater the increase in the torque requirement value, the greater the acceleration of the hybrid vehicle. When the acceleration of the hybrid vehicle is increased, even if vibrations due to engine start-up occur in the hybrid vehicle, the occupants of the hybrid vehicle are less likely to feel uncomfortable due to such vibrations. On the other hand, when the increase in the torque requirement value is relatively small and the acceleration of the hybrid vehicle is not so large, the occupants are more likely to feel uncomfortable due to vibrations due to engine start-up.

[0007] When starting the engine by the first start processing, the timing at which combustion begins in the engine is delayed compared to when starting the engine by the second start processing. Therefore, vibrations caused by starting the engine are less likely to become large in the first start processing, whereas vibrations caused by starting the engine are more likely to become large in the second start processing.

[0008] In the above configuration, when starting the engine, if the increase in the torque request value is equal to or greater than the increase amount determination value, the engine is started by the second start processing. In this case, the engine start can be completed early, and even if vibration caused by engine start occurs, the occupants are unlikely to feel uncomfortable. On the other hand, when starting the engine, if the increase in the torque request value is less than the increase amount determination value, the engine is started by the first start processing. In this case, although there is a delay in completing the engine start, vibration caused by engine start is unlikely to occur.

[0009] Therefore, the above-described hybrid vehicle control device can simultaneously suppress discomfort felt by occupants when the engine is started and quickly complete the starting of the engine. In one example of the control device for a hybrid vehicle, when starting the engine, the execution device executes the second start processing if at least one of the following is true: a system shaft torque, which is a shaft torque of the drive shaft, is equal to or greater than a shaft torque judgment value, and an increase in the torque request value is equal to or greater than the increase amount judgment value. On the other hand, the execution device executes the first start processing if neither the system shaft torque is equal to or greater than the shaft torque judgment value, nor the increase in the torque request value is equal to or greater than the increase amount judgment value.

[0010] When the engine is started by the second start process under a condition where the system shaft torque, which is the torque input from the vehicle power source to the transmission, is relatively large, vibration caused by starting the engine is unlikely to become large. Therefore, in the above configuration, when the system shaft torque is equal to or greater than the shaft torque judgment value, the system shaft torque is large, so that the engine is started by the second start process even if the increase in the torque request value is less than the increase amount judgment value. In other words, the opportunities for executing the second start process can be increased.

[0011] In one example of the control device for a hybrid vehicle, the execution device executes a provisional selection process that selects the first start-up process when a system shaft torque, which is a shaft torque of the drive shaft, is less than a shaft torque judgment value, and selects the second start-up process when the system shaft torque is equal to or greater than the shaft torque judgment value. Also, when a start of the engine is requested under a condition in which the first start-up process has been selected in the provisional selection process, the execution device executes the second start-up process when an increase in the torque request value is equal to or greater than the increase amount judgment value, and executes the first start-up process when the increase in the torque request value is less than the increase amount judgment value.

[0012] In the above configuration, even if the first start procedure is selected in the provisional selection procedure because the system shaft torque is small, if the increase in the torque request value is equal to or greater than the increase determination value, it is possible to determine that the passengers are unlikely to feel uncomfortable even if the vibration occurs, and therefore the engine is started by the second start procedure. In other words, it is possible to increase the number of opportunities to execute the second start procedure.

[0013] In one example of the above-mentioned control device for a hybrid vehicle, the execution device sets a smaller value as the increase amount determination value, as the predicted value of the torque capacity of the clutch when it is assumed that the engine is started in the second start process is smaller.

[0014] When the torque capacity of the clutch is small, when the engine torque, which is the output torque of the engine, rises suddenly, the clutch is more likely to attenuate the fluctuation in the engine torque. In other words, when the engine torque rises suddenly, the rotation speed of the drive shaft of the motor generator is less likely to fluctuate, so that vibration caused by starting the engine is less likely to occur. Therefore, in the above configuration, the smaller the predicted value of the torque capacity, the smaller the value set as the increase amount determination value. As a result, when the clutch capacity becomes small when the engine is started by the second start process, the second start process is more likely to be executed.

[0015] The hybrid vehicle to which the hybrid vehicle control device is applied may be equipped with a hydraulically driven clutch as the clutch. In this case, it is preferable that the execution device sets the increase amount determination value to a smaller value as the temperature of the hydraulic oil of the clutch increases.

[0016] When the temperature of the hydraulic oil of the clutch is low, the viscosity of the hydraulic oil increases, and the responsiveness of the clutch hydraulic oil, which is the hydraulic oil supplied to the clutch, decreases. The lower the responsiveness of the clutch hydraulic oil, the more likely it is that a delay will occur in adjusting the torque capacity of the clutch. When starting the engine by the second start process under circumstances where a delay is likely to occur in adjusting the torque capacity, it is difficult to adjust the torque transmission efficiency from the engine to the motor generator by the clutch. As a result, when the engine torque increases rapidly, the rotation speed of the drive shaft of the motor generator fluctuates greatly, and the vibration caused by the start of the engine is likely to increase. In other words, when the temperature of the hydraulic oil is not low, the viscosity of the hydraulic oil is relatively low, and therefore the response speed of the clutch hydraulic oil is relatively high. Therefore, the above vibration is unlikely to increase when the engine is started by the second start process. Therefore, in the above configuration, the higher the temperature of the hydraulic oil, the smaller the value set as the increase amount determination value. As a result, when the temperature of the hydraulic oil is high and the response speed of the clutch hydraulic oil is high, the second start process is likely to be executed.

[0017] A hybrid vehicle to which the control device for a hybrid vehicle is applied may include a transmission, and the motor generator may be disposed between the clutch and the transmission in a torque transmission path. In this case, it is preferable that the execution device sets the increase amount determination value to a smaller value as the gear stage selected by the transmission is a higher gear stage.

[0018] When a higher gear is selected as the gear of the transmission, vibration caused by starting the engine is less likely to become large compared to when a lower gear is selected as the gear of the transmission. Therefore, in the above configuration, the higher the gear selected by the transmission, the smaller the value set as the increase amount determination value. As a result, the higher the gear selected by the transmission, the more likely it is that the second start process will be executed. [Brief description of the drawings]

[0019] [Figure 1] FIG. 1 is a diagram showing a schematic configuration of a hybrid vehicle equipped with a control device which is one embodiment of a control device for a hybrid vehicle. [Diagram 2] FIG. 2 is a time chart when the engine is started by the first starting process. [Diagram 3] FIG. 3 is a time chart when the engine is started by the second starting process. [Figure 4] FIG. 4 is a block diagram illustrating a plurality of processes executed by a CPU included in the control device. [Diagram 5] FIG. 5 is a flowchart showing the final decision process. [Figure 6] FIG. 6 is a time chart showing the transition of the accelerator opening degree. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Hereinafter, one embodiment of a control device for a hybrid vehicle will be described with reference to Figs. 1 shows a schematic configuration of a hybrid vehicle 500 including a control device 100, which is an example of a hybrid vehicle control device. Hereinafter, the hybrid vehicle 500 will be simply referred to as "vehicle 500".

[0021] <Vehicle configuration> The vehicle 500 includes an engine 10 and a motor generator 30 as a power source of the vehicle. A clutch 20 is disposed between the engine 10 and the motor generator 30 in a torque transmission path. The torque output from the engine 10 or the motor generator 30 is transmitted to a plurality of drive wheels 65 via a transmission 40 and a differential 60. The torque input from the power source of the vehicle to the transmission 40 is referred to as "system shaft torque."

[0022] The engine 10 includes a plurality of fuel injection valves 12 that inject fuel, and a plurality of cylinders. The engine 10 also includes an intake passage 13 connected to the plurality of cylinders, and an electric throttle valve 14 that adjusts the amount of air flowing through the intake passage 13. In the plurality of cylinders, an air-fuel mixture containing air introduced from the intake passage 13 and fuel injected from the fuel injection valve 12 is burned. Exhaust gas generated by the combustion of the air-fuel mixture is discharged from the plurality of cylinders to an exhaust passage 16. A catalyst 17 that purifies the exhaust gas is provided in the exhaust passage 16.

[0023] The engine 10 includes a crankshaft 18 which is an output shaft of the engine 10. The crankshaft 18 rotates in a predetermined direction by the force obtained by the combustion of the air-fuel mixture in the multiple cylinders. That is, the engine torque Te which is the output torque of the engine 10 is output from the crankshaft 18.

[0024] The clutch 20 is connected to the crankshaft 18 of the engine 10. When the clutch 20 is in an engaged state, torque can be transmitted between the engine 10 and the motor generator 30. On the other hand, when the clutch 20 is in a disengaged state, torque cannot be transmitted between the engine 10 and the motor generator 30.

[0025] In this embodiment, the clutch 20 can be engaged in either full engagement or slip engagement. Full engagement is an engagement in which the engagement force of the clutch 20 is greater than that of slip engagement. The greater the engagement force of the clutch 20, the greater the torque capacity Tc of the clutch 20. Therefore, when the clutch 20 is fully engaged, the torque transmission efficiency between the engine 10 and the motor generator 30 is high. On the other hand, when the clutch 20 is in slip engagement, the torque capacity Tc of the clutch 20 is smaller than when the clutch 20 is fully engaged. Therefore, when the clutch 20 is in slip engagement, the torque transmission efficiency is low, although torque is transmitted between the engine 10 and the motor generator 30. That is, when the torque transmission efficiency between the engine 10 and the motor generator 30 is intentionally reduced, the clutch 20 may be slip engaged.

[0026] The clutch 20 is a hydraulically driven clutch. In the clutch 20, the higher the clutch hydraulic pressure Pc, which is the hydraulic pressure supplied to the clutch 20, the greater the engagement force of the clutch 20. That is, by adjusting the clutch hydraulic pressure Pc, the clutch 20 can be slip-engaged or fully engaged. And, the higher the clutch hydraulic pressure Pc, the greater the torque capacity Tc of the clutch 20, and therefore the higher the torque transmission efficiency between the engine 10 and the motor generator 30. That is, when the clutch 20 is in an engaged state, the torque capacity Tc is changed by adjusting the clutch hydraulic pressure Pc, and thus the torque transmission efficiency of the clutch 20 is adjusted.

[0027] The motor generator 30 has a drive shaft 31 connected to the clutch 20. That is, when the motor generator 30 functions as an electric motor, the drive shaft 31 rotates by power supplied from the battery via the inverter. On the other hand, when the motor generator 30 functions as a generator, regenerative power corresponding to the rotation of the drive shaft 31 is generated in the motor generator 30 and the regenerative power is supplied to the battery via the inverter. When the output torque of the motor generator 30 is defined as "motor torque Tm," the sum of the torque input from the crankshaft 18 via the clutch 20 to the drive shaft 31, out of the engine torque Te, and the motor torque Tm becomes the system shaft torque Tsys.

[0028] The transmission 40 has a torque converter 41 and a speed change mechanism 46. The torque converter 41 has a pump impeller 42, a turbine impeller 43, and a lock-up clutch 44. The pump impeller 42 is connected to the drive shaft 31 of the motor generator 30. The turbine impeller 43 is connected to the speed change mechanism 46. When the lock-up clutch 44 is disengaged, torque is transmitted from the pump impeller 42 to the turbine impeller 43 via hydraulic oil in the torque converter 41. On the other hand, when the lock-up clutch 44 is engaged, torque is transmitted directly from the pump impeller 42 to the turbine impeller 43 without passing through hydraulic oil.

[0029] The transmission mechanism 46 is, for example, a stepped transmission mechanism. The transmission mechanism 46 has an input shaft 47 to which torque is input from the torque converter 41, and an output shaft 48 that outputs the torque. The input shaft 47 is connected to the turbine impeller 43 of the torque converter 41. The transmission mechanism 46 outputs the torque input from the input shaft 47 from the output shaft 48 toward the differential 60 in a reduced speed state.

[0030] In this embodiment, the vehicle 500 includes an electric pump 80 and a hydraulic control circuit 90. The electric pump 80 pressurizes hydraulic oil and supplies it to the hydraulic control circuit 90. The hydraulic control circuit 90 supplies the high-pressure hydraulic oil supplied from the electric pump 80 to the transmission mechanism 46, the torque converter 41, and the clutch 20. For example, the hydraulic control circuit 90 has a plurality of oil control valves. By controlling the plurality of oil control valves, the supply and discharge of hydraulic oil to the supply targets of the hydraulic oil and the supply hydraulic pressure of the hydraulic oil to the supply targets are controlled. That is, the hydraulic control circuit 90 is configured to be able to adjust the clutch hydraulic pressure Pc.

[0031] <Vehicle detection system> The detection system of the vehicle 500 includes a plurality of sensors that output detection signals corresponding to the detection results to the control device 100. That is, the vehicle 500 includes a crank angle sensor 111, an air flow meter 112, an accelerator opening sensor 113, a motor angle sensor 114, an input shaft sensor 115, and an oil temperature sensor 116. The crank angle sensor 111 outputs a detection signal corresponding to the engine speed Ne, which is the rotation speed of the crankshaft 18. The air flow meter 112 detects the intake air amount GA, which is the amount of air flowing through the intake passage 13, and outputs a detection signal corresponding to the detection result. The accelerator opening sensor 113 detects the accelerator opening ACCP, which is the amount of operation of the accelerator pedal, and outputs a detection signal corresponding to the detection result. The motor angle sensor 114 outputs a detection signal corresponding to the motor rotation speed Nm, which is the rotation speed of the drive shaft 31 of the motor generator 30. The input shaft sensor 115 outputs a detection signal corresponding to the input shaft rotation speed Nat, which is the rotation speed of the input shaft 47 of the transmission mechanism 46. The oil temperature sensor 116 detects an oil temperature TOIL, which is the temperature of the hydraulic oil discharged by the electric pump 80, and outputs a detection signal according to the detection result.

[0032] <Control device> The control device 100 includes a CPU 101, a ROM 102, and a RAM 103. The ROM 102 stores various control programs executed by the CPU 101. The RAM 103 stores the calculation results of the CPU 101. The CPU 101 controls the engine 10 and the motor generator 30 by executing the control programs. The CPU 101 also controls the electric pump 80 and the hydraulic control circuit 90, thereby controlling the clutch 20 and the transmission 40. Therefore, in this embodiment, the CPU 101 corresponds to the "execution device."

[0033] The CPU 101 calculates the engine speed Ne based on the detection signal Scr of the crank angle sensor 111. The CPU 101 calculates the engine load factor KL based on the engine speed Ne and the intake air amount GA.

[0034] The CPU 101 derives a torque requirement value TsR, which is a requirement value of torque for the power source of the vehicle, based on the accelerator opening ACCP. The torque requirement value TsR here is a requirement value of torque input from the drive shaft 31 to the transmission 40. For example, the CPU 101 derives a larger value as the accelerator opening ACCP increases. The CPU 101 then controls the power source of the vehicle, i.e., the engine 10 and the motor generator 30, based on the torque requirement value TsR.

[0035] The vehicle 500 has two driving modes: an electric driving mode and a hybrid driving mode. The electric driving mode is a mode in which torque is output only from the motor generator 30 out of the engine 10 and the motor generator 30. Therefore, when the electric driving mode is selected, the CPU 101 controls the motor generator 30 based on the torque request value TsR. When the electric driving mode is selected, the CPU 101 releases the clutch 20 so that the engine 10 is not operated.

[0036] The hybrid driving mode is a mode in which torque is output from both the engine 10 and the motor generator 30. When the engine 10 is operated, the CPU 101 controls the engine 10 and the motor generator 30 based on the torque request value TsR with the clutch 20 engaged. When the hybrid driving mode is selected, the CPU 101 may intermittently stop the operation of the engine 10. In this case, the CPU 101 controls the motor generator 30 based on the torque request value TsR with the clutch 20 disengaged.

[0037] When the operation of the engine 10 is stopped under a condition in which the hybrid driving mode is selected, if the torque request value TsR increases due to an increase in the accelerator opening ACCP, for example, the CPU 101 may start the operation of the engine 10. In this case, the CPU 101 engages the clutch 20 in addition to starting the engine 10. In this embodiment, when starting the engine 10, the CPU 101 selects either the first start processing or the second start processing, and starts the engine 10 by executing the selected processing.

[0038] The first start-up process will be described with reference to FIG. In the first start process, when a start of the engine 10 is requested at timing t11, the clutch 20 is engaged. In this case, the clutch 20 is slip-engaged. The CPU 101 controls the electric pump 80 and the hydraulic control circuit 90 to increase the clutch oil pressure Pc. This increases the engagement force of the clutch 20. When the engagement force increases, the torque capacity Tc of the clutch 20 increases as shown in FIG. 2A. When the clutch 20 is slip-engaged, the motor torque Tm is input to the crankshaft 18. Then, the engine 10 is cranked by the motor generator 30, and the engine speed Ne increases as shown in FIG. 2B. Then, the engine speed Ne rises to the motor speed Nm. Then, the clutch oil pressure Pc is increased and the torque capacity Tc of the clutch 20 is increased. As a result, the clutch 20 is fully engaged.

[0039] The timing at which the engine speed Ne becomes substantially the same as the motor speed Nm is also referred to as the "synchronization timing of the clutch 20." Combustion in the engine 10 starts at the synchronization timing of the clutch 20 or at timing t12 slightly after the synchronization timing. In other words, combustion in the engine 10 starts after the clutch 20 is fully engaged.

[0040] The second start-up process will be described with reference to FIG. In the second start process, when a request to start the engine 10 is made at timing t21, the clutch 20 is engaged. In this case, the clutch 20 is slip-engaged. The CPU 101 increases the clutch oil pressure Pc by controlling the electric pump 80 and the hydraulic control circuit 90. This increases the engagement force of the clutch 20. When the engagement force increases, the torque capacity Tc of the clutch 20 increases, as shown in FIG. 3A. When the clutch 20 is slip-engaged, the motor torque Tm is input to the crankshaft 18. Then, the engine 10 is cranked by the motor generator 30, and the engine speed Ne increases, as shown in FIG. 3B.

[0041] In the second starting process, unlike the first starting process, combustion in the engine 10 is started at timing t22 before the engine speed Ne reaches the motor speed Nm. In this embodiment, combustion in the engine 10 is started when the crankshaft 18 has rotated once or when the crankshaft 18 has rotated two times due to cranking by the motor generator 30.

[0042] Therefore, after timing t22, the engine speed Ne is abruptly increased by both the cranking by the motor generator 30 and the increase in engine torque Te. When the engine 10 is started, before the engine speed Ne reaches the motor speed Nm, the torque capacity Tc of the clutch 20 is adjusted. That is, the CPU 101 controls the hydraulic control circuit 90 to reduce the clutch oil pressure Pc. Then, from timing t23, the torque capacity Tc of the clutch 20 is reduced. When the torque capacity Tc is reduced, the torque transmitted from the crankshaft 18 to the drive shaft 31 via the clutch 20 becomes smaller. This reduces the torque transmission efficiency of the clutch 20. In this way, during the period from the start of combustion in the engine 10 until the engine speed Ne reaches the motor speed Nm, the torque capacity Tc of the clutch 20 is adjusted to adjust the engine torque Te transmitted to the drive shaft 31. This suppresses abrupt increases in the motor speed Nm.

[0043] When the engine speed Ne becomes substantially equal to the motor speed Nm at timing t24, the clutch oil pressure Pc is increased by the control of the hydraulic control circuit 90 by the CPU 101. As a result, the torque capacity Tc of the clutch 20 is increased as shown in Fig. 3(B). This causes the clutch 20 to be fully engaged, maximizing the torque transmission efficiency of the clutch 20.

[0044] <Processing to be performed when starting the engine> The process executed by the CPU 101 when starting the engine 10 will be described with reference to FIGS.

[0045] 4, the CPU 101 executes a torque capacity prediction process M11 and a turbine speed prediction process M13. The CPU 101 also executes a first determination value candidate setting process M15, a second determination value candidate setting process M17, a setting process M19, and a provisional selection process M21. The CPU 101 also executes an increase amount determination value setting process M23, a final determination process M25, and a start process M27.

[0046] <Torque capacity prediction process> The torque capacity prediction process M11 is a process for deriving a predicted torque capacity Tce, which is a predicted value of the torque capacity Tc of the clutch 20. The predicted torque capacity Tce is the torque capacity Tc at the synchronization timing of the clutch 20 when it is assumed that the engine 10 is started by the second start process. When the engine 10 is started by the second start process, the CPU 101 adjusts the command value of the clutch oil pressure Pc in a predetermined manner. The response of the actual value of the clutch oil pressure Pc to the fluctuation of the command value can be estimated to some extent from the motor rotation speed Nm, the system shaft torque Tsys, and the input shaft rotation speed Nat.

[0047] Therefore, in the torque capacity prediction process M11, the CPU 101 derives a predicted torque capacity Tce based on the motor rotation speed Nm, the system shaft torque Tsys, and the input shaft rotation speed Nat. For example, it can be estimated that the synchronization timing of the clutch 20 will be delayed as the motor rotation speed Nm increases. Therefore, the CPU 101 derives a smaller value as the predicted torque capacity Tce as the motor rotation speed Nm increases. Also, for example, it can be estimated that the synchronization timing of the clutch 20 will be delayed as the system shaft torque Tsys increases. Therefore, the CPU 101 derives a smaller value as the predicted torque capacity Tce as the system shaft torque Tsys increases. Also, for example, it can be estimated that the synchronization timing of the clutch 20 will be delayed as the input shaft rotation speed Nat increases. Therefore, the CPU 101 derives a smaller value as the predicted torque capacity Tce as the input shaft rotation speed Nat increases.

[0048] When the engine 10 is not operating, the clutch 20 is disengaged, and therefore the CPU 101 obtains the motor torque Tm as the system shaft torque Tsys. <Turbine rotation speed prediction process> The turbine speed prediction process M13 is a process for deriving a predicted turbine speed Nte, which is a predicted value of the rotation speed of the turbine impeller 43. The rotation speed of the turbine impeller 43 is defined as the "turbine speed". The predicted turbine speed Nte is the turbine speed at the synchronization timing of the clutch 20 when it is assumed that the engine 10 is started in the second start process. Since the turbine impeller 43 of the torque converter 41 is connected to the input shaft 47 of the speed change mechanism 46, the turbine speed is substantially the same as the input shaft speed Nat. In other words, the predicted turbine speed Nte can also be said to be a predicted value of the input shaft speed Nat.

[0049] In a turbine rotation speed prediction process M13, the CPU 101 subtracts the deceleration correction value ΔNat from the input shaft rotation speed Nat to obtain a predicted turbine rotation speed Nte. The deceleration correction value ΔNat is a value determined from the specifications of the drive system of the vehicle 500.

[0050] <First judgment value candidate setting process> The first judgment value candidate setting process M15 derives a first shaft torque judgment value TsysTh1, which is one of the candidate values ​​of the shaft torque judgment value, by referring to a first map MAP1. The first map MAP1 is a map showing the relationship between the predicted turbine speed Nte and the system shaft torque Tsys. In the first map MAP1, when the predicted turbine speed Nte is less than the first reference speed Nte1, the system shaft torque Tsys corresponding to the predicted turbine speed Nte becomes a positive value. Specifically, when the predicted turbine speed Nte is less than the first reference speed Nte1, the system shaft torque Tsys corresponding to the predicted turbine speed Nte becomes larger as the predicted turbine speed Nte becomes smaller. On the other hand, when the predicted turbine speed Nte is equal to or greater than the first reference speed Nte1, the system shaft torque Tsys corresponding to the predicted turbine speed Nte becomes a negative value. Specifically, when the predicted turbine speed Nte is equal to or greater than the first reference speed Nte1, the absolute value of the system shaft torque Tsys corresponding to the predicted turbine speed Nte becomes larger as the predicted turbine speed Nte becomes larger.

[0051] In a first judgment value candidate setting process M15, the CPU 101 derives the system shaft torque Tsys corresponding to the predicted turbine speed Nte by referring to the first map MAP1. Then, the CPU 101 sets the system shaft torque Tsys derived by referring to the first map MAP1 as a first shaft torque judgment value TsysTh1.

[0052] The first map MAP1 is a map for the case where the predicted torque capacity Tce is less than the reference torque capacity Tcb, which will be described in detail later. When the predicted torque capacity Tce is less than the reference torque capacity Tcb, if the system shaft torque Tsys is equal to or greater than the first shaft torque determination value TsysTh1 set by referring to the first map MAP1, the generation of vibrations caused by starting the engine 10 can be suppressed even if the engine 10 is started in the second start process.

[0053] <Second judgment value candidate setting process> The second judgment value candidate setting process M17 derives the second shaft torque judgment value TsysTh2, which is one of the candidate values ​​of the shaft torque judgment value, by referring to the second map MAP2. The second map MAP2 is a map showing the relationship between the predicted turbine speed Nte and the system shaft torque Tsys. In the second map MAP2, when the predicted turbine speed Nte is less than the second reference speed Nte2, the system shaft torque Tsys corresponding to the predicted turbine speed Nte becomes a positive value. Specifically, when the predicted turbine speed Nte is less than the second reference speed Nte2, the system shaft torque Tsys corresponding to the predicted turbine speed Nte becomes larger as the predicted turbine speed Nte becomes smaller. On the other hand, when the predicted turbine speed Nte is equal to or greater than the second reference speed Nte2, the system shaft torque Tsys corresponding to the predicted turbine speed Nte becomes a negative value. Specifically, when the predicted turbine speed Nte is equal to or greater than the second reference speed Nte2, the absolute value of the system shaft torque Tsys corresponding to the predicted turbine speed Nte becomes larger as the predicted turbine speed Nte becomes larger. The second reference rotation speed Nte2 is set to a value greater than the first reference rotation speed Nte1.

[0054] In a second judgment value candidate setting process M17, the CPU 101 derives the system shaft torque Tsys corresponding to the predicted turbine rotation speed Nte by referring to the second map MAP2. Then, the CPU 101 sets the system shaft torque Tsys derived by referring to the second map MAP2 as the second shaft torque judgment value TsysTh2.

[0055] The second map MAP2 is a map for the case where the predicted torque capacity Tce is equal to or greater than the reference torque capacity Tcb, as described in detail below. When the predicted torque capacity Tce is equal to or greater than the reference torque capacity Tcb, if the system shaft torque Tsys is equal to or greater than the second shaft torque determination value TsysTh2 set by referring to the second map MAP2, the generation of vibrations caused by starting the engine 10 can be suppressed even if the engine 10 is started by the second start process.

[0056] Further, the first shaft torque determination value TsysTh1 is set in the first determination value candidate setting process M15, and the second shaft torque determination value TsysTh2 is set in the second determination value candidate setting process M17. Both the first shaft torque determination value TsysTh1 and the second shaft torque determination value TsysTh2 are torques corresponding to the predicted turbine speed Nte. In this embodiment, the first map MAP1 and the second map MAP2 are created so that the second shaft torque determination value TsysTh2 is larger than the first shaft torque determination value TsysTh1. Note that the dashed line in the graph showing the second map MAP2 is a line showing the relationship between the predicted turbine speed Nte and the system shaft torque Tsys in the first map MAP1.

[0057] <Settings process> The setting process M19 is a process for setting one of the first shaft torque judgment value TsysTh1 and the second shaft torque judgment value TsysTh2 as the shaft torque judgment value TsysTh. In the setting process M19, the CPU 101 sets the shaft torque judgment value TsysTh based on the above-mentioned predicted torque capacity Tce. Specifically, when the predicted torque capacity Tce is less than the reference torque capacity Tcb, the CPU 101 sets the first shaft torque judgment value TsysTh1 as the shaft torque judgment value TsysTh. On the other hand, when the predicted torque capacity Tce is equal to or greater than the reference torque capacity Tcb, the CPU 101 sets the second shaft torque judgment value TsysTh2 as the shaft torque judgment value TsysTh. Therefore, when the predicted torque capacity Tce is large, a value larger than when the predicted torque capacity Tce is small is set as the shaft torque judgment value TsysTh.

[0058] <Provisional Selection Process> The provisional selection process M21 is a process for provisionally selecting either the first start-up process or the second start-up process based on the shaft torque determination value TsysTh and the system shaft torque Tsys. In the provisional selection process M21, the CPU 101 provisionally selects the first start-up process when the system shaft torque Tsys is less than the shaft torque determination value TsysTh. On the other hand, the CPU 101 provisionally selects the second start-up process when the system shaft torque Tsys is equal to or greater than the shaft torque determination value TsysTh.

[0059] <Increase amount judgment value setting process> The increase amount determination value setting process M23 is a process for setting an increase amount determination value ΔTsRTh, which will be described later. In the increase amount determination value setting process M23, the CPU 101 sets the increase amount determination value ΔTsRTh based on the above-mentioned predicted torque capacity Tce, oil temperature TOIL, and gear position Z selected by the transmission mechanism 46. In this embodiment, the CPU 101 sets, as the increase amount determination value ΔTsRTh, a value obtained by correcting a reference increase amount determination value ΔTsRThb, which is a reference value of the increase amount determination value ΔTsRTh, based on the predicted torque capacity Tce, oil temperature TOIL, and gear position Z.

[0060] The CPU 101 sets a smaller value as the first correction gain G1 as the predicted torque capacity Tce is smaller. The CPU 101 sets a smaller value as the second correction gain G2 as the oil temperature TOIL is higher. The CPU 101 sets a smaller value as the third correction gain G3 as the gear stage Z selected by the transmission mechanism 46 is a higher gear stage. The multiple correction gains G1, G2, G3 are set to values ​​greater than 0 (zero) and less than or equal to 1. The CPU 101 then sets the product of the reference increase amount determination value ΔTsRThb, the first correction gain G1, the second correction gain G2, and the third correction gain G3 as the increase amount determination value ΔTsRTh.

[0061] <Final decision process> The final decision process M25 is a process for finally deciding the start process of the engine 10 when the start of the engine 10 is actually requested.

[0062] The final decision process M25 will be described with reference to Fig. 5. The CPU 101 repeatedly executes the final decision process M25 at each predetermined control cycle. In step S11, CPU 101 determines whether or not there is a request to start engine 10. If there is no request to start engine 10 (S11: NO), CPU 101 temporarily terminates final decision process M25. On the other hand, if there is a request to start engine 10 (S11: YES), CPU 101 shifts the process to step S13. In step S13, CPU 101 determines whether or not the first start process has been provisionally selected in provisional selection process M21. If the first start process has been provisionally selected (S13: YES), CPU 101 shifts the process to step S15. On the other hand, if the second start process has been provisionally selected (S13: NO), CPU 101 shifts the process to step S19.

[0063] In step S15, the CPU 101 determines whether the motor torque Tm has a margin. In this embodiment, the CPU 101 derives a maximum motor torque value at startup, which is a maximum value of the motor torque Tm at startup of the engine 10. Specifically, the CPU 101 derives a predicted value of the system shaft torque when electric power is most required at startup of the engine 10, using a torque request value TsR based on the accelerator opening ACCP. Next, the CPU 101 derives the sum of the predicted value of the system shaft torque and the reaction torque of the cranking torque as the maximum motor torque value at startup. Then, the CPU 101 determines that the motor torque Tm has a margin if the motor generator 30 can output the maximum motor torque at startup. On the other hand, the CPU 101 determines that the motor torque Tm does not have a margin if the motor generator 30 cannot output the maximum motor torque at startup. Then, when it is determined that the motor torque Tm has a margin (S15: YES), the CPU 101 shifts the process to step S21. On the other hand, when it is determined that the motor torque Tm has no margin (S15: NO), the CPU 101 shifts the process to step S17.

[0064] In step S17, CPU 101 determines whether or not the increase amount ΔTsR of torque request value TsR is equal to or greater than the increase amount determination value ΔTsRTh. When engine 10 is requested to start while the driver of vehicle 500 is operating the accelerator pedal, CPU 101 determines whether or not the increase amount ΔTsR of torque request value is equal to or greater than the increase amount determination value ΔTsRTh based on the increase amount of accelerator opening ACCP. For example, CPU 101 determines that the increase amount ΔTsR of torque request value is equal to or greater than the increase amount determination value ΔTsRTh based on the increase amount ΔACCP of accelerator opening ACCP within a predetermined period.

[0065] As shown in FIG. 6, the CPU 101 acquires the current value ACCP1 of the accelerator opening ACCP and the accelerator opening ACCP at a point in time a predetermined time TA before the present time as a reference accelerator opening ACCPb. The predetermined time TA is the length of the above-mentioned predetermined period. The CPU 101 derives the value obtained by subtracting the reference accelerator opening ACCPb from the current value ACCP1 of the accelerator opening as the increase amount ΔACCP of the accelerator opening within the predetermined period. Then, when the increase amount ΔACCP of the accelerator opening is equal to or greater than the opening increase amount judgment value ΔACCPth, the CPU 101 determines that the increase amount ΔTsR of the torque request value is equal to or greater than the increase amount judgment value ΔTsRTh. On the other hand, when the increase amount ΔACCP of the accelerator opening is less than the opening increase amount judgment value ΔACCPth, the CPU 101 determines that the increase amount ΔTsR of the torque request value is less than the increase amount judgment value ΔTsRTh.

[0066] In this embodiment, the increase amount determination value ΔTsRTh varies depending on the predicted torque capacity Tce, the oil temperature TOIL, and the gear position Z. Therefore, the larger the increase amount determination value ΔTsRTh, the larger the opening increase amount determination value ΔACCPth is set.

[0067] 5, if it is determined in step S17 that the increase amount ΔTsR of the torque request value is equal to or greater than the increase amount determination value ΔTsRTh (YES), the CPU 101 proceeds to step S19. On the other hand, if it is determined that the increase amount ΔTsR of the torque request value is less than the increase amount determination value ΔTsRTh (S17: NO), the CPU 101 proceeds to step S21.

[0068] In step S19, the CPU 101 determines the second start process as the process for starting the engine 10. After that, the CPU 101 ends the final determination process M25. In step S21, the CPU 101 determines the first start process as the process for starting the engine 10. After that, the CPU 101 ends the final determination process M25.

[0069] <Startup process> The start process M27 is a process for starting the engine 10. The CPU 101 starts the engine 10 by the start process determined in the final decision process M25. If the start process determined in the final decision process M25 is the first start process, the CPU 101 executes the first start process as the start process M27. If the start process determined in the final decision process M25 is the second start process, the CPU 101 executes the second start process as the start process M27.

[0070] <Actions and Effects of the Present Embodiment> When the hybrid driving mode is selected and the operation of the engine 10 is stopped, if the torque request value TsR increases due to the driver starting to operate the accelerator pedal, etc., a request may be made to start the engine 10. The control device 100 provides a first start process and a second start process as processes for starting the engine 10.

[0071] When starting the engine 10 in the first start process, as described with reference to Fig. 2, combustion in the engine 10 starts after the engine speed Ne is increased to the motor speed Nm. Therefore, fluctuations in the motor speed Nm caused by the start of the engine 10 can be easily suppressed by the motor generator 30 and the clutch 20. When starting the engine 10 in the first start process, a sudden change in the motor speed Nm caused by a sudden increase in the engine speed Ne can be suppressed, so vibrations caused by the start of the engine 10 are less likely to occur in the vehicle 500. However, because combustion does not start in the engine 10 until the engine speed Ne increases to the motor speed Nm, completion of the start of the engine 10 is delayed.

[0072] When starting the engine 10 in the second start process, combustion in the engine 10 starts in a state where the engine speed Ne is less than the motor speed Nm, as described with reference to Fig. 3. Therefore, it is difficult to suppress fluctuations in the motor speed Nm caused by the start of the engine 10 by the motor generator 30 or the clutch 20. As a result, vibrations caused by the start of the engine 10 are likely to occur in the vehicle 500. However, because the engine 10 is started before the engine speed Ne reaches the motor speed Nm, the start of the engine 10 can be completed early.

[0073] Here, the reason why vibrations due to the start of the engine 10 are more likely to occur in the vehicle 500 when the second start process is executed than when the first start process is executed will be described in detail. Immediately after the start of combustion in the engine 10, more specifically, immediately after the first explosion, the engine torque Te and the torque capacity Tc of the clutch 20 vary, so that the increase speed of the engine speed Ne is likely to vary. At this time, if the motor speed Nm is sufficiently high, the variation in the increase speed of the engine speed Ne converges, so that the synchronization timing of the clutch 20 does not vary much. On the other hand, if the motor speed Nm is relatively low, the variation in the increase speed of the engine speed Ne does not converge easily, so that the synchronization timing of the clutch 20 is likely to vary. The vibrations due to the start of the engine 10 can be alleviated by the motor torque Tm. However, since there is a response delay in the detection of the crank angle sensor 111 and the motor angle sensor 114, and a response delay in the motor torque Tm, it is necessary to predict the synchronization timing of the clutch 20 based on the increase speed of the engine speed Ne. In the first start process, since no combustion is occurring in the engine 10 prior to the synchronization timing, the rate of increase in the engine speed Ne is low and does not vary much. As a result, the synchronization timing of the clutch 20 can be predicted with high accuracy, and vibrations due to the start of the engine 10 are unlikely to occur.

[0074] In contrast, in the second start-up process, the increase rate of the engine speed Ne varies, so that the synchronization timing of the clutch 20 cannot be predicted with high accuracy. Therefore, the torque capacity Tc of the clutch 20 is temporarily reduced at the timing t23 shown in FIG. 3 to suppress vibrations caused by starting the engine 10. However, if the second start-up process is executed in a state where the motor torque Tm is relatively small, the synchronization timing of the clutch 20 may occur before the timing t23 at which the torque capacity Tc starts to be reduced. In this case, the torque capacity Tc is not reduced in time, so vibrations caused by starting the engine 10 occur.

[0075] Incidentally, the greater the increase ΔTsR in the torque request value, the greater the acceleration of the vehicle 500. When the acceleration of the vehicle 500 is large, compared to when the acceleration is small, the passengers of the vehicle 500 are less likely to feel uncomfortable due to vibrations occurring in the vehicle 500. Also, when the increase ΔTsR in the torque request value is large, it is desirable to complete the start of the engine 10 early and quickly increase the engine torque Te.

[0076] In this embodiment, when starting the engine 10, if the increase amount ΔTsR of the torque request value is equal to or greater than the increase amount determination value ΔTsRTh, the engine 10 is started by the second start processing. In this case, the start of the engine 10 can be completed early, and even if vibrations due to the start of the engine 10 occur in the vehicle 500, the passengers are unlikely to feel uncomfortable due to the vibrations. On the other hand, when starting the engine 10, if the increase amount ΔTsR of the torque request value is less than the increase amount determination value ΔTsRTh, the engine 10 is started by the first start processing. In this case, although a delay occurs in the completion of the start of the engine 10, vibrations due to the start of the engine 10 are unlikely to occur in the vehicle 500.

[0077] Therefore, the control device 100 can simultaneously suppress discomfort felt by the occupants when the engine 10 is started and quickly complete the starting of the engine 10. In addition, the present embodiment can further provide the following effects.

[0078] (1) When the increase amount ΔTsR of the torque request value is equal to or greater than the increase amount determination value ΔTsRTh, the second start process is executed, and the start of the engine 10 is completed early. That is, a state in which the system shaft torque Tsys can be increased by the engine torque Te can be created early. Therefore, a response delay in the increase of the system shaft torque Tsys to the increase of the torque request value TsR can be suppressed. On the other hand, when the increase amount ΔTsR of the torque request value is less than the increase amount determination value ΔTsRTh, the increase speed of the system shaft torque Tsys does not need to be so large. Therefore, the engine 10 is started by the first start process. Therefore, when the vehicle 500 is not required to rapidly accelerate, the generation of vibrations accompanying the start of the engine 10 can be suppressed, and the occupants are less likely to feel uncomfortable when the engine 10 is started.

[0079] (2) In this embodiment, when the start of the engine 10 is not requested, either the first start process or the second start process is provisionally selected as a process for starting the engine 10. Specifically, when the system shaft torque Tsys is less than the shaft torque determination value TsysTh, the first start process is provisionally selected. When the system shaft torque Tsys is equal to or greater than the shaft torque determination value TsysTh, the second start process is provisionally selected.

[0080] Here, when the system shaft torque Tsys is equal to or greater than the shaft torque judgment value TsysTh, the motor speed Nm is unlikely to fluctuate even if the engine speed Ne increases suddenly. That is, vibrations caused by starting the engine 10 are unlikely to occur in the vehicle 500.

[0081] Then, when the start of the engine 10 is requested while the second start process is provisionally selected, the engine 10 is started by the second start process even if the increase amount ΔTsR of the torque request value is less than the increase amount determination value ΔTsRTh. Therefore, it is possible to complete the start of the engine 10 early while suppressing discomfort felt by the driver when starting the engine 10. Also, it is possible to increase the opportunities to start the engine 10 by the second start process.

[0082] On the other hand, when the first start process is provisionally selected and start of the engine 10 is requested, and the increase amount ΔTsR of the torque request value is less than the increase amount determination value ΔTsRTh, the engine 10 is started by the first start process. That is, when the system shaft torque Tsys is small and vibrations are likely to occur in the vehicle 500 when starting the engine 10, the first start process is executed. When starting the engine 10 by the first start process, vibrations are unlikely to occur in the vehicle 500, and therefore passengers are unlikely to feel uncomfortable when starting the engine 10.

[0083] (3) In the case where the torque capacity Tc of the clutch 20 is small when the engine 10 is assumed to be started in the second start process, when the engine torque Te rises suddenly, the clutch 20 is likely to attenuate the fluctuation of the engine torque Te. That is, the smaller the torque capacity Tc is when the engine 10 is assumed to be started in the second start process, the less likely vibrations caused by the start of the engine 10 are to occur in the vehicle 500. Therefore, in this embodiment, the smaller the predicted torque capacity Tce, which is the predicted value of the torque capacity when the engine 10 is assumed to be started in the second start process, the smaller the value is set as the increase amount determination value ΔTsRTh. As a result, when it is predicted that the torque capacity Tc can be reduced when the engine 10 is started in the second start process, the second start process is likely to be executed. That is, it is possible to increase the opportunities for executing the second start process while suppressing vibrations from occurring in the vehicle 500 when the engine 10 is started.

[0084] (4) When the oil temperature TOIL is high and the viscosity of the hydraulic oil is low, it is easy to adjust the clutch hydraulic pressure Pc. That is, when a command is issued to reduce the clutch hydraulic pressure Pc, the clutch hydraulic pressure Pc starts to decrease quickly. On the other hand, when the oil temperature TOIL is low and the viscosity of the hydraulic oil is high, it is difficult to adjust the clutch hydraulic pressure Pc. That is, the responsiveness of the clutch hydraulic pressure Pc when a command is issued to reduce the clutch hydraulic pressure Pc is low. For example, even if a command is issued to reduce the clutch hydraulic pressure Pc to reduce the torque capacity Tc of the clutch 20 at timing t23 shown in FIG. 3, the start of the decrease in the clutch hydraulic pressure Pc is delayed. As a result, the engine speed Ne increases before the torque capacity Tc actually decreases, and vibrations caused by the start of the engine 10 are likely to occur.

[0085] In this embodiment, the higher the oil temperature TOIL, the smaller the value set as the increase amount determination value ΔTsRTh. As a result, when the oil temperature TOIL is high and the responsiveness of the clutch oil pressure Pc is high, the second start-up process is more likely to be executed. In other words, it is possible to increase the opportunities for executing the second start-up process while suppressing the generation of vibrations in the vehicle 500 when the engine 10 is started.

[0086] (5) When a higher gear is selected as the gear Z of the transmission mechanism 46, vibrations caused by starting the engine 10 are less likely to become large compared to when a lower gear is selected as the gear Z of the transmission mechanism 46. In this embodiment, the higher the gear Z selected by the transmission mechanism 46, the smaller the value set as the increase amount determination value ΔTsRTh. This makes it easier to execute the second start process as the gear Z is a higher gear. That is, it is possible to increase the opportunities for executing the second start process while suppressing vibrations from occurring in the vehicle 500 when the engine 10 is started.

[0087] <Example of change> The above embodiment can be modified as follows: The above embodiment and the following modifications can be combined with each other to the extent that no technical contradiction occurs.

[0088] The increase amount determination value ΔTsRTh does not have to be variable according to the gear position Z selected by the transmission mechanism 46. In this case, the vehicle 500 may not be equipped with a transmission.

[0089] The increase amount determination value ΔTsRTh does not have to be varied in response to the oil temperature TOIL. In this case, an electromagnetically driven clutch may be used as the clutch disposed between the engine 10 and the motor generator 30.

[0090] The increase amount determination value ΔTsRTh does not have to be varied in accordance with the predicted torque capacity Tce. In the above embodiment, the increase amount determination value ΔTsRTh is varied based on the predicted torque capacity Tce, the gear Z, and the oil temperature TOIL, while the length of the predetermined period is fixed, but this is not limited thereto. For example, the increase amount determination value ΔTsRTh may be fixed, and the length of the predetermined period may be varied according to at least one parameter among the predicted torque capacity Tce, the gear Z, and the oil temperature TOIL. For example, the smaller the predicted torque capacity Tce is, the longer the length of the predetermined period may be. Also, for example, the higher the gear Z is, the longer the length of the predetermined period may be. Also, for example, the higher the oil temperature TOIL is, the longer the length of the predetermined period may be.

[0091] In cases where the vehicle 500 has a function of automatically controlling the vehicle speed, acceleration of the vehicle 500 may be requested from a control device other than the control device 100. Examples of the other control devices include a control device that controls the brakes of the vehicle 500 and a control device that generates various commands related to automatic driving. In this case, the control device 100 derives the torque request value TsR based on the request or command from the other control device. Then, using the increase amount ΔTsR of the torque request value at this time, it is determined whether to execute the first start-up process or the second start-up process.

[0092] In the above embodiment, when there is no request to start the engine 10, the temporary selection process M21 temporarily selects either the first start process or the second start process as a process for starting the engine 10, but this is not limiting. In other words, the temporary selection process M21 does not have to be executed.

[0093] For example, when a start of the engine 10 is requested, it may be determined whether the system shaft torque Tsys is equal to or greater than the shaft torque determination value TsysTh and whether the increase amount ΔTsR of the torque request value is equal to or greater than the increase amount determination value ΔTsRTh. If at least one of the following is true: the system shaft torque Tsys is equal to or greater than the shaft torque determination value TsysTh and the increase amount ΔTsR of the torque request value is equal to or greater than the increase amount determination value ΔTsRTh, it is preferable to execute the second start processing. On the other hand, if neither the system shaft torque Tsys is equal to or greater than the shaft torque determination value TsysTh nor the increase amount ΔTsR of the torque request value is equal to or greater than the increase amount determination value ΔTsRTh is true, it is preferable to execute the first start processing.

[0094] Also, for example, when a request is made to start the engine 10, it may be determined whether the increase amount ΔTsR of the torque request value is equal to or greater than the increase amount determination value ΔTsRTh, and if the increase amount ΔTsR of the torque request value is equal to or greater than the increase amount determination value ΔTsRTh, the second start-up process is executed. On the other hand, if the increase amount ΔTsR of the torque request value is less than the increase amount determination value ΔTsRTh, the first start-up process is executed. In this case, the process to be executed is determined from the first start-up process and the second start-up process, regardless of the magnitude of the system shaft torque Tsys.

[0095] In the final decision process M25 shown in FIG. 5, the determination in step S15 may be omitted. There may be a plurality of first maps MAP1 corresponding to the motor rotation speed Nm. In this case, in the first judgment value candidate setting process M15, the first map MAP1 corresponding to the motor rotation speed Nm at that time is selected from the plurality of first maps MAP1. Then, by referring to the selected first map MAP1, the system shaft torque Tsys corresponding to the predicted turbine rotation speed Nte is set as the first shaft torque judgment value TsysTh1.

[0096] There may be a plurality of second maps MAP2 corresponding to the motor rotation speed Nm. In this case, in the second judgment value candidate setting process M17, the second map MAP2 corresponding to the motor rotation speed Nm at that time is selected from the plurality of second maps MAP2. Then, by referring to the selected second map MAP2, the system shaft torque Tsys corresponding to the predicted turbine rotation speed Nte is set as the second shaft torque judgment value TsysTh2.

[0097] In the above embodiment, the electric pump 80 and the hydraulic control circuit 90 that supply hydraulic oil to the transmission 40 also serve as a system for supplying hydraulic pressure to the clutch 20, but this is not limited to the above. A device that supplies hydraulic pressure to the clutch 20 may be provided separately from the electric pump 80 and the hydraulic control circuit 90.

[0098] The transmission may not include a torque converter. The transmission mechanism may be a continuously variable transmission mechanism. In this case, the increase amount determination value ΔTsRTh may be set according to the gear ratio of the transmission mechanism.

[0099] The control device 100 is not limited to a device having a CPU and ROM and executing software processing. That is, the control device 100 may have any one of the following configurations (a) to (c).

[0100] (a) The control device 100 includes one or more processors that execute various processes according to a computer program. The processor includes a CPU and memory such as RAM and ROM. The memory stores program codes or instructions that are configured to cause the CPU to execute processes. The memory, i.e., computer-readable medium, includes any available medium that can be accessed by a general-purpose or special-purpose computer.

[0101] (b) The control device 100 includes one or more dedicated hardware circuits that execute various processes. Examples of the dedicated hardware circuits include application specific integrated circuits, i.e., ASIC and FPGA. ASIC is an abbreviation for "Application Specific Integrated Circuit" and FPGA is an abbreviation for "Field Programmable Gate Array."

[0102] (c) The control device 100 includes a processor that executes some of the various processes in accordance with a computer program, and a dedicated hardware circuit that executes the remaining processes among the various processes. [Explanation of symbols]

[0103] 10…Engine 18…Crankshaft 20…Clutch 30…Motor generator 31...Drive shaft 40…Gearbox 46…Gearbox 100...Control device 101...CPU 500…Hybrid vehicle

Claims

1. The present invention is applied to a hybrid vehicle that includes an engine having a crankshaft and a motor generator having a driveshaft as a power source of the vehicle, and a clutch is disposed between the crankshaft and the driveshaft, an execution device for controlling the engine, the motor generator, and the clutch; The execution device is when starting the engine under a condition where an increase amount of a torque request value, which is a torque request value for the power source, is less than an increase amount determination value, a first start process is executed to increase an engine speed, which is the rotation speed of the crankshaft, to a motor speed, which is the rotation speed of the drive shaft, by engaging the clutch, and then start combustion in the engine; when starting the engine under a condition where an increase amount of the torque requirement value is equal to or greater than the increase amount determination value, when the crankshaft starts to rotate by engaging the clutch, a second start process is executed to start combustion in the engine before the engine speed reaches the motor speed; When starting the engine, if at least one of the following is true: a system shaft torque, which is a shaft torque of the drive shaft, is equal to or greater than a shaft torque judgment value, and an increase in the torque request value is equal to or greater than the increase amount judgment value, the second start-up process is executed; whereas if neither the system shaft torque is equal to or greater than the shaft torque judgment value, nor the increase in the torque request value is equal to or greater than the increase amount judgment value, the first start-up process is executed. Hybrid vehicle control device.

2. The present invention is applied to a hybrid vehicle that includes an engine having a crankshaft and a motor generator having a driveshaft as a power source of the vehicle, and a clutch is disposed between the crankshaft and the driveshaft, an execution device for controlling the engine, the motor generator, and the clutch; The execution device is when starting the engine under a condition where an increase amount of a torque request value, which is a torque request value for the power source, is less than an increase amount determination value, a first start process is executed to increase an engine speed, which is the rotation speed of the crankshaft, to a motor speed, which is the rotation speed of the drive shaft, by engaging the clutch, and then start combustion in the engine; when starting the engine under a condition where an increase amount of the torque requirement value is equal to or greater than the increase amount determination value, when the crankshaft starts to rotate by engaging the clutch, a second start process is executed to start combustion in the engine before the engine speed reaches the motor speed; The increase amount determination value is set to a smaller value as the predicted value of the torque capacity of the clutch when it is assumed that the engine is started in the second start process is smaller. Hybrid vehicle control device.

3. The present invention is applied to a hybrid vehicle that includes an engine having a crankshaft and a motor generator having a driveshaft as a power source of the vehicle, and a clutch is disposed between the crankshaft and the driveshaft, an execution device for controlling the engine, the motor generator, and the clutch; The execution device is when starting the engine under a condition where an increase amount of a torque request value, which is a torque request value for the power source, is less than an increase amount determination value, a first start process is executed to increase an engine speed, which is the rotation speed of the crankshaft, to a motor speed, which is the rotation speed of the drive shaft, by engaging the clutch, and then start combustion in the engine; when starting the engine under a condition where an increase amount of the torque requirement value is equal to or greater than the increase amount determination value, when the crankshaft starts to rotate by engaging the clutch, a second start process is executed to start combustion in the engine before the engine speed reaches the motor speed; The hybrid vehicle includes a hydraulically driven clutch as the clutch, The execution device sets the increase amount determination value to a smaller value as the temperature of the hydraulic oil of the clutch increases. Hybrid vehicle control device.

4. the hybrid vehicle includes a transmission, and the motor generator is disposed between the clutch and the transmission in a torque transmission path; The execution device sets the increase amount determination value to a smaller value as the gear stage selected by the transmission becomes a higher gear stage. The control device for a hybrid vehicle according to claim 2 or 3.

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