Hybrid vehicle control device

Abstract

To provide a control device of a hybrid vehicle that can reduce a feeling of strangeness that a driver has in starting control of an internal combustion engine.SOLUTION: An electronic control device 90 measures a deviation period of time Pdev during which a difference between target system shaft torque Tsystgt which is a required value by a driver for system shaft torque Tsys which is torque outputted from a driving force source PG for travelling to a driving wheel 34 side during execution of cranking of an engine 12, and an upper limit guard value Tsysgd of the system shaft torque Tsys that can be outputted from an electric motor MG deviates beyond a predetermined value α (a), and when the deviation period of time Pdev is long, performs control so that a target increase rate βtgt of an indicated value Tsyscm for the system shaft torque Tsys becomes lower after a time point when the upper limit guard value Tsysgd reaches the maximum MG torque Tmgmax, after a time point when engine torque Te can be used as the system shaft torque Tsys, in comparison with when the variation period is short (b).SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a control device for a hybrid vehicle that includes an internal combustion engine and an electric motor as driving power sources for traveling, and a friction engagement device that connects and disconnects power transmission between the internal combustion engine and the electric motor. [Background technology]

[0002] In a hybrid vehicle equipped with an internal combustion engine and an electric motor as driving force sources for driving, and a friction engagement device for connecting and disconnecting the power transmission between the internal combustion engine and the electric motor, there is known a method in which, when the internal combustion engine is started, the friction engagement device is engaged and the electric motor cranks the internal combustion engine. For example, this is described in Patent Document 1. Patent Document 1 also discloses a method in which, in controlling the driving torque of the hybrid vehicle, the torque output from the driving force source for driving to the driving wheels is treated as a system shaft torque, and a required value (target value) of the system shaft torque by the driver is calculated when performing various controls of the driving torque of the hybrid vehicle, and the driving force source for driving is controlled according to the required value. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2013-23155 A Summary of the Invention [Problem to be solved by the invention]

[0004] During the cranking in the start control of the internal combustion engine, an upper limit may be set for the system shaft torque, and the difference between the required value of the system shaft torque and the upper limit of the system shaft torque may exceed a predetermined value. If the difference between the required value of the system shaft torque and the upper limit of the system shaft torque during the cranking exceeds the predetermined value for a long period of time, if the change (=increase) per unit time of the system shaft torque after the completion of the cranking is large, the driver is likely to feel a sudden and sudden increase in the system shaft torque (uncomfortable feeling).

[0005] The present invention has been made against the background of the above circumstances, and an object of the present invention is to provide a control device for a hybrid vehicle that can reduce the sense of discomfort felt by the driver during start-up control of the internal combustion engine. [Means for solving the problem]

[0006] The gist of the first invention is a control device for a hybrid vehicle having an internal combustion engine and an electric motor as driving force sources for driving, and a friction engagement device that disconnects power transmission between the internal combustion engine and the electric motor, which (a) when starting the internal combustion engine, cranks the internal combustion engine using the electric motor while engaging the friction engagement device, (b) measures a deviation period during which the difference between a driver's requested value of system shaft torque, which is the torque output from the driving force source for driving to the drive wheels, and an upper limit value of the system shaft torque that can be output from the electric motor exceeds a predetermined value, and (c) when the deviation period is long, controls so that the amount of change per unit time of the system shaft torque after the output of the internal combustion engine becomes usable as the system shaft torque and after the upper limit value reaches the maximum value that the electric motor can output is smaller than when the deviation period is short. Effect of the Invention

[0007] According to the control device for a hybrid vehicle of the first invention, (a) when the internal combustion engine is started, the friction engagement device is engaged and the electric motor cranks the internal combustion engine, (b) a deviation period during which the difference between a driver's request value of the system shaft torque, which is the torque output from the driving force source for driving to the drive wheels, and an upper limit value of the system shaft torque that can be output from the electric motor exceeds a predetermined value is measured, and (c) when the deviation period is long, the system shaft torque is controlled so that the change in the system shaft torque per unit time after the output of the internal combustion engine becomes usable as the system shaft torque and after the upper limit value reaches the maximum value that the electric motor can output is smaller than when the deviation period is short. When the deviation period during cranking is long, the driver is more likely to feel (uncomfortable) that the system shaft torque suddenly increases if the change in the system shaft torque per unit time after cranking is large compared to when the deviation period is short. When the deviation period is long, the amount of change per unit time of the system shaft torque after the output of the internal combustion engine becomes usable as system shaft torque and after the upper limit value of the maximum value that the electric motor can output is reached is controlled to be smaller than when the deviation period is short, thereby reducing the discomfort felt by the driver.

[0008] According to the control device for a hybrid vehicle of the second invention, in the first invention, when the deviation period is long, the amount of change per unit time of the system shaft torque during the period from the completion of cranking of the internal combustion engine to the time when the upper limit of the maximum value that the electric motor can output is reached is controlled to be smaller than when the deviation period is short. When the deviation period is long, the amount of change per unit time of the system shaft torque during the period from the completion of cranking of the internal combustion engine to the time when the upper limit of the maximum value that the electric motor can output is reached is controlled to be smaller than when the deviation period is short, thereby reducing the discomfort felt by the driver. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic configuration diagram of a hybrid vehicle equipped with an electronic control device according to a first embodiment of the present invention, and is also a functional block diagram showing essential parts of control functions for various controls in the electronic control device. [Diagram 2] 10 is a diagram illustrating an example of a predetermined relationship between an accelerator opening degree and a deviation period, and a target increase rate of an instruction value of a system shaft torque. FIG. [Diagram 3] 2 is an example of a flowchart illustrating a control operation of the electronic control device shown in FIG. 1. [Figure 4] 4 is an example of a time chart in the case where the flowchart of FIG. 3 is executed when the engine is started from a stopped state by the early ignition start method according to the first embodiment of the present invention. [Diagram 5] 5 is an example of a time chart in a case where the flowchart of FIG. 3 is executed when the engine is restarted by the early ignition start method from a state in which the engine is under stop control according to the second embodiment of the present invention. [Figure 6] 10 is an example of a time chart in a case where the flowchart of FIG. 3 is executed when the engine is started from a stopped state by a push start method according to a third embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, each embodiment of the present invention will be described in detail with reference to the drawings. Note that in each embodiment, the drawings are appropriately simplified or modified, and the dimensional ratios and shapes of each part are not necessarily drawn accurately. EXAMPLES

[0011] FIG. 1 is a schematic configuration diagram of a hybrid vehicle 10 (hereinafter simply referred to as “vehicle 10”) equipped with an electronic control device 90 according to a first embodiment of the present invention, and is also a functional block diagram showing the main control functions for various controls in vehicle 10.

[0012] The vehicle 10 includes an engine 12 and an electric motor MG, which are driving power sources PG for traveling, and a power transmission device 14 provided on a power transmission path PT between the engine 12 and a pair of drive wheels 34. The vehicle 10 is a hybrid vehicle. The vehicle 10 also includes an inverter 52, a hydraulic control circuit 50, a battery 54, and an electronic control device 90.

[0013] The engine 12 is a well-known internal combustion engine. An electronic control device 90, which will be described later, controls a throttle actuator, a fuel injection device, an ignition device, and the like provided in the engine 12, thereby controlling an engine torque Te [Nm] that is an output torque of the engine 12. When the engine 12 is in an operating state, the engine 12 outputs the engine torque Te, and when the engine 12 is in a stopped state, the engine 12 does not output the engine torque Te. In this specification, unless otherwise specified, the terms torque, driving force, motive power, and force (power) are synonymous.

[0014] The power transmission device 14 includes, in order from the engine 12 side, an engine connecting shaft 32, a clutch K0, a rotor shaft 40 of the electric motor MG, a torque converter 16, an AT input shaft 36 which is an input rotating member of the automatic transmission 18, the automatic transmission 18, etc., within a case 20 which is a non-rotating member attached to the vehicle body. The power transmission device 14 also includes a differential gear 28 which is connected to an AT output shaft 24 which is an output rotating member of the automatic transmission 18, a pair of axles 30 which are connected to the differential gear 28, etc.

[0015] The engine connecting shaft 32 is a member that connects the engine 12 and the clutch K0, and is, for example, a crankshaft.

[0016] The electric motor MG is a so-called motor generator having a function as an electric motor that generates mechanical power from electric energy (electric motor function) and a function as a generator that generates electric energy from mechanical power (generator function). The electric motor MG is connected to a battery 54 provided in the vehicle 10 via an inverter 52 described later. The battery 54 is an electricity storage device that supplies and receives electric power to the electric motor MG. The electric motor MG has an MG torque Tmg [Nm], which is an output torque of the electric motor MG, controlled by an electronic control device 90 described later controlling the inverter 52.

[0017] A clutch K0 is provided between an engine connecting shaft 32 connected to the engine 12 and a rotor shaft 40 connected to a rotor of the electric motor MG. The clutch K0 is an engagement device capable of connecting and disconnecting the power transmission between the engine 12 and the rotor shaft 40, and is, for example, a wet-type multi-plate hydraulic friction engagement device. When the clutch K0 is fully engaged, the clutch K0 enables the power transmission between the engine 12 and the electric motor MG. When the clutch K0 is released, the clutch K0 cuts off the power transmission between the engine 12 and the electric motor MG. When the clutch K0 is half-engaged, i.e., in a slip engagement state, the clutch K0 enables the power transmission between the engine 12 and the electric motor MG according to a transmission torque capacity (engagement force of the clutch K0) based on the slip engagement state. The clutch K0 corresponds to the "friction engagement device" in the present invention.

[0018] The electric motor MG is driven to rotate by the electric power stored in the battery 54, and outputs the driving force for running the hybrid vehicle 10. The electric motor MG also generates electric power using the driving force for running input from the engine 12 via the clutch K0, and also generates electric power by converting the driven force input from the drive wheels 34 side into electric power through regeneration. The generated electric power is charged to the battery 54 via the inverter 52.

[0019] The inverter 52 is a power supply circuit provided between the electric motor MG and the battery 54, and converts direct current to alternating current or alternating current to direct current under the control of the electronic control device 90. For example, the inverter 52 converts direct current supplied from the battery 54 into alternating current and outputs it to the electric motor MG to drive it, or converts alternating current generated by the electric motor MG into direct current and outputs it to the battery 54.

[0020] The battery 54 is a chargeable and dischargeable secondary battery such as a lithium ion battery, a nickel metal hydride battery, etc. The battery 54 is mainly used to supply power for driving the electric motor MG and to store electric power generated by the electric motor MG through regeneration.

[0021] The torque converter 16 is a well-known torque converter. The torque converter 16 includes a pump wheel 16a connected to a rotor shaft 40, a turbine wheel 16b connected to an AT input shaft 36, and a lock-up clutch 38 that directly connects the pump wheel 16a and the turbine wheel 16b. The torque converter 16 is disposed in a power transmission path PT between a driving force source PG (engine 12, electric motor MG) and drive wheels 34, and is a fluid-type transmission device that can transmit the driving force for traveling output from the driving force source PG to the AT input shaft 36 via a fluid from the rotor shaft 40. The vehicle 10 includes a mechanical oil pump 22. The oil pump 22 is connected to the pump wheel 16a, and is rotationally driven by the driving force source PG (engine 12, electric motor MG) to discharge hydraulic oil OIL used in the power transmission device 14.

[0022] The automatic transmission 18 is a known automatic transmission that changes the speed of the driving force input from the driving force source PG (engine 12, electric motor MG) to the AT input shaft 36 and outputs the changed speed to the AT output shaft 24, and is, for example, a stepped transmission of a planetary gear type or a constant meshing parallel shaft type, or a continuously variable transmission of a belt type or a power roller type. The automatic transmission 18 is controlled by a hydraulic control circuit 50 controlled by an electronic control device 90 so that a desired gear ratio γ (=AT input rotation speed Nin [rpm] / AT output rotation speed Nout [rpm]) is formed. The gear ratio γ is also called a gear ratio. In this embodiment, the automatic transmission 18 is a known planetary gear type automatic transmission that includes a plurality of planetary gear devices and a plurality of shift engagement devices CB. Each of the shift engagement devices CB is switched between an engagement / disengagement state, such as a fully engaged state, a half-engaged state, and a disengaged state, by adjusting the hydraulic pressure supplied from the hydraulic control circuit 50 to a hydraulic actuator that controls the engagement / disengagement state of the shift engagement devices CB. In the automatic transmission 18, one of a plurality of gear stages (also referred to as gear stages) having different gear ratios γ is formed by engagement of any of the engagement devices of the shift engagement devices CB.

[0023] The differential gear 28 is a well-known differential gear that receives the driving force for traveling transmitted from the AT output shaft 24 of the automatic transmission 18 and transmits equal driving torque to a pair of axles 30 while allowing an appropriate difference in rotational speed.

[0024] The hydraulic control circuit 50 uses the hydraulic pressure of the hydraulic oil OIL discharged from the oil pump 22 as the source pressure and supplies the necessary hydraulic oil OIL to each part in the case 20. For example, the hydraulic control circuit 50 generates hydraulic pressure for controlling the engagement and disengagement of the clutch K0, hydraulic pressure for controlling the shifting of the automatic transmission 18, and hydraulic pressure for controlling the engagement and disengagement of the lock-up clutch 38 of the torque converter 16, and supplies these to each hydraulic actuator in the case 20.

[0025] In the power transmission device 14, when the clutch K0 is in a fully engaged state, the driving force for traveling output from the engine 12 is transmitted from the engine connecting shaft 32 to the drive wheels 34 via the clutch K0, the rotor shaft 40, the torque converter 16, the automatic transmission 18, the differential gear 28, the pair of axles 30, etc. in this order. The driving force for traveling output from the electric motor MG is transmitted from the rotor shaft 40 to the drive wheels 34 via the torque converter 16, the automatic transmission 18, the differential gear 28, the pair of axles 30, etc. in this order, regardless of whether the clutch K0 is engaged or disengaged. In this manner, the driving torque Tr for traveling is transmitted from at least one of the engine 12 and the electric motor MG to the drive wheels 34.

[0026] In the vehicle 10, either of the driving modes of the BEV driving mode and the engine driving mode, i.e., the HEV driving mode, can be selected. The BEV driving mode is a driving mode in which the motor MG is powered while the engine 12 is stopped, thereby performing BEV (Battery Electric Vehicle) driving using only the motor MG as a driving force source among the driving force sources PG for driving. In the BEV driving mode, the clutch K0 is in a released state, and the BEV driving is performed. The HEV driving mode is a driving mode in which the engine 12 is operated while performing HEV (Hybrid Electric Vehicle) driving using at least the engine 12 as a driving force source among the driving force sources PG for driving. In the HEV driving mode, the clutch K0 is in a fully engaged state, and the HEV driving is performed.

[0027] The driving mode of the vehicle 10 is switched between the BEV driving mode and the HEV driving mode, for example, by a driving force source switching map. The driving force source switching map is a relationship in which the driving mode is predetermined in two-dimensional coordinates with, for example, the vehicle speed V [km / h] and the target system shaft torque Tsystgt [Nm] as variables. The target system shaft torque Tsystgt is a target value (request value) of the system shaft torque Tsys [Nm] based on a request from the driver. The system shaft torque Tsys is a driving torque output from the driving force source PG to the driving wheels 34 and transmitted to the driving wheels 34, for example, a driving torque at the rotor shaft 40 input to the torque converter 16. A calculation method of the target system shaft torque Tsystgt will be described later. The target system shaft torque Tsystgt corresponds to the "driver's request value of the system shaft torque" in the present invention.

[0028] Generally, the BEV driving mode is selected in a low vehicle speed region where the vehicle speed V is relatively low and the target system shaft torque Tsystgt is relatively low (= the accelerator opening θacc [%] is relatively low), where engine efficiency is reduced. On the other hand, the HEV driving mode is selected in a high vehicle speed region where the vehicle speed V is relatively high or in a high load region where the target system shaft torque Tsystgt is relatively high (= the accelerator opening θacc is relatively high).

[0029] The electronic control device 90 includes a so-called microcomputer equipped with, for example, a CPU, RAM, ROM, an input / output interface, etc., and the CPU executes various controls of the vehicle 10 by performing signal processing according to a program previously stored in the ROM while utilizing the temporary storage function of the RAM. The electronic control device 90 includes computers for engine control, electric motor control, hydraulic control, etc. as necessary. The electronic control device 90 corresponds to the "control device" in this invention.

[0030] The electronic control device 90 receives various signals based on detection values ​​from various sensors provided in the vehicle 10 (e.g., engine rotation speed sensor 70, turbine rotation speed sensor 72, output shaft rotation speed sensor 74, MG rotation speed sensor 76, accelerator opening sensor 78, throttle valve opening sensor 80, battery sensor 82, etc.) (e.g., engine rotation speed Ne [rpm] which is the rotation speed of the engine 12, turbine rotation speed Nt [rpm] which is the same value as the AT input rotation speed Nin [rpm], AT output rotation speed Nout [rpm] which corresponds to the vehicle speed V, MG rotation speed Nmg [rpm] which is the rotation speed of the electric motor MG, accelerator opening θacc [%] which is the driver's accelerator operation amount which indicates the magnitude of the driver's acceleration operation, throttle valve opening θth [%] which is the opening of the electronic throttle valve, battery temperature THbat [°C] of the battery 54, battery charge / discharge current Ibat [A], battery voltage Vbat [V], etc.).

[0031] The electronic control device 90 outputs various command signals (e.g., an engine control signal Se for controlling the engine 12, an MG control signal Smg for controlling the electric motor MG, a shift control signal Sat for controlling the shift engagement device CB, a K0 control signal Sk0 for controlling the clutch K0, and an LU control signal Slu for controlling the lock-up clutch 38) to each device (e.g., the engine 12, the inverter 52, the hydraulic control circuit 50, etc.) provided in the vehicle 10.

[0032] The electronic control unit 90 functionally comprises a hybrid control unit 92, a clutch control unit 94, a gear shift control unit 96, and a system shaft torque control unit 98.

[0033] The hybrid control unit 92 functionally comprises an engine control unit 92a that controls the operation of the engine 12, and an electric motor control unit 92b that controls the operation of the electric motor MG via the inverter 52, and performs hybrid drive control using the engine 12 and the electric motor MG, etc., using these control functions.

[0034] The clutch control unit 94 controls the engagement / disengagement state of the clutch K0 according to the driving mode. For example, in the BEV driving mode, the clutch control unit 94 controls the clutch K0 to be in a released state. For example, in the HEV driving mode, the clutch control unit 94 controls the clutch K0 to be in a fully engaged state. In the HEV driving mode, the MG rotation speed Nmg is equal to the engine rotation speed Ne.

[0035] The shift control unit 96 judges whether or not to shift the automatic transmission 18 by using, for example, a shift map, and outputs a shift control signal Sat for executing shift control to the hydraulic control circuit 50. The shift map is a predetermined relationship having a shift line for judging whether or not to shift the automatic transmission 18 on a two-dimensional coordinate system having, for example, the vehicle speed V and the target system shaft torque Tsystgt as variables. In the shift map, the AT output rotation speed Nout or the like may be used instead of the vehicle speed V, and the required driving force Frdem, accelerator opening θacc, throttle valve opening θth, or the like, which will be described later, may be used instead of the target system shaft torque Tsystgt.

[0036] The hybrid control unit 92 calculates a drive amount required by the driver for the vehicle 10 (for example, a target system shaft torque Tsystgt) by applying the actual accelerator opening θacc and the vehicle speed V to a required drive amount map, for example. The required drive amount map is a map in which the relationship between the accelerator opening θacc and the vehicle speed V and the required drive amount is determined in advance experimentally or by design and stored. The required drive amount is a drive amount required for the vehicle 10, for example, a target system shaft torque Tsystgt. In other words, the target system shaft torque Tsystgt is a required drive power Prdem [W] at the vehicle speed V at that time. As the required drive amount, a required drive torque Trdem [Nm] at the drive wheels 34, a required drive force Frdem [N] at the drive wheels 34, a required output torque at the AT output shaft 24, etc. may also be used. In calculating the required drive amount, an AT output rotation speed Nout, etc. may be used instead of the vehicle speed V. In this way, the target system shaft torque Tsystgt, the required driving torque Trdem, the required driving power Prdem, the required driving force Frdem, and the required output torque at the AT output shaft 24 are all the same in that they are the required driving amounts of the vehicle 10.

[0037] The hybrid control unit 92 outputs an engine control signal Se for controlling the engine 12 and an MG control signal Smg for controlling the electric motor MG so as to realize the required driving power Prdem, taking into consideration the transmission loss, the auxiliary load, the gear ratio γ of the automatic transmission 18, the chargeable power Win [W] and the dischargeable power Wout [W] of the battery 54, etc. The engine control signal Se is, for example, an indication value (=command value) of the engine power Pe [W], which is the power of the engine 12 that outputs the engine torque Te at the engine rotation speed Ne at that time. The MG control signal Smg is, for example, an indication value of the power consumption Wm [W] of the electric motor MG that outputs the MG torque Tmg at the MG rotation speed Nmg at that time.

[0038] The chargeable power Win of the battery 54 is the maximum power that can be input, which specifies the limit on the input power of the battery 54, and indicates the input limit of the battery 54. The dischargeable power Wout of the battery 54 is the maximum power that can be output, which specifies the limit on the output power of the battery 54, and indicates the output limit of the battery 54. The chargeable power Win and the dischargeable power Wout of the battery 54 are calculated by the electronic control device 90, for example, based on the battery temperature THbat and the state of charge value SOC [%] of the battery 54 (the ratio of the amount of charge actually stored to a predetermined full charge capacity). The state of charge value SOC is a value that indicates the state of charge of the battery 54, and is calculated by the electronic control device 90, for example, based on the battery charge / discharge current Ibat and the battery voltage Vbat.

[0039] The hybrid control unit 92 controls the vehicle 10 in a driving mode (BEV driving mode, HEV driving mode) according to the state of the vehicle 10. For example, the driving mode according to the state of the vehicle 10 is selected by the driving power source switching map described above.

[0040] The engine control unit 92a controls the engine torque Te so as to realize a required drive amount for the vehicle 10. The electric motor control unit 92b controls the MG torque Tmg so as to realize a required drive amount for the vehicle 10. Specifically, when traveling in the BEV traveling mode, the electric motor control unit 92b controls the MG torque Tmg so as to realize the target system shaft torque Tsystgt. When traveling in the HEV traveling mode, the engine control unit 92a controls the engine torque Te so as to realize all or a part of the target system shaft torque Tsystgt, and the electric motor control unit 92b controls the MG torque Tmg so as to compensate for the torque that is insufficient in the engine torque Te with respect to the target system shaft torque Tsystgt.

[0041] The hybrid control unit 92 further includes a starting control unit 92c. The starting control unit 92c and the clutch control unit 94 execute engine starting control to crank the engine 12 using the electric motor MG and the clutch K0 as necessary to start the engine 12. Specifically, the starting control unit 92c controls the electric motor MG to output a cranking torque Tcr [Nm] until cranking is completed, in accordance with the clutch control unit 94 switching the clutch K0 from a released state to a fully engaged state via a half-engaged state. The starting control unit 92c also controls fuel supply to the engine 12, ignition, and the like, in conjunction with the cranking of the engine 12 by the clutch K0 and the electric motor MG. Note that the "engine starting control" referred to here refers not only to the period until the engine 12 is completely exploded (starts operation) and becomes capable of independent operation, but also to a series of control operations related to engine starting until the clutch K0 is fully engaged and the engine torque Te is output from the engine 12. Note that the starting control unit 92c determines whether the engine 12 is under starting control, and determines whether cranking is completed.

[0042] From here, a case where the engine 12 is started in an accelerator-on state will be described. The accelerator-on state is a state where the driver requests acceleration (for example, a state where the accelerator opening θacc is greater than zero and an accelerator pedal (not shown) is depressed).

[0043] The system shaft torque control unit 98 functionally comprises a deviation period measurement unit 98a and an increase rate control unit 98b.

[0044] The deviation period measuring unit 98a measures a deviation period Pdev [ms] during which the difference (=Tsystgt-Tsysgd) between the target system shaft torque Tsystgt and the upper limit guard value Tsysgd that limits the upper limit of the system shaft torque Tsys that the electric motor MG can output to the drive wheels 34 exceeds a predetermined value α [Nm] during the cranking in the start control of the engine 12. The deviation period Pdev is a period during which the command value Tsyscm (hereinafter simply referred to as the "command value Tsyscm") of the system shaft torque Tsys cannot be increased toward the target system shaft torque Tsystgt because it is limited by the upper limit guard value Tsysgd, and is a period during which the driving force of the vehicle 10 is stagnant compared to the case where there is no limit by the upper limit guard value Tsysgd. During the execution of cranking, the MG torque Tmg, which is the output torque of the electric motor MG, is set to the sum of the system shaft torque Tsys output from the electric motor MG to the drive wheels 34 and used as a driving force for traveling, and the cranking torque Tcr output from the electric motor MG to the engine 12 and used for cranking. The MG torque Tmg also has a maximum MG torque Tmgmax [Nm], which is the maximum torque that the electric motor MG can output, which is determined experimentally or by design according to the electrical and mechanical characteristics of the electric motor MG. For example, the maximum MG torque Tmgmax varies depending on the MG rotation speed Nmg. For example, the upper limit guard value Tsysgd is set to the remainder after the cranking torque Tcr is secured from the maximum MG torque Tmgmax during the execution of cranking. The predetermined value α is a value equal to or greater than zero, which is determined experimentally or by design, so that the driver does not feel that the system shaft torque Tsys is stagnant even if there is a deviation between the target system shaft torque Tsystgt and the upper limit guard value Tsysgd. The upper limit guard value Tsysgd corresponds to the "upper limit" in the present invention.

[0045] When the deviation period measuring unit 98a measures the deviation period Pdev, the increase rate control unit 98b sets a target increase rate βtgt [Nm / ms], which is a target value of the increase rate of the command value Tsyscm after the completion of cranking, based on the deviation period Pdev. The increase rate of the command value Tsyscm is the amount of change (=increase) per unit time of the command value Tsyscm.

[0046] 2 is a diagram for explaining an example of a predetermined relationship between the accelerator opening θacc and the deviation period Pdev and the target increase rate βtgt. For example, the relationship in FIG. 2 is stored in the electronic control device 90 as a map that is experimentally or design-wise predetermined so that the feeling (uncomfortable feeling) of a sudden rapid increase in the system shaft torque Tsys described later falls within an acceptable range.

[0047] As shown in Fig. 2, the target increase rate βtgt of the system shaft torque Tsys is set lower as the deviation period Pdev is longer, and is set higher as the accelerator opening θacc is higher. When the deviation period Pdev during cranking, during which the difference between the target system shaft torque Tsystgt and the upper guard value Tsysgd exceeds a predetermined value α, is long, the target increase rate βtgt is set lower than when the deviation period Pdev is short. Also, when the accelerator opening θacc is high, the target increase rate βtgt is set higher because it is considered that the driver requires the system shaft torque Tsys to be quickly realized as the target system shaft torque Tsystgt, compared to when the accelerator opening θacc is low.

[0048] Returning to Fig. 1, when the deviation period Pdev is long, the increase rate control unit 98b sets the target increase rate βtgt lower than when the deviation period Pdev is short. For example, when the deviation period Pdev is long, the increase rate control unit 98b sets the target increase rate βtgt lower during the period from the completion of cranking to the point at which the upper limit guard value Tsysgd reaches the maximum MG torque Tmgmax, or sets the target increase rate βtgt lower after the point at which the engine torque Te becomes usable as the system shaft torque Tsys and after the point at which the upper limit guard value Tsysgd reaches the maximum MG torque Tmgmax. The target increase rate βtgt corresponds to the "change amount per unit time of the system shaft torque" in the present invention.

[0049] When the target increase rate βtgt is set, the increase rate control unit 98b controls the increase rate of the command value Tsyscm after the completion of cranking so that it becomes the target increase rate βtgt. Specifically, the increase rate control unit 98b controls the command value Tsyscm (= the sum of the command value of the engine torque Te and the command value of the MG torque Tmg) to increase at the increase rate of the target increase rate βtgt via the engine control unit 92a and the electric motor control unit 92b.

[0050] Fig. 3 is an example of a flowchart illustrating the control operation of the electronic control device 90 shown in Fig. 1. The flowchart in Fig. 3 is repeatedly executed at predetermined time intervals.

[0051] First, in step S10 (hereinafter, the word "step" will be omitted) corresponding to the function of the start control unit 92c, it is determined whether or not the engine 12 is under start control. If the determination in S10 is positive, in S20 corresponding to the function of the start control unit 92c, it is determined whether or not cranking has been completed. If the determination in S10 is negative, in S80 corresponding to the function of the deviation period measurement unit 98a, the count value CNT of a deviation period measurement counter for measuring the deviation period Pdev is reset to zero, and then the process returns.

[0052] If the determination in S20 is negative, in S30 corresponding to the function of the deviation period measurement unit 98a, it is determined whether or not the difference between the target system shaft torque Tsystgt and the upper limit guard value Tsysgd has deviated beyond a predetermined value α. If the determination in S30 is positive, in S40 corresponding to the function of the deviation period measurement unit 98a, the count value CNT of the deviation period measurement counter is counted up, and then the process returns. If the determination in S30 is negative, in S50 corresponding to the function of the deviation period measurement unit 98a, the count value CNT of the deviation period measurement counter is reset to zero, and then the process returns.

[0053] If the determination in S20 is positive, in S60, which corresponds to the function of the deviation period measurement unit 98a, the count value CNT of the deviation period measurement counter is maintained (held). After execution of S60, in S70, which corresponds to the function of the increase rate control unit 98b, the increase rate β of the instruction value Tsyscm is controlled based on the count value CNT of the deviation period measurement counter. The deviation period Pdev is proportional to the count value CNT maintained in S60. After execution of S70, the process returns.

[0054] FIG. 4 is an example of a time chart in the case where the flow chart of FIG. 3 is executed when the engine 12 is started from a stopped state by the early ignition start method according to this embodiment. The horizontal axis of FIG. 4 (as well as FIG. 5 and FIG. 6 described later) is time t [ms]. FIG. 4 (as well as FIG. 5 and FIG. 6 described later) shows an example where the predetermined value α is zero. The early ignition start method is a method in which the clutch K0 is engaged to crank the engine 12 by the electric motor MG, fuel is injected and ignited into the engine 12 before the clutch K0 is synchronized, and when the combustion can be continued, the clutch K0 is once released, and then the clutch K0 is fully engaged again. "Synchronization of the clutch K0" means that the engine rotation speed Ne on one side of the power transmission path PT controlled to be connected and disconnected by the clutch K0 and the MG rotation speed Nmg on the other side become the same. In this time chart, the system shaft torque Tsys, command value Tsyscm, upper guard value Tsysgd, and deviation period Pdev are shown as actual value Tsys1, command value Tsyscm1, upper guard value Tsysgd1, and deviation period Pdev1, respectively.

[0055] At time t0, the target system shaft torque Tsystgt starts to increase, and at time t1 (>t0), start-up control of the engine 12 starts. At time t2 (>t1), the difference between the target system shaft torque Tsystgt and the upper guard value Tsysgd1 becomes greater than zero (=predetermined value α). After time t2, the command value Tsyscm1 is limited by the upper guard value Tsysgd1, while the target system shaft torque Tsystgt continues to be greater than the upper guard value Tsysgd1. During cranking, in the period from time t1 to time t2 when the target system shaft torque Tsystgt is equal to or less than the upper guard value Tsysgd1, the command value Tsyscm1 is set to the target system shaft torque Tsystgt, and in the period from time t2 to time t5 when the target system shaft torque Tsystgt is greater than the upper guard value Tsysgd1, the command value Tsyscm1 is set to the upper guard value Tsysgd1.

[0056] At time t3 (>t2), cranking is started. At time t4 (>t3), engine speed Ne starts to increase. At time t5 (>t4), cranking is completed. Time t5 is the time point at which cranking of the engine 12 is completed. At time t5, the engine 12 is in a state in which combustion can continue, and the clutch K0 is temporarily switched to a released state. During the period from time t2 to time t5 (= deviation period Pdev1), the count value CNT of the deviation period measuring counter is counted up to a value C1. Based on the value C1 corresponding to the deviation period Pdev1, a target increase rate βtgt for a period A1 [ms] and a period B1 [ms] described later is set to a value β1.

[0057] During the period from time t5 to time t6 (>t5), the cranking torque Tcr is decreased, while the upper guard value Tsysgd1 is increased, thereby increasing the command value Tsyscm1. The upper guard value Tsysgd1 is also increased after time t6, and at time t7 (>t6), the upper guard value Tsysgd1 reaches the maximum MG torque Tmgmax. At time t7, the clutch K0 is fully engaged, i.e., the clutch K0 is synchronized, and the engine torque Te can be used as the system shaft torque Tsys. The clutch K0, which was once released during the period immediately before time t7, is switched back to the fully engaged state. The period from time t1 to time t7 is the start control execution period Pexe1 [ms] during which the start control of the engine 12 is executed. Time t7 corresponds to "the point in time after the output of the internal combustion engine becomes usable as the system shaft torque and the upper limit reaches the maximum value that the electric motor can output" in the present invention. In a period A1 from time t5 to time t7, the command value Tsyscm1 is increased at an increase rate of value β1.

[0058] At time t8 (>t7), the command value Tsyscm1 reaches the target system shaft torque Tsystgt. During a period B1 from time t7 to time t8, the command value Tsyscm1 is increased at an increase rate of β1.

[0059] In the period from time t1 to time t8, the actual value Tsys1 is changed in accordance with the change in the command value Tsyscm1. For example, in the period A1 or period B1, the command value Tsyscm1 is increased at the increase rate of the value β1, so that the actual value Tsys1 is increased at the increase rate according to the value β1.

[0060] According to this embodiment, (a) when the engine 12 is started, the clutch K0 is engaged and the engine 12 is cranked by the electric motor MG, (b) during the cranking of the engine 12, a deviation period Pdev1 during which the difference between the target system shaft torque Tsystgt and the upper limit guard value Tsysgd1 exceeds a predetermined value α is measured, and (c) when the deviation period Pdev1 is long, the target increase rate βtgt of the command value Tsyscm1 in the period (=period B1) after the engine torque Te becomes usable as the system shaft torque Tsys and after the upper limit guard value Tsysgd1 reaches the maximum MG torque Tmgmax is controlled to be lower than when the deviation period Pdev1 is short. When the deviation period Pdev1 during cranking is long, the driver is more likely to feel (uncomfortable) that the system shaft torque Tsys suddenly increases if the target increase rate βtgt of the command value Tsyscm1 is large after cranking is performed, compared to when the deviation period Pdev1 is short. When the deviation period Pdev1 is long, the target increase rate βtgt of the command value Tsyscm1 during the period B1 is controlled to be lower, compared to when the deviation period Pdev1 is short, and the amount of change per unit time of the actual value Tsys1 is controlled to be smaller, thereby reducing the discomfort felt by the driver.

[0061] According to this embodiment, when the deviation period Pdev1 is long, the target increase rate βtgt of the command value Tsyscm1 during the period (=period A1) from the completion of cranking of the engine 12 to the arrival of the upper limit guard value Tsysgd1 at the maximum MG torque Tmgmax is controlled to be lower than when the deviation period Pdev1 is short. When the deviation period Pdev1 is long, the target increase rate βtgt of the command value Tsyscm1 during the period A1 is controlled to be lower than when the deviation period Pdev1 is short, thereby controlling the amount of change per unit time of the actual value Tsys1 to be smaller, thereby reducing the discomfort felt by the driver. EXAMPLES

[0062] The schematic configuration diagram of a hybrid vehicle 10 according to the second embodiment of the present invention and the control functions for various controls in an electronic control unit 90 are similar to those of the first embodiment described above, and therefore description thereof will be omitted.

[0063] Fig. 5 is an example of a time chart in the case where the flow chart of Fig. 3 is executed when the engine 12 is restarted by the early ignition start method from a state during stop control according to this embodiment. During the stop control, the stop control for switching the engine 12 from an operating state to a stopped state is being executed. In this time chart, the system shaft torque Tsys, the command value Tsyscm, the upper guard value Tsysgd, and the deviation period Pdev are shown as the actual value Tsys2, the command value Tsyscm2, the upper guard value Tsysgd2, and the deviation period Pdev2, respectively. In Fig. 5, the cranking torque Tcr is not shown.

[0064] At time t10, the accelerator opening θacc starts to increase, thereby starting to increase the target system shaft torque Tsystgt, and at time t11 (>t10), start-up control of the engine 12 is started. At time t12 (>t11), the difference between the target system shaft torque Tsystgt and the upper guard value Tsysgd2 becomes greater than zero (=predetermined value α). After time t12, the command value Tsyscm2 is limited by the upper guard value Tsysgd2, while the target system shaft torque Tsystgt continues to be greater than the upper guard value Tsysgd2. During the execution of cranking, in the period from time t11 to time t12 when the target system shaft torque Tsystgt is equal to or smaller than the upper guard value Tsysgd2, the command value Tsyscm2 is set to the target system shaft torque Tsystgt, and in the period from time t12 to time t13 when the target system shaft torque Tsystgt is greater than the upper guard value Tsysgd2, the command value Tsyscm2 is set to the upper guard value Tsysgd2. Note that, while the above-described first embodiment is a case in which the engine 12 is started from a stopped state, this embodiment is a case in which the engine 12 is restarted from a state in which it is under stop control, so the cranking torque Tcr may be small. Therefore, the upper guard value Tsysgd2 during the execution of cranking is greater than the upper guard value Tsysgd1 in the first embodiment.

[0065] After time t12, cranking is started, and at time t13 (> t12), cranking is completed. Time t13 is the time when the cranking of engine 12 is completed. During the period from time t12 to time t13 (= deviation period Pdev2), the count value CNT of the counter for measuring the deviation period is incremented up to the value C2. In this embodiment, since engine 12 is restarted from the state of being under stop control, the difference (= Nmg - Ne) between the MG rotational speed Nmg and the engine rotational speed Ne at the time of executing the engine start control is smaller compared to the aforementioned embodiment 1. Therefore, the period for increasing the engine rotational speed Ne to the MG rotational speed Nmg, that is, the period required for cranking, can be shortened, and the deviation period Pdev2 is shorter than the aforementioned deviation period Pdev1 (= the value C2 is smaller than the value C1). Based on the value C2 (< C1) corresponding to the deviation period Pdev2, the target increase rate βtgt in the subsequent period B2 [ms] is set to the value β2 (> β1). Also, the target increase rate βtgt in the subsequent period A2 [ms] is set to the value β1 (< β2) according to the aforementioned embodiment 1.

[0066] At time t14 (> t13), the clutch K0 becomes fully engaged, and the engine torque Te can be used as the system shaft torque Tsys. The period from time t11 to time t14 is the start control execution period Pexe2 [ms] during which the start control of engine 12 is executed. Time t14 corresponds to "after the time when the output of the internal combustion engine becomes available as the system shaft torque and before the time when the upper limit value of the maximum value that the electric motor can output is reached" in the present invention.

[0067] In the period after time t14, the indicated value Tsyscm2 is increased by increasing the upper limit guard value Tsysgd2. At time t15 (> t14), the upper limit guard value Tsysgd2 reaches the maximum MG torque Tmgmax. In the period A1 from time t13 to time t15, the indicated value Tsyscm2 is increased at the increase rate of the value β1.

[0068] At time t16 (>t15), the command value Tsyscm2 reaches the target system shaft torque Tsystgt. During a period B2 from time t15 to time t16, the command value Tsyscm2 is increased at an increase rate of β2.

[0069] In the period from time t11 to time t16, the actual value Tsyscm2 is changed in accordance with the change in the command value Tsyscm2. For example, in the period A2, the command value Tsyscm2 is increased at a rate of increase of value β1, so that the actual value Tsyscm2 is increased at a rate of increase corresponding to value β1, and in the period B2, the command value Tsyscm2 is increased at a rate of increase of value β2, so that the actual value Tsyscm2 is increased at a rate of increase corresponding to value β2.

[0070] According to this embodiment, (a) when the engine 12 is started, the clutch K0 is engaged and the motor MG cranks the engine 12, (b) a deviation period Pdev2 during which the difference between the target system shaft torque Tsystgt and the upper guard value Tsysgd2 exceeds a predetermined value α is measured during the cranking of the engine 12, and (c) when the deviation period Pdev2 is long, the target increase rate βtgt of the command value Tsyscm2 during the period (=period B2) after the engine torque Te becomes usable as the system shaft torque Tsys and after the upper guard value Tsysgd2 reaches the maximum MG torque Tmgmax is controlled to be lower than when the deviation period Pdev2 is short. This provides the same effects as the first embodiment described above. EXAMPLES

[0071] The schematic configuration diagram of a hybrid vehicle 10 according to the third embodiment of the present invention and the control functions for various controls in an electronic control unit 90 are similar to those of the first embodiment described above, and therefore description thereof will be omitted.

[0072] FIG. 6 is an example of a time chart in which the flowchart of FIG. 3 is executed when the engine 12 is started from a stopped state by the push start method according to this embodiment. The push start method is a method in which the clutch K0 is engaged to increase the engine rotation speed Ne by the electric motor MG, and after the clutch K0 is synchronized, fuel is injected into the engine 12 and ignited to start the engine. FIG. 6 shows a comparison between a case where the MG rotation speed Nmg is a low rotation speed, and a case where the MG rotation speed Nmg is a high rotation speed. FIG. 6 shows the cranking torque Tcr in the case where the MG rotation speed is low, but does not show the cranking torque Tcr in the case where the MG rotation speed is high.

[0073] First, the case of low MG rotation will be described. In this time chart, the system shaft torque Tsys, command value Tsyscm, maximum MG torque Tmgmax, upper limit guard value Tsysgd, and deviation period Pdev are shown as actual value Tsys3, command value Tsyscm3, maximum MG torque Tmgmax3, upper limit guard value Tsysgd3, and deviation period Pdev3, respectively.

[0074] At time t20, the target system shaft torque Tsystgt starts to increase, and at time t21 (>t20), start-up control of the engine 12 starts. At time t23 (>t21), the difference between the target system shaft torque Tsystgt and the upper guard value Tsysgd3 becomes greater than zero (=predetermined value α). After time t23, the command value Tsyscm3 is limited by the upper guard value Tsysgd3, while the target system shaft torque Tsystgt continues to be greater than the upper guard value Tsysgd3. During cranking, in the period from time t21 to time t23 when the target system shaft torque Tsystgt is equal to or less than the upper guard value Tsysgd3, the command value Tsyscm3 is set to the target system shaft torque Tsystgt, and in the period from time t23 to time t26 when the target system shaft torque Tsystgt is greater than the upper guard value Tsysgd3, the command value Tsyscm3 is set to the upper guard value Tsysgd3.

[0075] At time t24 (>t23), cranking is started. At time t25 (>t24), the engine speed Ne starts to increase. At time t26 (>t25), the clutch K0 is fully engaged, cranking is completed, and the engine 12 is ignited and started. Time t26 is the time point at which cranking of the engine 12 is completed. The period from time t21 to time t26 is a start control execution period Pexe3 [ms] during which start control of the engine 12 is executed. During the period from time t23 to time t26 (= deviation period Pdev3), the count value CNT of the deviation period measurement counter is counted up to a value C3 (>C1). Based on the value C3 corresponding to the deviation period Pdev3, the target increase rate βtgt during a period A3 [ms] and a period B3 [ms] described later is set to a value β3 (<β1).

[0076] During the period from time t26 to time t27 (>t26), the cranking torque Tcr is decreased, while the upper guard value Tsysgd3 is increased, thereby increasing the command value Tsyscm3. The upper guard value Tsysgd3 is also increased after time t27, and at time t28 (>t27), the upper guard value Tsysgd3 reaches the maximum MG torque Tmgmax3. At time t28, the engine torque Te is available as the system shaft torque Tsys. Time t28 corresponds to the "time when the upper limit reaches the maximum value that the electric motor can output after the output of the internal combustion engine becomes available as the system shaft torque" in the present invention. During the period A3 from time t26 to time t28, the command value Tsyscm3 is increased at an increase rate of value β3.

[0077] At time t30 (>t28), the command value Tsyscm3 reaches the target system shaft torque Tsystgt. During a period B3 from time t28 to time t30, the command value Tsyscm3 is increased at an increase rate of value β3.

[0078] In the period from time t21 to time t30, the actual value Tsyscm3 is changed in accordance with the change in the command value Tsyscm3. For example, in periods A3 and B3, the command value Tsyscm3 is increased at the increase rate of the value β3, so that the actual value Tsyscm3 is increased at the increase rate according to the value β3.

[0079] Next, the case of high MG rotation will be described. The upper limit guard value Tsysgd4 in the case of high MG rotation is lower than the upper limit guard value Tsysgd3 in the case of low MG rotation described above. In this time chart, the system shaft torque Tsys, command value Tsyscm, maximum MG torque Tmgmax, upper limit guard value Tsysgd, and deviation period Pdev are shown as actual value Tsys4, command value Tsyscm4, maximum MG torque Tmgmax4, upper limit guard value Tsysgd4, and deviation period Pdev4, respectively.

[0080] At time t20, the target system shaft torque Tsystgt starts to increase, and at time t21 (>t20), start-up control of the engine 12 starts. At time t22 (t23>t22>t21), the difference between the target system shaft torque Tsystgt and the upper guard value Tsysgd4 becomes greater than zero (=predetermined value α). After time t22, the command value Tsyscm4 is limited by the upper guard value Tsysgd4, while the target system shaft torque Tsystgt continues to be greater than the upper guard value Tsysgd4. During cranking, in the period from time t21 to time t22 when the target system shaft torque Tsystgt is equal to or less than the upper guard value Tsysgd4, the command value Tsyscm4 is set to the target system shaft torque Tsystgt, and in the period from time t22 to time t29 when the target system shaft torque Tsystgt is greater than the upper guard value Tsysgd4, the command value Tsyscm4 is set to the upper guard value Tsysgd4.

[0081] At time t24 (>t22), cranking is started. At time t25 (>t24), the engine speed Ne starts to increase. At time t29 (>t25), the clutch K0 is fully engaged and cranking is completed. Time t29 is the time point at which cranking of the engine 12 is completed. The period from time t21 to time t29 is a start control execution period Pexe4 [ms] during which start control of the engine 12 is executed. During the period from time t22 to time t29 (= deviation period Pdev4), the count value CNT of the deviation period measurement counter is counted up to a value C4 (>C3). Based on the value C4 corresponding to the deviation period Pdev4, the target increase rate βtgt during a period A4 [ms] and a period B4 [ms] described later is set to a value β4 (<β3).

[0082] During the period from time t29 onwards, the cranking torque Tcr is decreased while the upper guard value Tsysgd4 is increased, thereby increasing the command value Tsyscm4. At time t31 (>t29), the upper guard value Tsysgd4 reaches the maximum MG torque Tmgmax4. At time t31, the engine torque Te can be used as the system shaft torque Tsys. Time t31 corresponds to the "point in time after the output of the internal combustion engine becomes usable as the system shaft torque and when the upper limit value reaches the maximum value that the electric motor can output" in the present invention. During the period A4 from time t29 to time t31, the command value Tsyscm4 is increased at an increase rate of value β4.

[0083] At time t32 (>t31), the command value Tsyscm4 reaches the target system shaft torque Tsystgt. During a period B4 from time t31 to time t32, the command value Tsyscm4 is increased at an increase rate of a value β4.

[0084] In the period from time t21 to time t32, the actual value Tsyscm4 is changed in accordance with the change in the command value Tsyscm4. For example, in periods A4 and B4, the command value Tsyscm4 is increased at the increase rate of the value β4, so that the actual value Tsyscm4 is increased at the increase rate according to the value β4.

[0085] According to this embodiment, (a) when the engine 12 is started, the clutch K0 is engaged and the engine 12 is cranked by the electric motor MG, (b) during the cranking of the engine 12, deviation periods Pdev3, Pdev4 in which the difference between the target system shaft torque Tsystgt and the upper limit guard values ​​Tsysgd3, Tsysgd4 exceeds a predetermined value α are measured, and (c) when the deviation periods Pdev3, Pdev4 are long, the target increase rate βtgt of the command values ​​Tsyscm3, Tsyscm4 in the period (=periods B3, B4) after the engine torque Te becomes usable as the system shaft torque Tsys and after the upper limit guard values ​​Tsysgd3, Tsysgd4 reach the maximum MG torque Tmgmax3, Tmgmax4 is controlled to be lower than when the deviation periods Pdev3, Pdev4 are short. In addition, when the deviation periods Pdev3, Pdev4 are long, the target increase rates βtgt of the command values ​​Tsyscm3, Tsyscm4 in the period from the completion of cranking of the engine 12 to the time when the upper limit guard values ​​Tsysgd3, Tsysgd4 reach the maximum MG torques Tmgmax3, Tmgmax4 (=periods A3, A4) are controlled to be lower than when the deviation periods Pdev3, Pdev4 are short. This provides the same effects as those in the first embodiment.

[0086] Although the embodiments of the present invention have been described in detail above with reference to the drawings, the present invention can be applied to other embodiments as well.

[0087] In the above-mentioned first and third embodiments, the target increase rates βtgt of the command values ​​Tsyscm1, Tsyscm3, and Tsyscm4 are set to the same values ​​β1, β3, and β4 in the periods A1, A3, and A4 and the periods B1, B3, and B4, respectively, but may be set to different values ​​in the periods A1, A3, and A4 and the periods B1, B3, and B4, respectively. Preferably, the target increase rates βtgt in the periods A1, A3, and A4 are set to values ​​equal to or lower than the target increase rates βtgt in the periods B1, B3, and B4 in order to make it difficult for the driver to feel (uncomfortable feeling) that the system shaft torque Tsys suddenly increases. In addition, in the above-mentioned Example 2, the target increase rate βtgt of the command value Tsyscm2 differs between period A2 and period B2, and the target increase rate βtgt of the command value Tsyscm2 in period A2 is set to the value β1. However, for example, the target increase rate βtgt of the command value Tsyscm2 in period A2 may be set to the same value β2 as in period B2.

[0088] In the above-mentioned embodiments 1, 2, and 3, no smoothing process (= a process for slowing down the change in the command value Tsyscm) was performed when setting the target increase rate βtgt of the command value Tsyscm. However, for example, the present invention may be configured in such a way that smoothing process is performed on the target increase rate βtgt of the command value Tsyscm.

[0089] In the above-described first, second and third embodiments, the clutch K0 is a wet friction engagement device, but is not limited to this and may be a dry friction engagement device.

[0090] In the above-described first, second and third embodiments, the torque converter 16, which is a fluid-type power transmission device, is provided in the power transmission path PT between the driving power source PG for driving and the automatic transmission 18, but the present invention is not limited to this embodiment. For example, instead of the torque converter 16, another fluid-type power transmission device, such as a fluid coupling that does not have a torque amplifying effect, may be used. Also, the fluid-type power transmission device does not necessarily have to be provided, and may be replaced with, for example, a starting clutch.

[0091] In the above-described first, second and third embodiments, an automatic transmission 18 was provided in the power transmission path PT between the driving power source PG for driving and the driving wheels 34, but the present invention may also be configured such that an automatic transmission 18 is not provided.

[0092] It should be noted that the above-described embodiments are merely examples of the present invention, and the present invention can be embodied in various forms with various modifications and improvements based on the knowledge of those skilled in the art without departing from the spirit of the present invention. [Explanation of symbols]

[0093] 10: Hybrid vehicles 12: Engine (internal combustion engine) 34: Drive wheel 90: Electronic control device (control device) K0: Clutch (friction engagement device) MG: Electric motor PG: Driving power source Pdev: Deviation period Tsys: System shaft torque Tsysgd: Upper limit guard value (upper limit) Tsystgt: Target system torque (driver's request for system torque) α: Predetermined value βtgt: Target increase rate (change in system torque per unit time) t7, t14, t28, t31: Time (the time when the output of the internal combustion engine becomes available as the system shaft torque and when the electric motor reaches the upper limit of the maximum output value)

Claims

[Claim 1] A control device for a hybrid vehicle including an internal combustion engine and an electric motor as driving power sources for traveling, and a friction engagement device that connects and disconnects power transmission between the internal combustion engine and the electric motor, When starting the internal combustion engine, cranking of the internal combustion engine is performed by the electric motor while engaging the friction engagement device; measuring a period of time during which a difference between a driver's requested value of a system shaft torque, which is a torque output from the driving force source for driving to a drive wheel side, and an upper limit value of the system shaft torque that can be output from the electric motor, exceeds a predetermined value; When the deviation period is long, control is performed so that the amount of change in the system shaft torque per unit time after the output of the internal combustion engine becomes usable as the system shaft torque and after the upper limit value reaches the maximum value that the electric motor can output, becomes smaller than when the deviation period is short. A control device for a hybrid vehicle.

Images