Vehicle control device

Abstract

To provide a vehicle controller capable of inhibiting a start shock and improving drivability.SOLUTION: A vehicle electronic controller, during BEV running and before requiring start of an engine, (a) starts torque capacity control corresponding to input torque inputted as a command value of torque capacity of a start clutch which is a second clutch, from an electric motor to the start clutch, and (b) starts rotation speed control for controlling a rotation speed of the electric motor so that a differential rotation at the start clutch becomes a predetermined target differential rotation value in at least either of the cases that the differential rotation at the start clutch is a predetermined determination differential rotation value or more and that a difference between an actual value of the torque capacity of the start clutch and the input torque is within a predetermined torque range and the input torque increases and is estimated to continue to increase.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a control device for a vehicle equipped with a clutch that mechanically connects and disconnects a power transmission path between an engine and an electric motor as a power source and drive wheels. [Background technology]

[0002] There are known vehicle control devices that include a lock-up clutch for a torque converter that mechanically connects and disconnects a power transmission path between an engine and an electric motor as a power source and drive wheels, such as the vehicle control device described in Patent Document 1. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5794377 Summary of the Invention [Problem to be solved by the invention]

[0004] It is known that engine start control is initiated after a lockup clutch is slipped or released to suppress the occurrence of start-up shock caused by torque fluctuations being transmitted to the drive wheels during engine start. In the vehicle described in Patent Document 1, while the vehicle is running as a BEV (BEV) using only an electric motor as a power source, the torque capacity of the lockup clutch is reduced before a request to start the engine is made, compared to when the vehicle is running using the engine as at least one power source. This allows the lockup clutch to be quickly switched from fully engaged to slipped or released after a request to start the engine, thereby suppressing start-up shock and improving drivability. However, further suppression of start-up shock and improvement of drivability are desired.

[0005] The present invention has been made in light of the above circumstances, and an object of the present invention is to provide a vehicle control device that suppresses starting shock and improves drivability. [Means for solving the problem]

[0006] The gist of the present invention is a control device for a vehicle including an engine and an electric motor as a power source, a first clutch that connects and disconnects power transmission between the engine and the electric motor, and a second clutch that mechanically connects and disconnects a power transmission path between the power source and drive wheels, the control device (a) initiating torque capacity control in which a command value for the torque capacity of the second clutch corresponds to an input torque input from the electric motor to the second clutch before a start of the engine is requested during BEV running in which the first clutch is released and the second clutch is fully engaged and power is output only from the electric motor, and (b) after starting the torque capacity control, When the differential rotation speed obtained by subtracting the rotation speed of the drive wheel side from the rotation speed of the electric motor side in the second clutch is equal to or greater than a predetermined judgment differential rotation value, or when the difference between the actual value of the torque capacity of the second clutch and the input torque is within a predetermined torque range and the input torque is increasing and is estimated to continue to increase in the future, rotation speed control is started to control the rotation speed of the electric motor so that the differential rotation speed in the second clutch becomes a predetermined target differential rotation value, and (c) when starting of the engine is requested, the first clutch is switched from released to fully engaged and the output torque of the electric motor is increased to start the engine. [Effects of the Invention]

[0007] According to the vehicle control device of the present invention, torque capacity control is initiated during BEV driving before engine start is requested, and rotational speed control is initiated in at least one of the following cases: (a) when the differential rotation speed in the second clutch is equal to or greater than a predetermined reference differential rotation speed; and (b) when the torque difference between the actual torque capacity of the second clutch and the input torque is within a predetermined torque range, the input torque is increasing, and it is estimated that the input torque will continue to increase. In (a), the second clutch is in slip engagement, so even if rotational speed control is initiated, the drive torque transmitted from the electric motor to the drive wheels will not increase abruptly. In (b), the input torque is currently increasing and will continue to increase, i.e., the second clutch immediately enters slip engagement due to an increase in input torque, so even if rotational speed control is initiated, the drive torque transmitted from the electric motor to the drive wheels will not increase abruptly. When engine start is requested and engine start control is executed after rotational speed control is initiated, the second clutch is already in slip engagement. Therefore, engine start control is initiated more quickly than in other cases, thereby achieving both suppression of start-up shock and drivability. Furthermore, even if engine start control is executed upon request to start the engine before the rotation speed control is initiated, the command value for the torque capacity of the second clutch is set in advance according to the input torque, which allows the second clutch to be slip-engaged more quickly than in other cases to initiate engine start control, thereby achieving both suppression of start-up shock and drivability. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a diagram illustrating a schematic configuration of a vehicle to which the present invention is applied, and is also a diagram illustrating main parts of control functions for various controls in the vehicle. [Figure 2] 4 is a diagram illustrating an example of the relationship between a WSC input torque and a target differential rotation value in rotation speed control. FIG. [Figure 3] 2 is an example of a flowchart illustrating a main part of the control operation of the electronic control device shown in FIG. [Figure 4]4 is an example of a time chart when rotation speed control is executed in the flowchart of FIG. 3. [Figure 5] 10 is a time chart illustrating the occurrence of engine start shock, comparing a case where torque capacity control is started before a request to start the engine with a case where torque capacity control is started after a request to start the engine. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that in the following embodiments, the drawings are appropriately simplified or modified, and the dimensional ratios and shapes of the various parts are not necessarily drawn accurately. [Example]

[0010] FIG. 1 is a diagram illustrating the schematic configuration of a vehicle 10 to which the present invention is applied, and also illustrates the main parts of the control functions for various controls in the vehicle 10. The vehicle 10 is a hybrid vehicle equipped with an engine 12 and an electric motor MG, which function as a power source. In the vehicle 10, a power transmission path PT between the power source and drive wheels 14 is connected, in order from the power source side, to an electric motor connecting shaft 32, a starting clutch WSC, a transmission input shaft 38, an automatic transmission 20, a reduction gear mechanism 22, a differential gear 24, and a pair of drive shafts 28, all of which are well-known components. The vehicle 10 also includes an inverter 52, a battery 54, a hydraulic control circuit 56, and an electronic control device 90.

[0011] The engine 12 is a well-known internal combustion engine such as a gasoline engine or a diesel engine. The engine 12 is controlled by an engine control device 50, which includes a throttle actuator, a fuel injection device, an ignition device, etc., to control the engine torque Te [Nm], which is the output torque of the engine 12. The electric motor MG is a rotating electric machine that functions as both a motor and a generator, and is a so-called motor generator. The electric motor MG outputs the MG torque Tmg [Nm], which is the output torque of the electric motor MG, as power by controlling an inverter 52 using power supplied from a battery 54. The electric motor MG also generates power using the power of the engine 12 and the driven force input from the drive wheels 14, and the generated power is charged into the battery 54. When no particular distinction is made, the above-mentioned power can also be referred to as driving force, torque, and force.

[0012] The on-off clutch K0 is a clutch that connects and disconnects the power transmission between the engine 12 and the electric motor MG. The starting clutch WSC is a clutch that mechanically connects and disconnects the power transmission path PT, particularly between the electric motor MG and the automatic transmission 20. The on-off clutch K0 and the starting clutch WSC correspond to the "first clutch" and the "second clutch," respectively, in the present invention. The engine connecting shaft 30 is disposed between the engine 12 and the on-off clutch K0, and the electric motor MG is connected to an electric motor connecting shaft 32 disposed between the on-off clutch K0 and the starting clutch WSC so as to be capable of transmitting power. Each of the on-off clutch K0 and the starting clutch WSC is a hydraulic friction engagement device constituted by, for example, a multi-plate or single-plate clutch pressed by an actuator. The on-off clutch K0 and the starting clutch WSC each have their torque capacity changed by the adjusted hydraulic pressure supplied from the hydraulic control circuit 56, thereby switching between control states such as full engagement, slip engagement, and release. Hereinafter, when there is no need to particularly distinguish between full engagement and slip engagement, it will be referred to simply as “engagement.” Torque capacity is the amount of torque that a clutch can transmit, and is the same as the clutch engagement force.

[0013] The automatic transmission 20 is a well-known planetary gear automatic transmission including, for example, one or more planetary gear devices (not shown) and engagement devices CB. The engagement devices CB include, for example, a plurality of well-known hydraulic friction engagement devices. The automatic transmission 20 is a stepped transmission in which one of a plurality of gear stages (also referred to as gear ratios) with different speed ratios (also referred to as gear ratios) γat (=AT input rotation speed Ni [rpm] / AT output rotation speed No [rpm]) is formed by engaging any of the engagement devices CB. The AT input rotation speed Ni is the rotation speed of a transmission input shaft 38, which is an input member of the automatic transmission 20, and the AT output rotation speed No is the rotation speed of a transmission output gear 26, which is an output member of the automatic transmission 20. The automatic transmission 20 can also be placed in a neutral state by, for example, disengaging all of the engagement devices CB.

[0014] The hydraulic control circuit 56 uses the hydraulic oil discharged from at least one of a mechanical oil pump or an electric oil pump (not shown) provided on the vehicle 10 as the source pressure, and supplies adjusted hydraulic pressure to the actuators that control the control states of the on-off clutch K0, the starting clutch WSC, and the engagement device CB.

[0015] When both the on-off clutch K0 and the starting clutch WSC are engaged, the power output from the engine 12 is transmitted to the drive wheels 14 via the power transmission path PT. When the starting clutch WSC is engaged, the power output from the electric motor MG is transmitted to the drive wheels 14 via the power transmission path PT, regardless of the control state of the on-off clutch K0.

[0016] The vehicle 10 is equipped with an electronic control device 90 as a controller including a control device for the vehicle 10. The electronic control device 90 is configured to include 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 stored in advance in the ROM while utilizing the temporary storage function of the RAM.

[0017] The electronic control device 90 receives various signals (e.g., engine rotation speed Ne [rpm] which is the rotation speed of the engine 12, MG rotation speed Nmg [rpm] which is the rotation speed of the electric motor MG and also the rotation speed of the input side member of the starting clutch WSC, AT input rotation speed Ni, AT output rotation speed No corresponding to vehicle speed V [km / h], accelerator pedal opening θacc [%] which is the driver's accelerator operation amount which indicates the magnitude of the driver's acceleration operation, etc.) based on detection values ​​from various sensors provided on the vehicle 10 (e.g., engine rotation speed sensor 70, MG rotation speed sensor 72, input rotation speed sensor 74, output rotation speed sensor 76, accelerator pedal opening sensor 78, etc.). The electronic control device 90 corresponds to the "control device" in this invention.

[0018] The electronic control device 90 outputs various signals (e.g., an engine control signal Se for controlling the engine 12, an MG control signal Smg for controlling the drive of the electric motor MG, a CB hydraulic control signal Scb for controlling the engagement and disengagement of the engagement device CB, a K0 hydraulic control signal Sk0 for controlling the engagement and disengagement of the disengagement clutch K0, a WSC hydraulic control signal Swsc for controlling the engagement and disengagement of the starting clutch WSC, etc.) to each device provided in the vehicle 10 (e.g., the engine control device 50, the inverter 52, the hydraulic control circuit 56, etc.).

[0019] The electronic control device 90 functionally includes a power source control unit 92, a clutch control unit 94, a transmission control unit 96, and a rotational speed control unit 98 in order to realize various controls in the vehicle 10.

[0020] The power source control unit 92 includes a function for controlling the operation of the engine 12 and a function for controlling the operation of the electric motor MG, and executes hybrid drive control by the engine 12 and the electric motor MG using these control functions.

[0021] The power source control unit 92 selectively switches between a BEV drive mode, which realizes BEV (Battery Electric Vehicle) driving using only the electric motor MG as a power source, and an HEV drive mode, which realizes HEV (Hybrid Electric Vehicle) driving using at least the engine 12 as a power source. During BEV driving, the disconnecting clutch K0 is released and the starting clutch WSC is engaged. During HEV driving, the disconnecting clutch K0 and the starting clutch WSC are both engaged. During BEV driving, the start of the engine 12 is requested in cases where the amount of drive power required by the driver for the vehicle 10 cannot be met without using the output of the engine 12, where charging of the battery 54 is required, where warming up of the engine 12, etc. is required, etc. When start of the engine 12 is requested, engine start control is executed to start the engine 12, and the HEV drive mode is selected.

[0022] The power source control unit 92 calculates a drive demand for the vehicle 10 from the driver, for example, by applying the accelerator opening θacc and the vehicle speed V to a drive demand map. The drive demand map is a relationship for calculating the drive demand, which is determined experimentally or by design and stored in advance. The drive demand is a drive demand required for the vehicle 10. Examples of the drive demand may include a required drive torque Trdem [Nm] at the drive wheels 14, a required amount of AT output torque To [Nm] output from the transmission output gear 26 of the automatic transmission 20, a required drive force Frdem [N] at the drive wheels 14, and a required drive power Prdem [W] at the vehicle speed V at that time. The power source 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 drive power Prdem, for example, taking into account transmission loss, auxiliary load, the gear ratio γat of the automatic transmission 20, and the like.

[0023] The make-and-break clutch control unit 94 controls the make-and-break state of the make-and-break clutch K0 during engine start control. For example, when a request is made to start the engine 12, the make-and-break clutch control unit 94 controls the make-and-break clutch K0 to go from release to slip engagement to full engagement in order to transmit to the engine 12 cranking torque Tcr [Nm], which is a torque that increases the engine rotation speed Ne and is required for cranking the engine 12.

[0024] The transmission control unit 96 determines whether to shift the automatic transmission 20 using a shift map, for example, and outputs a CB hydraulic control signal Sbc to the hydraulic control circuit 56 to execute shift control as necessary. The shift map is a predetermined relationship having shift lines for determining whether to shift the automatic transmission 20 on a two-dimensional coordinate system using, for example, vehicle speed V and required drive torque Trdem as variables. In the shift map, the AT output rotation speed No may be used instead of the vehicle speed V, and the required amount of AT output torque To [Nm], accelerator opening θacc, or throttle valve opening θth [%], which is the opening of the electronic throttle valve, may be used instead of the required drive torque Trdem.

[0025] The rotational speed control unit 98 functionally includes a torque determination unit 98a, a starting clutch control unit 98b, a start determination unit 98c, and a differential rotation control unit 98d.

[0026] The torque determination unit 98a determines whether the WSC input torque Twsc [Nm], which is the torque input from the electric motor MG to the starting clutch WSC during BEV running, is less than the torque value Twsc_jdgx (>0). The torque value Twsc_jdgx is a determination value that is determined in advance experimentally or by design in order to suppress a decrease in the power generation efficiency of the electric motor MG due to regenerative braking. The WSC input torque Twsc corresponds to the "input torque" in this invention. The torque value Twsc_jdgx corresponds to the "predetermined second torque value" in this invention.

[0027] The torque determination unit 98a determines whether the WSC input torque Twsc exceeds a torque value Twsc_jdgy. The torque value Twsc_jdgy is a determination value set to be equal to or greater than a torque value Twsc_jdgx that is predetermined experimentally or by design. Preferably, the torque value Twsc_jdgy is set higher than the torque value Twsc_jdgx so that the start and end of the rotation speed control, which will be described later, are not frequently repeated. The torque value Twsc_jdgy corresponds to the "predetermined first torque value" in this invention.

[0028] When the torque determination unit 98a determines that the WSC input torque Twsc exceeds the torque value Twsc_jdgy during BEV driving, the starting clutch control unit 98b initiates torque capacity control to equalize the torque capacity command value Tc_tgt [Nm], which is a command value for the torque capacity Tc [Nm] of the starting clutch WSC, with the WSC input torque Twsc. The torque capacity command value Tc_tgt corresponds to the "command value" in this invention. The "WSC input torque Twsc" for which the torque capacity command value Tc_tgt is equalized corresponds to "corresponding to the input torque" in this invention. The "corresponding to the input torque" refers to a torque capacity command value Tc_tgt that can transmit the input WSC input torque Twsc to the drive wheels 14 at substantially the same magnitude, i.e., a value close to the torque capacity command value Tc_tgt at which the starting clutch WSC switches from full engagement to slip engagement.

[0029] After the start clutch control unit 98b starts torque capacity control, the start determination unit 98c determines whether or not a start condition for rotational speed control is satisfied. The start condition for rotational speed control is that either of the following is satisfied: (a) a rotational speed difference ΔN (=Nmg-Ni) obtained by subtracting an AT input rotational speed Ni, which is the rotational speed of the drive wheel 14 side of the start clutch WSC, from an MG rotational speed Nmg, is equal to or greater than a predetermined determination rotational speed difference value ΔN_jdg (>0), or (b) a torque difference ΔT (=Tc_real-Twsc) between an actual torque capacity value Tc_real, which is the actual value of the torque capacity Tc of the start clutch WSC, is within a predetermined torque range ΔT_jdg, a change rate (change rate) α [Nm / sec] of a command value To_tgt (dynamic) of an AT output torque To [Nm] is a positive value, and it is estimated that the command value To_tgt (dynamic) will continue to increase. The predetermined determination differential rotation value ΔN_jdg is a value determined experimentally or by design, and is, for example, a positive value near zero, in order to determine whether the starting clutch WSC is actually in slip engagement. The actual torque capacity value Tc_real can be estimated, for example, based on the oil pressure supplied to an actuator that controls the engagement and disengagement of the starting clutch WSC, detected by a sensor (not shown). The predetermined torque range ΔT_jdg is a determination value determined experimentally or by design, within which shock caused by an increase in drive torque transmitted from the electric motor MG to the drive wheels 14 falls within an acceptable range even when rotational speed control is initiated. The command value To_tgt (dynamic) will be described later.

[0030] When the start determination unit 98c determines that the start condition for rotation speed control is satisfied, the differential rotation control unit 98d starts rotation speed control by feedback-controlling the MG rotation speed Nmg so that the differential rotation speed ΔN becomes a predetermined target differential rotation speed value ΔN_tgt. The target differential rotation speed value ΔN_tgt is a target value for the differential rotation speed ΔN and is a predetermined value determined experimentally or by design. FIG. 2 is a diagram illustrating an example of the relationship between the WSC input torque Twsc and the target differential rotation speed value ΔN_tgt in rotation speed control. In rotation speed control, for example, as shown in FIG. 2, when the WSC input torque Twsc exceeds the torque value Twsc_jdgx, the target differential rotation speed value ΔN_tgt is increased as the WSC input torque Twsc increases and gradually saturated at a constant value. Furthermore, when the WSC input torque Twsc is equal to or less than the torque value Twsc_jdgx, the target differential rotation speed value ΔN_tgt is set to zero. Therefore, the target MG rotation speed Nmg_tgt [rpm], which is the target value of the MG rotation speed Nmg during execution of the rotation speed control, is the sum of the AT input rotation speed Ni and the target differential rotation value ΔN_tgt.

[0031] Returning to Figure 1, if the torque determination unit 98a determines that the WSC input torque Twsc is less than the torque value Twsc_jdgx during BEV driving, the differential rotation control unit 98d terminates the rotational speed control, and then the starting clutch control unit 98b controls the torque capacity command value Tc_tgt to be higher than the WSC input torque Twsc so that the starting clutch WSC is fully engaged.

[0032] Once the rotation speed control is started by the differential rotation control unit 98d, the execution of the rotation speed control continues until the torque determination unit 98a determines that the WSC input torque Twsc is less than the torque value Twsc_jdgx during BEV running.

[0033] When a request to start the engine 12 is made during BEV running, the power source control unit 92 and the make-or-break clutch control unit 94 use the electric motor MG and the make-or-break clutch K0 to crank the engine 12. During this cranking, in accordance with the switching of the control state of the make-or-break clutch K0 from disengagement to full engagement by the make-or-break clutch control unit 94, the power source control unit 92 controls the electric motor MG to output a cranking torque Tcr until cranking is completed. In other words, the electric motor MG outputs an MG torque Tmg, which is the sum of the WSC input torque Twsc that generates the required drive torque Trdem and the cranking torque Tcr.

[0034] Fig. 3 is an example of a flowchart illustrating the main control operations of the electronic control unit 90 shown in Fig. 1. The flowchart in Fig. 3 is repeatedly executed while the BEV is running.

[0035] First, in step S10 (hereinafter, "step" is omitted) corresponding to the function of the torque determination unit 98a, it is determined whether the WSC input torque Twsc is less than the torque value Twsc_jdgx. If the determination in S10 is positive, the rotation speed control is terminated in S20 corresponding to the function of the differential rotation control unit 98d, and the torque capacity control is terminated in S30 corresponding to the function of the starting clutch control unit 98b, and then the process returns.

[0036] If the determination in S10 is negative, S40, which corresponds to the function of the torque determination unit 98a, determines whether the WSC input torque Twsc exceeds the torque value Twsc_jdgy. If the determination in S40 is positive, S50, which corresponds to the function of the starting clutch control unit 98b, starts torque capacity control. S60, which corresponds to the function of the start determination unit 98c, determines whether the differential rotation speed ΔN is equal to or greater than a predetermined determination differential rotation speed value ΔN_jdg. If the determination in S60 is negative, S70, which corresponds to the function of the start determination unit 98c, determines whether the torque difference ΔT is within a predetermined torque range ΔT_jdg, the change amount α in the command value To_tgt (dynamic) is positive, and the command value To_tgt (dynamic) is estimated to continue to increase. If the determination in either S60 or S70 is positive, rotation speed control is started in S80, which corresponds to the function of the differential rotation speed control unit 98d, and the process returns. If the determination in either S40 or S70 is negative, the process returns.

[0037] Fig. 4 is an example of a time chart when the rotation speed control is executed in the flowchart of Fig. 3. Fig. 4 shows an example in which S80 is executed when the determination in S60 or S70 in Fig. 3 is positive. For convenience, Fig. 4 shows a case in which the determinations in both S60 and S70 are positive.

[0038] Incidentally, when the AT output torque To is changed, a slow-change process (also called a smoothing process) is performed because there is a risk that a sudden change in the driving force of the vehicle 10 will cause torsional vibrations in the power transmission path PT. The command value To_tgt (static) of the AT output torque To shown in Fig. 4 is a target value of the AT output torque To calculated based on the current vehicle speed V and accelerator opening θacc, and the command value To_tgt (dynamic) of the AT output torque To is the command value To_tgt (static) that has been subjected to the slow-change process.

[0039] The MG torque Tmg, which is equivalent to the WSC input torque Twsc during BEV driving, is controlled based on the command value To_tgt (dynamic). From the perspective of the drive demand of the vehicle 10 during BEV driving, the command value To_tgt (dynamic) and the required WSC input torque Twscrq, which is the required value (target value) of the WSC input torque Twsc, are the same. Because the command value To_tgt (dynamic) changes with a delay from the command value To_tgt (static), it is possible to estimate not only the current change amount α of the command value To_tgt (dynamic), but also the future change amount α of the command value To_tgt (dynamic). Therefore, it is possible to estimate that the MG torque Tmg during BEV driving, i.e., the WSC input torque Twsc, is currently increasing and will continue to increase. Note that because the control of the electrically controlled electric motor MG has good responsiveness, there is almost no difference between the WSC input torque Twsc and the required WSC input torque Twscrq.

[0040] At time t1, the determination in S40 is affirmative, and execution of S50 is initiated. Specifically, because the required WSC input torque Twscrq exceeds the torque value Twsc_jdgy, the torque capacity command value Tc_tgt is reduced from the capacity value Tc1 that fully engages the starting clutch WSC to a capacity value Tc2 equal to the WSC input torque Twsc. Note that the capacity value Tc2 corresponds to "corresponding to the input torque" in this invention. FIG. 4 illustrates a case in which the torque capacity command value Tc_tgt is on the higher side of the range of control variation in the torque capacity Tc of the starting clutch WSC. This control variation in the torque capacity Tc of the starting clutch WSC arises from variations in components such as the friction plates of the starting clutch WSC and variations in the controllability of the actuator that controls the engagement and disengagement of the starting clutch WSC. Because the engagement and disengagement control of the starting clutch WSC is hydraulically controlled, the actual torque capacity value Tc_real changes in response to changes in the torque capacity command value Tc_tgt with a delay. On the other hand, the required WSC input torque Twscrq is controlled by the MG torque Tmg of the electric motor MG, which provides higher responsiveness than hydraulic control. That is, while a difference between the actual torque capacity value Tc_real and the torque capacity command value Tc_tgt is likely to occur due to the relatively low responsiveness, a difference between the actual value and the command value of the MG torque Tmg is unlikely to occur due to the relatively high responsiveness. Note that, even if torque capacity control is initiated after time t1 and until time t2 (described later), due to the control variability described above, it is unclear whether the starting clutch WSC will slip. For example, as shown in FIG. 4, if the torque capacity command value Tc_tgt is on the high side of the range of control variability, the starting clutch WSC may not slip.

[0041] At time t2 (>t1), (a) for example, if the differential rotation speed ΔN is equal to or greater than a predetermined reference differential rotation speed value ΔN_jdg, rotation speed control is initiated. Alternatively, (b) for example, at time t2, rotation speed control is initiated if the torque difference ΔT is within a predetermined torque range ΔT_jdg, the change amount α is a positive value, and it is estimated that the command value To_tgt (dynamic) will continue to increase. Note that (b) refers to a case in which it is estimated that the increase in the WSC input torque Twsc corresponding to the future increase in the command value To_tgt (dynamic) due to the change amount α at time t2 will exceed the range of control variation of the starting clutch WSC, causing the starting clutch WSC to slip. For example, when the required WSC input torque Twscrq increases due to an increase in the accelerator opening θacc, the required WSC input torque Twscrq increases faster than the actual torque capacity value Tc_real due to the difference in responsiveness described above. This causes the starting clutch WSC to slip.

[0042] If the torque capacity command value Tc_tgt is on the high side of the range of control variation and the starting clutch WSC is not in slip engagement, when the rotational speed control is executed, the starting clutch WSC is put into slip engagement, which increases the MG torque Tmg and causes a sudden increase in driving force by the amount of the control variation. This may cause a shock that the driver feels uncomfortable. Furthermore, depending on the feedback gain of the rotational speed control, a sudden increase in the MG torque Tmg may cause a shock that the driver feels uncomfortable.

[0043] FIG. 5 is a time chart illustrating the occurrence of a starting shock of the engine 12, comparing (a) a case where torque capacity control is initiated after a start request for the engine 12 is made ("without torque capacity control" in FIG. 5) with (b) a case where torque capacity control is initiated before a start request for the engine 12 is made ("with torque capacity control" in FIG. 5). In FIG. 5, the case (a) above is a comparative example, and the case (b) above is this embodiment. Note that the MG torque Tmg shown in FIG. 5 indicates the WSC input torque Twsc that generates the required drive torque Trdem and the torque required for rotational speed control, and the cranking torque Tcr component is not shown.

[0044] At time t11, a request is made to start the engine 12 while the vehicle is running as a BEV.

[0045] In the comparative example, the starting clutch WSC is fully engaged at time t11. Therefore, in order to suppress starting shock, after a request to start the engine 12 is made, the torque capacity command value Tc_tgt is reduced to the WSC input torque Twsc, and from the time when it is estimated that the actual torque capacity value Tc_real has reduced to the WSC input torque Twsc (see time t12), the MG torque Tmg is increased to start rotation speed control. Then, after the starting clutch WSC is engaged in slipping, engine start control is started.

[0046] In this embodiment, at time t11, there are two cases: (b1) the starting clutch WSC is in slip engagement and rotational speed control is being performed, and (b2) the starting clutch WSC is fully engaged but the actual torque capacity value Tc_real is so low that it is prone to slip engagement.

[0047] In the case of (b1) of this embodiment, although not shown in Figure 5, even if engine start control is started immediately from time t11, the starting clutch WSC is already in slip engagement, so that starting shock can be suppressed while maintaining drivability, compared to other cases.

[0048] In the case of (b2) of this embodiment, as shown in FIG. 5, the MG torque Tmg is increased immediately at time t11 to start rotational speed control. Then, after the starting clutch WSC is put into slip engagement, engine start control is started. In the case of (b2) of this embodiment, torque capacity control is already executed at time t11. Therefore, when the period from the time when the start of the engine 12 is requested to be started to the completion of engine start control is the same, it is possible to set a longer period during which the starting clutch WSC is put into slip engagement by rotational speed control compared to the comparative example. Therefore, compared to the comparative example, the MG rotational speed Nmg can be increased more gradually in rotational speed control, and therefore the torque increase amount by feedback control in rotational speed control, for example, the P term of PID control, can also be increased more gradually. Therefore, the vehicle acceleration Acc [m / sec], which is the acceleration in the forward / rearward direction in which the vehicle 10 travels, can be increased more gradually. 2 ] changes more gradually, suppressing starting shock.

[0049] According to this embodiment, torque capacity control is initiated during BEV driving before a start-up request for the engine 12 is made, and rotational speed control is initiated in at least one of the following cases: (a) the rotational speed difference ΔN is equal to or greater than a predetermined determination rotational speed difference value ΔN_jdg; and (b) the torque difference ΔT is within a predetermined torque range ΔT_jdg, the change amount α in the command value To_tgt (dynamic) is a positive value, and it is estimated that the WSC input torque T wsc will continue to increase. In case (a), the starting clutch WSC is in a slipping engagement, so even if rotational speed control is initiated, the drive torque transmitted from the electric motor MG to the drive wheels 14 will not increase abruptly. In case (b), the starting clutch WSC is currently and will continue to increase, i.e., the starting clutch WSC will immediately enter a slipping engagement due to an increase in the WSC input torque T wsc. Therefore, even if rotational speed control is initiated, the drive torque transmitted from the electric motor MG to the drive wheels 14 will not increase abruptly. When engine start control is executed upon request to start the engine 12 after the rotation speed control has been initiated, the starting clutch WSC is already in slip engagement. Therefore, engine start control is initiated more quickly than in a case where this is not the case, thereby achieving both suppression of starting shock and drivability. Furthermore, even when engine start control is initiated upon request to start the engine 12 before the rotation speed control is initiated, the torque capacity command value Tc_tgt is already set according to the WSC input torque Twsc. Therefore, engine start control can be initiated by slipping the starting clutch WSC more quickly than in a case where this is not the case, thereby achieving both suppression of starting shock and drivability.

[0050] According to this embodiment, if the WSC input torque Twsc exceeds the torque value Twsc_jdgy before a start-up request for the engine 12 is received during BEV driving, torque capacity control is initiated. If the WSC input torque Twsc is less than the torque value Twsc_jdgx, torque capacity control is terminated and the torque capacity command value Tc_tgt is controlled so that the starting clutch WSC is fully engaged. This prevents a decrease in the power generation efficiency of the electric motor MG due to regenerative braking and also prevents the occurrence of a start-up shock when the engine 12 is started. Furthermore, the difference between the torque values ​​Twsc_jdgy and Twsc_jdgx prevents the rotational speed control from being started and terminated frequently.

[0051] Although the embodiments of the present invention have been described in detail above with reference to the drawings, the present invention can also be applied to other embodiments.

[0052] In the above-described embodiment, torque capacity control is initiated when the WSC input torque Twsc exceeds the torque value Twsc_jdgy and terminated when the WSC input torque Twsc is less than the torque value Twsc_jdgx. However, for example, the torque values ​​Twsc_jdgy and Twsc_jdgx may be the same. Even in this embodiment, there is a risk that the start and end of rotation speed control may be repeated frequently, but otherwise the same effects as the above-described embodiment are achieved. Furthermore, for example, torque capacity control may be initiated regardless of the value of the WSC input torque Twsc. Even in this embodiment, there is a risk that the reduction in the power generation efficiency of the electric motor MG due to regenerative braking may not be suppressed, but otherwise the same effects as the above-described embodiment are achieved.

[0053] In the above-described embodiment, the starting clutch WSC is the "second clutch," but, for example, instead of the starting clutch WSC, an engagement device CB that mechanically connects and disconnects the power transmission path PT within the automatic transmission 20 may be used. Also, instead of the starting clutch WSC, a fluid-type power transmission device such as a torque converter or a fluid coupling may be provided, and an engagement device (for example, a lock-up clutch) that mechanically connects and disconnects the power transmission path PT within the fluid-type power transmission device may be used.

[0054] It should be noted that the above is merely an example 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]

[0055] 10: vehicle, 12: engine, 14: drive wheels, 90: electronic control unit (control unit), K0: disconnection clutch (first clutch), MG: electric motor, Ni: AT input rotation speed (rotation speed of drive wheels), Nmg: MG rotation speed (rotation speed of electric motor), PT: power transmission path, Tc: torque capacity (torque capacity of second clutch), Tc_tgt: torque capacity command value (command value), Tc_real: torque capacity actual value (actual value), Tmg: MG torque (output torque of electric motor), Twsc: WSC input torque (input torque), Twsc_jdgx: torque value (predetermined second torque value), Twsc_jdgy: torque value (predetermined first torque value), WSC: starting clutch (second clutch), ΔN: differential rotation, ΔN_jdg: judgment differential rotation value, ΔN_tgt: target differential rotation value, ΔT: torque difference, ΔT_jdg: predetermined torque range

Claims

1. A control device for a vehicle including an engine and an electric motor as a power source, a first clutch that connects and disconnects power transmission between the engine and the electric motor, and a second clutch that mechanically connects and disconnects a power transmission path between the power source and a drive wheel, a torque capacity control is started to set a command value of the torque capacity of the second clutch according to the input torque input from the electric motor before a start of the engine is requested during the BEV traveling in which the first clutch is released and the second clutch is fully engaged and power is output only from the electric motor; After the torque capacity control is started, in at least one of the cases where a differential rotation speed obtained by subtracting the rotation speed of the drive wheel side from the rotation speed of the electric motor side in the second clutch is equal to or greater than a predetermined judgment differential rotation value, and where a torque difference between the actual value of the torque capacity of the second clutch and the input torque is within a predetermined torque range and the input torque has increased and is estimated to continue to increase, a rotation speed control is started to control the rotation speed of the electric motor so that the differential rotation speed in the second clutch becomes a predetermined target differential rotation value, When a start of the engine is requested, the first clutch is switched from released to fully engaged and the output torque of the electric motor is increased to start the engine. A vehicle control device characterized by:

2. When the input torque exceeds a predetermined first torque value before a request to start the engine is made during the BEV traveling, the torque capacity control is started, and when the input torque is less than a predetermined second torque value that is lower than the first torque value, the torque capacity control is ended and a command value of the torque capacity of the second clutch is controlled so that the second clutch is fully engaged.

2. The vehicle control device according to claim 1.

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