Vehicle control device

Abstract

To execute damping control while suppressing the occurrence of a shock due to unintentional slip of a power connection-disconnection device in a case where the power connection-disconnection device is switched to a slip engagement state prior to the engine startup.SOLUTION: When performing damping control in a case where a start clutch WSC being a power connection-disconnection device is switched to the slip engagement state in the startup of an engine, an upper limit guard value Ginc of damping torque Tdamp set to zero (S4), and the damping control is executed followed by damping torque restrictions that restrict a change amount on the positive side while permitting a change on the negative side of the damping torque Tdamp.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a vehicle control device, and more particularly to a technique for suppressing torsional vibration in a power transmission path by controlling the torque of an electric motor. [Background technology]

[0002] A vehicle control device is known that relates to (a) a vehicle having a power source including an engine and an electric motor, and a power connection / disconnection device capable of slipping engagement that connects and disconnects a power transmission path between the power source and drive wheels, and (b) an engagement control unit that, in a motor-driven driving mode in which the engine is stopped and the vehicle is driven using the electric motor, brings the power connection / disconnection device into a fully engaged state without slipping, and, when starting the engine in the motor-driven driving mode, brings the power connection / disconnection device into a slipping engagement state prior to starting the engine. Patent Documents 1 and 2 are examples of such devices, and by bringing the power connection / disconnection device into a slipping engagement state when the engine is started, torque fluctuations at engine start are suppressed from being transmitted to the drive wheels via the power transmission path, causing shocks such as fluctuations in driving force.

[0003] On the other hand, Patent Document 3 proposes a technology for performing vibration damping control by applying a damping torque that changes between positive and negative in response to torsional vibration to the torque of an electric motor so as to suppress torsional vibration in the power transmission path. The torsional vibration can be generated by a sudden change in drive torque, for example, during tip-in acceleration, when the vehicle transitions from driven driving with the accelerator off to driving driving in response to an acceleration request from the driver. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5884894 [Patent Document 2] Patent No. 5794377 [Patent Document 3] Japanese Patent Application Laid-Open No. 2001-28809 Summary of the Invention [Problem to be solved by the invention]

[0005] It is conceivable to apply the vibration damping control described in Patent Document 3 and the like to the hybrid vehicles described in Patent Documents 1 and 2, thereby suppressing torsional vibrations by controlling the torque of the electric motor used as a power source. In this case, when the engagement torque of the power disconnector is reduced to switch to a slip engagement state at engine start, if the power disconnector enters a slip engagement state, the mass is reduced and torsional vibrations are less likely to occur, so vibration damping control is not necessarily required. However, when the slip of the power disconnector is zero during the process of reducing the engagement torque to switch to the slip engagement state, torsional vibrations become a problem, so it is desirable to perform vibration damping control as needed. However, if vibration damping control is performed during the process of reducing the engagement torque, the power disconnector may slip unintentionally, causing shocks due to changes in the electric motor torque caused by the vibration damping control.

[0006] The present invention was made against the background of the above circumstances, and its purpose is to enable vibration damping control to be performed while preventing the power disconnection device from slipping unintentionally when the power disconnection device is switched to a slip engagement state prior to engine start. [Means for solving the problem]

[0007] In order to achieve this object, the first invention relates to a vehicle control device that (a) has a power source having an engine and an electric motor, and a power connection / disconnection device capable of slipping engagement that connects and disconnects a power transmission path between the power source and drive wheels, (b) has an engagement control unit that, when in a motor-driven driving mode in which the engine is stopped and the vehicle is traveling using the electric motor, engages the power connection / disconnection device in a fully engaged state without slipping, and when starting the engine in the motor-driven driving mode, puts the power connection / disconnection device in a slipping engagement state prior to starting the engine, (c) has a vibration damping control unit that performs vibration damping control by applying a vibration damping torque to the torque of the electric motor that changes to the positive and negative sides in response to torsional vibrations in the power transmission path so that the torsional vibrations in the power transmission path are suppressed, and (d) when performing the vibration damping control when the power connection / disconnection device is switched to the slipping engagement state at the start of the engine, the vibration damping control unit performs vibration damping torque limiting that limits the amount of change in the positive side of the vibration damping torque while allowing a change in the negative side of the vibration damping torque.

[0008] The second invention is characterized in that, in the vehicle control device of the first invention, (a) the engagement control unit reduces the engagement torque of the power disconnecting device when switching the power disconnecting device from the fully engaged state to the slipping engaged state, causing slippage in the power disconnecting device, and (b) the vibration damping control unit executes the vibration damping torque limitation until slippage occurs in the power disconnecting device, and terminates the vibration damping control itself when slippage occurs.

[0009] The third invention is a vehicle control device according to the second invention, characterized in that (a) the engagement control unit reduces the engagement torque of the power disconnection device, and then controls the command value of the engagement torque to match the input torque of the power disconnection device, while feedback-controlling the torque of the electric motor to bring the slip of the power disconnection device into the slip engagement state so that it becomes a predetermined target slip amount, and (b) the vibration damping control unit executes the vibration damping torque limitation until the feedback control is started by the engagement control unit, and terminates the vibration damping control when the feedback control is started. [Effects of the Invention]

[0010] According to this vehicle control device, when the power disconnector is switched from a fully engaged state to a slipping engaged state prior to engine start, vibration control is performed with a vibration damping torque limit that allows a negative change in the vibration damping torque while limiting a positive change in the vibration damping torque. Therefore, regardless of a decrease in the engagement torque of the power disconnector to switch to the slipping engaged state, unintended slippage of the power disconnector due to an increase or decrease in the electric motor torque caused by the vibration damping control is suppressed. In other words, since the electric motor is driven by a positive target torque in the motor-driven driving mode when the engine is started, if a positive vibration damping torque is added to the target torque, a large electric motor torque periodically acts on the power disconnector, making it more likely to slip. Therefore, by limiting the positive change in the vibration damping torque, slippage of the power disconnector can be appropriately suppressed. Meanwhile, since a negative change in the vibration damping torque is allowed, torsional vibration is suppressed by the negative vibration damping torque.

[0011] In the second and third inventions, vibration damping torque limitation is performed until slippage occurs in the power disconnecting device, and once slippage occurs, vibration damping control itself is terminated. Therefore, vibration damping control is performed while limiting the vibration damping torque only while the power disconnecting device is in a fully engaged state with zero slippage, which makes it possible to suppress torsional vibration while suppressing unintended slippage of the power disconnecting device, and also prevents unnecessary vibration damping control from being performed in a slip engagement state. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a diagram illustrating the schematic configuration of a vehicle having a control device to which the present invention is applied, and is also a diagram illustrating the control functions and main parts of a control system for various controls. [Figure 2] This is a flowchart that explains the operation of the vibration damping control unit, which is functionally provided in the electronic control device of Figure 1, to limit the amount of change in the positive side of the vibration damping torque when the starting clutch WSC is switched to a slip engagement state prior to engine start. [Figure 3] 3 is an example of a time chart illustrating changes in the operating state of each part when vibration damping control is performed according to the flowchart of FIG. 2 when the starting clutch WSC is switched to a slip engagement state. DETAILED DESCRIPTION OF THE INVENTION

[0013] The present invention can be applied to various hybrid vehicles that have an engine and an electric motor as power sources and are capable of operating in a motor-driven driving mode in which the engine is stopped and the vehicle runs using the electric motor. For example, if an automatic transmission is provided between the power source and the drive wheels, the power disengagement device that connects and disconnects the power transmission path is a starting clutch or the like provided between the automatic transmission and the power source, but a clutch or the like provided in the automatic transmission can also be used. Furthermore, if the vehicle is provided with a fluid-type transmission device such as a torque converter with a lock-up clutch, the lock-up clutch can also be used as the power disengagement device.

[0014] The vibration damping control unit is configured to, for example, zero the amount of change on the positive side of the vibration damping torque while leaving the negative side change unchanged when the power disconnecting device is switched from a fully engaged state to a slipping engaged state at engine start, but it is not necessary to completely zero the amount of change on the positive side, and it may be sufficient to simply reduce it by, for example, a predetermined fixed rate or value. Also, it is possible to limit the amount of change on the negative side of the vibration damping torque to a range smaller than that on the positive side, as necessary. [Example]

[0015] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram illustrating a schematic configuration of a vehicle 10 to which the present invention is applied, as well as a diagram illustrating key parts of control functions and control systems for various controls in the vehicle 10. In FIG. 1, the vehicle 10 is a hybrid electric vehicle equipped with an engine 12 and an electric motor MG as power sources. The vehicle 10 also includes drive wheels 14 and a power transmission device 16 provided in a power transmission path between the engine 12 and the drive wheels 14. The engine 12 is a known internal combustion engine such as a gasoline engine or a diesel engine. An engine control device 50, which includes a fuel injection device and an ignition device, is controlled by an electronic control device 90 (described later), thereby controlling engine torque Te, which is the output torque of the engine 12. The electric motor MG is a rotating electric machine, a so-called motor generator, that functions as both an engine that generates mechanical power from electric power and a generator that generates electric power from mechanical power. The electric motor MG is connected to a battery 54 via an inverter 52. The inverter 52 is controlled by the electronic control device 90, thereby controlling MG torque Tm, which is the torque of the electric motor MG.

[0016] The power transmission device 16 is a so-called transaxle that includes a make-and-break clutch K0, a starting clutch WSC, an automatic transmission 20, a reduction gear mechanism 22, a differential gear 24, and the like, housed within a case 18 attached to the vehicle body. The power transmission device 16 also includes a pair of drive shafts 28 connected to the differential gear 24. The power transmission device 16 also includes, within the case 18, an engine connecting shaft 30 that connects the engine 12 and the make-and-break clutch K0, and an electric motor connecting shaft 32 that connects the make-and-break clutch K0 and the starting clutch WSC, and the electric motor MG is connected to the electric motor connecting shaft 32 so as to be able to transmit power. The power transmission device 16 also includes, within the case 18, a mechanical oil pump 34 that is connected to the electric motor connecting shaft 32 via a transmission member 36 such as a sprocket and a chain, and is rotated.

[0017] The on-off clutch K0 and the starting clutch WSC are both wet or dry friction engagement devices constituted by, for example, a multi-plate or single-plate clutch pressed by an actuator. The on-off clutch K0 switches between operating states, i.e., control states, such as a fully engaged state, a slipping engaged state, and a released state, by changing the torque capacity, i.e., K0 torque Tk0, using the K0 oil pressure PRk0 supplied from the hydraulic control circuit 56. The starting clutch WSC switches between operating states, i.e., a fully engaged state, a slipping engaged state, and a released state, by changing the torque capacity, i.e., WSC torque Twsc, using the WSC oil pressure PRwsc supplied from the hydraulic control circuit 56. The fully engaged state is a state in which the clutch is engaged without slipping, i.e., without differential rotation, and the slipping engaged state is a state in which the clutch is engaged while slipping. The disconnecting clutch K0 is a slip-engageable engine disconnecting device that connects or disconnects the engine 12 to or from the electric motor MG, and the starting clutch WSC is a slip-engageable power disconnecting device that connects or disconnects the power transmission path between the engine 12 and electric motor MG, which are the power sources, and the drive wheels 14.

[0018] The automatic transmission 20 is a known planetary gear automatic transmission including, for example, one or more planetary gear sets (not shown) and engagement devices CB. Each engagement device CB switches between operating states such as a fully engaged state, a slip-engaged state, and a disengaged state by varying its torque capacity (CB torque Tcb) using a CB oil pressure PRcb, which is a regulated oil pressure supplied from a hydraulic control circuit 56. The automatic transmission 20 is a stepped transmission in which one of a plurality of gears with different gear ratios γat (=AT input rotation speed Ni / AT output rotation speed No) is established by engaging one of the engagement devices CB. The AT input rotation speed Ni is the rotation speed of the transmission input shaft 38 and is also the rotation speed of an output member of the starting clutch WSC. The AT output rotation speed No is the rotation speed of the transmission output gear 26.

[0019] The mechanical oil pump 34 is driven by a power source (engine 12, electric motor MG) and discharges hydraulic oil OIL. The vehicle 10 is further equipped with an electric oil pump 58, which is an electric oil pump. The electric oil pump 58 is driven by a pump motor 60, which is a dedicated motor, and discharges hydraulic oil OIL. The hydraulic oil OIL discharged from the mechanical oil pump 34 and the electric oil pump 58 is supplied to the hydraulic control circuit 56, and its pressure is adjusted by a solenoid valve or the like controlled by an electronic control device 90. The hydraulic oil OIL is output as the K0 hydraulic pressure PRk0, the WSC hydraulic pressure PRwsc, the CB hydraulic pressure PRcb, etc., and is also used for lubrication of various parts of the power transmission device 16.

[0020] 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 a CPU, RAM, ROM, an input / output interface, etc., and the CPU executes various controls of the vehicle 10 by performing signal processing in accordance with programs stored in the ROM in advance while utilizing the temporary storage function of the RAM. The electronic control device 90 is configured to include computers for engine control, electric motor control, hydraulic control, etc. as necessary.

[0021] The electronic control device 90 is supplied with various signals based on detection values ​​from various sensors provided in 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 opening sensor 78, throttle valve opening sensor 80, battery sensor 84, oil temperature sensor 86, etc.) (e.g., engine rotation speed Ne, which is the rotation speed of the engine 12; MG rotation speed Nm, 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, which corresponds to the vehicle speed V; accelerator opening θacc, which is the amount of accelerator operation indicating the magnitude of the driver's acceleration request; throttle valve opening θth, which is the opening of the electronic throttle valve; battery temperature THbat, battery charge / discharge current Ibat, and battery voltage Vbat of the battery 54; and oil temperature THoil, which is the temperature of the hydraulic oil OIL in the hydraulic control circuit 56). The MG rotational speed Nm is the same as the rotational speed of the input member of the starting clutch WSC, and the AT input rotational speed Ni is the same as the rotational speed of the output member of the starting clutch WSC. From these rotational speeds Nm and Ni, the operating state of the starting clutch WSC, i.e., whether it is in a fully engaged state, a slipping engaged state, or a released state, can be determined.

[0022] The electronic control device 90 outputs various command signals (e.g., an engine control command signal Se for controlling the engine 12, an MG control command signal Sm for controlling the electric motor MG, a CB hydraulic control command signal Scb for controlling the engagement device CB, a K0 hydraulic control command signal Sk0 for controlling the make-and-break clutch K0, a WSC hydraulic control command signal Swsc for controlling the starting clutch WSC, an electric oil pump control command signal Seop for controlling the electric oil pump 58, etc.) to each device provided in the vehicle 10 (e.g., the engine control device 50, the inverter 52, the hydraulic control circuit 56, the pump motor 60, etc.).

[0023] The electronic control unit 90 functionally comprises a power source control unit 92, a WSC engagement control unit 96, and a vibration damping control unit 98 in order to realize various controls in the vehicle 10.

[0024] The power source control unit 92 calculates the amount of driving demanded by the driver for the vehicle 10, for example, by applying the accelerator opening θacc and the vehicle speed V to a driving demand map. The driving demand map is a relationship for calculating the driving demand, which is determined experimentally or by design and stored in advance, i.e., a predetermined relationship. The driving demand may be, for example, a required driving torque Trdem [Nm], a required driving force Frdem [N], or a required driving power Prdem [W] at the drive wheels 14. The power source control unit 92 calculates a required input torque Tidem at the transmission input shaft 38 that can achieve the required driving demand, taking into account transmission loss, accessory load, the gear ratio γat of the automatic transmission 20, and the like, and then calculates a target engine torque Tetgt and a target MG torque Tmtgt that will achieve the required input torque Tidem. The power source control unit 92 then outputs an engine control command signal Se that controls the engine 12 to output the target engine torque Tetgt, and outputs an MG control command signal Sm that controls the electric motor MG to output the target MG torque Tmtgt.

[0025] When the required drive torque Trdem can be satisfied solely by the output of the electric motor MG, the power source control unit 92 sets the drive mode for driving the vehicle 10 to the BEV drive mode. The BEV drive mode is a motor drive mode that enables motor driving (=BEV driving) using only the electric motor MG as a power source when the on-off clutch K0 is in a disengaged state. On the other hand, when the required drive torque Trdem cannot be satisfied without using the output of the engine 12, the power source control unit 92 sets the drive mode to the HEV drive mode. The HEV drive mode is a hybrid drive mode that enables engine driving (=HEV driving) using at least the engine 12 as a power source when the on-off clutch K0 is in an engaged state. On the other hand, even when the required drive torque Trdem can be satisfied solely by the output of the electric motor MG, the power source control unit 92 establishes the HEV drive mode when, for example, the battery 54 needs to be charged or the engine 12 needs to be warmed up. The BEV drive mode corresponds to the motor drive mode, and the HEV drive mode corresponds to the engine drive mode.

[0026] The power source control unit 92 determines whether there is an engine start request to switch the control state of the engine 12 from a stopped state to an operating state. For example, in the BEV drive mode, the power source control unit 92 determines whether there is an engine start request based on whether the required drive torque Trdem has increased beyond the range that can be covered by the output of the electric motor MG alone, whether the engine 12 and the like need to be warmed up, or whether the battery 54 needs to be charged. In other words, it determines whether there is a need to switch from the BEV drive mode to the HEV drive mode. The power source control unit 92 functionally includes an engine start control unit 94, and when it determines that there is an engine start request, the engine start control unit 94 starts the engine 12.

[0027] The engine start control unit 94 outputs a K0 hydraulic control command signal Sk0 to shift the disengaged make-and-break clutch K0 into a slip engagement state so as to obtain a K0 torque Tk0 for transmitting a cranking torque Tcr to the engine 12 for increasing the engine rotation speed Ne. The engine start control unit 94 also controls the engine 12 and the electric motor MG to execute start control of the engine 12. For example, in response to the switching of the make-and-break clutch K0 to the slip engagement state, the engine start control unit 94 outputs an MG control command signal Sm to cause the electric motor MG to output the cranking torque Tcr. The engine start control unit 94 also outputs an engine control command signal Se to execute start processing such as fuel supply and engine ignition in conjunction with the cranking of the engine 12. That is, the engine start control unit 94 executes engine start control by shifting the make-and-break clutch K0 into slip engagement and increasing the MG torque Tm to increase the engine rotation speed Ne, and then executes start processing such as ignition to start the engine 12 so that the engine 12 rotates under its own power.

[0028] The WSC engagement control unit 96 controls the starting clutch WSC to maintain a released state or a slipping engagement state when the vehicle 10 is stopped. By maintaining the starting clutch WSC in a slipping engagement state when the vehicle is stopped, for example, when the brake is released with the accelerator pedal still released, the vehicle 10 can be driven in a so-called creep driving mode, in which the vehicle moves slowly. Furthermore, when the vehicle 10 is driving in the BEV drive mode or the HEV drive mode, the starting clutch WSC is controlled to maintain a fully engaged state. However, if the AT input rotation speed Ni falls below the operable rotation speed of the engine 12 while driving in the HEV drive mode at low vehicle speed, the starting clutch WSC is controlled to a slipping engagement state.

[0029] When engine start control is performed by the engine start control unit 94 during BEV driving with the start clutch WSC in a fully engaged state, the WSC engagement control unit 96 switches the start clutch WSC to a slip engagement state prior to the engine start control. Slip control that switches the start clutch WSC to a slip engagement state reduces the engagement torque (WSC torque) Twsc of the start clutch WSC, i.e., the WSC oil pressure PRwsc, to enable the generation of a differential rotation ΔNmi (=Nm -Ni) between the MG rotation speed Nm and the AT input rotation speed Ni, which are the rotational speeds on both sides of the start clutch WSC, and feedback controls the torque Tm of the electric motor MG so that the differential rotation ΔNmi becomes a predetermined target differential rotation ΔNtgt. Specifically, the MG torque Tm is feedback controlled so that the MG rotation speed Nm becomes the rotation speed (Ni + ΔNtgt) obtained by adding the target differential rotation speed ΔNtgt to the AT input rotation speed Ni, which is determined according to the vehicle speed V and the gear position of the automatic transmission 20. By placing the start clutch WSC in a slip engagement state in this way, torque fluctuations at the start of the engine 12 are suppressed from being transmitted from the power transmission device 16 to the drive wheels 14, thereby preventing shocks such as fluctuations in driving force. The differential rotation speed ΔNmi corresponds to the amount of slip, and the target differential rotation speed ΔNtgt corresponds to the target amount of slip.

[0030] FIG. 3 is an example of a time chart illustrating the changes in the operating state of various components when slip control is performed to switch the starting clutch WSC from a fully engaged state to a slipping state. Slip control is initiated at time t1. Time t1 is the time when a predetermined slip control initiation condition is met. In this example, a predicted engine start request is determined based on the required input torque Tidem. Specifically, this determination is based on whether the required input torque Tidem exceeds a predetermined threshold value during tip-in acceleration. The slip control initiation condition can be appropriately determined, such as initiating slip control when an engine start request is actually received. When the slip control initiation condition is met, the command value of the WSC torque Twsc is reduced to a predetermined initial slip value Twsc1. Furthermore, when the required input torque Tidem, which corresponds to the input torque of the starting clutch WSC, exceeds the initial slip value Twsc1, the command value of the WSC torque Twsc is controlled to match the required input torque Tidem. At this stage, the required input torque Tidem matches the target MG torque Tmtgt.

[0031] The actual WSC torque Twsc (hereinafter referred to as actual Twsc) is varied with a predetermined response delay relative to the command value. When the actual Twsc substantially matches the required input torque Tidem at time t2, feedback control of the MG torque Tm is enabled to control the differential rotation speed ΔNmi to the target differential rotation speed ΔNtgt. Time t2 marks the start of feedback control of the MG torque Tm, which adjusts the differential rotation speed ΔNmi to the target differential rotation speed ΔNtgt. The start timing of this feedback control can be determined, for example, by detecting the WSC oil pressure PRwsc using an oil pressure sensor to obtain the actual Twsc (estimated value), and checking whether actual Twsc = Tidem. The output torque To in Figure 3 is the output torque of the transaxle in this embodiment, i.e., the output torque of the reduction gear mechanism 22. The To command value in the output torque To column corresponds to the required drive torque Trdem. The static To command value corresponds to the accelerator opening θacc, and actual To is the actual output torque To.

[0032] The vibration damping control unit 98 executes vibration damping control to suppress torsional vibration when there is a possibility of torsional vibration occurring in the drive shaft 28 or other components of the power transmission device 16, which is the power transmission path, such as during acceleration, regenerative braking, tip-in acceleration, or tip-out. This vibration damping control predicts torsional vibration using, for example, a predetermined vibration model, and controls the torque Tm of the electric motor MG so as to suppress the torsional vibration. That is, to suppress torsional vibration in the power transmission path, the vibration damping control unit 98 calculates a vibration damping torque Tdamp that changes positively and negatively in antiphase with the torsional vibration, and controls the electric motor MG so as to output a corrected MG torque Tm (=Tmtgt+Tdamp) by adding the vibration damping torque Tdamp to the target MG torque Tmtgt. In this embodiment, an upper limit guard value Ginc and a lower limit guard value Gdec of the vibration damping torque Tdamp are predetermined, and fluctuations in the vibration damping torque Tdamp are restricted within the range of these upper limit guard values ​​Ginc and Gdec. The range indicated by diagonal lines between upper and lower guard values ​​Ginc and Gdec in FIG. 3 is the operating range of vibration damping torque Tdamp, which in normal vibration damping control is restricted by the reference value indicated before time t1.

[0033] When the WSC engagement control unit 96 switches the starting clutch WSC from a fully engaged state to a slipping engaged state when starting the engine 12 while the vehicle is traveling in BEV drive mode, the vibration damping control unit 98 executes signal processing in accordance with steps S1 to S5 (hereinafter, the steps will be omitted and simply referred to as S1 to S5) of the flowchart in Fig. 2. The flowchart in Fig. 2 is executed when a determination is made that the vibration damping control unit 98 should execute vibration damping control while traveling in BEV drive mode. In Fig. 2, YES in the determination steps indicated by diamonds means affirmative, and NO means negative.

[0034] In S1 of FIG. 2, it is determined whether WSC slip control is in operation, i.e., whether slip control for placing the starting clutch WSC in a slip engagement state is in operation, including during a transition when the starting clutch WSC is switched from a fully engaged state to a slip engagement state. Therefore, if the starting of the engine 12 is expected or requested, and the WSC engagement control unit 96 performs slip control of the starting clutch WSC, the determination in S1 is YES. If the determination in S1 is YES, S2 and subsequent steps are executed. If the determination is NO, i.e., if the starting clutch WSC remains in a fully engaged state, normal vibration damping control is executed in S5. The normal vibration damping control controls the MG torque Tm by adding the vibration damping torque Tdamp to the target MG torque Tmtgt while restricting the operating range of the vibration damping torque Tdamp within the range of the upper limit guard value Ginc and the lower limit guard value Gdec before time t1 in FIG. 3.

[0035] In S2, it is determined whether feedback (F / B) control of the MG torque Tm is in operation, which controls the differential rotation speed ΔNmi (=Nm -Ni) of the starting clutch WSC to the target differential rotation speed ΔNtgt. If feedback control is in operation, S3 is executed to end the vibration damping control. In other words, if the starting clutch WSC is in a slip engagement state with a predetermined differential rotation speed ΔNmi, the mass is reduced and torsional vibration is less likely to occur, so there is no need to perform vibration damping control.

[0036] On the other hand, when feedback control of MG torque Tm is not in operation, the differential rotation speed ΔNmi (= Nm - Ni) of the starting clutch WSC is zero, i.e., Nm = Ni, and the starting clutch WSC is still fully engaged. Therefore, S4 is executed to perform vibration suppression control while limiting the upper limit guard value Ginc of the damping torque Tdamp. When the starting clutch WSC is fully engaged, torsional vibration becomes a problem, so it is desirable to perform vibration suppression control. However, if the WSC oil pressure PRwsc is reduced to switch to the slip engagement state and the WSC torque Twsc is reduced accordingly, the starting clutch WSC may slip unintentionally due to the increase or decrease in the MG torque Tm caused by the vibration suppression control. This slippage mainly occurs when the MG torque Tm increases, so the upper limit guard value Ginc, which restricts the amount of change on the positive side of the upward and downward fluctuations in the damping torque Tdamp, is more limited than usual. In this embodiment, the upper limit guard value Ginc = 0 so that the amount of change on the positive side becomes zero. Of the upward and downward fluctuations in the damping torque Tdamp, it is desirable to maintain the lower limit guard value Gdec, which restricts changes on the negative side, at a normal value in order to suppress torsional vibration. S4 is a step in which damping torque limitation is executed.

[0037] The time chart of Fig. 3 illustrates the case where vibration damping control is performed according to the flowchart of Fig. 2 when the starting clutch WSC is switched to the slip engagement state prior to engine start. In Fig. 3, vibration damping control is performed from a stage before time t1, when slip control of the starting clutch WSC is initiated. Before time t1, S1 is followed by S5, and normal vibration damping control is performed by varying vibration damping torque Tdamp up and down within the range indicated by the diagonal lines between upper limit guard value Ginc and lower limit guard value Gdec. Before time t1, upper limit guard value Ginc and lower limit guard value Gdec are both reference values, and sufficient variation in vibration damping torque Tdamp is ensured on both the positive and negative sides, so vibration damping control is performed appropriately based on that vibration damping torque Tdamp.

[0038] When slip control is initiated at time t1, S1 in FIG. 2 is followed by S2 and S4, and the upper guard value Ginc of damping torque Tdamp is set to zero. This enables only negative changes in damping torque Tdamp, and MG torque Tm is increased or decreased based on this damping torque Tdamp, thereby suppressing torsional vibration while suppressing unintended slip of the starting clutch WSC. While the lower guard value Gdec may remain at a reference value, in FIG. 3 it is set slightly smaller than the reference value. Furthermore, when feedback control of MG torque Tm is initiated at time t2, such that differential rotation ΔNmi of the starting clutch WSC becomes equal to the target differential rotation ΔNtgt, S3 in FIG. 2 is executed, and damping control is terminated. Then, for example, after time t3 when differential rotation ΔNmi of the starting clutch WSC becomes equal to the target differential rotation ΔNtgt, start control of engine 12 is initiated. Even after vibration damping control ends, the upper limit guard value Ginc and the lower limit guard value Gdec of the vibration damping torque Tdamp are maintained as they are.

[0039] As described above, according to the electronic control device 90 of the vehicle 10 of this embodiment, when the engine 12 is started while the vehicle is traveling in the BEV drive mode, which is a motor-driven travel mode, the starting clutch WSC is switched from the fully engaged state to the slip engaged state prior to starting the engine 12. In this case, when slip control for switching to the slip engaged state is initiated, the upper limit guard value Ginc of the damping torque Tdamp is set to zero in S4, and damping control is performed with damping torque limitation that allows changes on the negative side while limiting the amount of change on the positive side. Therefore, regardless of a decrease in the WSC torque Twsc (actual Twsc) due to the slip control, unintended slip of the starting clutch WSC caused by an increase or decrease in the MG torque Tm due to the damping control is suppressed. That is, when starting the engine 12 in BEV drive mode, the electric motor MG is driven by a positive target MG torque Tmtgt, and when a positive damping torque Tdamp is added to that target MG torque Tmtgt, a large MG torque Tm periodically acts on the starting clutch WSC, making it more likely to slip; by limiting the amount of change in damping torque Tdamp on the positive side, slippage of the starting clutch WSC can be appropriately suppressed. On the other hand, because the lower limit guard value Gdec remains approximately at the reference value and damping torque Tdamp is allowed to change on the negative side, torsional vibrations are suppressed by the negative damping torque Tdamp.

[0040] Furthermore, vibration damping torque limitation in S4 is executed until MG torque Tm is feedback controlled so as to cause starting clutch WSC to slip at target differential rotation ΔNtgt, in other words, until slippage occurs in starting clutch WSC, and once slippage occurs, vibration damping control itself is terminated in S3. Therefore, vibration damping control is executed while limiting vibration damping torque only while the starting clutch WSC is in a fully engaged state where the differential rotation ΔNmi is zero, making it possible to suppress torsional vibration while suppressing unintended slippage of the starting clutch WSC, and also preventing unnecessary execution of vibration damping control in a slip engagement state where differential rotation ΔNmi occurs.

[0041] Although the embodiments of the present invention have been described in detail above with reference to the drawings, this is merely one embodiment, and the present invention can be implemented in various forms with various modifications and improvements based on the knowledge of those skilled in the art. [Explanation of symbols]

[0042] 10: Vehicle 12: Engine 14: Drive wheels 16: Power transmission device (power transmission path) 90: Electronic control device (control device) 96: WSC engagement control section (engagement control section) 98: Damping control section MG: Electric motor WSC: Starting clutch (power disconnecting device) ΔNmi: Differential rotation (slip amount) ΔNtgt: Target differential rotation (target slip amount) Tidem: Required input torque (input torque) Twsc: WSC torque (engagement torque) Tdamp: Damping torque Ginc: Upper limit guard value (positive side guard value) Gdec: Lower limit guard value (negative side guard value)

Claims

1. A vehicle having a power source including an engine and an electric motor, and a slip-engageable power disconnecting device that connects and disconnects a power transmission path between the power source and drive wheels, a control device for a vehicle having an engagement control unit that brings the power disconnecting device into a fully engaged state in which it is engaged without slipping during a motor-driven running mode in which the engine is stopped and the vehicle is running using the electric motor, and that brings the power disconnecting device into a slipping engaged state prior to starting the engine during the motor-driven running mode; a vibration damping control unit that performs vibration damping control by applying a vibration damping torque that changes between a positive side and a negative side in response to the torsional vibration to the torque of the electric motor so that the torsional vibration of the power transmission path is suppressed; When performing the vibration damping control when the power disconnecting device is switched to the slip engagement state at the start of the engine, the vibration damping control unit executes vibration damping torque limitation that limits a positive side change in the vibration damping torque while allowing a negative side change in the vibration damping torque. A vehicle control device characterized by:

2. the engagement control unit reduces an engagement torque of the power connecting / disconnecting device to cause slippage in the power connecting / disconnecting device when switching the power connecting / disconnecting device from the fully engaged state to the slipping engaged state, The vibration damping control unit executes the vibration damping torque limitation until slippage occurs in the power disconnecting device, and terminates the vibration damping control itself when slippage occurs.

2. The vehicle control device according to claim 1.

3. The engagement control unit, after reducing the engagement torque of the power connecting / disconnecting device, controls the command value of the engagement torque so that it coincides with the input torque of the power connecting / disconnecting device, and feedback controls the torque of the electric motor so that the slip amount of the power connecting / disconnecting device becomes a predetermined target slip amount, thereby bringing the power connecting / disconnecting device into the slip engagement state, The vibration damping control section executes the vibration damping torque limitation until the feedback control is started by the engagement control section, and ends the vibration damping control itself when the feedback control is started.

3. The vehicle control device according to claim 2.

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