Vehicle control device

Abstract

To speedily decrease clutch oil pressure while suppressing clutch slip, when switching an engine from an operating state to a stopped state.SOLUTION: When there is an engine stop request, a hydraulic control circuit is controlled so that a correction oil pressure is applied to an engagement maintaining oil pressure at least from the point in time that oil pressure switch is started and so that the correction oil pressure is decreased toward zero by the point in time that engine output torque decreases to predetermined low torque. Therefore, even if undershoot of actual clutch oil pressure arises when clutch oil pressure is switched from original pressure to the adjusted oil pressure, the actual clutch oil pressure is increased to such high oil pressure that clutch slip can be suppressed, and the correction oil pressure is maintained at zero during transition of switching of the clutch to a release state. Accordingly, when the engine is switched from an operating state to a stopped state, the clutch oil pressure can be speedily decreased while clutch slip is suppressed.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a control device for a vehicle having a clutch provided between an engine and an electric motor. [Background technology]

[0002] A vehicle control device is well known, which includes an engine, an electric motor connected to a power transmission path between the engine and driving wheels so as to be capable of transmitting power, a clutch provided between the engine and the electric motor in the power transmission path, and a hydraulic control circuit that selectively supplies one of an original pressure of the clutch hydraulic pressure and a regulated pressure obtained by regulating the original pressure as a clutch hydraulic pressure that is a hydraulic pressure for switching a control state of the clutch. For example, a hybrid vehicle is described in Patent Document 1. Patent Document 1 discloses that, when switching from an engine operating state in which a clutch provided between the engine and the electric motor is in a fully engaged state to an engine stopped state in which the clutch is in a fully released state, an engine stop control is performed in which the clutch hydraulic pressure is switched from the original line pressure to a regulated pressure hydraulic pressure and the regulated pressure hydraulic pressure is reduced from the line pressure to switch the clutch to a fully released state. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-93639 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, when the clutch oil pressure is switched from the base pressure to the regulated oil pressure, there is a possibility that the actual clutch oil pressure will fall below the required value, i.e., the command value, of the oil pressure that generates the torque capacity of the clutch capable of transmitting the engine torque, resulting in an undershoot of the actual clutch oil pressure. If this happens, the undershoot of the actual clutch oil pressure may cause the clutch to slip, which may result in an increase in the engine speed.

[0005] The present invention has been made against the background of the above circumstances, and its object is to provide a vehicle control device that can quickly reduce clutch oil pressure while suppressing clutch slippage when switching the engine from an operating state to a stopped state. [Means for solving the problem]

[0006] The gist of a first invention is a control device for a vehicle including: (a) an engine; an electric motor connected to a power transmission path between the engine and driving wheels so as to be capable of transmitting power; a clutch provided in the power transmission path between the engine and the electric motor; and a hydraulic control circuit that selectively supplies, as a clutch hydraulic pressure which is a hydraulic pressure for switching a control state of the clutch, one of an original pressure of the clutch hydraulic pressure and a regulated hydraulic pressure obtained by regulating the original pressure, (b) a clutch control unit that controls the hydraulic control circuit so that the original pressure is supplied to the clutch in an operating state of the engine in which the clutch is in a fully engaged state, and controls the hydraulic control circuit so that the regulated hydraulic pressure is supplied to the clutch with a value of the regulated hydraulic pressure set to zero in a stopped state of the engine in which the clutch is in a fully released state; and (c) the clutch control unit controls the engine to operate in the operating state of the engine. during a transition in which the output torque of the engine is gradually reduced in accordance with an engine stop request for switching the clutch oil pressure from the base pressure to the regulated oil pressure, and also controls the hydraulic control circuit to set the regulated oil pressure to an engagement maintaining oil pressure that generates a torque capacity of the clutch corresponding to the output torque of the engine with the clutch maintained in an engaged state; and (d) when there is an engine stop request, at least from a point in time when the clutch oil pressure starts to be switched from the base pressure to the regulated oil pressure, the hydraulic control circuit adds a predetermined correction oil pressure to the engagement maintaining oil pressure to prevent the clutch from being in a slip state, and controls the hydraulic control circuit to reduce the correction oil pressure toward zero by a point in time when the output torque of the engine decreases to a predetermined low torque at which it is determined that the clutch can be switched to a released state. (e) the clutch control unit sets the correction oil pressure to an oil pressure corresponding to an input torque of the clutch, and controls the hydraulic control circuit so as to reduce the correction oil pressure toward zero after a predetermined time has elapsed from the start of the hydraulic pressure switching while maintaining the value of the input torque used for setting the correction oil pressure at the value of the input torque at the start of the hydraulic pressure switching. The point is...

[0007] In addition, a second aspect of the present invention is the control device for a vehicle according to the first aspect of the present invention, wherein the clutch control unit, when there is a request to stop the engine, The regulating oil pressure is set to zero until the output torque of the engine is reduced to a predetermined engine torque that can suppress hydraulic vibration when the engagement maintaining oil pressure is output. The hydraulic control circuit is controlled.

[0008] Also, the third inventionThe gist of the present invention is a control device for a vehicle including: (a) an engine; an electric motor connected to a power transmission path between the engine and driving wheels so as to be capable of transmitting power; a clutch provided between the engine and the electric motor in the power transmission path; and a hydraulic control circuit that selectively supplies, as a clutch hydraulic pressure which is a hydraulic pressure for switching a control state of the clutch, one of an original pressure of the clutch hydraulic pressure and a regulated hydraulic pressure obtained by regulating the original pressure, (b) a clutch control unit that controls the hydraulic control circuit so that the original pressure is supplied to the clutch in an operating state of the engine in which the clutch is in a fully engaged state, and controls the hydraulic control circuit so that the regulated hydraulic pressure is supplied to the clutch with a value of the regulated hydraulic pressure set to zero in a stopped state of the engine in which the clutch is in a fully released state; and (c) the clutch control unit controls the engine from the operating state to the stopped state. (d) when there is an engine stop request, the hydraulic control circuit is controlled so as to switch the clutch oil pressure from the base pressure to the regulated oil pressure during a transition in which the output torque of the engine is gradually reduced in response to an engine stop request for switching the clutch to a stopped state, and the hydraulic control circuit is controlled so as to set the regulated oil pressure to an engagement maintaining oil pressure that generates a torque capacity of the clutch corresponding to the output torque of the engine while the clutch is maintained in an engaged state; and (e) when there is an engine stop request, the hydraulic control circuit is controlled so as to add a predetermined correction oil pressure to the engagement maintaining oil pressure so as not to put the clutch in a slip state, from at least a point in time when the clutch oil pressure starts to be switched from the base pressure to the regulated oil pressure, and to reduce the correction oil pressure toward zero by a point in time when the output torque of the engine decreases to a predetermined low torque at which it is determined that the clutch can be switched to a released state; The clutch control unit is When the engine stop request is received, the regulating oil pressure is set to zero until the output torque of the engine is reduced to a predetermined engine torque that can suppress hydraulic vibration when the engagement maintaining oil pressure is output. The hydraulic control circuit is controlled.

[0009] Further, a fourth aspect of the present invention is the control device for a vehicle according to any one of the first to third aspects of the present invention, wherein the clutch control unit is When the engine stop request is made, the hydraulic control circuit is controlled so that the regulated hydraulic pressure is set to the engagement maintaining hydraulic pressure and the correction hydraulic pressure is added to the engagement maintaining hydraulic pressure before the hydraulic pressure switching start time. The point is...

[0010] Further, a fifth aspect of the present invention is a vehicle control device according to any one of the first to fourth aspects of the present invention, wherein the clutch control unit is The output torque of the engine used when setting the engagement maintaining hydraulic pressure is a value obtained by multiplying the actual value of the output torque of the engine by a safety factor larger than 1. The point is... Effect of the Invention

[0011] According to the first invention, during a transition in which the engine output torque is gradually reduced in response to an engine stop request, the hydraulic control circuit is controlled to switch the clutch hydraulic pressure from the base pressure to the regulated hydraulic pressure and set the regulated hydraulic pressure to the engagement maintaining hydraulic pressure, and when an engine stop request is made, the hydraulic control circuit is controlled to add a correction hydraulic pressure to the engagement maintaining hydraulic pressure at least from the start of the hydraulic pressure switchover and to reduce the correction hydraulic pressure toward zero by the time the engine output torque drops to a predetermined low torque, so that even if an undershoot of the actual clutch hydraulic pressure occurs when the clutch hydraulic pressure is switched from the base pressure to the regulated hydraulic pressure, the actual clutch hydraulic pressure is set to a hydraulic pressure high enough to suppress clutch slippage, and the correction hydraulic pressure is set to zero during the transition to the clutch release state. Therefore, when the engine is switched from an operating state to a stopped state, the clutch hydraulic pressure can be quickly reduced while suppressing clutch slippage. In addition, according to the first invention, the correction oil pressure is set to an oil pressure corresponding to the input torque of the clutch, and the value of the input torque used to set the correction oil pressure is maintained at the value of the input torque at the start of the hydraulic pressure switching, while the hydraulic control circuit is controlled to reduce the correction oil pressure toward zero after a predetermined time has elapsed from the start of the hydraulic pressure switching.Therefore, even if an undershoot of the actual clutch oil pressure occurs when the clutch oil pressure is switched from the base pressure to the regulated oil pressure, the actual clutch oil pressure is set to an appropriately high oil pressure that is capable of suppressing clutch slippage, and the correction oil pressure is appropriately set to zero during the transition of switching the clutch to the released state.

[0012] According to the second aspect of the present invention, when an engine stop request is made, Since the hydraulic control circuit is controlled so that the regulating hydraulic pressure is set to zero until the engine output torque decreases to a predetermined engine torque, hydraulic vibrations are suppressed when the regulating hydraulic pressure is set to an engagement maintaining hydraulic pressure corresponding to the engine output torque.

[0013] According to the third aspect of the present invention, During a transition in which the engine output torque is gradually reduced in response to an engine stop request, the hydraulic control circuit is controlled to switch the clutch hydraulic pressure from the base pressure to the regulated hydraulic pressure and set the regulated hydraulic pressure to the engagement maintaining hydraulic pressure, and when an engine stop request is made, the hydraulic control circuit is controlled to add a correction hydraulic pressure to the engagement maintaining hydraulic pressure at least from the start of the hydraulic pressure switchover and to reduce the correction hydraulic pressure toward zero by the time the engine output torque drops to a predetermined low torque, so that even if an undershoot of the actual clutch hydraulic pressure occurs when the clutch hydraulic pressure is switched from the base pressure to the regulated hydraulic pressure, the actual clutch hydraulic pressure is set to a hydraulic pressure high enough to suppress clutch slippage, and the correction hydraulic pressure is set to zero during the transition in which the clutch is switched to the released state. Therefore, when the engine is switched from an operating state to a stopped state, the clutch hydraulic pressure can be quickly reduced while suppressing clutch slippage. Furthermore, according to the third aspect of the present invention, when there is a request to stop the engine, the hydraulic control circuit is controlled so that the regulating hydraulic pressure is set to zero until the engine output torque decreases to a predetermined engine torque, so that hydraulic vibrations are suppressed when the regulating hydraulic pressure is set to an engagement maintaining hydraulic pressure corresponding to the engine output torque.

[0014] According to the fourth aspect of the present invention, When there is a request to stop the engine, the hydraulic control circuit is controlled to set the regulated hydraulic pressure to the engagement maintenance hydraulic pressure and add a correction hydraulic pressure to the engagement maintenance hydraulic pressure before the hydraulic pressure switching starts, so that the oil passage to which the regulated hydraulic pressure is supplied at the start of the hydraulic pressure switching is easily filled with hydraulic oil quickly, and when the clutch hydraulic pressure is switched from the base pressure to the regulated hydraulic pressure, the actual clutch hydraulic pressure is easily made to be a hydraulic pressure high enough to suppress clutch slippage.

[0015] According to the fifth aspect of the present invention, The engine output torque used when setting the engagement maintenance oil pressure is the actual value of the engine output torque multiplied by a safety factor. Therefore, even if an undershoot of the actual clutch oil pressure occurs when the clutch oil pressure is switched from the base pressure to the regulated oil pressure, the actual clutch oil pressure is set to a high enough oil pressure to suppress clutch slippage. [Brief description of the drawings]

[0016] [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 and a control system for various controls in the vehicle. [Diagram 2] FIG. 2 is a diagram for explaining a portion of the hydraulic control circuit that is involved in supplying hydraulic pressure to the K0 clutch, and is also a diagram for explaining a hydraulic source that supplies hydraulic oil to the hydraulic control circuit. [Diagram 3] 6 is a time chart illustrating an example of each phase of the K0 clutch during the engine stopping process. [Figure 4] 1 is a flowchart illustrating the main control operations of the electronic control device, and is a flowchart illustrating the control operations for quickly reducing the K0 oil pressure while suppressing slippage of the K0 clutch when switching the engine from an operating state to a stopped state. [Diagram 5] 5 is a diagram showing an example of a time chart when the control operation shown in the flowchart of FIG. 4 is executed. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. EXAMPLES

[0018] Fig. 1 is a diagram illustrating a schematic configuration of a vehicle 10 to which the present invention is applied, and also illustrates the main parts of the control functions and control system for various controls in the vehicle 10. In Fig. 1, the vehicle 10 is a hybrid vehicle equipped with an engine 12 and an electric motor MG, which are driving power sources for traveling. The vehicle 10 also has driving wheels 14 and a power transmission device 16 provided in a power transmission path between the engine 12 and the driving wheels 14.

[0019] The engine 12 is a known internal combustion engine such as a gasoline engine, a diesel engine, etc. An engine control device 50 including a throttle actuator, a fuel injection device, an ignition device, etc., provided in the vehicle 10 is controlled by an electronic control device 90 described later, whereby an engine torque Te, which is an output torque of the engine 12, is controlled.

[0020] The electric motor MG is a rotating electric machine having a function as a motor that generates mechanical power from electric power and a function as a generator that generates electric power from mechanical power, and is a so-called motor generator. The electric motor MG is connected to a battery 54 provided in the vehicle 10 via an inverter 52 provided in the vehicle 10. The battery 54 is an electricity storage device that supplies and receives electric power to the electric motor MG. The electric motor MG controls the MG torque Tm, which is the output torque of the electric motor MG, by controlling the inverter 52 by an electronic control device 90 described later. For example, when the rotation direction of the electric motor MG is a positive rotation that is the same as the rotation direction when the engine 12 is in operation, the MG torque Tm is a powering torque when it is a positive torque on the acceleration side, and a regenerative torque when it is a negative torque on the deceleration side. The electric power also means electric energy when there is no particular distinction. The power also means torque and force when there is no particular distinction.

[0021] The power transmission device 16 includes a K0 clutch 20, a torque converter 22, an automatic transmission 24, and the like, in a case 18 that is a non-rotating member attached to the vehicle body. The K0 clutch 20 is a clutch provided between the engine 12 and the electric motor MG in a power transmission path between the engine 12 and the drive wheels 14. The torque converter 22 is connected to the engine 12 via the K0 clutch 20. The automatic transmission 24 is connected to the torque converter 22, and is interposed in the power transmission path between the torque converter 22 and the drive wheels 14. The power transmission device 16 also includes a propeller shaft 28 connected to a transmission output shaft 26 that is an output rotating member of the automatic transmission 24, a differential gear 30 connected to the propeller shaft 28, a pair of drive shafts 32 connected to the differential gear 30, and the like. The power transmission device 16 also includes an engine connecting shaft 34 that connects the engine 12 and the K0 clutch 20, an electric motor connecting shaft 36 that connects the K0 clutch 20 and the torque converter 22, and the like.

[0022] The electric motor MG is connected to the electric motor connecting shaft 36 in the case 18 so as to be capable of transmitting power. That is, the electric motor MG is connected to a power transmission path between the engine 12 and the drive wheels 14, in particular, to a power transmission path between the K0 clutch 20 and the torque converter 22. In other words, the electric motor MG is connected to the torque converter 22 and the automatic transmission 24 so as to be capable of transmitting power without passing through the K0 clutch 20.

[0023] The torque converter 22 includes a pump wheel 22a connected to the motor connecting shaft 36, and a turbine wheel 22b connected to a transmission input shaft 38 that is an input rotating member of the automatic transmission 24. The torque converter 22 is a fluid type power transmission device that transmits driving force from each of the driving force sources (engine 12, electric motor MG) from the motor connecting shaft 36 to the transmission input shaft 38 via fluid. The torque converter 22 includes an LU clutch 40 as a direct clutch that connects the pump wheel 22a and the turbine wheel 22b, that is, that connects the motor connecting shaft 36 and the transmission input shaft 38. The LU clutch 40 is a known lock-up clutch.

[0024] The automatic transmission 24 is a known planetary gear type automatic transmission including, for example, one or more planetary gear devices (not shown) and a plurality of engagement devices CB. The engagement devices CB are, for example, known hydraulic friction engagement devices. The engagement devices CB have their respective torque capacities, or CB torque Tcb, changed by the CB hydraulic pressure PRcb, or regulated hydraulic pressure, supplied from the hydraulic control circuit 56, thereby switching between operating states, such as an engaged state and a released state, i.e., control states.

[0025] The automatic transmission 24 is a stepped transmission in which one of a plurality of gear stages (also called gear stages) with different speed ratios (also called gear ratios) γat (=AT input rotation speed Ni / AT output rotation speed No) is formed by engaging one of the engagement devices CB. The automatic transmission 24 switches between gear stages formed according to the accelerator operation of the driver (=operator) and the vehicle speed V by an electronic control device 90 described later. The AT input rotation speed Ni is the rotation speed of the transmission input shaft 38, and is the input rotation speed of the automatic transmission 24. The AT input rotation speed Ni is the same value as the turbine rotation speed Nt, which is the output rotation speed of the torque converter 22. The AT input rotation speed Ni can be expressed by the turbine rotation speed Nt. The AT output rotation speed No is the rotation speed of the transmission output shaft 26, and is the output rotation speed of the automatic transmission 24.

[0026] The K0 clutch 20 is a hydraulic friction engagement device constituted by, for example, a multi-plate or single-plate clutch. The control state of the K0 clutch 20, such as an engaged state or a released state, is switched by changing the K0 torque Tk0, which is the torque capacity of the K0 clutch 20, by the K0 hydraulic pressure PRk0, which is the hydraulic pressure supplied from the hydraulic control circuit 56. The K0 hydraulic pressure PRk0 is a clutch hydraulic pressure that is a hydraulic pressure for switching the control state of the K0 clutch 20.

[0027] In the vehicle 10, when the K0 clutch 20 is in an engaged state, the engine 12 and the torque converter 22 are connected to each other so as to transmit power. On the other hand, when the K0 clutch 20 is in a disengaged state, power transmission between the engine 12 and the torque converter 22 is interrupted. Since the electric motor MG is connected to the torque converter 22, the K0 clutch 20 functions as a clutch that connects and disconnects the engine 12 from the electric motor MG.

[0028] In the power transmission device 16, when the K0 clutch 20 is engaged, the power output from the engine 12 is transmitted from the engine connecting shaft 34 to the driving wheels 14 via the K0 clutch 20, the electric motor connecting shaft 36, the torque converter 22, the automatic transmission 24, the propeller shaft 28, the differential gear 30, the drive shaft 32, etc. in this order. Moreover, the power output from the electric motor MG is transmitted from the electric motor connecting shaft 36 to the driving wheels 14 via the torque converter 22, the automatic transmission 24, the propeller shaft 28, the differential gear 30, the drive shaft 32, etc. in this order, regardless of the control state of the K0 clutch 20.

[0029] The vehicle 10 includes the MOP 58, which is a mechanical oil pump, the EOP 60, which is an electric oil pump, and a pump motor 62. The MOP 58 is connected to the pump impeller 22a, and is rotated and driven by a driving force source (the engine 12, the electric motor MG) to discharge hydraulic oil OIL used in the power transmission device 16 (see FIG. 2, which will be described later). The pump motor 62 is a motor dedicated to the EOP 60 for rotating and driving the EOP 60. The EOP 60 is rotated and driven by the pump motor 62 to discharge hydraulic oil OIL (see FIG. 2, which will be described later). The hydraulic oil OIL discharged by the MOP 58 and the EOP 60 is supplied to a hydraulic control circuit 56. The hydraulic control circuit 56 supplies the CB hydraulic pressure PRcb, the K0 hydraulic pressure PRk0, and the like, which are adjusted based on the hydraulic oil OIL discharged by the MOP 58 and / or the EOP 60.

[0030] FIG. 2 is a diagram for explaining a part of the hydraulic control circuit 56 related to the hydraulic supply to the K0 clutch 20, and is also a diagram for explaining a hydraulic source for supplying the hydraulic oil OIL to the hydraulic control circuit 56. In FIG. 2, the MOP 58 and the EOP 60 are provided in parallel in terms of the configuration of the oil passage through which the hydraulic oil OIL flows. The MOP 58 and the EOP 60 each suck up the hydraulic oil OIL that has returned to the oil pan 100 provided at the bottom of the case 18 through a strainer 102, which is a common suction port, and discharge it to each of the discharge oil passages 104, 106. The discharge oil passages 104, 106 are each connected to an oil passage provided in the hydraulic control circuit 56, for example, a line pressure oil passage 108, which is an oil passage through which the line pressure PL flows. The discharge oil passage 104 through which the hydraulic oil OIL is discharged from the MOP 58 is connected to the line pressure oil passage 108 through a MOP check valve 110 provided in the hydraulic control circuit 56. A discharge oil passage 106 through which the hydraulic oil OIL is discharged from the EOP 60 is connected to a line pressure oil passage 108 via an EOP check valve 112 provided in the hydraulic control circuit 56 .

[0031] In addition to the line pressure oil passage 108, the MOP check valve 110, and the EOP check valve 112, the hydraulic control circuit 56 also includes a regulator valve 114, a pressure regulating oil passage 116, a K0 supply oil passage 118, a PL solenoid valve SLT, a pressure regulating valve SK0, a K0 oil passage switching valve SCK0, and the like.

[0032] The regulator valve 114 adjusts the line pressure PL based on the hydraulic oil OIL discharged from at least one of the MOP 58 and the EOP 60. The PL solenoid valve SLT is, for example, a linear solenoid valve, and is controlled by the electronic control device 90 so as to output a pilot pressure Pslt corresponding to the input torque Tinat to the automatic transmission 24, etc., based on the modulator pressure PM to the regulator valve 114. The modulator pressure PM is, for example, a hydraulic pressure adjusted to a constant value by a modulator valve (not shown) using the line pressure PL as a base pressure.

[0033] The pressure regulating valve SK0 is, for example, a linear solenoid valve, and is controlled by the electronic control device 90 so as to regulate the SK0 oil pressure PRsk0, which is an oil pressure supplied to the pressure regulating oil passage 116, using the line pressure PL as a base pressure. The SK0 oil pressure PRsk0 is a regulated oil pressure obtained by regulating the line pressure PL.

[0034] The K0 oil passage switching valve SCK0 is a switching valve in which an oil passage is switched by the operation of a solenoid. Specifically, in an OFF state in which the solenoid is not energized, the K0 oil passage switching valve SCK0 blocks the oil passage between the pressure adjustment oil passage 116 and the K0 supply oil passage 118, and switches the oil passage so as to connect the line pressure oil passage 108 and the K0 supply oil passage 118. On the other hand, in an ON state in which the solenoid is energized, the K0 oil passage switching valve SCK0 blocks the oil passage between the line pressure oil passage 108 and the K0 supply oil passage 118, and switches the oil passage so as to connect the pressure adjustment oil passage 116 and the K0 supply oil passage 118. The K0 supply oil passage 118 is an oil passage connected to the K0 clutch 20, and is an oil passage through which the K0 oil pressure PRk0 supplied to the K0 clutch 20 flows. Therefore, when the K0 oil passage switching valve SCK0 is in the OFF state, the line pressure PL is set to the K0 oil pressure PRk0. On the other hand, when the K0 oil passage switching valve SCK0 is in the ON state, the SK0 oil pressure PRsk0 is set to the K0 oil pressure PRk0. The K0 oil passage switching valve SCK0 is controlled by the electronic control device 90 so as to switch between the OFF state and the ON state.

[0035] In this way, the hydraulic control circuit 56 selectively supplies to the K0 clutch 20, as the K0 hydraulic pressure PRk0, one of the line pressure PL, which is the base pressure of the K0 hydraulic pressure PRk0, and the SK0 hydraulic pressure PRsk0 obtained by regulating the line pressure PL.

[0036] The vehicle 10 further includes an electronic control device 90 including a control device for the vehicle 10. The electronic control device 90 includes a so-called microcomputer equipped with, for example, a CPU, RAM, ROM, an input / output interface, and the like, 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, and the like as necessary.

[0037] The electronic control device 90 is supplied with various signals based on detection values ​​by various sensors provided in the vehicle 10 (e.g., engine rotation speed sensor 70, turbine rotation speed sensor 72, output rotation speed sensor 74, MG rotation speed sensor 76, accelerator opening sensor 78, throttle valve opening sensor 80, brake switch 82, battery sensor 84, oil temperature sensor 86, etc.) (e.g., engine rotation speed Ne, which is the rotation speed of the engine 12, turbine rotation speed Nt, which is the same value as the AT input rotation speed Ni, AT output rotation speed No corresponding to the vehicle speed V, MG rotation speed Nm, which is the rotation speed of the electric motor MG, accelerator opening θacc, which is the amount of accelerator operation by the driver indicating the magnitude of the driver's acceleration operation, throttle valve opening θth, which is the opening of the electronic throttle valve, brake-on signal Bon, which is a signal indicating a state in which the brake pedal for operating the wheel brakes is being operated by the driver, battery temperature THbat, battery charge / discharge current Ibat, and battery voltage Vbat of the battery 54, and hydraulic oil temperature THoil, which is the temperature of the hydraulic oil OIL in the hydraulic control circuit 56).

[0038] 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 Sbc for controlling the engagement device CB, an SK0 hydraulic command value Ssk0 which is a command value for the SK0 hydraulic pressure PRsk0 for controlling the pressure regulating valve SK0 as a command value for controlling the K0 clutch 20, and an SCK0 command signal Ssck0 for controlling the on / off of the K0 oil path switching valve SCK0, an LU hydraulic control command signal Slu for controlling the LU clutch 40, an EOP control command signal Seop for controlling the EOP 60, etc.) to each device (e.g., the engine control device 50, the inverter 52, the hydraulic control circuit 56, the pump motor 62, etc.) provided in the vehicle 10.

[0039] The electronic control unit 90 includes a hybrid control means, i.e., a hybrid control unit 92 , a clutch control means, i.e., a clutch control unit 94 , and a gear shift control means, i.e., a gear shift control unit 96 in order to realize various controls in the vehicle 10 .

[0040] The hybrid control unit 92 includes a function as an engine control means, i.e., an engine control unit 92a, that controls the operation of the engine 12, and a function as an electric motor control means, i.e., 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.

[0041] The hybrid control unit 92 calculates the driving demand amount of the vehicle 10 by the driver, for example, by applying the accelerator opening θacc and the vehicle speed V to a driving demand amount map. The driving demand amount map is a relationship that is experimentally or design-wise obtained and stored in advance, that is, a predetermined relationship. The driving demand amount is, for example, a required driving torque Trdem at the driving wheels 14. In other words, the required driving torque Trdem [Nm] is a required driving power Prdem [W] at the vehicle speed V at that time. As the driving demand amount, a required driving force Frdem [N] at the driving wheels 14, a required AT output torque at the transmission output shaft 26, etc. can also be used. In calculating the driving demand amount, an AT output rotation speed No, etc. may be used instead of the vehicle speed V. The hybrid control unit 92 outputs an engine control command signal Se for controlling the engine 12 and an MG control command signal Sm for controlling the electric motor MG so as to realize the required driving power Prdem, taking into account a transmission loss, an auxiliary load, a gear ratio γat of the automatic transmission 24, etc.

[0042] When the required drive torque Trdem can be satisfied only by the output of the electric motor MG, the hybrid control unit 92 sets the drive mode to the motor drive (=EV drive) mode. In the EV drive mode, the hybrid control unit 92 performs EV drive by outputting drive force only from the electric motor MG among the drive power sources (engine 12, electric motor MG) when the K0 clutch 20 is in the released state. On the other hand, when the required drive torque Trdem cannot be satisfied without using at least the output of the engine 12, the hybrid control unit 92 sets the drive mode to the engine drive mode, i.e., hybrid drive (=HV drive) mode. In the HV drive mode, the hybrid control unit 92 performs engine drive by outputting drive force only from the engine 12 among the drive power sources (engine 12, electric motor MG) when the K0 clutch 20 is in the engaged state, i.e., HV drive. On the other hand, even when the required drive torque Trdem can be satisfied only by the output of the electric motor MG, the hybrid control unit 92 establishes the HV drive mode when, for example, the battery 54 needs to be charged or the engine 12 needs to be warmed up.

[0043] In an operating state of the engine 12 in which the K0 clutch 20 is fully engaged, such as in the HV driving mode, the clutch control unit 94 outputs an SCK0 command signal Ssck0 to control the hydraulic control circuit 56 so that the K0 oil passage switching valve SCK0 is in an off state and the line pressure PL is supplied to the K0 clutch 20. At this time, the clutch control unit 94 may control the hydraulic control circuit 56 by outputting an SK0 hydraulic command value Ssk0 and an SCK0 command signal Ssck0 so that the line pressure PL is supplied to the K0 clutch 20 with the value of the SK0 hydraulic pressure PRsk0 by the pressure regulating valve SK0 set to zero [kPa]. On the other hand, when the engine 12 is stopped and the K0 clutch 20 is in a completely released state, such as in the EV driving mode, the clutch control unit 94 controls the hydraulic control circuit 56 by outputting an SK0 hydraulic pressure command value Ssk0 and an SCK0 command signal Ssck0 so that the SK0 hydraulic pressure PRsk0 is supplied to the K0 clutch 20 by the on state of the K0 oil path switching valve SCK0, with the value of the SK0 hydraulic pressure PRsk0 by the pressure regulating valve SK0 set to zero.

[0044] The hybrid control unit 92 determines whether or not there is an engine start request, which is a request to start the engine 12 by switching the control state of the engine 12 from a stopped state to an operating state. For example, the hybrid control unit 92 determines whether or not there is an engine start request based on whether or not the required driving torque Trdem has increased beyond a range that can be covered only by the output of the electric motor MG during the EV driving mode, whether or not there is a need to warm up the engine 12, or whether or not there is a need to charge the battery 54, etc.

[0045] When the hybrid control unit 92 determines that there is an engine start request, the clutch control unit 94 outputs to the hydraulic control circuit 56 an SK0 oil pressure command value Ssk0 and an SCK0 command signal Ssck0 for controlling the K0 clutch 20 in the released state toward the engaged state with the SK0 oil pressure PRsk0 while keeping the K0 oil passage switching valve SCK0 in the on state so as to obtain a K0 torque Tk0 for transmitting the torque required for cranking the engine 12, which is a torque for increasing the engine rotation speed Ne, to the engine 12 side. In this embodiment, the torque required for cranking the engine 12 is referred to as a required cranking torque Tcrn.

[0046] When the hybrid control unit 92 determines that there is an engine start request, it outputs an MG control command signal Sm to the inverter 52 for causing the electric motor MG to output a required cranking torque Tcrn in accordance with switching of the K0 clutch 20 to the engaged state by the clutch control unit 94. Furthermore, when the hybrid control unit 92 determines that there is an engine start request, it outputs an engine control command signal Se to the engine control device 50 in conjunction with cranking of the engine 12 by the K0 clutch 20 and the electric motor MG for starting fuel supply, engine ignition, and the like.

[0047] After starting of the engine 12 by the hybrid control unit 92 is completed and switching of the K0 clutch 20 to the fully engaged state is completed, the clutch control unit 94 outputs an SCK0 command signal Ssck0 to the hydraulic control circuit 56 for switching the K0 oil passage switching valve SCK0 from the on state to the off state and supplying the line pressure PL to the K0 clutch 20. Thereafter, it is preferable that the clutch control unit 94 outputs an SK0 hydraulic pressure command value Ssk0 to the hydraulic control circuit 56 for setting the value of the SK0 hydraulic pressure PRsk0 to zero.

[0048] The hybrid control unit 92 determines whether or not there is an engine stop request, which is a request to stop the engine 12 by switching the control state of the engine 12 from an operating state to a stopped state. For example, the hybrid control unit 92 determines whether or not there is an engine stop request based on whether or not, during the HV traveling mode, the required drive torque Trdem is within a range that can be covered only by the output of the electric motor MG, warming up of the engine 12 and the like is not required, charging of the battery 54 is not required, and so on.

[0049] When the hybrid control unit 92 determines that there is an engine stop request, it outputs an engine control command signal Se for gradually decreasing the engine torque Te to the engine control device 50. After that, the hybrid control unit 92 outputs an engine control command signal Se for performing a fuel cut (=FC) to stop the supply of fuel to the engine 12 to the engine control device 50 after the K0 clutch 20 is switched to a completely released state by the clutch control unit 94 as described below.

[0050] When the hybrid control unit 92 determines that there is an engine stop request, the clutch control unit 94 outputs an SCK0 command signal Ssck0 to the hydraulic control circuit 56 during the transition in which the engine torque Te is gradually reduced, to switch the K0 oil path switching valve SCK0 from the off state to the on state and supply the SK0 oil pressure PRsk0 to the K0 clutch 20, and outputs an SK0 oil pressure command value Ssk0 to the hydraulic control circuit 56 to gradually reduce the value of the SK0 oil pressure PRsk0 from a value that puts the K0 clutch 20 in an engaged state to zero and switch the K0 clutch 20 to a completely released state.

[0051] The shift control unit 96 judges whether or not to shift the automatic transmission 24 by using, for example, a shift map which is a predetermined relationship, and outputs a CB hydraulic control command signal Sbc to the hydraulic control circuit 56 as necessary to execute shift control of the automatic transmission 24. The shift map is a predetermined relationship having a shift line for judging whether or not to shift the automatic transmission 24 on a two-dimensional coordinate system having, for example, vehicle speed V and required driving torque Trdem as variables. In the shift map, the AT output rotation speed No 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 may be used instead of the required driving torque Trdem.

[0052] Here, in order to control the control state of the K0 clutch 20 when the engine 12 is stopped, a plurality of progress stages, i.e., phases, are defined, which are divided according to the control state of the K0 clutch 20 that is switched during the process of stopping the engine 12.

[0053] Fig. 3 is a time chart illustrating an example of each phase of the K0 clutch 20 during the process of stopping the engine 12. In Fig. 3, "K0 control phase" indicates the transition state of each phase of the K0 clutch 20 during the process of stopping the engine 12. These phases are defined as "stop K0 standby", "standby before K0 pressure adjustment", "pressure adjustment before K0 release", "K0 release transition SW", "K0 complete release transition SW", "SW after K0 release", "K0 complete release", etc. "...SW" indicates "...sweep".

[0054] In Figure 3, time t1 indicates the time when, in HV driving mode, it is determined that there is an engine stop request, the stop control request flag is switched from off (=OFF) to on (=ON), and engine stop control is started to stop the engine 12, which is in an operating state.

[0055] After the engine stop control is started, a "stop K0 standby" phase (see time t1-t2) is executed. The "stop K0 standby" phase is a phase in which, in preparation for switching the K0 oil passage switching valve SCK0 from the off state to the on state after the engine stop control is started, that is, in preparation for switching the K0 oil pressure PRk0 from the line pressure PL to the SK0 oil pressure PRsk0, the SK0 oil pressure command value Ssk0 for securing the K0 torque Tk0 according to the engine torque Te is output in advance, in which the K0 oil pressure PRk0 is set to the line pressure PL and the SK0 oil pressure PRsk0 is set to the EV steady-state K0 oil pressure PRk0ev while ensuring the engagement of the K0 clutch 20 until the engine torque Te falls to a predetermined engine torque Tef. The EV steady-state K0 oil pressure PRk0ev is the SK0 oil pressure command value Ssk0 in the EV driving mode, and is the SK0 oil pressure command value Ssk0 for setting the SK0 oil pressure PRsk0 to zero [kPa].

[0056] The SK0 hydraulic pressure command value Ssk0 for securing the K0 torque Tk0 according to the engine torque Te is the SK0 hydraulic pressure command value Ssk0 for setting the SK0 hydraulic pressure PRsk0 to the engagement maintaining hydraulic pressure PRk0c that generates the K0 torque Tk0 according to the engine torque Te in a state in which the K0 clutch 20 is maintained in an engaged state when the K0 hydraulic pressure PRk0 is set to the SK0 hydraulic pressure PRsk0. For example, the engine torque Te when the engagement maintaining hydraulic pressure PRk0c is set is a value obtained by multiplying the actual engine torque Ter (see thick solid line) that is the actual value of the engine torque Te by a safety factor SF (see long dashed line). Specifically, the value obtained by multiplying the actual engine torque Ter by the safety factor SF is set to the required K0 torque Tk0d (see thin solid line), which is the required value of the K0 torque Tk0, and the total K0 hydraulic pressure PRk0 obtained by adding the equivalent of the pack end pressure of the K0 clutch 20 to the equivalent of the K0 hydraulic pressure PRk0 that generates the required K0 torque Tk0d is set as the engagement maintaining hydraulic pressure PRk0c. The pack end pressure of the K0 clutch 20 is the K0 hydraulic pressure PRk0 when the pack clearance of the K0 clutch 20 is reduced, that is, the K0 hydraulic pressure PRk0 for achieving a state in which the piston in the K0 clutch 20 reaches the stroke end and the K0 torque Tk0 is not generated. The K0 clutch 20 generates the K0 torque Tk0 by further increasing the K0 hydraulic pressure PRk0 from the packing completion state. The safety factor SF is a value larger than 1, and is a predetermined value that makes it easier to maintain the engagement state of the K0 clutch 20 with respect to the actual engine torque Ter, for example, within a range in which the engagement maintenance hydraulic pressure PRk0c is not made too large. The actual engine torque Ter is an estimated value of the engine torque Te calculated by applying the engine rotation speed Ne and the throttle valve opening θth to a predetermined engine torque map, for example.

[0057] The predetermined engine torque Tef is a predetermined threshold value that can suppress or prevent hydraulic vibration in the pressure regulating valve SK0 when the engagement maintaining hydraulic pressure PRk0c is output. The predetermined engine torque Tef may be a threshold value that is compared with the actual engine torque Ter, or may be a threshold value that is compared with a value obtained by multiplying the actual engine torque Ter by a safety factor SF.

[0058] In the "standby for stop K0" phase, when the engine torque Te falls to a predetermined engine torque Tef, the phase is transitioned to a "standby before K0 pressure adjustment" phase (see time t2-t3). The "standby before K0 pressure adjustment" phase is a phase in which the K0 oil pressure PRk0 is set to the line pressure PL, and the SK0 clutch 20 is engaged while ensuring that the K0 oil pressure PRsk0 is switched from the line pressure PL of the K0 oil pressure PRk0 to the SK0 oil pressure PRsk0, and an SK0 oil pressure command value Ssk0 is output to set the SK0 oil pressure PRsk0 to the engagement maintenance oil pressure PRk0c, until the pressure adjustment oil passage 116 to which the SK0 oil pressure PRsk0 is supplied is filled with hydraulic oil OIL. Therefore, until the "standby before K0 pressure adjustment" phase, the actual K0 torque Tk0r (see the short dashed line) is generated by the K0 oil pressure PRk0 set to the line pressure PL while ensuring that the K0 clutch 20 is engaged.

[0059] After the start of the "standby before K0 pressure adjustment" phase, when a predetermined filling time TMfil for filling the pressure adjustment oil passage 116 with hydraulic oil OIL has elapsed, the phase is transitioned to a "pressure adjustment before K0 release" phase (see time points t3-t4). The "pressure adjustment before K0 release" phase is a phase in which an SCK0 command signal Ssck0 is output to switch the K0 oil passage switching valve SCK0 from the OFF state to the ON state, switching the K0 oil pressure PRk0 from the line pressure PL to the SK0 oil pressure PRsk0, and outputting an SK0 oil pressure command value Ssk0 that sets the SK0 oil pressure PRsk0 to the engagement maintenance oil pressure PRk0c. The time t3 is the time when the SCK0 command signal Ssck0 is switched from a non-energized (OFF) signal in which the solenoid of the K0 oil passage switching valve SCK0 is de-energized to an energized (ON) signal in which the solenoid of the K0 oil passage switching valve SCK0 is energized, that is, the SK0 switching start time PTstsk0, which is the time when the hydraulic pressure switching from the line pressure PL of the K0 hydraulic pressure PRk0 to the SK0 hydraulic pressure PRsk0 starts. In the "Pressure Adjustment Before K0 Release" phase, the actual K0 torque Tk0r is generated by the SK0 hydraulic pressure PRsk0, that is, the K0 hydraulic pressure PRk0 set to the engagement maintaining hydraulic pressure PRk0c, and is therefore reduced toward the required K0 torque Tk0d. The "Pressure Adjustment Before K0 Release" phase is executed until the engine torque Te is reduced to a predetermined low torque Telow at which it is determined that the K0 clutch 20 can be switched to the released state. The predetermined low torque Telow is a predetermined threshold value that can suppress a step in the driving force Fr and / or a rise in the engine speed Ne when, for example, the K0 clutch 20 is switched to the released state, and is, for example, zero [Nm] or an idle torque Teidl in an idling operation state. The engine torque Te to be compared with the predetermined low torque Telow may be the actual engine torque Ter or a value obtained by multiplying the actual engine torque Ter by a safety factor SF.

[0060] In the "Pressure Adjustment before K0 Release" phase, when the engine torque Te drops to a predetermined low torque Telow, a transition is made to the "K0 Release Transition SW" phase (see time t4-t5). The "K0 Release Transition SW" phase is a phase in which an SK0 hydraulic pressure command value Ssk0 is output to sweep down (= gradually decrease) the SK0 hydraulic pressure PRsk0 from the engagement maintaining hydraulic pressure PRk0c to the pack end pressure of the K0 clutch 20 at a first gradient SW1 in order to release the K0 clutch 20. The "K0 Release Transition SW" phase is executed until the SK0 hydraulic pressure command value Ssk0 drops to the pack end pressure at which the K0 torque Tk0 becomes zero [Nm].

[0061] In the "K0 release transition SW" phase, when the SK0 hydraulic command value Ssk0 drops to the pack end pressure, a transition is made to the "K0 complete release transition SW" phase (see time t5-t6). The "K0 complete release transition SW" phase is a phase in which the SK0 hydraulic command value Ssk0 is output to sweep down the SK0 hydraulic pressure PRsk0 from the pack end pressure to the release assurance hydraulic pressure PRk0rl at a first gradient SW1. The release assurance hydraulic pressure PRk0rl is, for example, a predetermined SK0 hydraulic pressure PRsk0 value that can guarantee that the K0 clutch 20 is in a released state. The "K0 complete release transition SW" phase is executed until the SK0 hydraulic command value Ssk0 drops to the release assurance hydraulic pressure PRk0rl.

[0062] In the "K0 complete release transition SW" phase, when the SK0 hydraulic command value Ssk0 drops to the release guarantee hydraulic pressure PRk0rl, a transition is made to the "K0 post-release SW" phase (see time t6-t7). The "K0 post-release SW" phase is a phase in which the SK0 hydraulic command value Ssk0 is output, which sweeps down the SK0 hydraulic pressure PRsk0 from the release guarantee hydraulic pressure PRk0rl to the EV steady-state K0 hydraulic pressure PRk0ev (=0 [kPa]) at the second gradient SW2. The absolute value of the second gradient SW2 is set to a value greater than the absolute value of the first gradient SW1. The "K0 post-release SW" phase is executed until the SK0 hydraulic command value Ssk0 drops to the EV steady-state K0 hydraulic pressure PRk0ev.

[0063] In the "SW after K0 release" phase, when the SK0 oil pressure command value Ssk0 falls to the EV steady-state K0 oil pressure PRk0ev (=0), a transition is made to the "K0 complete release" phase (see time points t7-t9). The "K0 complete release" phase is a phase in which the SK0 oil pressure command value Ssk0 is output to set the SK0 oil pressure PRsk0 to the EV steady-state K0 oil pressure PRk0ev until the engine stop control is completed.

[0064] In the "K0 complete release" phase, for example, the engine 12 is made to wait in an independent operation state, for example, an idle operation state, as necessary (see time t7-t8). After that, the fuel of the engine 12 is cut off and the engine 12 is stopped (see time t8-t9). When it is determined that the engine speed Ne is zero [rpm], the engine stop control is completed (see time t9).

[0065] In the "Stop K0 standby" phase and the "standby before K0 pressure adjustment" phase, the K0 clutch 20 is in a fully engaged state. In the "K0 pressure adjustment before release" phase, the K0 clutch 20 is in a preparation state before being put into a released state. In the "K0 release transition SW" phase, the K0 clutch 20 is in a state in transition to a released state. In the "K0 complete release transition SW" phase, the K0 clutch 20 is in a state in transition to a completely released state. In the "After K0 release SW" phase and the "K0 complete release" phase, the K0 clutch 20 is in a completely released state.

[0066] In this way, during the transient period in which the engine torque Te is gradually reduced in response to an engine stop request, the clutch control unit 94 controls the hydraulic control circuit 56 to switch the K0 oil pressure PRk0 from the line pressure PL to the SK0 oil pressure PRsk0, and also controls the hydraulic control circuit 56 to set the SK0 oil pressure PRsk0 to the engagement maintenance oil pressure PRk0c.

[0067] Furthermore, the clutch control section 94 uses a value obtained by multiplying the actual engine torque Ter by a safety factor SF as the engine torque Te used when setting the engagement maintaining hydraulic pressure PRk0c.

[0068] Furthermore, when there is a request to stop the engine, the clutch control unit 94 controls the hydraulic control circuit 56 so that the SK0 hydraulic pressure PRsk0 is kept at zero until the engine torque Te decreases to a predetermined engine torque Tef.

[0069] Incidentally, during the transition of engine stop control, when the phase is transitioned from the "standby before K0 pressure adjustment" phase to the "pressure adjustment before K0 release" phase, the K0 oil passage switching valve SCK0 is switched from the off state to the on state, so that the actual K0 oil pressure PRk0r, which is the actual value of the K0 oil pressure PRk0, is reduced from the line pressure PL to the SK0 oil pressure PRsk0, i.e., the engagement maintaining oil pressure PRk0c. This may cause an undershoot of the actual K0 oil pressure PRk0r, in which the actual K0 oil pressure PRk0r falls below the SK0 oil pressure command value Ssk0. The undershoot of the actual K0 oil pressure PRk0r may cause the K0 clutch 20 to slip, which may cause the engine rotation speed Ne to rev up.

[0070] Therefore, when an engine stop request is made, the clutch control unit 94 adds the correction oil pressure PRk0add to the engagement maintaining oil pressure PRk0c from at least the SK0 switching start time PTstsk0, and controls the hydraulic control circuit 56 to reduce the correction oil pressure PRk0add toward zero [kPa] by the time the engine torque Te drops to a predetermined low torque Telow. In other words, the clutch control unit 94 outputs an SK0 oil pressure command value Ssk0 that adds the correction oil pressure PRk0add to the engagement maintaining oil pressure PRk0c from at least the start of the "K0 pre-release pressure adjustment" phase, and outputs an SK0 oil pressure command value Ssk0 that reduces the correction oil pressure PRk0add toward zero by the start of the "K0 release transition SW" phase. The correction oil pressure PRk0add is, for example, a predetermined added oil pressure so that the K0 clutch 20 is not put into a slip state. In other words, the correction oil pressure PRk0add is a predetermined added oil pressure that anticipates an undershoot of the actual K0 oil pressure PRk0r, which may occur, for example, when the actual K0 oil pressure PRk0r is switched from the line pressure PL to the SK0 oil pressure PRsk0, and ensures that the actual K0 oil pressure PRk0r is a high enough oil pressure to suppress or prevent slippage of the K0 clutch 20 even if such an undershoot occurs.

[0071] The clutch control unit 94 controls the hydraulic control circuit 56 to reduce the correction hydraulic pressure PRk0add toward zero after a predetermined time TMf has elapsed from the SK0 switching start time point PTstsk0. The predetermined time TMf is a predetermined time for making the correction hydraulic pressure PRk0add zero by the time the engine torque Te decreases to a predetermined low torque Telow while the effect of suppressing or preventing slippage of the K0 clutch 20 is obtained by the correction hydraulic pressure PRk0add, for example.

[0072] In the "K0 release transition SW" phase, the engine torque Te is reduced to a predetermined low torque Telow at which the K0 clutch 20 can be switched to the release state, and there is no need to add the correction oil pressure PRk0add. Also, in the "K0 release transition SW" phase, the K0 clutch 20 is released. Therefore, in the "K0 release transition SW" phase, the correction oil pressure PRk0add is set to zero, and the K0 clutch 20 is quickly released. Alternatively, if slippage occurs in the K0 clutch 20 and the transition to the "K0 release transition SW" phase occurs, a failure of the pressure regulating valve SK0 or the like is assumed. Therefore, when slippage occurs in the K0 clutch 20, the correction oil pressure PRk0add is set to zero in order to quickly release the K0 clutch 20.

[0073] When an engine stop request is made, the clutch control unit 94 may control the hydraulic control circuit 56 to set the SK0 hydraulic pressure PRsk0 to the engagement maintaining hydraulic pressure PRk0c and add the correction hydraulic pressure PRk0add to the engagement maintaining hydraulic pressure PRk0c from before the SK0 switching start time point PTstsk0. In other words, the clutch control unit 94 may output the SK0 hydraulic pressure command value Ssk0 obtained by adding the correction hydraulic pressure PRk0add to the engagement maintaining hydraulic pressure PRk0c from the start of the "standby before K0 pressure adjustment" phase.

[0074] The clutch control unit 94 may set the correction oil pressure PRk0add to an oil pressure corresponding to the input torque Tink0 of the K0 clutch 20, and may control the hydraulic control circuit 56 to lower the correction oil pressure PRk0add toward zero after a predetermined time TMf has elapsed from the SK0 switching start point PTstsk0 while maintaining the value of the input torque Tink0 used to set the correction oil pressure PRk0add at the value of the input torque Tink0 at the SK0 switching start point PTstsk0. The input torque Tink0 is basically the engine torque Te, and when the MG torque Tm is being output, the MG torque Tm is taken into consideration.

[0075] Specifically, when the hybrid control unit 92 determines that there is an engine stop request, it outputs an engine control command signal Se for gradually decreasing the actual engine torque Ter to the engine control device 50. At this time, the hybrid control unit 92 sets the FC flag to FC prohibition, which prohibits fuel cut.

[0076] When the hybrid control unit 92 determines that there is an engine stop request, the clutch control unit 94 sets the SK0 oil pressure command value Ssk0 to the EV steady-state K0 oil pressure PRk0ev (=0) while keeping the SCK0 command signal Ssck0 as a non-energized (OFF) signal.

[0077] When the hybrid control unit 92 determines that there is an engine stop request, the clutch control unit 94 determines, for example, whether the actual engine torque Ter has become equal to or less than a predetermined engine torque Tef during the transition in which the actual engine torque Ter is gradually reduced.

[0078] When the clutch control unit 94 determines that the actual engine torque Ter has become equal to or less than a predetermined engine torque Tef, it switches the SK0 oil pressure command value Ssk0 from the EV steady-state K0 oil pressure PRk0ev (=0) to a value obtained by adding the engagement maintenance oil pressure PRk0c to the correction oil pressure PRk0add, while keeping the SCK0 command signal Ssck0 as a non-energized (OFF) signal.

[0079] The clutch control unit 94 determines whether or not the pressure regulating oil passage 116 to which the SK0 oil pressure PRsk0 is supplied has been filled with hydraulic oil OIL based on whether or not a predetermined filling time TMfil has elapsed since the SK0 oil pressure command value Ssk0 was switched to a value obtained by adding the engagement maintenance oil pressure PRk0c to the correction oil pressure PRk0add.

[0080] When the clutch control unit 94 determines that the pressure regulating oil passage 116 has been filled with hydraulic oil OIL, it keeps the SK0 oil pressure command value Ssk0 at the engagement maintenance oil pressure PRk0c plus the correction oil pressure PRk0add, switches the SCK0 command signal Ssck0 from a non-energized (OFF) signal to an energized (ON) signal, and switches the K0 oil pressure PRk0 from the line pressure PL to the SK0 oil pressure PRsk0.

[0081] The clutch control unit 94 determines whether or not a predetermined time TMf has elapsed from the SK0 switching start point PTstsk0 at which the K0 hydraulic pressure PRk0 was switched to the SK0 hydraulic pressure PRsk0.

[0082] When the clutch control unit 94 determines that the predetermined time TMf has elapsed from the SK0 switching start time point PTstsk0, the clutch control unit 94 gradually decreases the correction oil pressure PRk0add of the SK0 oil pressure command value Ssk0 toward zero. After that, the clutch control unit 94 determines whether the actual engine torque Ter has decreased to a predetermined low torque Telow.

[0083] When the clutch control unit 94 determines that the actual engine torque Ter has decreased to the predetermined low torque Telow, it switches the SK0 oil pressure command value Ssk0 from the engagement maintaining oil pressure PRk0c to a value that transitions the K0 clutch 20 to a released state. After that, the clutch control unit 94 determines whether the SK0 oil pressure command value Ssk0 has become the EV steady state K0 oil pressure PRk0ev (=0).

[0084] When the clutch control unit 94 determines that the SK0 oil pressure command value Ssk0 has become the EV steady-state K0 oil pressure PRk0ev (=0), the hybrid control unit 92 outputs an engine control command signal Se to the engine control device 50 to place the engine 12 in an independent operation state as necessary. After that, the hybrid control unit 92 switches the FC flag to FC execution, which implements a fuel cut, and outputs an engine control command signal Se to the engine control device 50 to place the engine 12 in a stopped state.

[0085] Fig. 4 is a flowchart for explaining the main part of the control operation of the electronic control device 90, and is a flowchart for explaining the control operation for quickly lowering the K0 oil pressure PRk0 while suppressing slippage of the K0 clutch 20 when switching the engine 12 from an operating state to a stopped state, and is executed, for example, repeatedly. Fig. 5 is a diagram showing an example of a time chart when the control operation shown in the flowchart of Fig. 4 is executed.

[0086] In FIG. 4, first, in step S10 (hereinafter, step will be omitted) corresponding to the function of the hybrid control unit 92, it is determined whether or not there is an engine stop request. If the determination in S10 is negative, this routine is terminated. If the determination in S10 is positive, the actual engine torque Ter is gradually decreased in S20 corresponding to the function of the hybrid control unit 92. In addition, the FC flag is set to FC prohibited. Next, in S30 corresponding to the function of the clutch control unit 94, the SCK0 command signal Ssck0 is kept as a non-energized (OFF) signal, and the SK0 oil pressure command value Ssk0 is set to the EV steady-state K0 oil pressure PRk0ev (=0). Next, in S40 corresponding to the function of the clutch control unit 94, it is determined whether or not the actual engine torque Ter has become equal to or less than a predetermined engine torque Tef. If the determination in S40 is negative, this S40 is repeatedly executed. If the determination in S40 is positive, in S50 corresponding to the function of the clutch control unit 94, the SK0 oil pressure command value Ssk0 is switched from the EV steady-state K0 oil pressure PRk0ev (=0) to a value obtained by adding the engagement maintaining oil pressure PRk0c to the correction oil pressure PRk0add. Next, in S60 corresponding to the function of the clutch control unit 94, it is determined whether the pressure regulating oil passage 116 to which the SK0 oil pressure PRsk0 is supplied is filled with hydraulic oil OIL. If the determination in S60 is negative, this S60 is repeatedly executed. If the determination in S60 is positive, in S70 corresponding to the function of the clutch control unit 94, the SCK0 command signal Ssck0 is switched from a non-energized (OFF) signal to an energized (ON) signal, and the K0 oil pressure PRk0 is switched from the line pressure PL to the SK0 oil pressure PRsk0. Next, in S80 corresponding to the function of the clutch control unit 94, it is determined whether a predetermined time TMf has elapsed from the SK0 switching start time point PTstsk0. If the determination in S80 is negative, this S80 is repeatedly executed. If the determination in S80 is positive, in S90 corresponding to the function of the clutch control unit 94, the correction oil pressure PRk0add of the SK0 oil pressure command value Ssk0 is gradually decreased toward zero. Next, in S100 corresponding to the function of the clutch control unit 94, it is determined whether the actual engine torque Ter has decreased to a predetermined low torque Telow.If the determination in S100 is negative, this S100 is repeatedly executed. If the determination in S100 is positive, in S110 corresponding to the function of the clutch control unit 94, the SK0 hydraulic command value Ssk0 is switched from the engagement maintaining hydraulic pressure PRk0c to a value that transitions the K0 clutch 20 to a release state. Next, in S120 corresponding to the function of the clutch control unit 94, it is determined whether the SK0 hydraulic command value Ssk0 has become the EV steady-state K0 hydraulic pressure PRk0ev (=0). If the determination in S120 is negative, this S120 is repeatedly executed. If the determination in S120 is positive, in S130 corresponding to the function of the hybrid control unit 92, the engine 12 is made to wait in an independent operation state as necessary. Thereafter, the FC flag is switched to FC implementation, and the engine 12 is put into a stopped state.

[0087] 5 is a time chart for explaining an example of each phase of the K0 clutch 20 in the process of stopping the engine 12, similar to FIG. 3. In FIG. 5, time t1b, . . . , and time t9b correspond to time t1, . . . , and time t9 in FIG. 3, respectively. In the process of stopping the engine 12 in FIG. 5, differences from the process of stopping the engine 12 in FIG. 3 will be mainly explained. In the process of stopping the engine 12 in FIG. 5, in the "standby before K0 pressure adjustment" phase (see time t2b-t3b) and the "pressure adjustment before K0 release" phase (see time t3b-t4b), an SK0 oil pressure command value Ssk0 obtained by adding a correction oil pressure PRk0add to the engagement maintaining oil pressure PRk0c is output. As a result, even if an undershoot of the actual K0 oil pressure PRk0r occurs when the SCK0 command signal Ssck0 is switched from a non-energized (OFF) signal to an energized (ON) signal and the actual K0 oil pressure PRk0r is switched from the line pressure PL to the SK0 oil pressure PRsk0, the actual K0 oil pressure PRk0r is set to a higher oil pressure than when the correction oil pressure PRk0add is not added to the engagement maintenance oil pressure PRk0c, and is set to a high oil pressure that can suppress or prevent slippage of the K0 clutch 20, thereby suppressing or preventing slippage of the K0 clutch 20. In the "Pre-K0 Release Pressure Adjustment" phase, the correction oil pressure PRk0add is reduced toward zero after a predetermined time TMf has elapsed from the time t3b, and the correction oil pressure PRk0add is set to zero by the start of the "K0 Release Transition SW" phase (see the time t4b-t5b).

[0088] As described above, according to this embodiment, when there is an engine stop request, the hydraulic control circuit 56 is controlled so that the correction hydraulic pressure PRk0add is added to the engagement maintaining hydraulic pressure PRk0c from at least the SK0 switching start point PTstsk0, and the correction hydraulic pressure PRk0add is reduced toward zero by the time the engine torque Te drops to the predetermined low torque Telow. Therefore, even if an undershoot of the actual K0 hydraulic pressure PRk0r occurs when the actual K0 hydraulic pressure PRk0r is switched from the line pressure PL to the SK0 hydraulic pressure PRsk0, the actual K0 hydraulic pressure PRk0r is set to a hydraulic pressure high enough to suppress slippage of the K0 clutch 20, and the correction hydraulic pressure PRk0add is set to zero during the transition of switching to the release state of the K0 clutch 20. Therefore, when switching the engine 12 from the operating state to the stopped state, the K0 hydraulic pressure PRk0 can be quickly reduced while suppressing slippage of the K0 clutch 20.

[0089] Furthermore, according to this embodiment, when there is a request to stop the engine, the hydraulic control circuit 56 is controlled to set the SK0 oil pressure PRsk0 to the engagement maintenance oil pressure PRk0c and to add the correction oil pressure PRk0add to the engagement maintenance oil pressure PRk0c before the SK0 switching start time point PTstsk0. This makes it easier for the hydraulic oil OIL to be quickly filled into the pressure regulating oil passage 116 to which the SK0 oil pressure PRsk0 is supplied at the SK0 switching start time point PTstsk0, and makes it easier for the actual K0 oil pressure PRk0r to be set to a high oil pressure that is capable of suppressing slippage of the K0 clutch 20 when the actual K0 oil pressure PRk0r is switched from the line pressure PL to the SK0 oil pressure PRsk0.

[0090] In addition, according to this embodiment, the correction oil pressure PRk0add is set to an oil pressure corresponding to the input torque Tink0 of the K0 clutch 20, and the value of the input torque Tink0 used to set the correction oil pressure PRk0add is maintained at the value of the input torque Tink0 at the SK0 switching start point PTstsk0, while the hydraulic control circuit 56 is controlled to reduce the correction oil pressure PRk0add toward zero after a predetermined time TMf has elapsed from the SK0 switching start point PTstsk0. Therefore, even if an undershoot of the actual K0 oil pressure PRk0r occurs when the actual K0 oil pressure PRk0r is switched from the line pressure PL to the SK0 oil pressure PRsk0, the actual K0 oil pressure PRk0r is set to an appropriately high oil pressure that can suppress slippage of the K0 clutch 20, and the correction oil pressure PRk0add is appropriately set to zero during the transition of switching to the released state of the K0 clutch 20.

[0091] Furthermore, according to this embodiment, the engine torque Te used when setting the engagement maintenance oil pressure PRk0c is the actual engine torque Ter multiplied by the safety factor SF. Therefore, even if an undershoot of the actual K0 oil pressure PRk0r occurs when the actual K0 oil pressure PRk0r is switched from the line pressure PL to the SK0 oil pressure PRsk0, the actual K0 oil pressure PRk0r is set to a high enough oil pressure to suppress slippage of the K0 clutch 20.

[0092] Furthermore, according to this embodiment, when there is a request to stop the engine, the hydraulic control circuit 56 is controlled to keep the SK0 oil pressure PRsk0 at zero until the engine torque Te falls to a predetermined engine torque Tef, so that hydraulic vibrations in the pressure regulating valve SK0 are suppressed when the SK0 oil pressure PRsk0 is set to the engagement maintenance oil pressure PRk0c corresponding to the engine torque Te.

[0093] Although the embodiment of the present invention has been described in detail above with reference to the drawings, the present invention can be applied to other embodiments.

[0094] For example, in the above embodiment, the SK0 oil pressure command value Ssk0 obtained by adding the correction oil pressure PRk0add to the engagement maintaining oil pressure PRk0c was output in the "standby before K0 pressure adjustment" phase, but it is sufficient to output the SK0 oil pressure command value Ssk0 obtained by adding the correction oil pressure PRk0add to the engagement maintaining oil pressure PRk0c at least in the "pressure adjustment before K0 release" phase. Even in this way, even if an undershoot of the actual K0 oil pressure PRk0r occurs when the actual K0 oil pressure PRk0r is switched from the line pressure PL to the SK0 oil pressure PRsk0, a certain effect can be obtained that the actual K0 oil pressure PRk0r is set to a high oil pressure that can suppress slippage of the K0 clutch 20.

[0095] In the above embodiment, a planetary gear type automatic transmission is exemplified as the automatic transmission 24, but the present invention is not limited to this. The automatic transmission 24 may be a synchronous mesh type parallel two-shaft automatic transmission including a known DCT (Dual Clutch Transmission), a known belt type continuously variable transmission, or the like. Alternatively, the automatic transmission 24 does not necessarily have to be provided.

[0096] In the above embodiment, the torque converter 22 is used as the fluid transmission device, but the present invention is not limited to this. For example, instead of the torque converter 22, another fluid transmission device that does not amplify torque, such as a fluid coupling, may be used as the fluid transmission device. Alternatively, the fluid transmission device does not necessarily have to be provided, and may be replaced with, for example, a starting clutch.

[0097] It should be noted that the above is merely one embodiment, and the present invention can be embodied in various modified and improved forms based on the knowledge of those skilled in the art. [Explanation of symbols]

[0098] 10: Vehicle 12: Engine 14: Drive wheel 20:K0 clutch (clutch) 56: Hydraulic control circuit 90: Electronic control device (control device) 94: Clutch control unit MG: Electric motor PL: Line pressure (source pressure) PRk0: K0 hydraulic pressure (clutch hydraulic pressure) PRk0c: Engagement maintenance hydraulic pressure PRk0add: Correction oil pressure PRsk0: SK0 hydraulic pressure (pressure adjustment hydraulic pressure)

Claims

1. A control device for a vehicle including an engine, an electric motor connected to a power transmission path between the engine and drive wheels so as to be capable of transmitting power, a clutch provided between the engine and the electric motor in the power transmission path, and a hydraulic control circuit that selectively supplies one of an original pressure of the clutch hydraulic pressure and a regulated hydraulic pressure obtained by regulating the original pressure as a clutch hydraulic pressure which is a hydraulic pressure for switching a control state of the clutch, a clutch control unit that controls the hydraulic control circuit so that the base pressure is supplied to the clutch when the engine is in an operating state in which the clutch is in a fully engaged state, and controls the hydraulic control circuit so that the regulated pressure is supplied to the clutch with a value of the regulated pressure set to zero when the engine is in a stopped state in which the clutch is in a fully released state, the clutch control unit controls the hydraulic control circuit to switch the clutch hydraulic pressure from the base pressure to the regulated pressure hydraulic pressure during a transition in which the output torque of the engine is gradually reduced in response to an engine stop request for switching the engine from the operating state to the stopped state, and controls the hydraulic control circuit to set the regulated pressure hydraulic pressure to an engagement maintaining hydraulic pressure that generates a torque capacity of the clutch corresponding to the output torque of the engine with the clutch maintained in an engaged state, and when there is a request to stop the engine, controls the hydraulic control circuit to add a predetermined correction hydraulic pressure to the engagement maintaining hydraulic pressure so as not to put the clutch in a slip state, at least from a point in time when the clutch hydraulic pressure starts to be switched from the base pressure to the regulated pressure hydraulic pressure, and to reduce the correction hydraulic pressure toward zero by the time when the output torque of the engine decreases to a predetermined low torque at which it is determined that the clutch can be switched to a released state; The clutch control unit sets the correction oil pressure to an oil pressure corresponding to the input torque of the clutch, and controls the hydraulic control circuit to reduce the correction oil pressure toward zero after a predetermined time has elapsed from the start of the hydraulic pressure switching, while maintaining the value of the input torque used to set the correction oil pressure at the value of the input torque at the start of the hydraulic pressure switching.

2. 2. The vehicle control device according to claim 1, wherein the clutch control unit controls the hydraulic control circuit so that, when the engine stop request is received, the regulating hydraulic pressure is set to zero until the output torque of the engine decreases to a predetermined engine torque that can suppress hydraulic vibrations when the engagement maintaining hydraulic pressure is output.

3. A control device for a vehicle including an engine, an electric motor connected to a power transmission path between the engine and drive wheels so as to be capable of transmitting power, a clutch provided between the engine and the electric motor in the power transmission path, and a hydraulic control circuit which selectively supplies, as a clutch hydraulic pressure which is a hydraulic pressure for switching a control state of the clutch, either an original pressure of the clutch hydraulic pressure or a regulated hydraulic pressure obtained by regulating the original pressure, a clutch control unit that controls the hydraulic control circuit so that the base pressure is supplied to the clutch when the engine is in an operating state in which the clutch is in a fully engaged state, and controls the hydraulic control circuit so that the regulated pressure is supplied to the clutch with a value of the regulated pressure set to zero when the engine is in a stopped state in which the clutch is in a fully released state, the clutch control unit controls the hydraulic control circuit to switch the clutch hydraulic pressure from the base pressure to the regulated pressure hydraulic pressure during a transition in which the output torque of the engine is gradually reduced in response to an engine stop request for switching the engine from the operating state to the stopped state, and controls the hydraulic control circuit to set the regulated pressure hydraulic pressure to an engagement maintaining hydraulic pressure that generates a torque capacity of the clutch corresponding to the output torque of the engine with the clutch maintained in an engaged state, and when there is a request to stop the engine, controls the hydraulic control circuit to add a predetermined correction hydraulic pressure to the engagement maintaining hydraulic pressure so as not to put the clutch in a slip state, at least from a point in time when the clutch hydraulic pressure starts to be switched from the base pressure to the regulated pressure hydraulic pressure, and to reduce the correction hydraulic pressure toward zero by the time when the output torque of the engine decreases to a predetermined low torque at which it is determined that the clutch can be switched to a released state; The vehicle control device is characterized in that, when there is an engine stop request, the clutch control unit controls the hydraulic control circuit so as to set the regulating hydraulic pressure to zero until the output torque of the engine decreases to a predetermined specified engine torque that can suppress hydraulic vibrations when the engagement maintenance hydraulic pressure is output.

4. 4. The vehicle control device according to claim 1, wherein, when an engine stop request is received, the clutch control unit controls the hydraulic control circuit so that the regulated hydraulic pressure is set to the engagement maintaining hydraulic pressure and the correction hydraulic pressure is added to the engagement maintaining hydraulic pressure before the hydraulic pressure switching start point.

5. 5. A vehicle control device as claimed in any one of claims 1 to 4, characterized in that the clutch control unit uses a value obtained by multiplying the actual value of the output torque of the engine by a safety factor greater than 1 as the output torque of the engine used when setting the engagement maintenance hydraulic pressure.

Images