Hydraulic Control System

Abstract

To provide an inexpensive hydraulic pressure control system capable of enhancing high accuracy and responsiveness in a predetermined hydraulic pressure region even when demand torque for complete engagement of a friction engagement device is high.SOLUTION: A hydraulic pressure control system enables K0 clutch torque to be continuously changed because first hydraulic pressure Pk01 supplied to a hydraulic actuator 20a is adjusted with a linear solenoid valve SLK. In contrast, the hydraulic pressure control system enables a K0 clutch to be put into a complete engagement state with large engagement torque when high second hydraulic pressure Pk02 (=PL) is supplied to the hydraulic actuator 20a through ON / OFF operation of an ON / OFF solenoid valve SCK. Thus, the linear solenoid valve SLK is simply required to adjust the first hydraulic pressure Pk01 within a predetermined pressure adjustment control region which is lower than the second hydraulic pressure Pk02. With a narrowed control area, the linear solenoid valve can enhance control accuracy of the first hydraulic pressure Pk01 and responsiveness.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a hydraulic control system, and more particularly to a hydraulic control system that can provide high accuracy and responsiveness in a predetermined hydraulic pressure range even when a large torque capacity is required when a friction engagement device is fully engaged. [Background technology]

[0002] There is known a hydraulic control system that has a linear solenoid valve that can continuously change the hydraulic pressure, an ON-OFF solenoid valve that outputs and stops the output of the hydraulic pressure, and a hydraulic friction engagement device that is engaged with an engagement torque according to the supplied hydraulic pressure. The device described in Patent Document 1 is one example of such a system, in which hydraulic pressure is supplied from the linear solenoid valve to a friction engagement device (second clutch C2) that needs to have a continuously variable engagement torque, and hydraulic pressure is supplied from the ON-OFF solenoid valve to a friction engagement device (first clutch C1) that does not need to have a continuously variable engagement torque. In this specification, "supply of hydraulic pressure" means "supply of hydraulic oil of that hydraulic pressure." [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-63818 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when the engagement torque of a friction engagement device is continuously changed by a linear solenoid valve, if the torque capacity required for full engagement is large, the control range of the hydraulic pressure becomes large, which causes a problem of poor control accuracy and responsiveness of the hydraulic pressure, i.e., the engagement torque. This can be improved by using a large linear solenoid valve, but this increases costs.

[0005] The present invention was made against the background of the above circumstances, and its purpose is to provide an inexpensive hydraulic control system that can obtain high accuracy and responsiveness in a specified hydraulic pressure range even when the torque capacity required when the friction engagement device is fully engaged is large. [Means for solving the problem]

[0006] In order to achieve the above object, the first invention is a hydraulic control system having a linear solenoid valve capable of continuously changing hydraulic pressure, an ON-OFF solenoid valve that outputs and stops outputting hydraulic pressure, and a hydraulic friction engagement device that is engaged with an engagement torque according to a supplied hydraulic pressure, the system comprising: (a) a first hydraulic pressure regulated by the linear solenoid valve and an ON-OFF switching of the ON-OFF solenoid valve; Second hydraulic pressure that can be switched between output and no output states for the same friction engagement device a first oil passage for supplying the first hydraulic pressure to the friction engagement device and a second oil passage for supplying the second hydraulic pressure to the friction engagement device are provided so that the first hydraulic pressure can be supplied to the friction engagement device; and The linear solenoid valve the second hydraulic pressure in the output state and adjusting the first hydraulic pressure in a predetermined pressure adjustment control region lower than the a pressure on the higher side of the first hydraulic pressure and the second hydraulic pressure is supplied to the friction engagement device, and a check valve is provided in the first oil passage (b) a hydraulic control circuit that supplies the first hydraulic pressure to the friction engagement device and that controls the linear solenoid valve to The first hydraulic within the pressure regulation control range, and by switching on and off the ON-OFF solenoid valve when the friction engagement device is in a predetermined engagement state based on the first hydraulic pressure. the second hydraulic pressure in the output state of the friction engagement device By supplying the friction engagement device of the second hydraulic pressure in the output state and an engagement control section for bringing the vehicle into a fully engaged state with a high engagement torque based on the torque. The predetermined engagement state based on the first hydraulic pressure means a slip engagement state in which slip is caused by a predetermined engagement torque, or an engagement state in which there is no slip.

[0007] A second aspect of the present invention is a hydraulic control system according to the first aspect of the present invention, wherein the engagement control section adjusts the first hydraulic pressure supplied to the friction engagement device within the range of the pressure adjustment control region by the linear solenoid valve, thereby controlling the friction engagement device to be in an engagement state including a slip engagement state, and also controls the friction engagement device to be in an engagement state without slipping based on the first hydraulic pressure by switching on and off the ON-OFF solenoid valve. the second hydraulic pressure in the output state is supplied to the friction engagement device the friction engagement device is brought into the fully engaged state.

[0008] The third invention is a hydraulic control system according to the first or second invention, wherein the hydraulic pressure output from the ON-OFF solenoid valve is: a switching valve that switches the second hydraulic pressure between the output state and the output stop state; that it is equipped with A fourth invention is characterized in that, in the hydraulic control system of any one of the first to third inventions, the first hydraulic pressure is set to 0 when the second hydraulic pressure in the output state is supplied to the friction engagement device and the friction engagement device is in the fully engaged state.

[0009] Fifth Invention is the first invention Fourth Invention In any one of the hydraulic control systems described above, the friction engagement device is a disconnecting device that is provided between an engine and a rotary machine mounted on a vehicle and that connects and disconnects power transmission.

[0010] Sixth Invention teeth, Fifth Invention In the hydraulic control system of the present invention, the engagement control unit adjusts the first hydraulic pressure within the range of the pressure adjustment control region by the linear solenoid valve so that the first hydraulic pressure is supplied to the disconnecting device when the rotating machine is driven to rotate at a predetermined rotation speed, and the engine is cranked by slip engagement of the disconnecting device based on the first hydraulic pressure, and after the engine reaches a complete combustion state where it rotates by itself through start-up processing such as fuel injection and ignition, the engagement control unit adjusts the first hydraulic pressure within the range of the pressure adjustment control region by the linear solenoid valve the second hydraulic pressure in the output state The present invention is characterized in that the disconnecting device is brought into the fully engaged state by supplying a current to the disconnecting device.

[0011] Seventh Invention is the first invention Fourth InventionIn any one of the hydraulic control systems described above, the friction engagement device is a lock-up clutch of a fluid-type power transmission device mounted on a vehicle.

[0012] Eighth Invention is the first invention Fourth Invention In any one of the hydraulic control systems described above, the friction engagement device is a starting clutch that is provided between a driving power source mounted on a vehicle and a power transmission device, and that connects and disconnects power transmission. [Effects of the Invention]

[0014] In such a hydraulic control system, the first hydraulic pressure supplied to the friction engagement device is adjusted by the linear solenoid valve, so that the engagement torque of the friction engagement device can be continuously changed, and the ON-OFF switching of the ON-OFF solenoid valve can be Second oil pressure in output state When the torque is supplied to the friction engagement device, the friction engagement device is fully engaged with a large engagement torque, and the linear solenoid valve Second oil pressure in output state In other words, since the control range of the hydraulic pressure by the linear solenoid valve is narrowed, the control accuracy and responsiveness of the first hydraulic pressure by the linear solenoid valve are improved, and the large torque capacity required when the friction engagement device is fully engaged can be achieved. Second oil pressure in output state While ensuring this, in areas such as slip engagement where control of the engagement torque is required, the engagement torque can be controlled with high precision and high responsiveness by adjusting the first hydraulic pressure with the linear solenoid valve. Since a check valve is provided in the first oil passage, the second oil pressure in the output state can be supplied to the friction engagement device, thereby allowing the friction engagement device to be fully engaged with a high engagement torque based on the second oil pressure in the output state. Furthermore, since it is only necessary to combine and control the linear solenoid valve and the ON-OFF solenoid valve, the entire device can be constructed inexpensively.

[0015] In the second invention, when the friction engagement device is controlled to be in a slip engagement state by adjusting the first hydraulic pressure supplied to the friction engagement device using a linear solenoid valve, the friction engagement device is engaged without slipping based on the first hydraulic pressure, and the ON-OFF switching of the ON-OFF solenoid valve is performed. Second oil pressure in output stateThe friction engagement device is fully engaged by supplying the first hydraulic pressure to the first clutch while suppressing engagement shocks from the slip engagement state. Second oil pressure in output state This allows for a smooth transition to a fully engaged state.

[0016] In the third invention, the oil pressure output from the ON-OFF solenoid valve A switching valve that switches the second hydraulic pressure between an output state and an output stop state. Because it has Second oil pressure in output state It is possible to ensure a sufficient amount of oil, and the friction engagement device can be brought into a fully engaged state with high responsiveness. In the fourth invention, a check valve is provided in the first oil passage, so that when the second oil pressure in the output state is supplied to the friction engagement device and the friction engagement device is in a fully engaged state, the unnecessary first oil pressure can be reduced to zero.

[0017] Fifth Invention is related to the hydraulic control system of the disconnecting device, and when fully engaged Second oil pressure in output state While ensuring a large torque capacity, in slip engagement regions where engagement torque control is required, the engagement torque can be controlled with high precision and high responsiveness by regulating the first hydraulic pressure with a linear solenoid valve.This ensures a large torque capacity for transmitting driving force when the vehicle is running, while also making it possible to appropriately control the torque transmitted between the engine and the rotating machine when the vehicle starts using the engine or when the engine is started using the rotating machine.

[0018] Sixth Invention In the above, a first hydraulic pressure is supplied to the disconnecting device while the rotating machine is being driven to rotate, and the first hydraulic pressure is adjusted by the linear solenoid valve so that the engine is cranked by slip engagement of the disconnecting device based on the first hydraulic pressure. After the engine is started by a predetermined start process and reaches a full combustion state, the ON-OFF solenoid valve is switched ON / OFF. Second oil pressure in output state The linear solenoid valve that controls the disconnecting device to a slip engagement state during cranking is Second oil pressure in output stateIt is sufficient to regulate the first hydraulic pressure in a predetermined pressure regulation control region lower than the above, and the control range of the first hydraulic pressure by the linear solenoid valve may be narrow. Therefore, the slip engagement torque of the disconnecting device during cranking is controlled with high precision and high responsiveness by the linear solenoid valve, and the engine can be cranked and started appropriately. In addition, after the engine has reached a full combustion state, Second oil pressure in output state Since the disconnecting device is fully engaged with the large torque capacity provided by the torque converter, large engine torque can be reliably transmitted via the disconnecting device while the vehicle is running.

[0019] Seventh Invention is related to the hydraulic control system of the lock-up clutch, and when fully engaged Second oil pressure in output state While ensuring a large torque capacity, in slip engagement regions where engagement torque control is required, the engagement torque can be controlled with high precision and high responsiveness by regulating the first hydraulic pressure with a linear solenoid valve. This ensures a large torque capacity for transmitting driving force when the vehicle is running, while also making it possible to appropriately control the slip engagement torque of the lock-up clutch during slip engagement control and when the vehicle starts, etc.

[0020] Eighth Invention is related to the hydraulic control system of the starting clutch, and when fully engaged Second oil pressure in output state While ensuring a large torque capacity, in slip engagement regions where engagement torque control is required, the engagement torque can be controlled with high precision and high responsiveness by regulating the first hydraulic pressure with a linear solenoid valve. This ensures a large torque capacity for transmitting driving force when the vehicle is running, while also making it possible to appropriately control the slip engagement torque of the starting clutch when the vehicle starts, etc. [Brief explanation of the drawings]

[0022] [Figure 1] FIG. 1 is a schematic diagram illustrating the drive system of a hybrid electric vehicle equipped with a hydraulic control system according to one embodiment of the present invention, showing control functions for various controls and the main parts of the control system. [Figure 2]2 is a circuit diagram illustrating a hydraulic control system that controls the engagement state of a K0 clutch provided as a friction engagement device in the hybrid electric vehicle of FIG. 1. FIG. [Figure 3] 3 is a diagram illustrating the output hydraulic characteristics of a linear solenoid valve SLK provided in the hydraulic control system of FIG. 2. FIG. [Figure 4] 10 is a flowchart illustrating an operation when the K0 clutch is engaged after the engine is started, such as when the vehicle starts moving, in the hybrid electric vehicle of FIG. [Figure 5] 5 is an example of a time chart illustrating the operating state of each part when engagement control of the K0 clutch is performed according to the flowchart of FIG. 4. [Figure 6] 10 is an example of a time chart illustrating the operating states of each part when the engine is cranked and started by the rotary machine with the K0 clutch engaged. [Figure 7] FIG. 10 is a diagram for explaining another embodiment of the present invention, and is a schematic configuration diagram of a drive system for explaining an example of an engine-driven vehicle that does not include a rotary machine. [Figure 8] 8 is a circuit diagram illustrating a hydraulic control system that is provided in the engine-driven vehicle of FIG. 7 and controls the engagement state of the LU clutch. [Figure 9] 8 is a flowchart illustrating an operation when the LU clutch is engaged after the engine is started, such as when the vehicle starts moving, in the engine-driven vehicle of FIG. 7. [Figure 10] 10 is an example of a time chart illustrating the operating state of each part when engagement control of the LU clutch is performed according to the flowchart of FIG. 9. [Figure 11] FIG. 10 is a diagram for explaining yet another embodiment of the present invention, and is a schematic configuration diagram of a drive system for explaining an example of an engine-driven vehicle having a C0 clutch as a friction engagement device. [Figure 12] FIG. 12 is a circuit diagram illustrating a hydraulic control system that is provided in the engine-driven vehicle of FIG. 11 and controls the engagement state of the C0 clutch. [Figure 13]12 is a flowchart illustrating an operation when the C0 clutch is engaged after the engine is started, for example, when the vehicle is started, in the engine-driven vehicle of FIG. 11. [Figure 14] 14 is an example of a time chart illustrating the operating state of each part when engagement control of the C0 clutch is performed according to the flowchart of FIG. 13. DETAILED DESCRIPTION OF THE INVENTION

[0023] While the present invention is suitably applied to, for example, a hydraulic control system for a vehicle, it can also be applied to hydraulic control systems other than those for vehicles having friction engagement devices that require a large torque capacity at full engagement and that are required to control the engagement torque with high precision and high responsiveness in a predetermined engagement torque range, such as a slip engagement range. The present invention can be applied to hydraulic control systems for a variety of vehicles, including parallel-type hybrid electric vehicles that have an engine and a rotating machine as their driving power source, engine-driven vehicles that have only an engine as their driving power source, electric vehicles that have only a rotating machine as their driving power source, and series-type hybrid electric vehicles. A motor-generator that can be used alternatively as both an electric motor and a generator is suitable as the rotating machine used as the driving power source, but an electric motor that does not have the function of a generator can also be used.

[0024] The friction engagement devices that are the object of control by the hydraulic control system are various clutches and brakes that are frictionally engaged by hydraulic pressure, such as single-plate or multi-plate, dry or wet, etc. Hydraulic control systems for vehicles are suitably used to control, for example, a disconnecting device provided between an engine and a rotating machine, a lock-up clutch provided in a fluid-type power transmission, or a starting clutch provided between a driving force source and a power transmission device, but can also be applied to the control of other hydraulic friction engagement devices that require a large torque capacity at full engagement and that require control of the engagement torque with high precision and high responsiveness within a predetermined engagement torque range.

[0025] The hydraulic control circuit of the hydraulic control system may be provided with a hydraulic control valve that continuously changes the first hydraulic pressure according to the signal pressure when the hydraulic pressure output from the linear solenoid valve is supplied as the signal pressure, or the hydraulic pressure output from the ON-OFF solenoid valve is supplied as the ON-OFF switching hydraulic pressure, Second oil pressure higher than the first oil pressure Output state that outputs and a second hydraulic pressure higher than the first hydraulic pressure. Output stop state that stops the output of And, A switching valve that can be switched may be provided. It is also possible to configure the system so that the oil pressure output from the linear solenoid valve is supplied as is to the friction engagement device as the first oil pressure, and the oil pressure output from the ON-OFF solenoid valve is supplied as is to the friction engagement device as the second oil pressure, without providing the oil pressure control valve or the switching valve. Also, various modes are possible, such as the switching valve supplying the second oil pressure to the friction engagement device and cutting off the supply of the first oil pressure to the friction engagement device. The pressure regulation control region of the first oil pressure regulated by the linear solenoid valve is, for example, Second oil pressure in output state However, a range from the predetermined upper limit oil pressure to a predetermined lower limit oil pressure that does not include 0 may also be defined.

[0026] The engagement control unit of the hydraulic control system regulates and controls the first hydraulic pressure by the linear solenoid valve to engage the friction engagement device without slipping, and switches the ON-OFF of the ON-OFF solenoid valve Second oil pressure in output state It is desirable to supply the oil pressure to the friction engagement device to bring it into a fully engaged state, but the oil pressure can be reduced by switching the ON-OFF solenoid valve ON / OFF while the friction engagement device is in a slipping engagement state. Second oil pressure in output state It is also possible to supply a first hydraulic pressure to bring the friction engagement device into a fully engaged state. Second oil pressure in output state If the clutch has a function to supply the first hydraulic pressure to bring the clutch into a fully engaged state, Second oil pressure in output state By supplying the current, the friction engagement device is directly brought into a fully engaged state, or in the fully engaged state, Second oil pressure in output stateIt is possible to perform various controls using at least one of a linear solenoid valve and an ON-OFF solenoid valve, such as directly opening the valve by stopping the supply of air. [Example]

[0027] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that in the following embodiments, the drawings have been appropriately simplified or modified for the purpose of explanation, and the shapes, dimensional ratios, angles, etc. of the various parts are not necessarily drawn accurately.

[0028] FIG. 1 is a schematic diagram of the drive system of a hybrid electric vehicle 10 (hereinafter simply referred to as vehicle 10) equipped with a hydraulic control system 100 (see FIG. 2) according to one embodiment of the present invention, and also shows the control functions for various controls related to the vehicle 10 and the main parts of the control system. In FIG. 1, the vehicle 10 is a parallel-type hybrid electric vehicle equipped with an engine 12 and a rotary machine MG as sources of driving power for traveling. The vehicle 10 also includes a power transmission device 16 provided in a power transmission path between the engine 12 and drive wheels 14. The drive wheels 14 are the left and right rear wheels, and the vehicle 10 is a FR, rear-wheel-drive vehicle.

[0029] The engine 12 is an internal combustion engine such as a gasoline engine or a diesel engine. The engine 12 has an engine control device 50, which includes a throttle actuator, a fuel injection device, an ignition device, and the like, controlled by an electronic control device 90, thereby controlling the engine torque Te, which is the output torque of the engine 12. The engine 12 can be started by cranking using a rotating machine MG, and is provided with a starter 12s for cranking. The rotating machine MG is a motor generator that functions as both an electric motor that generates mechanical power from electric power and a generator that generates electric power from mechanical power. For example, the rotating machine MG is a three-phase AC synchronous motor with a permanent magnet disposed in the rotor, and is connected to a battery 54 via an inverter 52. The electronic control device 90 controls the inverter 52, thereby controlling the MG torque Tmg, which is the torque of the rotating machine MG, and the MG rotational speed Nmg, which is the rotational speed of the rotating machine MG. The rotating machine MG generates power for traveling using electric power supplied from the battery 54 via the inverter 52, instead of or in addition to the engine 12. The rotating machine MG also generates electricity by being controlled to function as a generator when it is rotationally driven by the power of the engine 12 or the driven force input from the drive wheels 14, and also generates regenerative braking when it is connected to the drive wheels 14. The electric power generated by the rotating machine MG is stored in a battery 54 via an inverter 52. The battery 54 is an electricity storage device that supplies and receives electric power to the rotating machine MG.

[0030] The power transmission device 16 includes a K0 clutch 20, a torque converter 22, and an automatic transmission 24 arranged in series from the engine 12 side within a case 18, which is a non-rotating member attached to the vehicle body. A rotary machine MG is connected to the power transmission path between the K0 clutch 20 and the torque converter 22. The K0 clutch 20 is a clutch provided between the engine 12 and the rotary machine MG in the power transmission path between the engine 12 and the drive wheels 14, and is a connecting / disconnecting device that connects / disconnects the rotary machine MG and the engine 12. The torque converter 22 is a fluid-type power transmission device provided between the rotary machine MG and the automatic transmission 24 and transmits power via hydraulic oil, which is a fluid, and is connected to the engine 12 via the K0 clutch 20. The automatic transmission 24 is connected to the torque converter 22 and is a transmission provided between the rotary machine MG and the drive wheels 14 in the power transmission path between the engine 12 and the drive wheels 14. The power transmission device 16 includes a propeller shaft 28 connected to a transmission output shaft 26, which is an output rotating member of the automatic transmission 24, a differential gear 30 connected to the propeller shaft 28, and a pair of drive shafts 32 connected to the differential gear 30. The power transmission device 16 also includes an engine connecting shaft 34 that connects the engine 12 and the K0 clutch 20, and an MG connecting shaft 36 that connects the K0 clutch 20 and the torque converter 22, and the rotor of the rotary machine MG is connected to the MG connecting shaft 36.

[0031] The K0 clutch 20 is a wet or dry friction engagement device (wet in this embodiment) composed of a multi-plate or single-plate clutch pressed by a hydraulic actuator. The K0 clutch 20 switches between control states such as an engaged state and a disengaged state by changing the K0 clutch torque (engagement torque) Tk0, which is the torque capacity of the K0 clutch 20, using the regulated K0 oil pressure Pk0 supplied from the hydraulic control circuit 56. An input side member of the K0 clutch 20 is connected to the engine connecting shaft 34 and rotates integrally therewith. An output side member of the K0 clutch 20 is connected to the MG connecting shaft 36 and rotates integrally therewith. When the K0 clutch 20 is engaged, the rotor of the rotary machine MG, the pump wheel 22a, and the engine 12 are rotated integrally via the engine connecting shaft 34. On the other hand, when the K0 clutch 20 is disengaged, power transmission between the rotor of the rotary machine MG, the pump wheel 22a, and the engine 12 is interrupted.

[0032] The rotary machine MG is connected to the MG connecting shaft 36 in the case 18 so as to be able to transmit power. The rotary machine MG is connected to a power transmission path between the engine 12 and the drive wheels 14, particularly to a power transmission path between the K0 clutch 20 and the torque converter 22 so as to be able to transmit power. In other words, the rotary machine MG is connected to the torque converter 22 and the automatic transmission 24 so as to be able to transmit power without passing through the K0 clutch 20. The torque converter 22 and the automatic transmission 24 transmit driving power from the driving power sources of the engine 12 and the rotary machine MG to the drive wheels 14, respectively.

[0033] The torque converter 22 includes a pump wheel 22a connected to an MG connecting shaft 36 and a turbine wheel 22b connected to a transmission input shaft 38, which is an input rotating member of the automatic transmission 24. The pump wheel 22a is connected to the engine 12 via the K0 clutch 20 and is also directly connected to the rotary machine MG. The pump wheel 22a is the input member of the torque converter 22, and the turbine wheel 22b is the output member of the torque converter 22. The MG connecting shaft 36 also serves as the input rotating member of the torque converter 22. The transmission input shaft 38 is also the output rotating member of the torque converter 22, formed integrally with a turbine shaft that is rotationally driven by the turbine wheel 22b. The torque converter 22 includes an LU clutch 40 that connects the pump wheel 22a and the turbine wheel 22b. The LU clutch 40 is a direct-coupled clutch that connects the input and output rotating members of the torque converter 22, i.e., a known lock-up clutch.

[0034] The LU clutch 40 switches between engagement states, i.e., operating states, by changing the LU clutch torque (engagement torque) Tlu, which is the torque capacity of the LU clutch 40, using the regulated LU hydraulic pressure Plu supplied from the hydraulic control circuit 56. The operating states of the LU clutch 40 include a release state in which the LU clutch 40 is fully released, a slip engagement state in which the LU clutch 40 is engaged with slip, and a lockup state (fully engaged state) in which the LU clutch 40 is fully engaged without slip. When the LU clutch 40 is in the release state, the torque converter 22 is in a torque converter state in which torque amplification is achieved. The lockup state of the LU clutch 40 is a state in which the pump wheel 22a and turbine wheel 22b of the torque converter 22 rotate integrally.

[0035] The automatic transmission 24 is a known planetary gear automatic transmission that includes, for example, one or more planetary gear devices and multiple engagement devices CB. The engagement devices CB are hydraulic friction engagement devices that include multiple-plate or single-plate clutches or brakes pressed by hydraulic actuators, and band brakes tightened by hydraulic actuators. Each engagement device CB has its torque capacity, or CB torque Tcb, changed by the regulated CB oil pressure Pcb supplied from the hydraulic control circuit 56, thereby switching its control state between an engaged state, a disengaged state, and the like.

[0036] The automatic transmission 24 is a stepped transmission that can establish multiple forward gears and reverse gears with different gear ratios γ (=AT input rotation speed Ni / AT output rotation speed No) by engaging any of the engagement devices CB. The automatic transmission 24 selectively establishes multiple gears by switching between the gears established by an electronic control device 90 in response to driving conditions such as the driver's accelerator operation and vehicle speed V. Furthermore, when all of the engagement devices CB are disengaged, the automatic transmission enters a neutral position, cutting off power transmission. 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 also the rotation speed of the output rotating member of the torque converter 22 and is equal to the turbine rotation speed Nt, which is the output rotation speed of the torque converter 22. 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.

[0037] 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 drive wheels 14 via the K0 clutch 20, MG connecting shaft 36, torque converter 22, automatic transmission 24, propeller shaft 28, differential gear 30, drive shaft 32, etc. in that order. Similarly, the power output from the rotary machine MG is transmitted from the MG connecting shaft 36 to the drive wheels 14 via the torque converter 22, automatic transmission 24, propeller shaft 28, differential gear 30, drive shaft 32, etc. in that order, regardless of the control state of the K0 clutch 20.

[0038] The vehicle 10 is equipped with a mechanical oil pump MOP 58, an electric oil pump EOP 60, a pump motor 62, and the like. The MOP 58 is connected to the pump impeller 22a and is driven to rotate by a driving power source (the engine 12, the rotary machine MG) to discharge hydraulic oil OIL for use in the power transmission device 16. The pump motor 62 is an electric motor dedicated to the EOP 60 for driving the EOP 60. The EOP 60 is driven to rotate by the pump motor 62 to discharge hydraulic oil OIL, and can discharge hydraulic oil OIL at any time, including when the vehicle 10 is stopped. 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 outputs CB hydraulic pressure Pcb, K0 hydraulic pressure Pk0, LU hydraulic pressure Plu, and the like, each adjusted based on the hydraulic oil OIL discharged by the MOP 58 and / or the EOP 60. The hydraulic oil OIL is supplied to the torque converter 22 for power transmission, and is also used for lubricating and cooling various parts. The hydraulic oil OIL is accumulated in an oil reservoir such as an oil pan provided at the bottom of the case 18, and is pumped up by the MOP 58 and / or EOP 60 and supplied to the hydraulic control circuit 56. The MOP 58 and EOP 60 are hydraulic pressure supply sources for the hydraulic control circuit 56.

[0039] The vehicle 10 is equipped with an electronic control unit 90 as a control device that executes various types of control. The electronic control unit 90 is configured to include a so-called microcomputer equipped with, for example, a CPU, RAM, ROM, an input / output interface, etc., and the CPU executes various types of control 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 unit 90 is configured to include multiple computers for engine control, MG control, hydraulic control, etc. as necessary.

[0040] The electronic control device 90 receives various signals based on detected values from various sensors provided in the vehicle 10 (for example, an engine rotation speed sensor 70, a turbine rotation speed sensor 72, an output rotation speed sensor 74, a MG rotation speed sensor 76, an accelerator opening sensor 78, a throttle valve opening sensor 80, a brake switch 82, a battery sensor 84, an oil temperature sensor 86, a lever position sensor 88, etc.) (for example, an engine rotation speed Ne which is the rotation speed of the engine 12, a turbine rotation speed Nt which is the same value as the AT input rotation speed Ni, an AT output rotation speed No which corresponds to the vehicle speed V, an MG rotation speed Nmg which is the rotation speed of the rotary machine MG, an accelerator opening θacc which is the operation amount of an accelerator operating member 79 such as an accelerator pedal and which represents the amount of acceleration required by the driver, a throttle valve opening θth which is the opening amount of the electronic throttle valve, a 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, a battery temperature THbat, a battery charge / discharge current Ibat, and a battery voltage Vbat of the battery 54). , an oil temperature THoil that is the temperature of the hydraulic oil OIL in the hydraulic control circuit 56, a signal that indicates the operating position POSsh of a shift lever 64 provided in the vehicle 10, etc.

[0041] The shift lever 64 is located near the driver's seat and is a shift operation member operated by the driver to change the shift range, which is the power transmission state of the automatic transmission 24, and has multiple operation positions POSsh. The operation positions POSsh include multiple positions, for example, P, R, N, and D, which allow the driver to select one of the P, R, N, and D ranges as the shift range. The P position is an operation position for selecting the P (parking) range, which places the automatic transmission 24 in a neutral state in which power transmission is interrupted and mechanically prevents rotation of the transmission output shaft 26. The neutral state is a state in which all engagement devices CB of the automatic transmission 24 are disengaged. The R position is an operation position for selecting the R (reverse) range, which places the automatic transmission 24 in a reverse gear, for traveling backward. The N position is an operation position for selecting the N (neutral) range, which places the automatic transmission 24 in a neutral state, similar to the P position. The D position is an operating position for selecting a D (drive) range for forward travel, which automatically switches between multiple forward gears of the automatic transmission 24 in accordance with driving conditions such as the vehicle speed V and accelerator opening θacc. The shift lever 64 may be one that is positioned and held at each of the P, R, N, and D operating positions POSsh, or may be an automatic return type that automatically returns to a predetermined home position. Furthermore, a push button switch or the like that selects each of the above shift ranges may be used as the shift operating member.

[0042] 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 Smg for controlling the rotating machine MG, a CB hydraulic control command signal Sbc for controlling the engagement device CB, a K0 hydraulic control command signal Sk0 for controlling the K0 clutch 20, 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. The hydraulic control circuit 56 is provided with a plurality of solenoid valves that switch oil paths and control oil pressure in accordance with the CB hydraulic control command signal Sbc, the K0 hydraulic control command signal Sk0, and the LU hydraulic control command signal Slu.

[0043] 2 is a circuit diagram specifically illustrating a hydraulic control system 100 that controls the K0 hydraulic pressure Pk0 of the K0 clutch 20, and includes a K0 hydraulic control circuit 102 that is involved in the hydraulic control of the K0 clutch 20 in the hydraulic control circuit 56, and a K0 engagement control unit 104 that is functionally provided in the electronic control device 90 to control the K0 hydraulic pressure Pk0. The K0 hydraulic control circuit 102 includes a line pressure oil passage 106 to which line pressure PL is supplied from the hydraulic supply sources MOP 58 and EOP 60, a linear solenoid valve SLK that can continuously adjust the first hydraulic pressure Pk01 that is the output hydraulic pressure using the line pressure PL as the source pressure, a changeover valve 108 that is mechanically switched between an ON state in which the line pressure PL is output as is as the second hydraulic pressure Pk02 and an OFF state in which the output of the second hydraulic pressure Pk02 is stopped, and an ON-OFF solenoid valve SCK that switches the ON and OFF states of the changeover valve 108. The line pressure PL is adjusted by a line pressure adjusting device (not shown) having a linear solenoid valve or the like in accordance with, for example, the accelerator opening θacc, which is the required output amount, and is supplied to a line pressure oil passage 106. The first oil pressure Pk01 output from the linear solenoid valve SLK is supplied to the hydraulic actuator 20a of the K0 clutch 20 via a first oil passage 110, and a damper 112 is provided in the first oil passage 110. Second oil pressure in output statePk02 is supplied to the hydraulic actuator 20a via a second oil passage 114, and the second oil passage 114 is connected to a junction 110p between the damper 112 of the first oil passage 110 and the hydraulic actuator 20a. Therefore, the higher pressure of the first oil pressure Pk01 and the second oil pressure Pk02 is supplied to the hydraulic actuator 20a as the K0 oil pressure Pk0. A check valve or the like is provided, as necessary, on the first oil passage 110 and the second oil passage 114 before the junction 110p.

[0044] The K0 engagement control unit 104 outputs a first command signal Sk01 and a second command signal Sk02 as the K0 hydraulic control command signal Sk0. The first command signal Sk01 controls the linear solenoid valve SLK and adjusts the first hydraulic pressure Pk01 within a predetermined pressure adjustment control region Pslk (see FIG. 3). The second command signal Sk02 controls the ON / OFF solenoid valve SCK. In this embodiment, the line pressure PL is output as is as the ON-OFF switching hydraulic pressure Psck by ON control. When the switching valve 108 is switched to the ON state by the ON-OFF switching hydraulic pressure Psck, the line pressure PL supplied from the line pressure oil passage 106 to the switching valve 108 is output as is to the second oil passage 114 as the second hydraulic pressure Pk02.

[0045] FIG. 3 illustrates the output hydraulic pressure characteristics of the linear solenoid valve SLK. The dashed-dotted line represents a conventional example, and the solid line represents this embodiment. The K0 clutch 20 requires a relatively large torque capacity to reliably transmit the torque Te of the engine 12 during vehicle operation. During engine operation, when the engine 12 is used as a driving force source, a high full-engagement hydraulic pressure Pk0comp is required as the K0 hydraulic pressure Pk0. The K0 clutch 20 is used as a starting clutch to start the vehicle 10 using the engine 12 as a driving force source. It is also used for cranking control, where, when an engine start request is received while the engine 12 is stopped, the K0 clutch 20 is slip-engaged while the rotating machine MG is rotating at a predetermined rotational speed to increase the engine rotational speed Ne. The control range of the K0 hydraulic pressure Pk0 required for engine start control and cranking control can be set to a torque control hydraulic pressure Pk0torq or less, which is sufficiently lower than the full-engagement hydraulic pressure Pk0comp. In this case, a linear solenoid valve SLK capable of adjusting pressure up to the full engagement hydraulic pressure Pk0comp as shown by the dashed line in Fig. 3 has conventionally been used, but in this embodiment, a linear solenoid valve SLK capable of adjusting pressure within a pressure adjustment control region Pslk that is slightly above the torque control hydraulic pressure Pk0torq as shown by the solid line is employed. That is, during engine start control or cranking control at engine start, the first hydraulic pressure Pk01 adjusted by the linear solenoid valve SLK in the relatively low pressure adjustment control region Pslk is supplied to the hydraulic actuator 20a as the K0 hydraulic pressure Pk0, and the K0 clutch torque Tk0 is controlled so that, for example, the MG rotation speed Nmg or the engine rotation speed Ne is increased at a predetermined rate. On the other hand, during vehicle running when the full engagement hydraulic pressure Pk0comp is required, the first hydraulic pressure Pk01 output from the changeover valve 108 is adjusted within the pressure adjustment control region Pslk of a relatively low pressure. Second oil pressure in output state By controlling the ON-OFF solenoid valve SCK so that Pk02 is supplied to the hydraulic actuator 20a as the K0 oil pressure Pk0, the K0 clutch 20 can be engaged with a large torque capacity by the second oil pressure Pk02 (=PL) which is higher than the full engagement oil pressure Pk0comp.

[0046] Here, the linear solenoid valve SLK regulates the first hydraulic pressure Pk01 during the engine start control and cranking control within a relatively narrow pressure regulation control range Pslk, thereby improving the control accuracy and responsiveness of the first hydraulic pressure Pk01. That is, as shown in FIG. 3 , when regulating the first hydraulic pressure Pk01 within a range below the excitation current Imax, comparing the hydraulic pressure change ranges ΔP1 and ΔP2 per a constant current change ΔI for this embodiment (shown by the solid line) and the conventional example (shown by the dashed-dotted line), the hydraulic pressure change range ΔP1 in this embodiment is smaller than the hydraulic pressure change range ΔP2 in the conventional example (shown by the wide pressure regulation control range), thereby enabling the first hydraulic pressure Pk01 to be regulated with correspondingly higher accuracy. Furthermore, the amount of spool displacement, i.e., the amount of change in the flow cross-sectional area, per the same hydraulic pressure change can be increased, improving the responsiveness of the hydraulic pressure change.

[0047] Returning to FIG. 1, the electronic control device 90 functionally includes a hybrid control unit 92, a gear shift control unit 94, and an engine start control unit 96 in addition to the K0 engagement control unit 104 described above in order to realize various controls in the vehicle 10.

[0048] The hybrid control unit 92 has a function of controlling the operation of the engine 12 and the rotary machine MG in a coordinated manner, and includes an engine control unit 92a that controls the engine 12 and an MG control unit 92b that controls the rotary machine MG. The hybrid control unit 92 calculates a drive demand amount for the vehicle 10 from the driver, for example, by applying the accelerator opening θacc and the vehicle speed V to a drive demand amount map. The drive demand amount is, for example, a required drive torque Trdem at the drive wheels 14. The hybrid control unit 92 calculates a required input torque Tindem, which is the input torque of the torque converter 22 required to achieve the required drive torque Trdem, taking into account transmission loss, the auxiliary load, the gear ratio γ of the automatic transmission 24, the torque ratio of the torque converter 22, the chargeable power Win and dischargeable power Wout of the battery 54, and the like, and outputs an engine control command signal Se that controls the engine 12 and an MG control command signal Smg that controls the rotary machine MG so that the required input torque Tindem is obtained. The chargeable power Win and dischargeable power Wout of the battery 54 are calculated by the electronic control unit 90 based on, for example, the battery temperature THbat and the state-of-charge value SOC [%] of the battery 54. The state-of-charge value SOC of the battery 54 is a value indicating the state of charge of the battery 54, i.e., the remaining amount of power stored, and can be calculated based on, for example, the battery charge / discharge current Ibat and the battery voltage Vbat.

[0049] When the required input torque Tindem can be met solely with the output of the rotating machine MG, the hybrid control unit 92 selects a BEV (Battery Electric Vehicle) driving mode, which is a motor driving mode in which the rotating machine MG is driven solely by power from the battery 54. In the BEV driving mode, the K0 clutch 20 is disengaged to stop the engine 12, and BEV driving is performed, in which the vehicle is driven solely by the rotating machine MG as a driving force source. In this BEV driving mode, the MG torque Tmg is controlled to achieve the required input torque Tindem. On the other hand, when the required input torque Tindem cannot be met without using at least the output of the engine 12, the hybrid control unit 92 selects an HEV (Hybrid Electric Vehicle) driving mode, which is an engine driving mode. In the HEV driving mode, the K0 clutch 20 is engaged to drive the vehicle using at least the engine 12 as a driving force source, i.e., HEV driving. In the HEV driving mode, the engine torque Te is controlled to realize all or part of the required input torque Tindem, and the MG torque Tmg is controlled to compensate for the torque that is insufficient in the engine torque Te relative to the required input torque Tindem. On the other hand, the hybrid control unit 92 establishes the HEV driving mode when warming up of the engine 12 or the like is required, even if the required input torque Tindem can be achieved solely by the output of the rotary machine MG. In this way, the hybrid control unit 92 switches between the BEV driving mode and the HEV driving mode by automatically stopping the engine 12 during HEV driving, restarting the engine 12 after the engine has stopped, starting the engine 12 during BEV driving, or automatically stopping and starting the engine 12 while the vehicle is stopped, based on the required input torque Tindem, etc.

[0050] When the D range is selected, the shift control unit 94 determines whether to shift the automatic transmission 24 using a predetermined shift map or the like with driving conditions such as the vehicle speed V and accelerator opening θacc as variables, and executes automatic shift control by outputting a CB hydraulic control command signal Sbc to the hydraulic control circuit 56 as necessary to automatically shift between multiple forward gears of the automatic transmission 24. Furthermore, when the driver operates the shift lever 64 or a manual shift operation member provided near the driver's seat and a shift instruction signal is supplied, the shift control unit 94 executes manual shift control to shift the forward gears of the automatic transmission 24 in accordance with the shift instruction.

[0051] When an engine start request is made by operating the shift lever 64 or the accelerator operating member 79, the engine start control unit 96 starts the engine 12 in accordance with the engine start request.The engine start control unit 96 cranks the engine 12 using the starter 12s or the rotating machine MG, and when the engine rotation speed Ne reaches a predetermined startable rotation speed, it performs start processing such as fuel injection and ignition to start the engine 12 so that it rotates under its own power.

[0052] The K0 engagement control unit 104 controls the engagement torque Tk0, i.e., the K0 hydraulic pressure Pk0, of the K0 clutch 20 during engine launch control and engine starting control, and fully engages the K0 clutch 20 with a large engagement torque capacity when traveling using the engine 12 as a driving force source. FIG. 4 is a flowchart illustrating the operation when the K0 engagement control unit 104 engages the K0 clutch 20 to start the vehicle 10 or generate creep torque following engine start by the starter 12s, and signal processing is performed according to steps S1 to S12 (hereinafter, the steps will be omitted and simply referred to as S1 to S12; the same applies to other flowcharts). In these flowcharts, YES in the diamond-shaped decision steps means affirmative, and NO means negative. FIG. 5 is an example of a time chart illustrating the operating states of each unit when engagement control of the K0 clutch 20 is performed according to the flowchart of FIG. 4.

[0053] S1 in FIG. 4 is executed by the engine start control unit 96, which cranks the engine 12 using the starter 12s and performs predetermined start processing such as fuel injection to start the engine 12. Time t1 in FIG. 5 is the time when cranking of the engine 12 is initiated by the starter 12s in response to an engine start request. S2 and subsequent steps are executed by the K0 engagement control unit 104, which determines whether predetermined cryogenic mode conditions are met in S2. The cryogenic mode conditions are, for example, when the oil temperature THoil is low and the viscosity of the hydraulic oil is high, such that normal engagement control would cause an engagement shock. If the cryogenic mode conditions are met, S3 and subsequent steps are executed. If the cryogenic mode conditions are not met, another K0 engagement method is executed in S12. In S12, the K0 clutch 20 is engaged using normal engagement control, such as feedforward control or feedback control.

[0054] In S3, a K0 oil pressure Pk0 is output to pack the hydraulic actuator 20a of the K0 clutch 20, and the K0 oil pressure Pk0 is rapidly charged to a state just before engagement. Here, a first command signal Sk01 is output to the linear solenoid valve SLK, and the first oil pressure Pk01 output from the linear solenoid valve SLK is supplied to the hydraulic actuator 20a as the K0 oil pressure Pk0. Time t2 in Figure 5 is the time when packing in S3 begins. The dashed-dotted line in the oil pressure command value column represents the first oil pressure Pk01, and the solid line represents the K0 oil pressure Pk0. In S4, a determination is made as to whether the engine rotation speed Ne has decreased from, for example, the idle rotation speed Ne due to slip engagement of the K0 clutch 20. If the engine rotation speed Ne has decreased, S5 is executed; if the engine rotation speed Ne has not decreased, S6 and subsequent steps are immediately executed. In S5, a determination is made as to whether the decrease gradient of the engine rotation speed Ne is equal to or less than a specified value, i.e., whether the absolute value of the decrease gradient is small. If the decrease gradient is equal to or less than the specified value, S6 is executed. If the rate of decrease is greater than the specified value, i.e., if the rate of decrease of the engine rotation speed Ne is large, S7 is executed, and the K0 oil pressure Pk0 is decreased by a specified value by controlling the linear solenoid valve SLK using the first command signal Sk01, and then S4 and subsequent steps are executed again. Then, if the decrease in the engine rotation speed Ne becomes approximately 0 or the rate of decrease is equal to or less than the specified value, S6 is executed.

[0055] In S6, the linear solenoid valve SLK is controlled by the first command signal Sk01 so as to increase the K0 oil pressure Pk0 by a predetermined value. In S8, it is determined whether the slip engagement of the K0 clutch 20 can increase the MG rotation speed Nmg so as to approach the engine rotation speed Ne, and S6 is repeated to gradually increase the K0 oil pressure Pk0 until the MG rotation speed Nmg can be increased. When the MG rotation speed Nmg can be increased and the determination in S8 becomes YES, S9 is executed. In S9, the linear solenoid valve SLK is controlled by the first command signal Sk01 so as to increase the K0 oil pressure Pk0 while monitoring the engine rotation speed Ne. In other words, the K0 oil pressure Pk0 is gradually increased so as to maintain the engine rotation speed Ne approximately at an idle rotation speed such as Needle. The control of the K0 oil pressure Pk0 in the above S6, S7, and S9, that is, the pressure regulation control of the first oil pressure Pk01 by the linear solenoid valve SLK, is performed within the pressure regulation control region Pslk.

[0056] In S10, it is determined whether the MG rotation speed Nmg has reached a predetermined target rotation speed, and S9 is repeatedly executed until the target rotation speed is reached. The target rotation speed is, for example, a rotation speed that substantially matches the engine rotation speed Ne and allows the K0 clutch 20 to be engaged without slippage, i.e., High pressure second oil pressure in output state This is the rotation speed at which shock does not occur even if Pk02 (=PL) is supplied to the hydraulic actuator 20a to fully engage the K0 clutch 20. Then, when the MG rotation speed Nmg reaches the target rotation and the determination in S10 becomes YES, S11 is executed to fully engage the K0 clutch 20. Specifically, the second command signal Sk02 is output to the ON-OFF solenoid valve SCK to switch the switching valve 108 to the ON state, Second oil pressure in output state Pk02 is supplied to the hydraulic actuator 20a as the K0 hydraulic pressure Pk0, and the K0 clutch 20 is fully engaged with a large torque capacity by the second hydraulic pressure Pk02 (=PL) which is higher than the full engagement hydraulic pressure Pk0comp. At time t3 in FIG. 5, S11 is executed and the K0 clutch 20 High pressure second oil pressure in output stateAt the time when the clutch is fully engaged by Pk02, the dashed line in the column for the hydraulic pressure command value is the second hydraulic pressure Pk02. Second oil pressure in output state When the K0 clutch 20 is fully engaged based on Pk02, the first hydraulic pressure Pk01 is no longer necessary, so at time t4, the output of the first command signal Sk01 to the linear solenoid valve SLK is stopped, and the first hydraulic pressure Pk01 is set to 0. Second oil pressure in output state Since the responsiveness of Pk02 is high, the output of the first command signal Sk01 may be stopped at the same time as the second command signal Sk02 is output at time t3.

[0057] On the other hand, when the engine 12 is cranked and started by the rotary machine MG, the K0 engagement control unit 104 and the engine start control unit 96 cooperate to perform start control of the engine 12. That is, the K0 engagement control unit 104 performs cranking control to crank the engine 12 by slip control of the K0 clutch 20, and when the engine rotation speed Ne reaches a predetermined startable rotation speed, it performs start processing such as fuel injection and ignition to start the engine 12 so that it rotates under its own power. Specifically, as shown in the time chart of Figure 6, for example, at time t1 when an engine start request is made, a first command signal Sk01 is output to the linear solenoid valve SLK as the K0 hydraulic control command signal Sk0, and the first hydraulic pressure Pk01 (dashed line) output from the linear solenoid valve SLK is supplied to the hydraulic actuator 20a as the K0 hydraulic pressure Pk0 (solid line), and the first hydraulic pressure Pk01 is regulated within the pressure regulation control region Pslk so that the engine rotation speed Ne increases at a predetermined rate due to slip engagement of the K0 clutch 20 caused by the first hydraulic pressure Pk01. Then, when it is determined by, for example, an engine start flag that the engine 12 has reached a state of complete combustion and is rotating under its own power through start-up processing such as fuel injection and ignition (time t2), the engine rotation speed Ne coincides with the MG rotation speed Nmg (time t3), and the K0 clutch 20 is engaged without slippage by control of the first hydraulic pressure Pk01, etc., at time t4, the second command signal Sk02 is output to the ON-OFF solenoid valve SCK as the K0 hydraulic pressure control command signal Sk0. This switches the switching valve 108 to the ON state, Second oil pressure in output state Pk02 (broken line) is supplied to the hydraulic actuator 20a as the K0 oil pressure Pk0, and the K0 clutch 20 is fully engaged with a large torque capacity by the second oil pressure Pk02 (=PL) which is higher than the full engagement oil pressure Pk0comp. In this state, the first oil pressure Pk01 is not required, so at time t5, the output of the first command signal Sk01 to the linear solenoid valve SLK is stopped and the first oil pressure Pk01 is set to 0. Second oil pressure in output state Since the responsiveness of Pk02 is high, the output of the first command signal Sk01 may be stopped at the same time as the second command signal Sk02 is output at time t4.

[0058] In this way, in the hydraulic control system 100 of this embodiment, the first hydraulic pressure Pk01 supplied to the K0 clutch 20 is adjusted by the linear solenoid valve SLK, so that the K0 clutch torque Tk0 can be continuously changed, and the ON-OFF switching of the ON-OFF solenoid valve SCK Second oil pressure in output state When Pk02 (=PL) is supplied to the K0 clutch 20, the K0 clutch 20 is fully engaged with a large engagement torque Tk0, so the linear solenoid valve SLK Second oil pressure in output state It is sufficient if the first hydraulic pressure Pk01 can be adjusted within a predetermined pressure adjustment control region Pslk that is lower than Pk02. In other words, the control range of the first hydraulic pressure Pk01 by the linear solenoid valve SLK is narrowed, so that the control accuracy and responsiveness of the first hydraulic pressure Pk01 by the linear solenoid valve SLK are improved, and the large torque capacity required when the K0 clutch 20 is fully engaged can be achieved. Second oil pressure in output state While ensuring the torque by the linear solenoid valve SLK, in the slip engagement region where control of the K0 clutch torque Tk0 is required for launch control, engine startup control, etc., the K0 clutch torque Tk0 can be controlled with high precision and high responsiveness by adjusting the first hydraulic pressure Pk01 by the linear solenoid valve SLK. Furthermore, because it is only necessary to control the linear solenoid valve SLK and the ON-OFF solenoid valve SCK in combination, the hydraulic control system 100 as a whole can be configured inexpensively.

[0059] In this embodiment, the first hydraulic pressure Pk01 supplied to the hydraulic actuator 20a of the K0 clutch 20 is adjusted by the linear solenoid valve SLK, thereby controlling the engagement of the K0 clutch 20, including the slip engagement state. However, when the K0 clutch 20 is engaged without slipping based on the first hydraulic pressure Pk01 (time t3 in FIG. 5, time t4 in FIG. 6), the ON-OFF switching of the ON-OFF solenoid valve SCK Second oil pressure in output state Pk02 is supplied to bring the K0 clutch 20 into a fully engaged state, while suppressing engagement shocks etc. from the slip engagement state caused by the first hydraulic pressure Pk01. Second oil pressure in output state A smooth transition to a fully engaged state by Pk02 can be achieved.

[0060] In this embodiment, the ON-OFF switching oil pressure Psck output from the ON-OFF solenoid valve SCK is used to determine whether or not the ON-OFF switching oil pressure Psck is present. Line pressure PL is used as the second hydraulic pressure Pk02. Output state to be output and Stop output of second hydraulic pressure Pk02 Output stopped Since the switch valve 108 is provided, Second oil pressure in output state It is possible to ensure a sufficient amount of oil in Pk02, and the K0 clutch 20 can be brought into a fully engaged state with high responsiveness.

[0061] This embodiment relates to a hydraulic control system 100 for the K0 clutch 20 provided between the engine 12 and the rotary machine MG. Second oil pressure in output state While ensuring a large torque capacity with Pk02, in areas such as slip engagement where control of the engagement torque Tk0 is required, the linear solenoid valve SLK regulates the first hydraulic pressure Pk01, making it possible to control the engagement torque Tk0 with high precision and high responsiveness, thereby achieving a large torque capacity for transmitting driving force when the vehicle is running. Second oil pressure in output state The torque capacity transmitted between the engine 12 and the rotary machine MG when the vehicle starts with the engine 12 or when the engine is started with the rotary machine MG can be appropriately controlled by the first hydraulic pressure Pk01 while being ensured by the first hydraulic pressure Pk02.

[0062] In the engine start control using the rotary machine MG shown in FIG. 6, the first hydraulic pressure Pk01 is supplied to the hydraulic actuator 20a of the K0 clutch 20 while the rotary machine MG is being rotationally driven, and the first hydraulic pressure Pk01 is adjusted by the linear solenoid valve SLK so that the engine 12 is cranked by slip engagement of the K0 clutch 20 based on the first hydraulic pressure Pk01. After the engine 12 is started by a predetermined start process and reaches a full combustion state, the ON-OFF switching of the ON-OFF solenoid valve SCK is performed. Second oil pressure in output state In order to supply Pk02 to place the K0 clutch 20 in a fully engaged state, the linear solenoid valve SLK that controls the K0 clutch 20 to a slip engaged state during cranking is Second oil pressure in output state It is sufficient that the first hydraulic pressure Pk01 be adjusted within a predetermined pressure adjustment control region Pslk that is lower than Pk02, and the control range of the first hydraulic pressure Pk01 by the linear solenoid valve SLK may be narrow. As a result, the engagement torque Tk0 of the K0 clutch 20, which is slip-engaged during cranking, is controlled with high precision and high responsiveness by the linear solenoid valve SLK, allowing the engine 12 to be cranked and started appropriately. Furthermore, after the engine 12 has reached a full combustion state, Second oil pressure in output state Since the K0 clutch 20 is fully engaged with the large torque capacity of Pk02, the large engine torque Te can be reliably transmitted via the K0 clutch 20 when the vehicle is running.

[0063] In the engine start control shown in Figs. 4 and 5, during normal driving after the vehicle starts, the ON-OFF solenoid valve SCK is switched ON and OFF. High pressure second oil pressure in output state In order to fully engage the K0 clutch 20 by supplying Pk02, the linear solenoid valve SLK that controls the slip engagement state of the K0 clutch 20 when the vehicle starts is Second oil pressure in output stateIt is sufficient that the first hydraulic pressure Pk01 be regulated within a predetermined pressure regulation control region Pslk that is lower than Pk02, and the control range of the first hydraulic pressure Pk01 by the linear solenoid valve SLK may be narrow. As a result, the engagement torque Tk0 of the K0 clutch 20, which is engaged in slip engagement when the vehicle starts, is controlled with high precision and high responsiveness by the linear solenoid valve SLK, allowing the vehicle 10 to start smoothly even at extremely low temperatures where the viscosity of the hydraulic oil is high.

[0064] Next, another embodiment of the present invention will be described. In the following embodiment, parts that are substantially the same as those in the previous embodiment will be given the same reference numerals and detailed description will be omitted.

[0065] A vehicle 118 in Fig. 7 is an engine-driven vehicle in which the rotary machine MG is omitted from the vehicle 10, and the engine connecting shaft 34 is connected to the pump impeller 22a of the torque converter 22, and the vehicle 118 is equipped with a hydraulic control system 120 in Fig. 8 in association with the LU clutch 40. Except for not being equipped with a rotary machine MG, the vehicle 118 is configured similarly to the vehicle 10 of the above-described embodiment, including having an electronic control device 90 as a control device. In this embodiment, the LU clutch 40 is a hydraulic friction engagement device that is the object of control by the hydraulic control system 120.

[0066] 8 includes an LU hydraulic control circuit 122 involved in hydraulic control of the LU clutch 40 in the hydraulic control circuit 56, and an LU engagement control unit 124 functionally provided in the electronic control device 90 to control the LU hydraulic pressure Plu. The LU hydraulic control circuit 122 includes a line pressure oil passage 126 to which line pressure PL is supplied from the hydraulic pressure supply sources MOP 58 and EOP 60, a linear solenoid valve SLL that can continuously adjust the first hydraulic pressure Plu1 that is the output hydraulic pressure using the line pressure PL as the source pressure, a changeover valve 128 that is mechanically switched between an ON state in which the line pressure PL is output as is as the second hydraulic pressure Plu2, and an OFF state in which the output of the second hydraulic pressure Plu2 is stopped, and an ON-OFF solenoid valve SCL that switches the ON and OFF states of the changeover valve 128. The first oil pressure Plu1 output from the linear solenoid valve SLL is supplied to the LU clutch 40 as the LU oil pressure Plu from the first oil passage 130 via the LU control valve 136, and a damper 132 is provided in the first oil passage 130. Second oil pressure in output state Plu2 is supplied to the LU clutch 40 as the LU hydraulic pressure Plu from the second oil passage 134 via the LU control valve 136, and the second oil passage 134 is connected to a junction 130p between the damper 132 of the first oil passage 130 and the LU control valve 136. Therefore, the higher hydraulic pressure of the first oil pressure Plu1 and the second oil pressure Plu2 is supplied to the LU clutch 40 as the LU hydraulic pressure Plu, and the operating state of the LU clutch 40, i.e., the LU clutch torque Tlu, is controlled according to the LU hydraulic pressure Plu. A check valve or the like is provided upstream of the junction 130p in the first oil passage 130 and the second oil passage 134, as necessary.

[0067] The LU engagement control unit 124 outputs a first command signal Slu1 and a second command signal Slu2 as the LU hydraulic pressure control command signal Slu. The first command signal Slu1 controls the linear solenoid valve SLL to adjust the first hydraulic pressure Plu1 within a predetermined, relatively low-pressure adjustment control region Psll (see FIG. 10). The second command signal Slu2 controls the ON / OFF solenoid valve SCL. In this embodiment, the line pressure PL is output as is as the ON-OFF switching hydraulic pressure Pscl by ON control. When the switching valve 128 is switched to the ON state by the ON-OFF switching hydraulic pressure Pscl, the line pressure PL supplied from the line pressure oil passage 126 to the switching valve 128 is output as is to the second oil passage 134 as the second hydraulic pressure Plu2. Second oil pressure in output state As is clear from Figure 10, Plu2 is a hydraulic pressure that is even higher than the maximum pressure of the pressure adjustment control region Psll of the first hydraulic pressure Plu1, and is a hydraulic pressure that can reliably transmit the large driving force when the vehicle is running without causing slippage in the LU clutch 40, and in this embodiment is the line pressure PL.

[0068] The LU engagement control unit 124 controls the engagement torque Tlu of the LU clutch 40, i.e., the LU hydraulic pressure Plu, when the vehicle starts, and fully engages the LU clutch 40 with a large torque capacity when the vehicle is running. FIG. 9 is a flowchart showing the operation when the LU engagement control unit 124 engages the LU clutch 40 to start the vehicle 10 following engine start by the starter 12s, and FIG. 10 is an example of a time chart showing the operating states of each part when engagement control of the LU clutch 40 is performed according to the flowchart of FIG. 9. The flowchart of FIG. 9 is substantially the same as the flowchart of FIG. 4, which relates to engagement control of the K0 clutch 20 when the engine starts in the above embodiment, and the time chart of FIG. 10 is substantially the same as FIG. 5. That is, the only difference is that when the vehicle starts, instead of increasing the MG rotation speed Nmg by slip engagement control of the K0 clutch 20, the AT input rotation speed Ni is increased by slip engagement control of the LU clutch 40.

[0069] In the start control shown in Figs. 9 and 10, during normal driving after the vehicle starts, the ON-OFF solenoid valve SCL is switched ON and OFF. High pressure second oil pressure in output state In order to supply Plu2 to fully engage the LU clutch 40, the linear solenoid valve SLL that controls the slip engagement state of the LU clutch 40 when the vehicle starts is Second oil pressure in output state It is sufficient that the first hydraulic pressure Plu1 be regulated within a predetermined pressure regulation control region Psll that is lower than Plu2, and the control range of the first hydraulic pressure Plu1 by the linear solenoid valve SLL may be narrow. As a result, the engagement torque Tlu of the LU clutch 40, which is brought into slip engagement when the vehicle starts, is controlled with high precision and high responsiveness by the linear solenoid valve SLL, allowing the vehicle 118 to start smoothly even at extremely low temperatures when the viscosity of the hydraulic oil is high.

[0070] In this way, in this embodiment as well, when the clutch is fully engaged, Second oil pressure in output state While ensuring a large torque capacity with Plu2, in slip engagement regions (SL3 to SL10 in FIG. 9) where control of engagement torque Tlu is necessary, it is possible to control that engagement torque Tlu with high precision and high responsiveness by adjusting the pressure of the first hydraulic pressure Plu1 with the linear solenoid valve SLL, and while ensuring a large torque capacity for transmitting driving force when the vehicle is running, it is possible to appropriately control the slip engagement torque Tlu of the LU clutch 40 when the vehicle starts using the engine 12. Also, because it is only necessary to control the linear solenoid valve SLL and the ON-OFF solenoid valve SCL in combination, it is possible to obtain the same effects as the above-described embodiment, such as the hydraulic control system 120 being able to be configured inexpensively as a whole.

[0071] FIG. 11 is a diagram illustrating yet another embodiment of the present invention. This vehicle 148 is an engine-driven vehicle that, compared to the vehicle 118 of FIG. 7, is provided with a CO clutch 150 as a starting clutch instead of the torque converter 22. The vehicle 148 is also provided with a hydraulic control system 160 shown in FIG. 12 in association with the CO clutch 150. The vehicle 148 is configured similarly to the vehicle 10 of the previous embodiment, including the electronic control device 90 as a control device, except that the CO clutch 150 is provided instead of the rotary machine MG and torque converter 22. A power transmission 152 of this vehicle 148 is primarily composed of the automatic transmission 24 and the CO clutch 150. Although the MOP 58 is provided on the transmission input shaft 38 in FIG. 11, it may also be provided on another power transmission location, such as the engine connecting shaft 34. In this embodiment, the CO clutch 150 is a hydraulic friction engagement device that is controlled by the hydraulic control system 160.

[0072] 12 has a C0 hydraulic control circuit 162 involved in the hydraulic control of the C0 clutch 150 in the hydraulic control circuit 56, and a C0 engagement control unit 164 functionally provided in the electronic control device 90 to control the C0 hydraulic pressure Pc0 supplied to the hydraulic actuator 150a of the C0 clutch 150. The C0 hydraulic control circuit 162 has a line pressure oil passage 166 to which the line pressure PL is supplied from the hydraulic supply sources MOP 58 and EOP 60, a linear solenoid valve SLC that can continuously adjust the first hydraulic pressure Pc01 that is the output hydraulic pressure using the line pressure PL as the source pressure, and a linear solenoid valve SLC that can continuously adjust the first hydraulic pressure Pc01 that is the output hydraulic pressure using the line pressure PL as the source pressure. Second oil pressure in output state The hydraulic actuator 150a is provided with a switching valve 168 that is mechanically switched between an ON state in which the first hydraulic pressure Pc01 is output as the C0 hydraulic pressure Pc02 and an OFF state in which the output of the second hydraulic pressure Pc02 is stopped, and an ON-OFF solenoid valve SCC that switches the ON and OFF states of the switching valve 168. The first hydraulic pressure Pc01 output from the linear solenoid valve SLC is supplied to the hydraulic actuator 150a as the C0 hydraulic pressure Pc0 via a first oil passage 170, and a damper 172 is provided in the first oil passage 170. Second oil pressure in output stateThe C0 oil pressure Pc02 is supplied to the hydraulic actuator 150a as the C0 oil pressure Pc0 via a second oil passage 174, and the second oil passage 174 is connected to a junction 170p between the damper 172 of the first oil passage 170 and the hydraulic actuator 150a. Therefore, the higher oil pressure of the first oil pressure Pc01 and the second oil pressure Pc02 is supplied to the hydraulic actuator 150a as the C0 oil pressure Pc0, and the engagement torque (C0 clutch torque) Tc0 of the C0 clutch 150 is controlled according to the C0 oil pressure Pc0. A check valve or the like is provided before the junction 170p in the first oil passage 170 and the second oil passage 174, as necessary.

[0073] The C0 engagement control unit 164 outputs a first command signal Sc01 and a second command signal Sc02 as the C0 hydraulic control command signal Sc0. The first command signal Sc01 controls the linear solenoid valve SLC and adjusts the first hydraulic pressure Pc01 within a predetermined relatively low pressure adjustment control region Pslc (see FIG. 14). The second command signal Sc02 controls the ON / OFF of the ON-OFF solenoid valve SCC. In this embodiment, the line pressure PL is output as is as the ON-OFF switching hydraulic pressure Pscc by ON control. When the switching valve 168 is switched to the ON state by the ON-OFF switching hydraulic pressure Pscc, the line pressure PL supplied from the line pressure oil passage 166 to the switching valve 168 is directly output as is. Second oil pressure in output state The oil pressure Pc02 is output to the second oil passage 174. Second oil pressure in output state As is clear from FIG. 14, Pc02 is a hydraulic pressure that is even higher than the maximum pressure in the pressure regulation control region Pslc of the first hydraulic pressure Pc01, and is a hydraulic pressure that can reliably transmit the large driving force when the vehicle is running without causing slippage in the C0 clutch 150, and in this embodiment is the line pressure PL.

[0074] The C0 engagement control unit 164 controls the engagement torque Tc0 of the C0 clutch 150, i.e., the C0 hydraulic pressure Pc0, when the vehicle is starting, and fully engages the C0 clutch 150 with a large torque capacity when the vehicle is running. FIG. 13 is a flowchart showing the operation when the C0 engagement control unit 164 engages the C0 clutch 150 to start the vehicle 148 following engine start by the starter 12s, and FIG. 14 is an example of a time chart showing the operating states of each part when engagement control of the C0 clutch 150 is performed according to the flowchart of FIG. 13. The flowchart of FIG. 13 is substantially the same as the flowchart of FIG. 4, which relates to engagement control of the K0 clutch 20 when the engine is starting in the above embodiment, and the time chart of FIG. 14 is substantially the same as FIG. 5. That is, the only difference is that when the vehicle is starting, instead of increasing the MG rotation speed Nmg by slip engagement control of the K0 clutch 20, the AT input rotation speed Ni is increased by slip engagement control of the C0 clutch 150.

[0075] In the start control shown in Figs. 13 and 14, during normal driving after the vehicle starts, the ON / OFF solenoid valve SCC is switched ON / OFF. High pressure second oil pressure in output state In order to supply Pc02 to fully engage the C0 clutch 150 when the vehicle starts, the linear solenoid valve SLC that controls the slip engagement state of the C0 clutch 150 is Second oil pressure in output state It is sufficient that the first hydraulic pressure Pc01 be regulated within a predetermined pressure regulation control region Pslc that is lower than Pc02, and the control range of the first hydraulic pressure Pc01 by the linear solenoid valve SLC may be narrow. As a result, the engagement torque Tc0 of the C0 clutch 150, which is brought into slip engagement when the vehicle starts, is controlled with high precision and high responsiveness by the linear solenoid valve SLC, allowing the vehicle 148 to start smoothly even at extremely low temperatures when the viscosity of the hydraulic oil is high.

[0076] In this way, in this embodiment as well, when the clutch is fully engaged, Second oil pressure in output stateWhile ensuring a large torque capacity with Pc02, in the slip engagement region (SC3 to SC10 in FIG. 13) where control of the engagement torque Tc0 is required, the engagement torque Tc0 can be controlled with high precision and high responsiveness by adjusting the first hydraulic pressure Pc01 with the linear solenoid valve SLC, and while ensuring a large torque capacity for transmitting driving force when the vehicle is running, the slip engagement torque Tc0 of the C0 clutch 150 can be appropriately controlled when the vehicle is started by the engine 12. Also, because it is only necessary to control the linear solenoid valve SLC and the ON-OFF solenoid valve SCC in combination, the hydraulic control system 160 as a whole can be configured inexpensively, and other effects similar to those of the above-described embodiment can be obtained.

[0077] Although the embodiments of the present invention have been described in detail above with reference to the drawings, these are merely embodiments, 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]

[0078] 10: Hybrid electric vehicle (vehicle) 12: Engine (driving force source) 16, 152: Power transmission device 20: K0 clutch (connection / disconnection device, friction engagement device) 22: Torque converter (fluid transmission device) 40: LU clutch (lock-up clutch, friction engagement device) 90: Electronic control device 100, 120, 160: Hydraulic control system 102: K0 hydraulic control circuit (hydraulic control circuit) 104: K0 engagement control unit (engagement control unit) 108, 128, 168: Switching valve 118, 148: Engine-driven vehicle (vehicle) 122: LU hydraulic control circuit (hydraulic control circuit) 124: LU engagement control unit (engagement control unit) 150: C0 clutch (starting clutch, friction engagement device) 162: C0 hydraulic control circuit (hydraulic control circuit) 164: C0 engagement control unit (engagement control unit) MG: Rotating machine (driving force source) SLK, SLL, SLC: Linear solenoid valve SCK, SCL, SCC: ON-OFF solenoid valve Pk01, Plu1, Pc01: First hydraulic pressure Pk02, Plu2, Pc02: Second hydraulic pressure Pslk, Psll, Pslc: Pressure adjustment control area

Claims

1. A hydraulic control system having a linear solenoid valve that can continuously change hydraulic pressure, an ON-OFF solenoid valve that outputs and stops outputting hydraulic pressure, and a hydraulic friction engagement device that is engaged with an engagement torque according to the supplied hydraulic pressure, a hydraulic control circuit in which a first oil passage is provided for supplying the first oil pressure to the friction engagement device and a second oil passage is provided for supplying the second oil pressure to the friction engagement device so that a first oil pressure regulated by the linear solenoid valve and a second oil pressure that is switched between an output state and an output stop state in accordance with ON-OFF switching of the ON-OFF solenoid valve can be supplied to the same friction engagement device, the linear solenoid valve is configured to regulate the first oil pressure within a predetermined pressure regulation control region that is lower than the second oil pressure in the output state, the higher-pressure oil pressure of the first oil pressure and the second oil pressure is supplied to the friction engagement device, and a check valve is provided in the first oil passage; an engagement control unit that supplies the first hydraulic pressure to the friction engagement device and adjusts the first hydraulic pressure within the pressure adjustment control region by the linear solenoid valve, and, while the friction engagement device is in a predetermined engaged state based on the first hydraulic pressure, supplies the second hydraulic pressure in the output state to the friction engagement device by switching the ON-OFF solenoid valve ON-OFF, thereby bringing the friction engagement device into a fully engaged state with a high engagement torque based on the second hydraulic pressure in the output state; A hydraulic control system comprising:

2. The engagement control unit adjusts the first hydraulic pressure supplied to the friction engagement device within the pressure adjustment control region by the linear solenoid valve, thereby controlling the friction engagement device to be in an engagement state including a slip engagement state, and also adjusts the ON-OFF solenoid valve to switch the ON-OFF solenoid valve ON and OFF to supply the second hydraulic pressure in the output state to the friction engagement device, thereby bringing the friction engagement device into the fully engaged state, while keeping the friction engagement device engaged without slipping based on the first hydraulic pressure.

2. The hydraulic control system according to claim 1.

3. The second hydraulic pressure is switched between the output state and the output stop state by a switching valve that switches the second hydraulic pressure between the output state and the output stop state according to the hydraulic pressure output from the ON-OFF solenoid valve.

3. The hydraulic control system according to claim 1 or 2.

4. When the second oil pressure in the output state is supplied to the friction engagement device and the friction engagement device is in the fully engaged state, the first oil pressure is set to 0.

4. The hydraulic control system according to claim 1, wherein the hydraulic control system comprises: a hydraulic control unit;

5. The friction engagement device is a disconnecting device that is provided between an engine and a rotary machine mounted on a vehicle and that connects and disconnects power transmission.

5. The hydraulic control system according to claim 1, wherein the hydraulic control system comprises: a hydraulic control unit;

6. The engagement control unit adjusts the first hydraulic pressure within the pressure regulation control range by the linear solenoid valve so that the first hydraulic pressure is supplied to the disconnecting device when the rotating machine is rotationally driven at a predetermined rotational speed, and the engine is cranked by slip engagement of the disconnecting device based on the first hydraulic pressure. After the engine reaches a complete explosion state in which it rotates by itself through start-up processing such as fuel injection and ignition, the engagement control unit adjusts the first hydraulic pressure within the pressure regulation control range by switching the ON-OFF solenoid valve ON and OFF, thereby supplying the second hydraulic pressure in the output state to the disconnecting device, thereby bringing the disconnecting device into the fully engaged state.

6. The hydraulic control system according to claim 5.

7. The friction engagement device is a lock-up clutch of a fluid-type power transmission device mounted on a vehicle.

5. The hydraulic control system according to claim 1, wherein the hydraulic control system comprises: a hydraulic control unit;

8. The friction engagement device is a starting clutch that is provided between a driving power source mounted on a vehicle and a power transmission device to connect and disconnect power transmission.

5. The hydraulic control system according to claim 1, wherein the hydraulic control system comprises: a hydraulic control unit;

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