Hybrid vehicle control device

Abstract

To provide a control device for a hybrid vehicle, capable of suppressing the occurrence of a shock caused by starting an engine or eliminating backlash in a power transmission path.SOLUTION: There is provided an electronic control device 90 for a hybrid vehicle 10 including: an engine 12 and an electric motor MG, as a driving force source PG; a connecting / disconnecting clutch K0 for connecting and disconnecting power transmission between the engine 12 and the electric motor MG; and a torque converter 24 which includes a lock-up clutch 40 and is provided in a power transmission path PT between the driving force source PG and a driving wheel 14. In traveling with driving torque output from only the electric motor MG, when re-acceleration is requested, and target system shaft torque Tsystgt is equal to or greater than second determination torque Tsystgt_jdg2, the electronic control device 90 allows an LU instruction pressure Plu for controlling the connection and disconnection of the lock-up clutch 40 to be held at a half-engagement pressure PA for putting the lock-up clutch 40 in a half-engaged state, until differential rotation ΔNlu of the lock-up clutch 40 becomes equal to or greater than prescribed difference ΔNlu_jdg.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a control device for a hybrid vehicle equipped with an engine and an electric motor as a driving force source, a disconnecting clutch that connects and disconnects the power transmission between the engine and the electric motor, and a torque converter that has a lock-up clutch and is provided in the power transmission path between the driving force source and the drive wheels. [Background technology]

[0002] There are known control devices for hybrid vehicles that include an engine and an electric motor as driving force sources, a connecting / disconnecting clutch that connects and disconnects the power transmission between the engine and the electric motor, and a torque converter that has a lock-up clutch and is provided in the power transmission path between the driving force source and the drive wheels. For example, the device described in Patent Document 1 is one such device. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-73705 Summary of the Invention [Problem to be solved by the invention]

[0004] In the control device for a hybrid vehicle described in Patent Document 1, when the vehicle is running with drive torque output only from the electric motor among the drive power sources, Acceleration required In this case, shocks may occur when the engine is started or when looseness in the power transmission path is eliminated. If the lock-up clutch is in a fully engaged state, these shocks are transmitted from the drive power source to the drive wheels via the power transmission path, which is in a mechanically direct state, and this may cause vehicle vibration.

[0005] The present invention has been made against the background of the above circumstances, and its purpose is to provide a control device for a hybrid vehicle that can suppress the occurrence of shocks caused by starting the engine or eliminating backlash in the power transmission path. [Means for solving the problem]

[0006] The gist of the present invention is a control device for a hybrid vehicle including an engine and an electric motor as a driving force source, a connecting / disconnecting clutch that connects and disconnects power transmission between the engine and the electric motor, and a torque converter that has a lock-up clutch and is provided in a power transmission path between the driving force source and drive wheels, (a) In a run in which a driving torque is output only from the electric motor of the driving power source, Acceleration is required When the target value of the input torque of the torque converter is equal to or greater than a predetermined torque, the command pressure for controlling the engagement and disengagement of the lock-up clutch is set at a predetermined pressure at which the lock-up clutch is in a half-engagement state until the differential rotation of the lock-up clutch becomes equal to or greater than the predetermined difference. When the differential rotation speed becomes equal to or greater than the predetermined difference, a tip-in LU control is executed to gradually transition the command pressure toward an engagement pressure at which the lock-up clutch is fully engaged, (b) the predetermined torque is a determination value for determining whether or not removal of backlash occurs in the power transmission path if the tip-in LU control is not executed, and (c) the predetermined difference is a determination value for determining whether or not a shock occurring due to removal of backlash in the power transmission path is suppressed within an allowable range even if the command pressure is transitioned from the predetermined pressure toward the engagement pressure in the tip-in LU control. The reason is that [Effects of the Invention]

[0007] According to the control device for a hybrid vehicle of the present invention, (a) In a run in which a driving torque is output only from the electric motor of the driving power source, Acceleration is required When the target value of the input torque of the torque converter is equal to or greater than a predetermined torque, the command pressure for controlling the engagement and disengagement of the lock-up clutch is set to a predetermined pressure at which the lock-up clutch is in a half-engagement state until the differential rotation of the lock-up clutch becomes equal to or greater than the predetermined difference. The system is kept on standby, and when the differential rotation speed becomes equal to or greater than the predetermined difference, tip-in LU control is executed in which the command pressure is gradually transitioned toward an engagement pressure at which the lock-up clutch is fully engaged, (b) the predetermined torque is a judgment value for determining whether backlash will be eliminated in the power transmission path if the tip-in LU control is not executed, and (c) the predetermined difference is a judgment value for determining whether the shock caused by backlash elimination in the power transmission path will be suppressed within an acceptable range even if the command pressure is transitioned from the predetermined pressure toward the engagement pressure in the tip-in LU control. In this way, when driving with driving torque output only from the electric motor among the driving power sources, Acceleration is requiredFurthermore, when the target value of the torque converter's input torque is equal to or greater than a predetermined torque, the lock-up clutch is placed in a partially engaged state (slip state). In other words, the power transmission in the torque converter is not mechanically directly coupled. Therefore, the shock that occurs when the engine is started or when backlash in the power transmission path is eliminated because the target value of the torque converter's input torque is equal to or greater than the predetermined torque is absorbed by the lock-up clutch, thereby reliably suppressing the occurrence of shock. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic configuration diagram of a hybrid vehicle equipped with an electronic control device according to an embodiment of the present invention, and is also a functional block diagram showing the main parts of control functions for various controls in the hybrid vehicle. [Figure 2] 2 is an example of a flowchart illustrating a control operation of the electronic control device shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

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

[0010] FIG. 1 is a schematic diagram of a hybrid vehicle 10 (hereinafter simply referred to as "vehicle 10") according to an embodiment of the present invention, and is also a functional block diagram showing the main parts of control functions for various controls in vehicle 10.

[0011] The vehicle 10 is a hybrid vehicle equipped with an engine 12 and an electric motor MG, which are driving power sources PG for traveling. A power transmission path PT is between the driving power source PG (engine 12, electric motor MG) and drive wheels 14. The vehicle 10 includes, in order from the engine 12 side, an engine connecting shaft 20, a disconnecting clutch K0, an electric motor connecting shaft 22, a torque converter 24, an AT input shaft 26, which is an input rotating member of the automatic transmission 28, and the automatic transmission 28, in the power transmission path PT within a case 18, which is a non-rotating member attached to the vehicle body. The vehicle 10 also includes, in the power transmission path PT, a differential gear 32 connected to an AT output shaft 30, which is an output rotating member of the automatic transmission 28, a pair of axles 34 connected to the differential gear 32, and the like. The vehicle 10 also includes an inverter 52, a hydraulic control circuit 54, a battery 60, and an electronic control device 90.

[0012] The engine 12 is a well-known internal combustion engine. An electronic control unit 90 (described later) controls an engine control unit 50 including a throttle actuator, a fuel injection device, an ignition device, and the like provided in the vehicle 10, thereby controlling the engine torque Te [Nm], which is the output torque of the engine 12. When the engine 12 is in an operating state, the engine 12 outputs the engine torque Te, and when the engine 12 is in a stopped state, the engine 12 does not output the engine torque Te. In this specification, unless otherwise specified, the terms torque, driving force, motive power, and force (power) are synonymous.

[0013] The engine connecting shaft 20 is a member that connects the engine 12 and the connect / disconnect clutch K0, and is, for example, a crankshaft.

[0014] The electric motor MG is a so-called motor generator that has a function as an electric motor that generates mechanical power from electrical energy (electric motor function) and a function as a generator that generates electrical energy from mechanical power (generator function). The electric motor MG is connected to a battery 60 provided in the vehicle 10 via an inverter 52, which will be described later. The battery 60 is an electricity storage device that supplies and receives electric power to the electric motor MG. The inverter 52 of the electric motor MG is controlled by an electronic control device 90, which will be described later, to control the electric motor torque Tmg [Nm], which is the output torque of the electric motor MG.

[0015] A disconnecting clutch K0 is provided between an engine connecting shaft 20 connected to the engine 12 and an electric motor connecting shaft 22 connected to the rotor of the electric motor MG. The disconnecting clutch K0 is a friction engagement device that connects and disconnects power transmission between the engine 12 and the electric motor MG, and is, for example, a wet-type multi-plate hydraulic friction engagement device. The disconnecting clutch K0 switches between connection and disconnection states, such as a fully engaged state, a half-engaged state, and a released state, by adjusting the hydraulic pressure supplied from a hydraulic control circuit 54 (described later) to a hydraulic actuator that controls the connection and disconnection state of the disconnecting clutch K0. When the disconnecting clutch K0 is in the fully engaged state, the disconnecting clutch K0 enables power transmission between the engine 12 and the electric motor MG. When the disconnecting clutch K0 is in the released state, the disconnecting clutch K0 disconnects power transmission between the engine 12 and the electric motor MG. When the make-and-break clutch K0 is brought into a half-engagement state, the make-and-break clutch K0 enables power transmission between the engine 12 and the electric motor MG in accordance with a transmission torque capacity (the engagement force of the make-and-break clutch K0) based on the half-engagement state. The make-and-break clutch K0 corresponds to the "make-and-break clutch" in this invention.

[0016] The electric motor MG is driven to rotate by the electric power stored in the battery 60 and outputs the driving force for running the vehicle 10. The electric motor MG also generates electric power using the driving force input from the engine 12 via the connect / disconnect clutch K0, and also generates electric power by converting the driven force input from the drive wheels 14 side into electric power through regeneration. The generated electric power is charged into the battery 60 via the inverter 52.

[0017] The inverter 52 is a power supply circuit that is provided between the electric motor MG and the battery 60 and that converts direct current to alternating current and vice versa under the control of the electronic control device 90. For example, the inverter 52 converts direct current supplied from the battery 60 into alternating current and outputs the converted alternating current to the electric motor MG to drive it, or converts alternating current generated by the electric motor MG into direct current and outputs the converted alternating current to the battery 60.

[0018] The battery 60 is a rechargeable secondary battery such as a lithium ion battery or a nickel-metal hydride battery, etc. The battery 60 is mainly used to supply power for driving the electric motor MG and to store the power generated by the electric motor MG through regeneration.

[0019] The torque converter 24 is a well-known torque converter. The torque converter 24 includes a pump wheel connected to the electric motor connecting shaft 22, a turbine wheel connected to the automatic transmission input shaft 26, and a lock-up clutch 40 that directly connects the pump wheel and the turbine wheel. The torque converter 24 is disposed in a power transmission path PT between the driving power source PG (engine 12, electric motor MG) and the drive wheels 14, and is a fluid-type power transmission device that can transmit the driving force output from the driving power source PG from the electric motor connecting shaft 22 to the automatic transmission input shaft 26 via a fluid. The lock-up clutch 40 is switched between engagement and disengagement states, such as a fully engaged state, a partially engaged state, and a disengaged state, by adjusting the hydraulic pressure supplied from a hydraulic control circuit 54 (described later) to a hydraulic actuator that controls the engagement and disengagement states of the lock-up clutch 40.

[0020] When the lockup clutch 40 is in a fully engaged state, the lockup clutch 40 mechanically couples the pump wheel and the turbine wheel of the torque converter 24 directly, and the driving force input from the driving force source PG is output to the automatic transmission 28 via the lockup clutch 40. That is, the power transmission path PT is in a state in which the driving force source PG is mechanically coupled directly to the drive wheels 14. When the lockup clutch 40 is in a disengaged state, the torque converter 24 cuts off the power transmission between the pump wheel and the turbine wheel via the lockup clutch 40, and the driving force input from the driving force source PG is output to the automatic transmission 28 via a fluid. That is, the power transmission path PT is in a state in which the driving force source PG is fluidly connected to the drive wheels 14. When the lockup clutch 40 is in a partially engaged state, the lockup clutch 40 allows the torque converter 24 to transmit power between the pump wheel and the turbine wheel at a transmission torque capacity based on the partially engaged state. In this case, torque converter 24 is in a state in which the pump wheel and turbine wheel are permitted to rotate relative to each other, and driving force input from driving power source PG is output to automatic transmission 28 via lock-up clutch 40, which is in a partially engaged state. In other words, power transmission path PT is not in a state in which driving power source PG and drive wheels 14 are mechanically directly connected. Vehicle 10 is equipped with MOP 42, which is a mechanical oil pump. MOP 42 is connected to the pump wheel and is rotationally driven by driving power source PG (engine 12, electric motor MG) to discharge hydraulic oil OIL used in various parts within case 18.

[0021] The automatic transmission 28 is a well-known automatic transmission that changes the speed of the driving force input from the driving force source PG (engine 12, electric motor MG) to the AT input shaft 26 and outputs the changed driving force to the AT output shaft 30. For example, the automatic transmission 28 may be a stepped transmission of a planetary gear type or a constantly meshing parallel shaft type, or a continuously variable transmission of a belt type or a power roller type. The automatic transmission 28 is controlled by a hydraulic control circuit 54, which is controlled by an electronic control unit 90, so as to form a desired gear ratio γat (= AT input rotation speed Ni [rpm] / AT output rotation speed No [rpm]) from among different gear ratios. The gear ratio γat is also referred to as a gear ratio. The AT input rotation speed Ni is the rotation speed of the AT input shaft 26, which is the input rotating member of the automatic transmission 28, and the AT output rotation speed No is the rotation speed of the AT output shaft 30, which is the output rotating member of the automatic transmission 28. In this embodiment, the automatic transmission 28 is a well-known planetary gear type automatic transmission that includes a plurality of planetary gear devices and a plurality of shift engagement devices CB. Each of the shift engagement devices CB is switched between engagement / disengagement states such as a fully engaged state, a partially engaged state, and a disengaged state by adjusting the hydraulic pressure supplied from a hydraulic control circuit 54 to a hydraulic actuator that controls the engagement / disengagement state of the shift engagement devices CB. The automatic transmission 28 establishes one of a plurality of gear stages (also referred to as gear stages) with different speed ratios γat by engaging one of the engagement devices CB.

[0022] The differential gear 32 is a well-known differential gear that receives the driving force transmitted from the AT output shaft 30 of the automatic transmission 28 and transmits equal driving torque to a pair of axles 34 while allowing for an appropriate difference in rotational speed.

[0023] The hydraulic control circuit 54 uses the hydraulic pressure of the hydraulic oil OIL discharged from the MOP 42 as the source pressure and supplies the necessary hydraulic oil O to each part within the case 18. For example, the hydraulic control circuit 54 generates hydraulic pressure for controlling the engagement and disengagement of the engagement / disengagement clutch K0, hydraulic pressure for controlling the shifting of the automatic transmission 28, and hydraulic pressure for controlling the engagement and disengagement of the lock-up clutch 40 of the torque converter 24, and supplies these to each hydraulic actuator within the case 18.

[0024] When the on-off clutch K0 is engaged, the driving force for running output from the engine 12 is transmitted from the engine connecting shaft 20 to the drive wheels 14 via the on-off clutch K0, the electric motor connecting shaft 22, the torque converter 24, the automatic transmission 28, the differential gear 32, the axles 34, etc. in this order. Regardless of the on-off state of the on-off clutch K0, the driving force for running output from the electric motor MG is transmitted from the electric motor connecting shaft 22 to the drive wheels 14 via the torque converter 24, the automatic transmission 28, the differential gear 32, the axles 34, etc. in this order. In this way, the driving torque Tr [Nm] for running is transmitted from at least one of the engine 12 and the electric motor MG to the drive wheels 14.

[0025] The vehicle 10 can select either a BEV driving mode or an engine driving mode, i.e., an HEV driving mode. The BEV driving mode is a driving mode in which the vehicle runs as a BEV (Battery Electric Vehicle) by outputting a driving torque, i.e., an electric motor torque Tmg, from only the electric motor MG while the engine 12 of the driving power source PG is stopped. In the BEV driving mode, the on-off clutch K0 is released to perform BEV driving. The HEV driving mode is a driving mode in which the vehicle runs as an HEV (Hybrid Electric Vehicle) by outputting a driving torque, i.e., an engine torque Te, from at least the engine 12 of the driving power source PG. In the HEV driving mode, the on-off clutch K0 is fully engaged to perform HEV driving.

[0026] The driving mode of the vehicle 10 can be switched between the BEV driving mode and the HEV driving mode, for example, using a driving force source switching map. The driving force source switching map is a relationship in which the driving mode is predetermined using two-dimensional coordinates with, for example, vehicle speed V [km / h] and target system axle torque Tsystgt [Nm] as variables. The target system axle torque Tsystgt is a target value (requested value) of the system axle torque Tsys [Nm] based on a driver's request. The system axle torque Tsys is the driving torque output from the driving force source PG to the driving wheels 14, and more specifically, the driving torque at the electric motor connecting shaft 22 input to the torque converter 24. A method for calculating the target system axle torque Tsystgt will be described later. The target system axle torque Tsystgt corresponds to the "target value of the input torque of the torque converter" in this invention.

[0027] Generally, the BEV driving mode is selected in a low vehicle speed region where the vehicle speed V is relatively low and the target system shaft torque Tsystgt is relatively low (= a region where the accelerator pedal opening θacc [%] is relatively low), where engine efficiency decreases. On the other hand, the HEV driving mode is selected in a high vehicle speed region where the vehicle speed V is relatively high or in a high load region where the target system shaft torque Tsystgt is relatively high (= a region where the accelerator pedal opening θacc is relatively high). The BEV driving mode is applied when the state of charge value SOC [%] of the battery 60 (the ratio of the actual amount of charge stored to a predetermined full charge capacity) is equal to or greater than a predetermined engine start threshold. In other words, when the state of charge value SOC of the battery 60 is less than the predetermined engine start threshold, there is no region in the driving force source switching map where the BEV driving mode is selected, and the HEV driving mode is selected everywhere. In the HEV driving mode, the motor rotation speed Nmg [rpm], which is the rotation speed of the electric motor MG, is equal to the engine rotation speed Ne [rpm], which is the rotation speed of the engine 12. The predetermined engine start threshold is a threshold set in advance for determining that the state of charge value SOC is at a level at which the engine 12 needs to be forcibly started and the battery 60 needs to be charged.

[0028] 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 performs various controls of the vehicle 10 by performing signal processing in accordance with programs stored in advance in the ROM while utilizing the temporary storage function of the RAM. The electronic control unit 90 corresponds to the "control unit" in this invention.

[0029] The electronic control device 90 receives various signals based on detection values ​​from various sensors provided on the vehicle 10 (e.g., engine rotation speed sensor 70, turbine rotation speed sensor 72, output rotation speed sensor 74, electric motor rotation speed sensor 76, accelerator opening sensor 78, throttle valve opening sensor 80, battery sensor 82, etc.) (e.g., engine rotation speed Ne [rpm] which is the rotation speed of the engine 12, turbine rotation speed Nt [rpm] which is the same value as the AT input rotation speed Ni [rpm], AT output rotation speed No [rpm] which corresponds to the vehicle speed V, electric motor rotation speed Nmg [rpm] which is the rotation speed of the electric motor MG, accelerator opening θacc [%] which is the amount of accelerator operation by the driver which indicates the magnitude of the driver's acceleration operation, throttle valve opening θth [%] which is the opening of the electronic throttle valve, battery temperature THbat [°C] of the battery 60, battery charge / discharge current Ibat [A], battery voltage Vbat [V], etc.).

[0030] The electronic control device 90 outputs various command signals (e.g., an engine control signal Se for controlling the engine 12, an electric motor control signal Smg for controlling the electric motor MG, a shift control signal Sat for controlling the shift engagement device CB, a K0 control signal Sk0 for controlling the connect / disconnect clutch K0, an LU control signal Slu for controlling the lock-up clutch 40, etc.) to each device (e.g., an engine control device 50, an inverter 52, a hydraulic control circuit 54, etc.) provided in the vehicle 10.

[0031] The electronic control device 90 functionally comprises a hybrid control unit 92 , a clutch / connection control unit 94 , a gear shift control unit 96 , and a lock-up clutch control unit 98 .

[0032] The hybrid control unit 92 calculates the target system shaft torque Tsystgt as the drive amount required by the driver for the vehicle 10, for example, by applying the actual accelerator opening θacc and vehicle speed V to a required drive amount map. The required drive amount map is a stored map in which the relationship between the accelerator opening θacc, vehicle speed V, and target system shaft torque Tsystgt is determined in advance through experimentation or design. In other words, the target system shaft torque Tsystgt is the required drive power Prdem [W] at the current vehicle speed V. In calculating the target system shaft torque Tsystgt, the AT output rotation speed No or the like may be used instead of the vehicle speed V.

[0033] The hybrid control unit 92 outputs an engine control signal Se for controlling the engine 12 and an electric motor control signal Smg for controlling the electric motor MG so as to realize the required driving power Prdem, taking into consideration factors such as transmission loss, the auxiliary load, the gear ratio γat of the automatic transmission 28, the chargeable power Win [W] and dischargeable power Wout [W] of the battery 60, etc. The engine control signal Se is, for example, an indication value (=command value) of the engine power Pe [W], which is the power of the engine 12 that outputs the engine torque Te at the engine rotation speed Ne at that time. The electric motor control signal Smg is, for example, an indication value of the power consumption Wm [W] of the electric motor MG that outputs the electric motor torque Tmg at the electric motor rotation speed Nmg at that time.

[0034] The chargeable power Win of the battery 60 is the maximum power that can be input, which defines the limit on the input power of the battery 60, and indicates the input limit of the battery 60. The dischargeable power Wout of the battery 60 is the maximum power that can be output, which defines the limit on the output power of the battery 60, and indicates the output limit of the battery 60. The chargeable power Win and dischargeable power Wout of the battery 60 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 60. The state of charge value SOC is a value that indicates the state of charge of the battery 60, and is calculated by the electronic control unit 90 based on, for example, the battery charge / discharge current Ibat and the battery voltage Vbat.

[0035] The hybrid control unit 92 controls the vehicle 10 in a driving mode (BEV driving mode, HEV driving mode) according to the state of the vehicle 10. For example, the driving mode according to the state of the vehicle 10 is selected by the driving power source switching map described above.

[0036] The hybrid control unit 92 functionally comprises an engine control unit 92a that controls the operation of the engine 12, and an electric motor control unit 92b that controls the operation of the electric motor MG via the inverter 52, and performs hybrid drive control using the engine 12 and the electric motor MG, etc., using these control functions.

[0037] The engine control unit 92a controls the engine torque Te so as to realize the target system shaft torque Tsystgt. The electric motor control unit 92b controls the electric motor torque Tmg so as to realize the target system shaft torque Tsystgt. Specifically, when traveling in the BEV traveling mode, the electric motor control unit 92b controls the electric motor torque Tmg so as to realize the target system shaft torque Tsystgt. When traveling in the HEV traveling mode, the engine control unit 92a controls the engine torque Te so as to realize all or part of the target system shaft torque Tsystgt, and the electric motor control unit 92b controls the electric motor torque Tmg so as to compensate for the torque that is insufficient in the engine torque Te with respect to the target system shaft torque Tsystgt.

[0038] The make-and-break clutch control unit 94 controls the make-and-break state of the make-and-break clutch K0 depending on the driving mode. For example, in the BEV driving mode, the make-and-break clutch control unit 94 controls the make-and-break clutch K0 to be in a released state. For example, in the HEV driving mode, the make-and-break clutch control unit 94 controls the make-and-break clutch K0 to be in a fully engaged state. In the HEV driving mode, the electric motor rotation speed Nmg is equal to the engine rotation speed Ne.

[0039] The shift control unit 96 determines whether to shift the automatic transmission 28 using, for example, a shift map, and outputs a shift control signal Sat to the hydraulic control circuit 54 to execute shift control as necessary. The shift map is a predetermined relationship having shift lines for determining whether to shift the automatic transmission 28 on a two-dimensional coordinate system using, for example, vehicle speed V and target system axle torque Tsystgt 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 [N], which is the driving force required for the drive wheels 14, the accelerator opening θacc, the throttle valve opening θth, or the like may be used instead of the target system axle torque Tsystgt.

[0040] The hybrid control unit 92 further functionally includes a start control unit 92c. The start control unit 92c and the make-or-break clutch control unit 94 execute engine start control to crank the engine 12 using the electric motor MG and the make-or-break clutch K0 as needed to start the engine 12. Specifically, the start control unit 92c controls the electric motor MG to output a cranking torque Tcr [Nm] until cranking is completed in accordance with the switching of the make-or-break clutch K0 by the make-or-break clutch control unit 94 from a released state to a fully engaged state via a partially engaged state. The start control unit 92c also controls the supply of fuel to the engine 12, ignition, and the like, in conjunction with the cranking of the engine 12 by the make-or-break clutch K0 and the electric motor MG.

[0041] From this point on, when driving in BEV mode, for example, the accelerator pedal (not shown) is depressed further. Acceleration required The following describes the case.

[0042] The lockup clutch control unit 98 controls the engagement and disengagement of the lockup clutch 40. The lockup clutch control unit 98 functionally includes an end condition determination unit 98a, a start condition determination unit 98b, a tip-in control unit 98c, an execution determination unit 98d, a differential rotation determination unit 98e, and a permission / prohibition setting unit 98f.

[0043] The termination condition determination unit 98a determines whether the target system shaft torque Tsystgt is less than a first determination torque Tsystgt_jdg1. The first determination torque Tsystgt_jdg1 is a torque determination value experimentally or design-based, which is used to stop the engine 12, switch to the BEV driving mode, and terminate the tip-in LU control. As described below, the tip-in LU control is a control of the lockup clutch 40 in which, when the differential rotation speed ΔNlu [rpm], which is the rotational speed difference of the lockup clutch 40, is less than a predetermined difference ΔNlu_jdg, the LU command pressure Plu [Pa], which is a command pressure for controlling the engagement / disengagement state of the lockup clutch 40, is set to a half-engagement pressure PA [Pa]. When the differential rotation speed ΔNlu of the lockup clutch 40 is equal to or greater than the predetermined difference ΔNlu_jdg, the LU command pressure Plu is gradually transitioned from the half-engagement pressure PA toward the engagement pressure PB [Pa]. The LU command pressure Plu corresponds to the "command pressure" in this invention.

[0044] The differential rotation speed ΔNlu is the difference (=Nmg-Ni) between the motor rotation speed Nmg, which is the rotation speed of the motor connecting shaft 22 connected to the pump wheel on one side of the rotating members that the lockup clutch 40 engages and disengages, and the AT input rotation speed Ni, which is the rotation speed of the AT input shaft 26 connected to the turbine wheel on the other side. The predetermined difference ΔNlu_jdg (>0) is a judgment value determined in advance through experimentation or design, so that shocks caused by starting the engine 12 or eliminating backlash in the power transmission path PT are suppressed within an acceptable range even when the LU command pressure Plu transitions from the half-engagement pressure PA to the engagement pressure PB during tip-in LU control. The half-engagement pressure PA is the command pressure at which the lockup clutch 40 is in a half-engagement state. Note that the half-engagement pressure PA corresponds to the "predetermined pressure" in this invention. The engagement pressure PB is the command pressure that fully engages the lockup clutch 40 when tip-in LU control is not being executed (hereinafter, when tip-in LU control is not being executed, this will be referred to as "normal operation").

[0045] When the termination condition determination unit 98a determines that the target system shaft torque Tsystgt is less than the first determination torque Tsystgt_jdg1, the tip-in control unit 98c sets the LU command pressure Plu to the normal engagement pressure PB to terminate the tip-in LU control, and the permission / prohibition setting unit 98f sets the permission / prohibition setting (hereinafter simply referred to as the "permission / prohibition setting"), which indicates whether the execution of the tip-in LU control is permitted or prohibited, to a permitted state (= permission on state).

[0046] The start condition determination unit 98b determines whether the vehicle is in the BEV driving mode. The start condition determination unit 98b determines whether the permission / denial setting is set to the permission state. The start condition determination unit 98b determines whether the target system shaft torque Tsystgt is equal to or greater than the second determination torque Tsystgt_jdg2. The second determination torque Tsystgt_jdg2 is a torque that causes backlash in the power transmission path PT to be eliminated if the engine 12 is started or tip-in LU control is not executed, and is a torque determination value that is experimentally or design-based in advance for starting tip-in LU control. Backlash refers to a gap (backlash) between contact surfaces of gears and spline fittings formed in the rotational direction of power transmission members provided on the power transmission path PT. The second determination torque Tsystgt_jdg2 corresponds to the "predetermined torque" in this invention.

[0047] When the start condition determination unit 98b determines that the vehicle is in the BEV driving mode, the permission / denial setting is in the permission state, and the target system shaft torque Tsystgt is equal to or greater than the second determination torque Tsystgt_jdg2, the tip-in control unit 98c executes the tip-in LU control, i.e., starts the tip-in LU control if it has not been started, and continues the tip-in LU control if it has been started. The fact that the permission / denial setting is set to the permission state and the target system shaft torque Tsystgt is equal to or greater than the second determination torque Tsystgt_jdg2 is both satisfied indicates that the vehicle 10 Acceleration is requiredThe start conditions for tip-in LU control are when any of the three conditions - that is, the BEV driving mode, the permission setting being set to the permission state, and the target system shaft torque Tsystgt being equal to or greater than the second determination torque Tsystgt_jdg2 - changes from an unsatisfied state to a state where all of the three conditions are satisfied.

[0048] The execution determination unit 98d determines whether or not the tip-in LU control is being executed. For example, when the tip-in LU control is being executed by the tip-in control unit 98c, it is determined that the tip-in LU control is being executed.

[0049] When the execution determination section 98d determines that tip-in LU control is being executed, the differential rotation determination section 98e determines whether the differential rotation ΔNlu of the lock-up clutch 40 is less than a predetermined difference ΔNlu_jdg.

[0050] When the differential rotation determination unit 98e determines that the differential rotation ΔNlu of the lock-up clutch 40 is less than the predetermined difference ΔNlu_jdg, the tip-in control unit 98c sets the LU command pressure Plu to the half-engagement pressure PA. That is, the tip-in control unit 98c keeps the LU command pressure Plu at the half-engagement pressure PA until the differential rotation ΔNlu of the lock-up clutch 40 becomes equal to or greater than the predetermined difference ΔNlu_jdg. For example, when the half-engagement pressure PA is a constant pressure, the LU command pressure Plu is kept at the constant half-engagement pressure PA.

[0051] When the differential rotation determination unit 98e determines that the differential rotation ΔNlu of the lock-up clutch 40 is equal to or greater than a predetermined difference ΔNlu_jdg, the tip-in control unit 98c gradually transitions the LU command pressure Plu from the half-engagement pressure PA toward the normal engagement pressure PB. That is, if the transition of the LU command pressure Plu from the half-engagement pressure PA toward the normal engagement pressure PB has not started, the tip-in control unit 98c starts the transition, and if the transition has started, the tip-in control unit 98c continues the transition. Specifically, if the transition of the LU command pressure Plu to the normal engagement pressure PB has not been completed (= the LU command pressure Plu has not reached the normal engagement pressure PB), the tip-in control unit 98c changes the LU command pressure Plu from the half-engagement pressure PA toward the normal engagement pressure PB, for example, by changing the increase in the LU command pressure Plu per hour at a predetermined change rate that is determined experimentally or by design. When the transition of the LU command pressure Plu to the normal engagement pressure PB is complete (= when the LU command pressure Plu has become the normal engagement pressure PB), the tip-in control unit 98c sets the LU command pressure Plu to the normal engagement pressure PB and terminates the tip-in LU control.

[0052] When the tip-in LU control is ended by the tip-in control unit 98c, the permission / denial setting unit 98f sets the permission / denial setting to the prohibited state (=permission OFF state).

[0053] Fig. 2 is an example of a flowchart illustrating the control operation of the electronic control device 90 shown in Fig. 1. The flowchart in Fig. 2 is repeatedly executed.

[0054] First, in step S10 (hereinafter, "step" will be omitted) corresponding to the function of the termination condition determination unit 98a, it is determined whether the target system shaft torque Tsystgt is less than the first determination torque Tsystgt_jdg1.

[0055] If the determination in S10 is affirmative, in S20 corresponding to the functions of the tip-in control unit 98c and the permission / prohibition setting unit 98f, the tip-in LU control is terminated and the permission / prohibition setting is set to the permission state (=permission on state). If the determination in S10 is negative, if the tip-in LU control is being executed, the execution of the tip-in LU control continues, and if the tip-in LU control is not being executed, the non-execution of the tip-in LU control continues.

[0056] If the determination in S10 is negative or after S20 is executed, in S30, which corresponds to the function of the start condition determination unit 98b, it is determined whether or not the start conditions for executing tip-in LU control are satisfied. That is, it is determined whether or not all of the following conditions are satisfied: the vehicle is in the BEV driving mode, the permission setting is set to the permission state, and the target system shaft torque Tsystgt is equal to or greater than the second determination torque Tsystgt_jdg2.

[0057] If the determination in S30 is positive, tip-in LU control is executed in S40, which corresponds to the function of the tip-in control unit 98c. If the determination in S30 is negative and tip-in LU control is currently being executed, execution of tip-in LU control continues, and if tip-in LU control is not currently being executed, non-execution of tip-in LU control continues, for example, maintaining the fully engaged state of the lock-up clutch 40. If the determination in S30 is negative or after execution of S40, it is determined in S50, which corresponds to the function of the execution determination unit 98d, whether tip-in LU control is currently being executed.

[0058] If the determination in S50 is positive, in S60, which corresponds to the function of the differential rotation determination unit 98e, it is determined whether the differential rotation ΔNlu of the lock-up clutch 40 is less than a predetermined difference ΔNlu_jdg. If the determination in S50 is negative, the process returns. If the determination in S60 is positive, in S70, which corresponds to the function of the tip-in control unit 98c, the LU command pressure Plu is set to the half-engagement pressure PA. After S70 is executed, the process returns. If the determination in S60 is negative, in S80, which corresponds to the function of the tip-in control unit 98c, the LU command pressure Plu is transitioned from the half-engagement pressure PA toward the normal engagement pressure PB.

[0059] After S80 is executed, S90, which corresponds to the function of the tip-in control unit 98c, determines whether the transition of the LU command pressure Plu to the normal engagement pressure PB is complete. If the determination in S90 is positive, S100, which corresponds to the functions of the tip-in control unit 98c and the permission / prohibition setting unit 98f, ends the tip-in LU control and sets the permission / prohibition setting to the prohibited state (=permission off state). If the determination in S90 is negative or after S100 is executed, the process returns.

[0060] According to this embodiment, in BEV driving Acceleration is required Furthermore, when the target system shaft torque Tsystgt is equal to or greater than the second determination torque Tsystgt_jdg2, the LU command pressure Plu is kept at the half-engagement pressure PA at which the lock-up clutch 40 is in a half-engagement state until the differential rotation ΔNlu of the lock-up clutch 40 becomes equal to or greater than the predetermined difference ΔNlu_jdg. Acceleration is requiredFurthermore, when the target system shaft torque Tsystgt is equal to or greater than the second determination torque Tsystgt_jdg2, the lockup clutch 40 is placed in a partially engaged state. That is, the power transmission in the torque converter 24 is not placed in a mechanically directly coupled state. Therefore, when the target system shaft torque Tsystgt is equal to or greater than the second determination torque Tsystgt_jdg2, shocks that occur when the engine 12 is started or when backlash in the power transmission path PT is eliminated are absorbed by the lockup clutch 40, and the occurrence of shocks is reliably suppressed. Furthermore, by placing the lockup clutch 40 in a partially engaged state, the responsiveness of the lockup clutch 40 is not impaired compared to when the lockup clutch 40 is released, and racing is suppressed when the lockup clutch 40 is subsequently placed in a fully engaged state.

[0061] Although the embodiments of the present invention have been described in detail above with reference to the drawings, the present invention can also be applied to other embodiments.

[0062] In the above-described embodiment, the make-and-break clutch K0 is a wet friction engagement device, but it is not limited to this and may be a dry friction engagement device.

[0063] In the above-described embodiment, the automatic transmission 28 is provided in the power transmission path PT between the torque converter 24 and the drive wheels 14, but the present invention may also be provided in an embodiment in which the automatic transmission 28 is not provided.

[0064] The first determination torque Tsystgt_jdg1 and the second determination torque Tsystgt_jdg2 described in the above embodiment may be different values ​​or may be the same value.

[0065] It should be noted that the above is merely an example of the present invention, and the present invention can be embodied in various forms with various modifications and improvements based on the knowledge of those skilled in the art, without departing from the spirit of the present invention. [Explanation of symbols]

[0066] 10: Hybrid car 12: Engine 14: Drive wheel 24: Torque converter 40: Lock-up clutch 90: Electronic control device (control device) K0: Disconnecting clutch MG: Electric motor PG: driving force source PT: Power transmission path Tsystgt: Target system torque (target value of torque converter input torque) Tsystgt_jdg2: Second judgment torque (predetermined torque) ΔNlu: differential rotation ΔNlu_jdg: Predetermined difference Plu: LU indicated pressure (indicated pressure) PA: Half-engagement pressure (predetermined pressure)

Claims

[Claim 1] A control device for a hybrid vehicle including an engine and an electric motor as a driving force source, a connecting / disconnecting clutch that connects and disconnects power transmission between the engine and the electric motor, and a torque converter that has a lock-up clutch and is provided in a power transmission path between the driving force source and drive wheels, When acceleration is required during travel in which drive torque is output only from the electric motor of the drive power source and the target value of the input torque of the torque converter is equal to or greater than a predetermined torque, the command pressure for controlling engagement and disengagement of the lock-up clutch is kept at a predetermined pressure at which the lock-up clutch is in a semi-engaged state until the differential rotation of the lock-up clutch becomes equal to or greater than a predetermined difference, and when the differential rotation becomes equal to or greater than the predetermined difference, tip-in LU control is executed in which the command pressure is gradually transitioned toward an engagement pressure at which the lock-up clutch is in a fully engaged state. The predetermined torque is a value for determining whether or not removal of backlash occurs in the power transmission path if the tip-in LU control is not executed, The predetermined difference is a value for determining whether a shock occurring due to clearance in the power transmission path is suppressed within an allowable range even when the command pressure is transitioned from the predetermined pressure to the engagement pressure during tip-in LU control. A control device for a hybrid vehicle.

Images