JP2023069078A - vehicle controller - Google Patents

Abstract

To secure hydraulic pressure of an engagement device while suppressing a speed change shock from being generated in down-shifting of an automatic transmission during a speed reduced travel in a low vehicle speed range.SOLUTION: If a down shift is determined during a speed reduced travel in a low vehicle speed range, speed change delay control is executed in which down-shift is started so that a progress stage of the down-shift is a preparation stage in which a release-side engagement device stands by with torque capacity large enough to accept input torque to an automatic transmission, and an engagement-side engagement device is placed in a packing completion state, and maintained in a state in which the preparation stage is completed until the vehicle stops, a preparation stage right after the preparation stage is started after the vehicle stops, to advance the down-shift, so the down-shift in a travel lasts until packing is completed, a speed change shock is hardly generated even if the down-shift is started earlier, and a down-shift after the vehicle stop starts from the packing completion state, thereby suppressing a deficiency in a flow rate of working oil needed for engagement control of the engagement devices.SELECTED DRAWING: Figure 2

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for a vehicle equipped with an automatic transmission in which a gear stage is formed by engagement of an engagement device.

A power source and any one of a plurality of gear stages by engagement of any one of a plurality of hydraulic engagement devices that form part of a power transmission path between the power source and drive wheels. is well known in the art. For example, a shift control device for an automatic transmission for a vehicle disclosed in Patent Document 1 is one of them. This patent document 1 discloses shifting an automatic transmission by controlling the operating state of a hydraulic engagement device so as to obtain a shift stage determined based on vehicle speed and accelerator opening. ing.

JP-A-5-44830

By the way, during deceleration running in the low vehicle speed range, the downshift of the automatic transmission is accelerated in preparation for re-acceleration in the low vehicle speed range, that is, shifting to the low vehicle speed side from the relatively high vehicle speed side. can be considered. If so, there is a risk that gear shift shock is likely to occur. On the other hand, in order to suppress the occurrence of shift shock, it is conceivable to delay the start of downshifting, that is, to start downshifting at a relatively low vehicle speed side or after stopping the vehicle. As a result, the flow rate of the hydraulic oil discharged from the oil pump that is rotationally driven by the power source decreases, so that the flow rate of the hydraulic oil required for engagement control of the engagement device becomes insufficient, and the hydraulic pressure of the engagement device is reduced. It may lead to a decline.

SUMMARY OF THE INVENTION The present invention has been made against the background of the above circumstances, and its object is to suppress the occurrence of shift shock when downshifting an automatic transmission during deceleration running in a low vehicle speed range, An object of the present invention is to provide a vehicle control device capable of ensuring hydraulic pressure of an engagement device.

The gist of the first invention is that: (a) a power source and any one of a plurality of hydraulic engagement devices that form part of a power transmission path between the power source and drive wheels; (b) a control device for a vehicle, comprising: an automatic transmission in which any one of a plurality of gear stages is established by engagement; a shift control unit that shifts the automatic transmission by switching an engagement device to a released state and switching an engagement side engagement device out of the engagement devices to an engaged state; (c) When the shift control unit determines that the automatic transmission should downshift during deceleration in a predetermined low vehicle speed range, The downshift is started so as to wait at a torque capacity that can handle the input torque to the automatic transmission and prepare the engagement side engagement device to be in a packing completion state in which the pack clearance is closed. until the vehicle stops, a shift delay control is executed to maintain the progress stage in a state in which the preparation stage is completed, and after the vehicle stops, the progress stage next to the preparation stage is started. to advance the downshift.

In a second aspect of the invention, in the vehicle control device according to the first aspect, when the shift control unit determines the downshift during the deceleration, the running mode of the vehicle is changed to the power performance mode. To proceed with the downshift without executing the shift delay control when the vehicle is in a predetermined running mode that places importance on

According to the first aspect of the present invention, when it is determined that the automatic transmission should downshift during deceleration in a predetermined low speed range, the downshift progress stage automatically shifts the disengagement side engagement device. The downshift is started so that the vehicle is put on standby with a torque capacity that can handle the input torque to the gear, and the downshift is started so as to be in a preparatory stage for putting the engagement side engagement device in the packing completion state, and the vehicle stops. Until then, shift delay control is executed to maintain the progress stage with the preparation stage completed, and after the vehicle stops, the next progress stage of the preparation stage is started and the downshift is progressed. Even if the start of the downshift is made earlier, the shift shock is less likely to occur, and the downshift after the vehicle stops starts from the state where the packing is completed, and the engagement device is engaged. Insufficient flow of hydraulic oil required for combination control is suppressed. Therefore, when the automatic transmission is downshifted during deceleration in the low vehicle speed range, the hydraulic pressure of the engagement device can be ensured while suppressing the occurrence of shift shock.

Further, according to the second aspect of the present invention, when it is determined that a downshift is to be performed during deceleration, if the running mode of the vehicle is a predetermined running mode emphasizing power performance, shift delay control is performed. Since the downshift proceeds without being executed, the desired driving torque can be easily achieved, and the deterioration of the rough road running performance can be suppressed.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram for explaining a schematic configuration of a vehicle to which the present invention is applied, and is a diagram for explaining main parts of a control system and control functions for various controls in the vehicle; 4 is a flow chart for explaining the main part of the control operation of the electronic control unit, and is a flow chart for ensuring the hydraulic pressure of the engagement device while suppressing the occurrence of shift shock when the automatic transmission is downshifted during deceleration in the low vehicle speed range. 4 is a flow chart for explaining control operation; FIG. 3 is a diagram showing an example of a time chart when the control operation shown in the flowchart of FIG. 2 is executed, and is a case when the brake is on and the vehicle is stopped. FIG. 3 is a diagram showing an example of a time chart when the control operation shown in the flow chart of FIG. 2 is executed, and shows a case where the brake is turned off during shifting. 4 is a chart summarizing whether or not to delay downshifting to the first speed gear for each driving mode; 2 is a flow chart for explaining the main part of the control operation of the electronic control unit, which is used to ensure the hydraulic pressure of the engagement device while suppressing the occurrence of shift shock when the automatic transmission downshifts during deceleration running in a low vehicle speed range. 3 is a flowchart for explaining the control operation of , which is an embodiment different from the flowchart of FIG. 2 .

In an embodiment of the present invention, the gear ratio in the automatic transmission is "rotational speed of input rotary member/rotational speed of output rotary member". The gear stage on the high side of the automatic transmission is a gear stage on the high vehicle speed side where the gear ratio is reduced. A gear stage on the low side of the automatic transmission is a gear stage on the low vehicle speed side where the gear ratio increases. For example, the lowest speed gear is the lowest vehicle speed gear that is the lowest vehicle speed, and is the maximum gear ratio gear that has the largest gear ratio.

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

FIG. 1 is a diagram for explaining a schematic configuration of a vehicle 10 to which the present invention is applied, and is a diagram for explaining control functions and main parts of a control system for various controls in the vehicle 10. As shown in FIG. In FIG. 1, a vehicle 10 is a hybrid vehicle having an engine 12 and an electric motor MG that function as a power source SP. The vehicle 10 also includes drive wheels 14 and a power transmission device 16 provided in a power transmission path between the engine 12 and the drive wheels 14 .

The engine 12 is a known internal combustion engine such as a gasoline engine or a diesel engine. An engine control device 50 including a throttle actuator, a fuel injection device, an ignition device, and the like provided in the vehicle 10 is controlled by an electronic control device 90, which will be described later, to control the engine 12. The engine torque Te, which is the output torque of the engine 12, is controlled by the engine 12. is controlled.

The electric motor MG is a rotating electric machine having a function as a motor that generates mechanical power from electric power and a function as a generator that generates power from mechanical power, and is a so-called motor generator. Electric motor MG is connected to a battery 54 provided in vehicle 10 via an inverter 52 provided in vehicle 10 . The battery 54 is a power storage device that transfers electric power to and from the electric motor MG. In the electric motor MG, the MG torque Tm, which is the output torque of the electric motor MG, is controlled by controlling the inverter 52 by the electronic control unit 90, which will be described later. For example, when the rotation direction of the electric motor MG is the same rotation direction as the engine 12 is running, the MG torque Tm is a power running torque when the positive torque is on the acceleration side, and is a regenerative torque when the negative torque is on the deceleration side. be. Electric power is also synonymous with electrical energy, if not specifically distinguished. The power is also synonymous with drive power, torque, and force unless otherwise distinguished.

The power transmission device 16 includes a K0 clutch 20, a torque converter 22, an automatic transmission 24, etc. in a case 18, which is a non-rotating member attached to the vehicle body. K0 clutch 20 is a clutch provided between engine 12 and electric motor MG in a power transmission path between engine 12 and driving wheels 14 . Torque converter 22 is connected to engine 12 via K0 clutch 20 . Automatic transmission 24 is connected to torque converter 22 and is interposed in a power transmission path between torque converter 22 and drive wheels 14 . The torque converter 22 and the automatic transmission 24 each form part of a power transmission path between the power source SP 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 an automatic transmission 24, a differential gear 30 connected to the propeller shaft 28, and a gear 1 connected to the differential gear 30. A pair of drive shafts 32 and the like are provided. The power transmission device 16 also includes an engine connection shaft 34 that connects the engine 12 and the K0 clutch 20, an electric motor connection shaft 36 that connects the K0 clutch 20 and the torque converter 22, and the like.

The electric motor MG is connected to the electric motor connecting shaft 36 within the case 18 so as to be able to transmit power. In other words, the electric motor MG is connected to a power transmission path between the engine 12 and the drive wheels 14, particularly a power transmission path between the K0 clutch 20 and the torque converter 22 so that power can be transmitted. In other words, the electric motor MG is connected to the torque converter 22 and the automatic transmission 24 without the K0 clutch 20 so that power can be transmitted.

The torque converter 22 includes a pump impeller 22 a connected to an electric motor connecting shaft 36 and a turbine impeller 22 b connected to a transmission input shaft 38 which is an input rotating member of the automatic transmission 24 . The torque converter 22 is a hydrodynamic transmission device that transmits power from the power source SP from the electric motor connecting shaft 36 to the transmission input shaft 38 via fluid. The torque converter 22 includes an LU clutch 40 as a direct clutch that connects the pump impeller 22a and the turbine impeller 22b, that is, connects the electric motor connecting shaft 36 and the transmission input shaft 38. The LU clutch 40 is a known lockup clutch.

The automatic transmission 24 is a known planetary gear type automatic transmission including, for example, one or more sets of planetary gears (not shown) and an engagement device CB. The engagement device CB includes, for example, a plurality of hydraulic engagement devices such as known friction engagement devices. CB torque Tcb, which is a torque capacity of each engagement device CB, is changed by a CB hydraulic pressure PRcb, which is a regulated hydraulic pressure supplied from a hydraulic control circuit 56 provided in the vehicle 10. The operating or control states are switched, such as engaged, slipped, and disengaged.

The automatic transmission 24 has a plurality of gear ratios (also referred to as gear ratios) γat (=AT input rotation speed Ni/AT output rotation speed No) that differ by engagement of any one of the engagement devices CB. (also referred to as gear stages). The automatic transmission 24 is controlled by an electronic control unit 90, which will be described later, according to the driver's accelerator operation, the vehicle speed V, etc. By switching the control state of , the gear stage to be formed is switched. In other words, in the shift control of the automatic transmission 24, the shift is executed, for example, by re-holding the engagement device involved in the shift. A so-called clutch-to-clutch shift is executed. The release-side engagement device is an engagement device that is in an engaged state before the shift of the automatic transmission 24, among the engagement devices involved in the shift, and is engaged during a transition of the shift of the automatic transmission 24. It is an engagement device that is controlled from a state to a released state. The engagement side engagement device is an engagement device that is in a disengaged state before the shift of the automatic transmission 24 among the engagement devices involved in the shift, and is in the disengaged state when the shift of the automatic transmission 24 is in transition. to the engaged state. The AT input rotation speed Ni is the rotation speed of the transmission input shaft 38 and the input rotation speed of the automatic transmission 24 . The AT input rotation speed Ni has the same value as the turbine rotation speed Nt, which is the output rotation speed of the torque converter 22 . The AT input rotation speed Ni can be represented by the turbine rotation speed Nt. The AT output rotation speed No is the rotation speed of the transmission output shaft 26 and the output rotation speed of the automatic transmission 24 .

The K0 clutch 20 is a hydraulic friction engagement device composed of, for example, a multi-plate or single-plate clutch. The K0 clutch 20 changes the K0 torque Tk0, which is the torque capacity of the K0 clutch 20, by the K0 hydraulic pressure PRk0, which is the regulated hydraulic pressure supplied from the hydraulic control circuit 56, so that the engaged state, the slip state, and the disengaged state. A control state such as state is switched.

In the vehicle 10, when the K0 clutch 20 is engaged, the engine 12 and the torque converter 22 are connected so as to be able to transmit power. On the other hand, when the K0 clutch 20 is released, power transmission between the engine 12 and the torque converter 22 is cut off. Since the electric motor MG is connected to the torque converter 22, the K0 clutch 20 functions as a clutch that connects and disconnects the engine 12 with the electric motor MG.

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 connection shaft 34 to the K0 clutch 20, the electric motor connection shaft 36, the torque converter 22, the automatic transmission 24, The power is transmitted to the drive wheels 14 through the propeller shaft 28, the differential gear 30, the drive shaft 32, and the like. The power output from the electric motor MG is transmitted from the electric motor connecting shaft 36 to the torque converter 22, the automatic transmission 24, the propeller shaft 28, the differential gear 30, the drive shaft 32, etc. regardless of the control state of the K0 clutch 20. The power is transmitted to the driving wheels 14 through successively.

The vehicle 10 includes 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 22 a and is driven to rotate by the power source SP to discharge hydraulic oil OIL used in the power transmission device 16 . The pump motor 62 is a motor dedicated to the EOP 60 for rotating the EOP 60 . The EOP 60 is rotationally driven by the pump motor 62 to discharge hydraulic oil OIL. Hydraulic oil OIL discharged from the MOP 58 and the EOP 60 is supplied to the hydraulic control circuit 56 . The hydraulic control circuit 56 supplies the CB hydraulic pressure PRcb, the K0 hydraulic pressure PRk0, etc., each of which is adjusted based on the hydraulic oil OIL discharged from the MOP 58 and/or the EOP 60 .

The vehicle 10 further includes an electronic control unit 90 that includes a control unit for the vehicle 10 . The electronic control unit 90 includes, for example, a so-called microcomputer having a CPU, a RAM, a ROM, and an input/output interface. Various controls of the vehicle 10 are executed by performing signal processing. The electronic control unit 90 includes computers for engine control, electric motor control, speed change control, etc., as required.

The electronic control unit 90 includes various sensors provided in the vehicle 10 (for example, the engine rotation speed sensor 70, the turbine rotation speed sensor 72, the output rotation speed sensor 74, the MG rotation speed sensor 76, the accelerator opening sensor 78, the throttle valve Various signals based on detection values by the opening sensor 80, the brake switch 82, the battery sensor 84, the oil temperature sensor 86, etc. (e.g., the engine rotation speed Ne, which is the rotation speed of the engine 12, and the AT input rotation speed Ni) Turbine rotation speed Nt, AT output rotation speed No corresponding to vehicle speed V, MG rotation speed Nm, which is the rotation speed of electric motor MG, and accelerator opening θacc, which is the amount of accelerator operation by the driver representing the magnitude of acceleration operation by the driver. , the throttle valve opening θth which is the opening of the electronic throttle valve, the brake-on signal Bon which is a signal indicating that the brake pedal for operating the wheel brake is being operated by the driver, the battery temperature THbat of the battery 54, and A battery charging/discharging current Ibat, a battery voltage Vbat, a working oil temperature THoil which is the temperature of the working oil OIL in the hydraulic control circuit 56, etc.) are respectively supplied.

From the electronic control device 90, various command signals (for example, engine Control command signal Se, MG control command signal Sm for controlling the electric motor MG, CB hydraulic control command signal Scb for controlling the engagement device CB, K0 hydraulic control command signals Sk0 and LU for controlling the K0 clutch 20 LU oil pressure control command signal Slu for controlling the clutch 40, EOP control command signal Seop for controlling the EOP 60, etc.) are respectively output.

Each hydraulic control command signal S will be described by exemplifying the CB hydraulic control command signal Scb. The electronic control unit 90 calculates command pressures of the engagement devices CB for supplying the regulated CB hydraulic pressures PRcb from the hydraulic control circuit 56 as command values of the CB hydraulic pressures PRcb corresponding to the respective engagement devices CB. do. The command pressure is the target hydraulic pressure commanded by the electronic control unit 90 for the hydraulic oil OIL supplied to the engagement device, and is the actual hydraulic pressure supplied to the engagement device according to this command pressure. Actual oil pressure changes. The electronic control unit 90 converts the indicated pressure of the engagement device CB into a CB indicated current value for driving the solenoid SLcb provided in the hydraulic control circuit 56 . The solenoid SLcb is each solenoid valve for the engagement device CB that outputs the CB hydraulic pressure PRcb corresponding to each engagement device CB. The CB indicated current value is the indicated current for the drive circuit provided in the electronic control unit 90 for driving the solenoid SLcb. The CB oil pressure control command signal Scb is a drive current or a drive voltage for the drive circuit to drive the solenoid SLcb based on the CB command current value. That is, the indicated pressure of the engagement device CB is converted into the CB hydraulic control command signal Scb and output to the hydraulic control circuit 56 . In this embodiment, for the sake of convenience, the indicated pressure of the engagement device CB and the CB hydraulic pressure control command signal Scb are treated as the same.

The electronic control unit 90 includes power source control means or a power source control section 92, clutch control means or a clutch control section 94, and shift control means or a shift control section 96 in order to realize various controls in the vehicle 10. .

The power source control unit 92 functions as engine control means, ie, an engine control unit 92a, for controlling the operation of the engine 12, and functions as an electric motor control unit, ie, an electric motor control unit 92b, for controlling the operation of the electric motor MG via the inverter 52. and , and is hybrid control means, ie, a hybrid control section, for executing hybrid drive control by the engine 12 and the electric motor MG by means of these control functions.

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

The power source control unit 92 sets the drive mode for driving the vehicle 10 to the BEV drive mode when the required drive torque Trdem can be covered only by the output of the electric motor MG. The BEV drive mode is a motor drive mode in which the vehicle can be driven using only the electric motor MG as the power source SP in the disengaged state of the K0 clutch 20 (=BEV drive). On the other hand, the power source control unit 92 sets the drive mode to the engine drive mode, that is, the HEV drive mode, when the required drive torque Trdem cannot be met unless at least the output of the engine 12 is used. The HEV drive mode is a hybrid drive mode in which engine running, that is, hybrid running (=HEV running), in which the vehicle runs using at least the engine 12 as the power source SP, is possible while the K0 clutch 20 is engaged. On the other hand, even if the required drive torque Trdem can be covered only by the output of the electric motor MG, the power source control unit 92 can be set to , to establish the HEV drive mode.

For example, when the engine 12 is stopped, the electric motor control unit 92b executes MG idling control, which is idling control of the electric motor MG. In the MG idling control, for example, the target MG rotation speed Nmtgt, which is the target value of the MG rotation speed Nm, is set to an idling rotation speed of the electric motor MG that is equal to or higher than a predetermined MG idling rotation speed Nmidlf, and the target MG rotation speed Nmtgt is set to the target MG rotation speed Nmtgt. This control is to control the MG rotation speed Nm to put the electric motor MG in the idling state. In the MG idling control, for example, when the accelerator is turned off while the engine 12 is stopped, the brake is turned off while the vehicle is temporarily stopped. This is a control for causing the electric motor MG to output a predetermined creep torque Tcpf for causing the phenomenon. The predetermined creep torque Tcpf is a predetermined torque that is predetermined for causing the vehicle 10 to run in a so-called creep run when the brake is turned off while the vehicle is stopped and the accelerator remains off.

The power source control unit 92, particularly the engine control unit 92a, determines whether or not there is an engine start request for switching the control state of the engine 12 from the stopped state to the operating state. For example, in the BEV drive mode, the engine control unit 92a determines whether or not the required driving torque Trdem has increased beyond the range that can be covered by the output of the electric motor MG alone, or whether or not the engine 12 or the like needs to be warmed up. Alternatively, it is determined whether or not there is an engine start request based on whether or not charging of the battery 54 is required.

When the power source control unit 92 determines that there is an engine start request, the clutch control unit 94 controls the K0 clutch 20 to start the engine 12 . For example, the clutch control unit 94 outputs a K0 oil pressure command for controlling the released K0 clutch 20 toward the engaged state so as to obtain the K0 torque Tk0 for transmitting the cranking torque Tcr to the engine 12 side. Output the value Spk0. The cranking torque Tcr is a torque required for cranking the engine 12 to raise the engine rotation speed Ne.

When the power source control unit 92 determines that there is an engine start request, the power source control unit 92 controls the engine 12 and the electric motor MG to start the engine 12 . For example, the electric motor control unit 92b outputs to the inverter 52 an MG control command signal Sm for causing the electric motor MG to output the cranking torque Tcr in accordance with the switching of the K0 clutch 20 to the engaged state. Further, the engine control unit 92 a outputs an engine control command signal Se for starting fuel supply, engine ignition, etc. to the engine control device 50 in conjunction with cranking of the engine 12 .

The shift control unit 96 performs shift determination for the automatic transmission 24 using, for example, a shift map having a predetermined relationship, and outputs a CB hydraulic control command signal for executing shift control of the automatic transmission 24 as necessary. Scb is output to the hydraulic control circuit 56 . In the shift control of the automatic transmission 24, the shift control unit 96 switches, for example, the disengagement side engagement device of the engagement device CB to the disengaged state, and the disengagement state of the engagement side engagement device of the engagement device CB. The shift of the automatic transmission 24 is performed by switching to the engaged state. The shift map is a predetermined relationship having a shift line for judging the shift of the automatic transmission 24 on two-dimensional coordinates having, for example, the vehicle speed V and the required driving torque Trdem as variables. In the shift map, the AT output rotational speed No may be used instead of the vehicle speed V, and the required driving force Frdem, the accelerator opening θacc, the throttle valve opening θth, etc. may be used instead of the required driving torque Trdem. can be

Progressive stages, or phases, of the shift of the automatic transmission 24 will be described by exemplifying a downshift during deceleration. When the shift control unit 96 determines that the automatic transmission 24 is to downshift, the shift control unit 96 waits for the downshift phase with a torque capacity that allows the disengagement side engagement device to take charge of the input torque Tin to the automatic transmission 24. At the same time, the CB hydraulic control command signal Scb is output to the hydraulic control circuit 56 to start the downshift, in order to enter a preparatory stage, that is, a preparatory phase, in which the engaging device on the engaging side is placed in a packing completion state in which the pack clearance is reduced. . The packing completion state of the engagement device CB is a state in which the engagement device CB starts to have a torque capacity if the CB oil pressure PRcb is increased from the packing completion state. The shift control unit 96 determines whether or not the preparation phase has been completed based on whether or not the predetermined preparation time TMpk has elapsed since the start of the preparation phase. The predetermined preparation time TMpk is, for example, a predetermined time during which the engagement device on the engagement side is in a packing completion state. When the shift control unit 96 determines that the preparation phase is completed, the shift control unit 96 outputs the CB oil pressure control command signal Scb for gradually decreasing the torque capacity of the disengagement side engagement device and gradually increasing the torque capacity of the engagement side engagement device. to the hydraulic control circuit 56 to initiate the torque phase. In the case of downshifting, this torque phase is a phase in which the torque capacity of the engagement side engagement device is brought out and the output torque of the automatic transmission 24 changes. When the turbine rotation speed Nt (=AT input rotation speed Ni) is increased toward the post-downshift synchronous rotation speed (=No x γat after downshift) during the downshift transition, the downshift phase becomes the torque phase. to the inertia phase. In the inertia phase, the shift control unit 96 outputs to the hydraulic control circuit 56 a CB hydraulic control command signal Scb for changing the turbine rotational speed Nt at a predetermined rising gradient in consideration of shift time and shift shock. do. The shift control unit 96 determines whether or not the downshift has been completed based on whether or not the turbine rotation speed Nt matches the synchronous rotation speed after the downshift. When the shift control unit 96 determines that the downshift is completed, it sets the CB oil pressure PRcb of the disengagement side engagement device to zero and sets the CB oil pressure PRcb of the engagement side engagement device to zero. A CB hydraulic pressure control command signal Scb for maintaining the CB hydraulic pressure PRcb in the fully engaged state is output to the hydraulic control circuit 56 to complete a series of shift control related to the downshift.

Here, when the vehicle speed V is in a predetermined low vehicle speed region and the vehicle is decelerating, it is determined to downshift between the low-side gear stages. The downshift between the gear stages on the low side is, for example, a 2→1 downshift in which the gear stage of the automatic transmission 24 is switched from the second gear to the first gear. The predetermined low vehicle speed range is, for example, a vehicle speed range close to a stop, and is a low vehicle speed range in which a shift line for determining a 2→1 downshift is determined in advance in the shift map. In the automatic transmission 24, for example, the first gear stage is formed by engaging both the first engagement device CB1 and the third engagement device CB3 of the engagement devices CB. Further, in the automatic transmission 24, for example, the second gear stage is formed by engaging both the second engagement device CB2 and the third engagement device CB3 of the engagement devices CB. When the shift control unit 96 determines that the automatic transmission 24 is downshifted from 2 to 1 during deceleration in a predetermined low vehicle speed range, the shift control unit 96 releases the second engagement device CB2, which is the disengagement side engagement device. state, and the first engagement device CB1, which becomes the engagement side engagement device, is switched to the engaged state. As a result, the automatic transmission 24 is switched from the second gear to the first gear.

By the way, it is considered that the frequency of re-acceleration is high in the low vehicle speed region near the stop. When re-acceleration is requested by operating the accelerator or the like, if the downshift is in transition, the generation of the driving torque Tr may be delayed and the acceleration responsiveness may deteriorate. Therefore, in preparation for reacceleration during deceleration in the low vehicle speed range, it is conceivable to perform the 2→1 downshift of the automatic transmission 24 at a relatively high vehicle speed side. If so, there is a risk that gear shift shock is likely to occur. On the other hand, in order to suppress the occurrence of shift shock, it is conceivable to start the 2→1 downshift at a relatively low vehicle speed side or after the vehicle has stopped. Then, the MOP 58 is rotationally driven while the rotation speed of the electric motor connecting shaft 36 is low, and the flow rate of the hydraulic oil OIL discharged from the MOP 58 is reduced. There is a risk that the flow rate will be insufficient and the hydraulic pressure of the first engagement device CB1 supplied from the hydraulic control circuit 56 will drop.

Therefore, when the shift control unit 96 determines that the automatic transmission 24 is to downshift, for example, downshift from 2 to 1 during deceleration in a predetermined low vehicle speed range, the shift control unit 96 shifts the phase of the downshift from 2 to 1 into the preparation phase. 2→1 downshift is started as follows. Furthermore, even after the preparation phase is completed, the shift control unit 96 executes the shift delay control CTsd to maintain the 2→1 downshift phase in the state where the preparation phase is completed until the vehicle 10 stops. Next, when the vehicle 10 stops, the shift control unit 96 cancels the shift delay control CTsd, gradually decreases the torque capacity of the disengagement side engagement device, and gradually increases the torque capacity of the engagement side engagement device. A control command signal Scb is output to the hydraulic control circuit 56 . That is, after the vehicle 10 stops, the shift control unit 96 starts the torque phase, which is the next phase of the preparation phase, and advances the 2→1 downshift. I do.

While the vehicle is decelerating in a predetermined low speed range, when the driver does not operate the brake, that is, when the brake is off, the vehicle is more likely to re-start than when the driver is operating the brake, that is, when the brake is on. It is considered that the acceleration frequency is high. Therefore, the shift control unit 96 executes the shift delay control CTsd, for example, when the brake is on. When the driver performs a brake off operation while the shift delay control CTsd is being executed, the shift control unit 96 cancels the shift delay control CTsd, quickly increases the oil pressure of the disengagement side engagement device, and engages. A CB oil pressure control command signal Scb is output to the oil pressure control circuit 56 for quickly reducing the oil pressure of the engagement side engagement device. As a result, the automatic transmission 24 is returned to the second gear stage, and the second gear stage is maintained.

FIG. 2 is a flow chart for explaining the essential part of the control operation of the electronic control unit 90. When the automatic transmission 24 is downshifted during deceleration in a low vehicle speed range, the CB oil pressure PRcb is controlled while suppressing the occurrence of shift shock. is a flow chart explaining the control operation for ensuring, for example, iteratively executed. 3 and 4 are diagrams showing examples of time charts when the control operation shown in the flowchart of FIG. 2 is executed.

In FIG. 2, each step in the flow chart corresponds to the function of the shift control section 96. As shown in FIG. In step (hereinafter, step is omitted) S10, it is determined whether or not the brake is turned on. If the determination in S10 is negative, this routine is terminated. If the determination in S10 is affirmative, it is determined in S20 whether or not a 2→1 downshift has been determined. If the determination in S20 is negative, this routine is terminated. If the determination in S20 is affirmative, in S30 control is performed to complete the preparation phase of the 2->1 downshift phase, that is, clutch preparation for first speed engagement is performed. Next, in S40, it is determined whether or not the brake is on and the vehicle is stopped. If the determination in S40 is negative, it is determined in S50 whether or not the brake-off operation has been performed. If the determination in S50 is negative, the process returns to S40. If the determination in S40 is affirmative, in S60, the downshift to the first speed gear stage following the preparation of the clutch for engagement of the first speed is advanced. On the other hand, if the determination in S50 is affirmative, in S70, the clutch preparation for engaging the first speed is released, the gear is returned to the second speed, and the second speed is maintained.

FIG. 3 is a diagram showing an example of a case in which the brake is turned on and the vehicle is stopped after a 2 to 1 downshift is started while the vehicle is decelerating in a predetermined low vehicle speed range. In FIG. 3, time t1a indicates the time at which clutch preparation for engaging the first gear is started at a predetermined low vehicle speed in a 2->1 downshift determined during deceleration. When the clutch preparation for first speed engagement is started, the second engagement device CB2, which is the disengagement side engagement device, is made to stand by with a torque capacity that can handle the input torque Tin to the automatic transmission 24, and the engagement side. Each indicated pressure is output to bring the first engagement device CB1, which is the engagement device, into a packing completion state in which the pack clearance is reduced (refer to time t1a-t2a). When the vehicle is stopped during execution of the shift delay control CTsd for maintaining the state in which the clutch preparation for first speed engagement is completed (see time t2a), the torque capacity of the second engagement device CB2 is gradually decreased and the torque capacity of the first engagement device CB1 is reduced. Each command pressure for gradually increasing the torque capacity is output, and the downshift to the first speed gear stage following the preparation of the clutch for engagement of the first speed is advanced (see after time t2a). Thus, when the brake is on and the vehicle is stopped, the 2→1 downshift is executed until it is completed.

FIG. 4 is a diagram showing an example of a case in which a brake-off operation is performed before the vehicle stops after a 2->1 downshift is started while the vehicle is decelerating in a predetermined low vehicle speed range. In FIG. 4, time t1b indicates the time at which clutch preparation for engaging the first gear is started at a predetermined low vehicle speed in the 2->1 downshift determined during deceleration. After the start of clutch preparation for first speed engagement, during the execution transition of clutch preparation for first speed engagement (see time t1b-t2b), if a brake off operation is performed before the vehicle stops (see time t2b), Instruction pressures for quickly increasing the hydraulic pressure of the second engagement device CB2 and quickly decreasing the hydraulic pressure of the first engagement device CB1 are output, and the gear is returned to the second gear stage (see time t2b and later). . In this way, when the brake is turned off during the shift delay control CTsd, the gear is returned to the second gear and the second gear is maintained.

As described above, according to this embodiment, when it is determined that the automatic transmission 24 should downshift during deceleration in a predetermined low vehicle speed range, the downshift phase is set to the preparation phase. The shift delay control CTsd is executed to keep the phase in the state where the preparation phase is completed until the vehicle stops, and after the vehicle stops, the phase next to the preparation phase is started and the downshift is started. is advanced, downshifting while driving is until packing is completed, and even if the start of downshifting is hastened, shift shock is unlikely to occur, and downshifting after stopping the vehicle is in a state where packing is completed. , and the shortage of the flow rate of the hydraulic oil OIL required for the engagement control of the engagement device CB is suppressed. Therefore, when the automatic transmission 24 is downshifted during deceleration in the low vehicle speed range, the CB oil pressure PRcb can be ensured while suppressing the occurrence of shift shock.

Another embodiment of the present invention will now be described. In the following description, the same reference numerals are given to the parts common to the embodiments, and the description thereof will be omitted.

The vehicle 10 may have a power performance-oriented mode MRpwr, which is a predetermined running mode that emphasizes power performance over suppression of shift shock, such as a towing mode, an AWD mode, and a manual mode. The towing mode is a predetermined traveling mode suitable for towing a vehicle to be towed, and is selected, for example, by the driver operating a towing mode selection switch (not shown). In the AWD mode, the driving state of the vehicle 10 is AWD (=all wheels drive mode, which is selected, for example, by the driver's operation of an AWD mode selection switch (not shown). For example, if the vehicle 10 includes a transfer (not shown) in the power transmission path between the automatic transmission 24 and the differential gear 30, the transfer transfers the power transmitted from the automatic transmission 24 to the drive wheels 14, for example. or distributed to the front and rear wheels respectively. Furthermore, when the transfer is provided with a sub-transmission that can be switched between a high gear that is a gear on the high speed side and a low gear that is a gear on the low speed side, and power is transmitted via this sub-transmission, AWD mode A high gear AWD mode in which the sub-transmission is in a high gear stage in AWD state and a low gear AWD mode in which the sub-transmission is in a low gear stage in AWD state can be selected by operating the AWD mode selection switch. . The manual mode is a predetermined traveling mode that enables manual shifting of the automatic transmission 24 by a driver's shift operation, and is selected by the driver's shift operation, for example. The shift operation by the driver for selecting the manual mode is, for example, a shift operation in which a shift operation position on a shift lever (not shown) is set to a manual shift operation position, or a paddle switch (not shown) provided on the steering wheel. is a shift operation by operating . The vehicle 10 further has, for example, a sport mode and a normal mode as driving modes, apart from the power performance-oriented mode MRpwr. The sports mode is a predetermined driving mode for improving driving performance, and is selected, for example, by the driver's operation of a sports mode selection switch (not shown). The normal mode is a predetermined running mode in which fuel consumption performance and power performance are well balanced, and is selected, for example, when the sport mode is not selected by the driver.

By the way, when the driving mode is set to the power performance emphasis mode MRpwr, if the shift delay control CTsd is executed in the 2→1 downshift to delay the switching to the first gear, the first gear There is a risk that the desired drive torque Tr at the stage and the ability to run on rough roads will be impaired.

Therefore, when the shift control unit 96 determines a downshift of the automatic transmission 24, for example, a 2→1 downshift during deceleration in a predetermined low vehicle speed range, the running mode of the vehicle 10 is set to the power performance emphasis mode MRpwr. In some cases, the shift delay control CTsd is prohibited, and the 2→1 downshift proceeds without executing the shift delay control CTsd. On the other hand, when the shift control unit 96 determines that the automatic transmission 24 should downshift during deceleration in a predetermined low vehicle speed range, the driving mode of the vehicle 10 is a driving mode other than the power performance emphasis mode MRpwr. In this case, the shift delay control CTsd is permitted and the shift delay control CTsd is executed.

FIG. 5 is a chart summarizing whether or not the shift delay control CTsd in the 2→1 downshift is executed, that is, whether or not the downshift to the first gear is delayed for each driving mode. In FIG. 5, the shift delay control CTsd is permitted when the running mode is, for example, the sport mode or the normal mode. On the other hand, when the driving mode is, for example, a high gear AWD mode, a power performance-oriented mode MRpwr such as a low gear AWD mode, a towing mode, or a manual mode, the shift delay control CTsd is prohibited.

In the power performance-oriented mode MRpwr, which requires driving torque Tr in rough roads and the driving torque Tr in the first gear, the state in which the operation of the engine 12 is continued, that is, the intermittent operation of the engine 12 is prohibited. It is thought that there are many Therefore, the operating state of the engine may be linked to whether or not the downshift to the first gear is delayed. For example, when intermittent operation of the engine 12 is prohibited, the shift delay control CTsd is prohibited.

FIG. 6 is a flow chart for explaining the main part of the control operation of the electronic control unit 90. When the automatic transmission 24 is downshifted during deceleration in a low vehicle speed range, the CB oil pressure PRcb is controlled while suppressing the occurrence of shift shock. is a flow chart explaining the control operation for ensuring, for example, iteratively executed. FIG. 6 is an embodiment different from the flow chart of FIG. In FIG. 6, points different from FIG. 2 will be mainly described.

In FIG. 6, following S30, in S35, it is determined whether or not the running mode of the vehicle 10 is the power performance emphasis mode MRpwr. If the determination in S35 is negative, S40 is executed. If the determination of S35 is affirmative, or if the determination of S40 is affirmative, S60 is executed.

As described above, according to this embodiment, when it is determined that the automatic transmission 24 should downshift during deceleration in a predetermined low vehicle speed range, the running mode of the vehicle 10 is the power performance-oriented mode MRpwr. In this case, the downshift proceeds without execution of the shift delay control CTsd, so that the desired drive torque Tr is easily achieved and deterioration of rough road running performance is suppressed.

Although the embodiments of the present invention have been described in detail above with reference to the drawings, the present invention is also applicable to other aspects.

For example, in the second embodiment described above, the high gear AWD mode, the low gear AWD mode, the towing mode, and the manual mode were exemplified as the power performance emphasis mode MRpwr, but the mode is not limited to this. For example, the power performance emphasis mode MRpwr may be an off-road mode, a circuit mode, or the like. The off-road mode is a predetermined driving mode for improving off-road drivability, and is selected, for example, by the driver operating an off-road mode selection switch (not shown). The circuit mode is a predetermined driving mode for improving driving performance on a closed course such as a circuit, and is selected, for example, by the driver's operation of a circuit mode selection switch (not shown). Alternatively, the sport mode may be included in the power performance emphasis mode MRpwr. In short, the power performance-oriented mode MRpwr may be any driving mode that requires rough road running performance and driving torque Tr in the first gear stage.

Further, in the above embodiment, the vehicle 10 including the engine 12, the electric motor MG, and the automatic transmission 24 was illustrated as the vehicle to which the present invention is applied, but the present invention is not limited to this aspect. For example, an engine vehicle having at least an engine as a power source, an electric vehicle having only an electric motor as a power source without an engine, a hybrid vehicle having an automatic transmission in series after a known electric continuously variable transmission, and the like. can also apply the present invention. Also, the automatic transmission 24 may be a known DCT (Dual Clutch Transmission) or the like. In the case of the DCT, the plurality of engagement devices are engagement devices connected to respective input shafts of two systems, one of the plurality of engagement devices corresponds to the release side engagement device, and the plurality of engagement devices The other corresponds to the engagement side engagement device. In short, it constitutes a part of the power transmission path between the power source and the driving wheels, and engages any one of a plurality of hydraulic engagement devices to shift any of a plurality of gear stages. The present invention can be applied to any vehicle provided with an automatic transmission in which gears are formed.

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

It should be noted that what has been described above is just one embodiment, and the present invention can be implemented in aspects with various modifications and improvements based on the knowledge of those skilled in the art.

10: Vehicle 14: Drive wheel 24: Automatic transmission 90: Electronic control device (control device)
96: shift control unit CB: engagement device CB1: first engagement device (engagement side engagement device)
CB2: Second engagement device (release side engagement device)
SP: power source

Claims (2)

A power source and any one of a plurality of gear stages by engagement of any one of a plurality of hydraulic engagement devices that form part of a power transmission path between the power source and drive wheels. A control device for a vehicle comprising an automatic transmission in which a gear stage of
The shift of the automatic transmission is performed by switching a release-side engagement device among the engagement devices to a released state and switching an engagement-side engagement device among the engagement devices to an engaged state. It includes a shift control unit that performs
When the shift control unit determines that the automatic transmission should downshift during deceleration in a predetermined low vehicle speed range, the shift control unit determines the progress stage of the downshift by setting the disengagement side engagement device to the automatic shift control unit. The downshift is started so as to make the engine stand by with a torque capacity that can handle the input torque to the machine and prepare the engagement side engagement device to be in a packing completion state in which the pack clearance is closed. and executing shift delay control to maintain the progress stage in the state where the preparation stage is completed until the vehicle stops, and after the vehicle stops, the progress stage next to the preparation stage is started and the progress stage is started. A control device for a vehicle, characterized by advancing a downshift. When the downshift is determined during deceleration, the shift control unit executes the shift delay control when the driving mode of the vehicle is a predetermined driving mode emphasizing power performance. 2. The control device for a vehicle according to claim 1, wherein said downshift is progressed without a shift.

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