JP2023114387A - Control device of vehicle - Google Patents

Abstract

To provide a control device of a vehicle capable of suppressing a shift shock due to a decrease in an indication pressure in a control device of a vehicle that learns and corrects an indication pressure of a release side engagement device and an engagement side engagement device during coast down shifting of an automatic transmission.SOLUTION: When executing coast down shifting to a first speed gear stage 1st of an automatic transmission 24 when a vehicle speed V is lower than a first predetermined vehicle speed V1, reflection gains K1 and K2 for previously learned learning values ΔPRcb1 and ΔPRcb2 are made small as compared to when the vehicle speed V is the first predetermined vehicle speed V1 or higher so that indication pressures PRcb1 and PRcb2 are inhibited from being excessively decompressed. Consequently, during coast down shifting after the vehicle is stopped, blow-up of a turbine rotation speed Nt (namely, AT input shaft rotation speed Ni) of the automatic transmission 24 is inhibited, and a shift shock attributed to the blow-up can be inhibited.SELECTED DRAWING: Figure 1

Description

The present invention relates to a control device for a vehicle having a stepped automatic transmission.

Patent Document 1 discloses a device that includes a stepped automatic transmission and corrects the command pressures of the release-side engagement device and the engagement-side engagement device by learning during the coast downshift of the automatic transmission. When the amount of change in the learning value of the side engaging device and the engaging side engaging device is a negative value (releasing of the releasing side engaging device is slow and engagement of the engaging side engaging device is fast), the releasing side It is described that prohibiting update of the learning value of the engagement device or prohibiting update of the learning value of the engagement side engagement device.

JP 2018-17310 A

By the way, when the vehicle is coasting down to the first gear while the vehicle is running at a low speed, the turbine rotation speed reaches the synchronous rotation speed early, and the shift control is completed relatively early. At this time, the instructed pressure of at least one of the release-side engagement device and the engagement-side engagement device is learned in the decreasing direction. After that, when the coast-down shift to the first gear is performed after the vehicle has stopped, the input shaft rotation speed of the automatic transmission may rev up, and there is a possibility that the shift shock may occur due to this turbine rev-up. .

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and its object is to learn command pressures of a disengagement side engagement device and an engagement side engagement device during coast downshifting of an automatic transmission. The object of the present invention is to provide a vehicle control device capable of suppressing a shift shock caused by an input shaft rotational speed jump.

The gist of the first invention is that: (a) it is configured to include a plurality of engagement devices, and is capable of shifting to a plurality of gear stages by switching the engagement states of the plurality of engagement devices. Applied to a vehicle equipped with a stepped automatic transmission, learning and correcting the instruction pressure of a disengagement side engagement device released during the coast downshift of the automatic transmission, and coasting downshift of the automatic transmission. 1. A control device for a vehicle, comprising: a learning control unit that learns and corrects an indicated pressure of an engagement-side engagement device engaged therein, wherein: (b) the learning control unit has a vehicle speed set in advance; When coasting downshifting to the first gear stage of the automatic transmission is carried out when the vehicle speed is less than the predetermined vehicle speed, the reflection gain for the learning value learned during the previous coasting downshifting is set to the predetermined vehicle speed or higher. It is characterized by being made smaller compared to the case of .

According to the first aspect of the invention, when the vehicle speed is less than the predetermined vehicle speed and the coast-down shift to the first gear of the automatic transmission is performed, the reflection gain for the previously learned learning value is equal to or greater than the predetermined vehicle speed. Since it is made smaller by comparison, excessive reduction of the indicated pressure is suppressed. As a result, in the coast downshift after the vehicle has stopped, the input shaft rotation speed of the automatic transmission can be suppressed from racing up, and the shift shock caused by this racing can be suppressed.

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 control functions and main parts of a control system for various controls in the vehicle; FIG. FIG. 2 is an engagement actuation table showing combinations of respective engagement devices for establishing gear stages of the automatic transmission of FIG. 1; FIG. FIG. 5 is a time chart for explaining a control state during coastdown from 2nd gear to 1st gear; FIG. 4 is a flow chart for explaining the main part of the control operation of the electronic control device;

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following examples, the drawings are appropriately simplified or modified, and the dimensional ratios, shapes, etc. of each part are not necessarily drawn accurately.

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 including an engine 12 and an electric motor MG, which are driving force sources for running. 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 so-called motor generator that has a function as a motor that generates mechanical power from electric power and a function as a generator that generates power from mechanical power. Electric motor MG is connected to a battery 54 provided in vehicle 10 via an inverter 52 provided in vehicle 10 . 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.

The electric motor MG generates power for running from electric power supplied from a battery 54 via an inverter 52 instead of or in addition to the engine 12 . Further, the electric motor MG generates power using the power of the engine 12 and the driven power input from the drive wheel 14 side. Electric power generated by electric power generation by electric motor MG is stored in battery 54 via inverter 52 . The battery 54 is a power storage device that transfers electric power to and from the electric motor MG. The electric power is the same as electric energy unless otherwise distinguished. In addition, the aforementioned motive power is synonymous with torque and force unless otherwise specified.

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 interposed in a power transmission path between torque converter 22 and drive wheels 14 . Torque converter 22 and automatic transmission 24 each form part of a power transmission path between engine 12 and drive wheels 14 . The power transmission device 16 also 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 differential gear 30 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. The electric motor MG is coupled to a power transmission path between the engine 12 and the driving wheels 14, particularly a power transmission path between the K0 clutch 20 and the torque converter 22 so as to be able to transmit power. That is, 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. From another point of view, the torque converter 22 and the automatic transmission 24 each form part of a power transmission path between the electric motor MG and the drive wheels 14 . Torque converter 22 and automatic transmission 24 each transmit the driving force from each of the driving force sources of engine 12 and electric motor MG to drive wheels 14 .

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 pump impeller 22a is connected to the engine 12 via the K0 clutch 20 and directly connected to the electric motor MG. Pump impeller 22 a is an input member of torque converter 22 , and turbine impeller 22 b is an output member of torque converter 22 . The electric motor connecting shaft 36 is also an input rotating member of the torque converter 22 . The transmission input shaft 38 is also an output rotating member of the torque converter 22 integrally formed with a turbine shaft rotationally driven by the turbine impeller 22b. Torque converter 22 is a hydrodynamic transmission device that transmits driving force from each of the driving force sources (engine 12, electric motor MG) to transmission input shaft 38 via fluid. The torque converter 22 includes an LU clutch 40 that connects and disconnects between the pump impeller 22a and the turbine impeller 22b. The LU clutch 40 is a known lockup clutch.

The LU clutch 40 is controlled by changing the LU clutch torque Tlu, which is the torque capacity of the LU clutch 40, by the regulated LU hydraulic pressure PRlu supplied from the hydraulic control circuit 56 provided in the vehicle 10. state can be switched. The control states of the LU clutch 40 include a completely released state in which the LU clutch 40 is released, a slip state in which the LU clutch 40 is engaged with slippage, and a non-slip engagement state. There is a fully engaged state, which is the state of engagement.

The automatic transmission 24 is a known planetary gear type automatic transmission including, for example, one or a plurality of sets of planetary gears (not shown) and a plurality of engagement devices CB. The engagement device CB is, for example, a hydraulic friction engagement device composed of a multi-plate or single-plate clutch or brake that is pressed by a hydraulic actuator, or a band brake that is tightened by a hydraulic actuator. Each of the engagement devices CB is controlled such as in the engagement state and the disengagement state by changing the CB torque Tcb, which is the respective torque capacity, by the regulated engagement pressure PRcb supplied from the hydraulic control circuit 56. state can be switched. In this embodiment, the engagement device CB is composed of, for example, four clutches C1 to C4 and two brakes B1 and B2.

The automatic transmission 24 has a gear ratio (also referred to as a gear ratio) γat (=AT input shaft rotation speed Ni/AT output shaft rotation speed) by engaging any one of the engagement devices CB. This is a stepped automatic transmission in which one of a plurality of gear stages (also referred to as gear stages) having different speed No. is formed. In other words, the automatic transmission 24 shifts to a plurality of speed stages by switching the engagement states of a plurality of engagement devices CB (clutches C1 to C4 and brakes B1 and B2). Specifically, the automatic transmission 24 is shifted based on an engagement actuation table representing combinations of the respective engagement devices CB for establishing the gear stages of the automatic transmission 24 shown in FIG. In FIG. 2, "o" indicates engagement of each engagement device CB (clutches C1 to C4 and brakes B1 and B2), and "x" indicates disengagement of each engagement device CB. As shown in FIG. 2, the automatic transmission 24 is configured to be switchable to the 10th gear by changing the combination of engagement and release of each engagement device CB.

The automatic transmission 24 determines the shift stage based on the accelerator opening θacc, which is the amount of operation of the accelerator pedal 42 by the driver, and the vehicle speed V by an electronic control unit 90, which will be described later. It should be noted that the shift determination may be made based not only on the accelerator opening .theta.acc, but also on a related value of the accelerator opening .theta.acc, such as the throttle valve opening .theta.th, which is correlated with the accelerator opening .theta.acc. Similarly, the gear shift may be determined based not only on the vehicle speed V, but also on a value related to the vehicle speed V, such as the AT output shaft rotation speed No. The AT input shaft rotation speed Ni is the rotation speed of the transmission input shaft 38 . The AT input shaft rotation speed Ni is also the rotation speed of the output rotation member of the torque converter 22 and has the same value as the turbine rotation speed Nt, which is the output rotation speed of the torque converter 22 . Therefore, the AT input shaft rotation speed Ni can be represented by the turbine rotation speed Nt. The AT output shaft rotation speed No is the rotation speed of the transmission output shaft 26 and the output shaft rotation speed of the automatic transmission 24 .

The K0 clutch 20 is a wet or dry friction engagement device composed of a multi-plate or single-plate clutch pressed by a hydraulic actuator (not shown). The K0 clutch 20 is switched between control states such as an engaged state and a disengaged state by controlling the operating state of a hydraulic actuator by an electronic control unit 90, which will be described later. In the K0 clutch 20, when the K0 hydraulic pressure PRk0 regulated from the hydraulic control circuit 56 is supplied to the hydraulic actuator, the K0 torque Tk0, which is the torque capacity of the K0 clutch 20, is changed, thereby changing the control state of the K0 clutch 20. can be switched.

In the engaged state of the K0 clutch 20, the pump impeller 22a and the engine 12 are integrally rotated via the engine connecting shaft . That is, the K0 clutch 20 couples the engine 12 and the drive wheels 14 so as to be able to transmit power when engaged. On the other hand, in the released state of the K0 clutch 20, power transmission between the engine 12 and the pump impeller 22a is interrupted. That is, the K0 clutch 20 disconnects the engine 12 and the drive wheels 14 by being released. Since the electric motor MG is connected to the pump impeller 22a, the K0 clutch 20 is provided in the power transmission path between the engine 12 and the electric motor MG and functions as a clutch that connects and disconnects the power transmission path. That is, the K0 clutch 20 is a connecting/disconnecting clutch that connects the engine 12 and the electric motor MG when it is engaged, and disconnects the connection between the engine 12 and the electric motor MG when it is released.

In the power transmission device 16, the power output from the engine 12 when the K0 clutch 20 is engaged 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. Further, regardless of the control state of the K0 clutch 20, 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, and the like. The power is transmitted to the driving wheels 14 through successively.

The vehicle 10 includes a mechanical oil pump 58 (hereinafter referred to as MOP 58), an electric oil pump 60 (hereinafter referred to as EOP 60), a pump motor 62, and the like. The MOP 58 is connected to the pump impeller 22a, and is driven to rotate by a driving force source (engine 12, electric motor MG) to discharge hydraulic oil used in the power transmission device 16. As shown in FIG. The pump motor 62 is a motor dedicated to the EOP 60 for driving the EOP 60 to rotate. The EOP 60 is rotationally driven by a pump motor 62 to discharge hydraulic oil. Hydraulic fluid discharged from the MOP 58 and the EOP 60 is supplied to the hydraulic control circuit 56 . The hydraulic control circuit 56 supplies the engagement pressure PRcb, the K0 hydraulic pressure PRk0, the LU hydraulic pressure PRlu, etc., which are adjusted based on the hydraulic fluid discharged by at least one of the MOP58 and the EOP60.

The vehicle 10 further includes an electronic control unit 90 including control units related to travel control of the vehicle 10 and the like. 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, hydraulic control, etc., as required. Note that the electronic control device 90 corresponds to the control device of the present invention.

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 shaft rotation speed sensor 74, the MG rotation speed sensor 76, the accelerator opening sensor 78, the throttle valve opening sensor 80, brake switch 82, battery sensor 84, oil temperature sensor 86). A certain turbine rotation speed Nt, AT output shaft rotation speed No corresponding to vehicle speed V, MG rotation speed Nm which is the rotation speed of the electric motor MG, and the operation amount of the accelerator pedal 42 by the driver representing the magnitude of the driver's acceleration operation. A certain accelerator opening .theta.acc, a throttle valve opening .theta.th which is the opening of the electronic throttle valve, a brake-on signal Bon which is a signal indicating that the brake pedal 44 for operating the wheel brake is being operated by the driver, and the battery 54. , a battery temperature THbat, a battery charging/discharging current Ibat, a battery voltage Vbat, and a working oil temperature THoil, which is the temperature of the working oil in the hydraulic control circuit 56, are supplied.

From the electronic control device 90, various command signals (for example, an engine signal for controlling the engine 12) are sent to each device (for example, the engine control device 50, the inverter 52, the hydraulic control circuit 56, the pump motor 62, etc.) provided in the vehicle 10. Control command signal Se, MG control command signal Sm for controlling electric motor MG, CB hydraulic control command signal Scb for controlling engagement device CB, K0 hydraulic control command signals Sko and LU for controlling 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.

In order to realize various controls in the vehicle 10, the electronic control unit 90 includes a hybrid control unit 92 functioning as hybrid control means, a clutch control unit 94 functioning as clutch control means, and a shift control unit functioning as shift control means. 96 and a learning control unit 98 functioning as learning control means.

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

The hybrid control unit 92 calculates the required drive amount for the vehicle 10 by the driver by applying the accelerator opening θacc and the vehicle speed V to the required drive amount map, for example. The required drive amount map is a relation that is experimentally or design-determined in advance and stored, that is, a predetermined relation. The required driving amount is, for example, the required driving torque Trdem in the driving 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 driving wheels 14, the required AT output torque at the transmission output shaft 26, and the like can be used. In calculating the required drive amount, the AT output shaft rotational speed No may be used instead of the vehicle speed V. FIG.

The hybrid control unit 92 realizes the required driving torque Trdem in consideration of the transmission loss, the auxiliary load, the gear ratio γat of the automatic transmission 24, the chargeable power Win and the dischargeable power Wout of the battery 54, and the like. and the target MG torque Tmdem of the electric motor MG are calculated. The hybrid control unit 92 outputs to the engine control device 50 an engine control command signal Se for the engine 12 outputting the calculated target engine torque Tedem. The hybrid control unit 92 also outputs to the inverter 52 an MG control command signal Sm for the electric motor MG to which the calculated target MG torque Tmdem is output. The engine control command signal Se is, for example, a command value of the engine power Pe, which is the power of the engine 12 that outputs the target engine torque Tedem at the engine rotation speed Ne at that time. The MG control command signal Sm is, for example, a command value for the power consumption Wm of the electric motor MG that outputs the target MG torque Tmdem at the MG rotational speed Nm at that time.

The chargeable power Win of the battery 54 is the maximum power that can be input that defines the limit of the input power of the battery 54 and indicates the input limit of the battery 54 . The dischargeable power Wout of the battery 54 is the maximum power that can be output that defines the limit of the output power of the battery 54 and indicates the output limit of the battery 54 . The chargeable power Win and the dischargeable power Wout of the battery 54 are calculated by the electronic control unit 90 based on the battery temperature THbat and the state of charge value SOC [%] of the battery 54, for example. The state-of-charge value SOC of the battery 54 is a value indicating the state of charge (amount of charge, remaining charge) of the battery 54, and is calculated by the electronic control unit 90 based on, for example, the battery charge/discharge current Ibat and the battery voltage Vbat. .

The hybrid control unit 92 sets the driving mode to the motor driving (hereinafter referred to as BEV driving) mode when the required drive torque Trdem can be covered only by the output of the electric motor MG. In the BEV travel mode, the hybrid control unit 92 performs BEV travel in which the K0 clutch 20 is released and only the electric motor MG is used as the driving force source. On the other hand, the hybrid control unit 92 sets the driving mode to the engine driving mode, that is, the hybrid driving (hereinafter referred to as HEV driving) mode when the required drive torque Trdem cannot be met without using at least the output of the engine 12 .

In the HEV travel mode, the hybrid control unit 92 performs engine travel, ie, HEV travel, in which the vehicle travels using the engine 12 and the electric motor MG as driving force sources while the K0 clutch 20 is engaged. On the other hand, even when the required drive torque Trdem can be covered only by the output of the electric motor MG, the hybrid control unit 92 controls the state of charge value SOC of the battery 54 to be less than the predetermined engine start threshold value or the engine 12 or the like. When it is necessary to warm up the engine, the HEV running mode is established. The engine start threshold is a predetermined threshold for determining the state of charge value SOC at which it is necessary to forcibly start the engine 12 and charge the battery 54 . In this manner, the hybrid control unit 92 automatically stops the engine 12 during HEV travel, restarts the engine 12 after stopping the engine, or restarts the engine 12 during BEV travel, based on the required driving torque Trdem. The BEV running mode and the HEV running mode are appropriately switched by starting the vehicle.

The clutch control unit 94 controls the K0 clutch 20 according to the running mode during running. For example, when switching to the HEV travel mode is determined during BEV travel, the clutch control unit 94 performs engagement control of the K0 clutch 20 so as to execute start control of the engine 12 . For example, when it is determined that there is a request to start the engine 12 based on the running state, the clutch control unit 94 controls the torque necessary for cranking the engine 12 (cranking torque) to the engine 12 side, the K0 hydraulic control command signal Sko for controlling the released K0 clutch 20 toward the engaged state is output to the hydraulic control circuit 56. do.

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 pressure control command signal for executing shift control for the automatic transmission 24 as necessary. Scb is output to the hydraulic control circuit 56 . 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 accelerator opening .theta.acc as variables. In the shift map, instead of the vehicle speed V, the AT output shaft rotational speed No may be used as a related value of the vehicle speed V, and instead of the accelerator opening θacc, a related value of the accelerator opening θacc may be , the required drive torque Trdem, the required drive force Frdem, the throttle valve opening θth, and the like may be used.

For example, when the shift control unit 96 determines that a downshift should be executed during coasting (inertia running) with the accelerator pedal 42 not depressed (accelerator pedal off), the automatic transmission with the accelerator pedal off. 24 starts coast downshift. At this time, the shift control unit 96 releases the disengagement-side engagement device CB (hereinafter referred to as disengagement-side engagement device CB1) that is disengaged during the shift, and disengages the engagement-side engagement device that is engaged during the shift. Clutch-to-clutch control is executed to engage the device CB (hereinafter referred to as engagement side engagement device CB2).

In the following, shift control during coast downshifting of the automatic transmission 24 will be described by taking downshifting from the 2nd gear 2nd to the 1st gear 1st as an example. FIG. 3 is a time chart showing the control state during the coast downshift from the 2nd gear stage 2nd to the 1st gear stage 1st. In the above time chart, when the vehicle speed V is extremely low, specifically, the turbine rotation speed Nt (that is, the input shaft rotation speed Nin) is lower than the preset idle rotation speed Neidle of the engine 12. corresponds to the case. In the downshift from the second gear stage 2nd to the first gear stage 1st, the brake B1 is released and the clutch C2 is engaged. That is, the brake B1 corresponds to the release side engagement device of the present invention, and the clutch C2 corresponds to the engagement side engagement device of the present invention.

During coasting (inertia running) with the accelerator pedal off, the shift control unit 96 shifts the downshift line (2-1 downshift line) predefined in the shift map as the vehicle speed V decreases. When it is determined that the vehicle has crossed over, the coast down shift to the first gear stage 1st is started. The start point of the coast down shift to the first gear 1st of the automatic transmission 24 corresponds to the point t1 in FIG.

When the coast downshift is started at time t1, the indicated pressure PRb1 of the brake B1, which is the disengagement side engagement device CB1, is rapidly lowered to a preset predetermined pressure. It is gradually decreased toward the set standby pressure Pst1 (time t1 to time t2). Further, regarding the clutch C2, which is the engaging device CB2, at time t1, a so-called quick fill is executed to temporarily increase the instructed pressure PRc2 of the clutch C2 to a preset predetermined pressure. Quick fill is performed to improve the responsiveness of the engagement hydraulic pressure PRc2 (actual hydraulic pressure) of the clutch C2. When the quick fill ends, the indicated pressure PRc2 is maintained at the preset standby pressure Pst2 (time t1 to time t2).

When the inertia phase starts at time t2, the turbine rotation speed Nt increases, and at time t3, the turbine rotation speed Nt rises above the 1st gear synchronous rotation speed N1, causing blow-up. It should be noted that the first gear synchronous rotation speed N1 is calculated as needed by multiplying the gear ratio γ1 of the first gear stage 1st by the output shaft rotation speed Nout. Here, the reason why the turbine rotation speed Nt blows up even in the coast down shift is that the turbine rotation speed Nt is lower than the idle rotation speed Neidle of the engine 12, so even during coasting. This is because it is substantially in a state of being driven by the engine 12 (a state in which the engine 12 increases the turbine rotation speed Nt).

When the turbine rotation speed Nt is detected to be racing up at time t3, the indicated pressure PRb1 for the brake B1 is reduced toward zero (that is, completely released). Also, the indicated pressure PRc2 for the clutch C2 is increased at a preset gradient. At time t4, when it is determined that the turbine rotation speed Nt has synchronized with the first-gear synchronous rotation speed N1, it is determined that the inertia phase has ended, and the indicated pressure PRc2 for the clutch C2 is raised to fully engage the clutch C2. be combined.

In this embodiment, the target value S* of the turbine blow-up amount S (hereinafter referred to as the blow-up amount S) at the turbine rotation speed Nt during the coast down shift of the automatic transmission 24, and the inertia phase start from the shift start time. A target value Ts* of the inertia phase start time Ts, which is the time up to the point in time, is set in advance. Then, during the coast downshift, the release side engagement device CB1 (the brake in the coast downshift from the above-described 2nd gear 2nd to the 1st gear 1st) is adjusted so that the inertia phase start time Ts becomes the target value Ts*. A command pressure PRcb1 (corresponding to the command pressure PRb1 in FIG. 3) of B1) is set. In addition, the engagement side engagement device CB2 (the clutch C2 in the downshift from the second gear 2nd to the first gear 1st) is adjusted so that the blow-up amount S of the turbine rotation speed Nt becomes the target value S*. is set as the indicated pressure PRcb2 (corresponding to the indicated pressure PRc2 in FIG. 3). The instruction pressure PRcb1 for the disengagement side engagement device CB1 and the instruction pressure PRcb2 for the engagement side engagement device CB2 are learned and corrected (updated) each time the coast down shift is performed. Since the turbine rotation speed Nt is the same as the input shaft rotation speed Nin of the transmission input shaft 38 of the automatic transmission 24, the blow-up amount S of the turbine rotation speed Nt is may be read as the blow-up amount S of the input shaft rotation speed Nin.

The learning control unit 98 learns and corrects the instruction pressure PRcb1 of the disengagement-side engagement device CB1 that is released during the coast downshift of the automatic transmission 24, and is engaged during the coast downshift of the automatic transmission 24. It has a function of learning and correcting the instructed pressure PRcb2 of the engagement side engagement device CB2. When it is determined that the automatic transmission 24 is to coast down, the learning control unit 98 starts learning the disengagement side engagement device CB1 and the engagement side engagement device CB2.

First, a method of calculating the learning value ΔPRcb1 of the indicated pressure PRcb1 of the disengagement side engagement device CB1 will be described. The learning control section 98 calculates a learning value ΔPRcb1 of the command pressure PRcb1 of the disengagement side engagement device CB1 based on the inertia phase start time Ts. When the coast downshift is started, the learning control unit 98 measures an inertia phase start time Ts (see FIG. 3) from the shift start time (time t1 in FIG. 3) to the start of the inertia phase. The start of the inertia phase is determined, for example, based on whether or not the amount of change (here, the amount of increase) of the turbine rotation speed Nt per unit time exceeds a predetermined determination threshold. When the coast down shift is completed, the inertia phase start time error ΔTs (=Ts−Ts*), which is the deviation (error) between the measured inertia phase start time Ts and the target value Ts* of the inertia phase start time Ts, is calculated. calculate.

The learning control unit 98 calculates a learning value ΔPRcb1 (correction amount) of the command pressure PRcb1 of the disengagement side engagement device CB1 based on the calculated inertia phase start time error ΔTs (hereinafter referred to as start time error ΔTs). The learning control unit 98 stores a relationship map between the preset start time error ΔTs and the learning value ΔPRcb1. By applying the calculated start time error ΔTs to this relationship map, the release side engagement A learning value ΔPRcb1 for the device CB1 is calculated.

Next, a method of calculating the learned value ΔPRcb2 of the indicated pressure PRcb2 of the engagement-side engagement device CB2 will be described. The learning control section 98 calculates a learning value ΔPRcb2 of the command pressure PRcb2 of the engagement side engagement device CB2. The learning control unit 98 detects an increase in the turbine rotational speed Nt that occurs during the inertia phase when the coast downshift is started. Specifically, when the turbine rotation speed Nt becomes higher than the first-gear synchronous rotation speed N1, the learning control unit 98 controls the turbine rotation speed Nt and the first-gear synchronous rotation speed, which are values related to the blow-up of the turbine rotation speed Nt. A difference ΔNt (=Nt−N1) from N1 is calculated at any time, and a racing amount S is calculated by integrating the difference ΔNt calculated at any time. When the turbine rotation speed Nt synchronizes with the first gear synchronous rotation speed N1, the learning control unit 98 determines that the blow-up of the turbine rotation speed Nt has converged, and ends the calculation of the difference ΔNt and the amount of blow-up S. . The blow-up amount S corresponds to the area of the hatched portion in FIG.

Next, the learning control section 98 calculates a learning value ΔPRcb2 of the indicated pressure PRcb2 of the engagement-side engagement device CB2 based on the calculated blow-up amount S. The learning control unit 98 stores, for example, a relationship map between the preset blow-up amount S and the learning value ΔPRcb2. A learned value ΔPRcb2 of the command pressure PRcb2 of the engagement device CB2 is calculated.

The learning control unit 98 calculates the learning value ΔPRcb1 of the disengagement side engagement device CB1 and the learning value ΔPRcb2 of the engagement side engagement device CB2 and stores each value. At the next coast downshift, the learning control unit 98 multiplies the instructed pressure PRcb1 of the disengagement side engagement device CB1 by the learning value ΔPRcb1 calculated at the previous coast downshift and the preset reflection gain K1. By adding (=K1×ΔPRcb1) (=PRcb1+K1×ΔPRcb1), the indicated pressure PRcb1 is corrected (updated) to a new value. Similarly, the learning control unit 98 adds the reflection gain K2 preset to the learning value ΔPRcb2 calculated at the previous coast down shift to the command pressure PRcb2 of the engagement side engagement device CB2 at the next coast down shift. By adding the multiplied value (K2×ΔPRcb2) (=PRcb2+K2×ΔPRcb2), the indicated pressure PRcb2 is corrected (updated) to a new value.

By the way, in the initial state of shipment of the vehicle 10, in order to avoid a shock due to the blow-up of the turbine rotation speed Nt in the coast downshift to the first gear stage 1st, the command pressure PRcb1 of the disengagement side engagement device CB1 and the engagement side Both the command pressure PRcb2 of the engagement device CB2 is set relatively high. Therefore, as the coast downshift to the first gear stage 1st progresses, at least one of the indicated pressure PRcb1 for the disengagement side engagement device CB1 and the indicated pressure PRcb2 for the engagement side engagement device CB2 is corrected to the pressure reducing side. becomes. Therefore, when at least one of the command pressures PRcb1 and PRcb2 is reduced and the coast downshift to the first gear stage 1st is performed while the vehicle is stopped, the turbine rotational speed Nt rises during the coastdown shift, and this There is a possibility that a shift shock due to racing may occur.

Since the turbine rotation speed Nt is zero when the vehicle is stopped, the turbine rotation speed Nt is synchronized with the post-shift synchronous rotation speed (zero rotation) when the coast down shift is started. Therefore, the torque phase is quickly started and the engagement pressure of the engagement side engagement device CB2 is increased, but the torque phase is started before the packing of the engagement side engagement device CB2 is completed. Therefore, the turbine rotational speed Nt is likely to blow up. Furthermore, if at least one of the indicated pressure PRcb1 for the disengagement side engagement device CB1 and the indicated pressure PRcb2 for the engagement side engagement device CB2 is corrected to the pressure reduction side each time the coast down shift is executed, the engagement device Due to the lack of hydraulic pressure in the CB, the turbine rotational speed Nt blows up.

On the other hand, when the vehicle speed V is less than the preset first predetermined vehicle speed V1, the learning control unit 98 performs the coast down shift to the first gear stage 1st of the automatic transmission 24. , the reflected gains K1 and K2 for the learned values .DELTA.PRcb1 and .DELTA.PRcb2 learned during the previous coast downshift are made smaller than when the vehicle speed V is equal to or higher than the first predetermined vehicle speed V1. The first predetermined vehicle speed V1 is obtained experimentally or by design in advance, and is set to a very low vehicle speed (for example, about 2 to 3 km/h) immediately before the vehicle 10 stops. Note that the first predetermined vehicle speed V1 corresponds to the predetermined vehicle speed of the present invention.

Further, the values of the reflected gains K1 and K2 are determined experimentally or by design in advance. is set to a value that suppresses blow-up of the turbine rotation speed Nt due to excessive pressure reduction. Also, the values of the reflection gains K1 and K2 may be changed according to the vehicle speed V. FIG. For example, the reflection gains K1 and K2 are reduced as the vehicle speed V decreases. That is, the reflection gains K1 and K2 are set so that the learning values ΔPRcb1 and ΔPRcb2 are reflected less as the vehicle speed V decreases. Also, the reflected gains K1 and K2 may be zero. In other words, reflection of the learned values ΔPRcb1 and ΔPRcb2 of the command pressures PRcb1 and PRcb2 may be prohibited.

When the vehicle speed V is at a very low speed less than the first predetermined vehicle speed V1, the difference in rotation between the turbine rotation speed Nt and the synchronous rotation speed N1 of the first gear is small. reaches the 1st gear synchronous rotation speed N1. Therefore, after that, the torque phase starts immediately, and the engagement pressure of the engagement side engagement device CB2 is increased. Since the engagement pressure of the engagement device CB2 starts to increase, the hydraulic pressure of the engagement side engagement device CB2 becomes insufficient, and the turbine rotation speed Nt tends to rise. On the other hand, when the vehicle speed V is less than the first predetermined vehicle speed V1, the reflected gains K1 and K2 are smaller than when the vehicle speed V is equal to or higher than the first predetermined vehicle speed V1. Decreases in PRcb1 and PRcb2 are reduced. Therefore, the blow-up of the turbine rotation speed Nt due to the excessive decrease of the indicated pressures PRcb1 and PRcb2 is suppressed. Also, it is possible to suppress the shift shock caused by the rising of the turbine rotational speed Nt.

Further, when the vehicle speed V is less than the preset second predetermined vehicle speed V2, the learning control unit 98 performs a coast downshift to the first gear stage 1st of the automatic transmission 24. Learning (hydraulic pressure learning) of the command pressure PRcb1 of the engagement device CB1 and the command pressure PRcb2 of the engagement side engagement device CB2 is prohibited. That is, when the vehicle speed V is less than the preset second predetermined vehicle speed V2, the learning control unit 98 performs the coast downshift to the first gear stage 1st of the automatic transmission 24. The learning value ΔPRcb1 of the engagement device CB1 and the learning value ΔPRcb2 of the engagement side engagement device CB2 are not calculated.

Here, the second predetermined vehicle speed V2 is obtained experimentally or by design in advance, and is a threshold value of the vehicle speed V at which the accuracy of the learning values ΔPRcb1 and ΔPRcb2 calculated during the coast downshift is ensured (for example, about 5 km/h). is set to When the vehicle speed V is lower than the second predetermined vehicle speed V2, the difference in rotation between the turbine rotation speed Nt and the synchronous rotation speed N1 of the first gear is small. The 1st gear synchronous rotation speed N1 is reached. As soon as the turbine rotation speed Nt reaches the first gear synchronous rotation speed N1, the torque phase is started, and the engagement pressure of the engagement side engagement device is decreased while the engagement pressure of the engagement side engagement device is increased. However, the start timing of the torque phase is earlier than when the vehicle speed is equal to or higher than the second predetermined vehicle speed V2, and learning in such a state may result in erroneous learning. Therefore, when the vehicle speed V is less than the second predetermined vehicle speed V2, learning of the instruction pressures PRcb1 and PRcb2 is prohibited, thereby avoiding erroneous learning of the instruction pressures PRcb1 and PRcb2.

The second predetermined vehicle speed V2 (approximately 5 km/h) is set to a higher value than the first predetermined vehicle speed V1 (approximately 2-3 km/h). The second predetermined vehicle speed V2 is higher than the first predetermined vehicle speed V1. This is because there is a region (that is, V1<V<V2) in which learning values ΔPRcb1 and ΔPRcb2 can be reflected even though it is difficult to learn PRcb1 and PRcb2. As a result, when the vehicle speed V is less than the second predetermined vehicle speed V2, learning of the instruction pressures PRcb1 and PRcb2 is prohibited during the coast downshift to the first gear stage 1st. Erroneous learning due to learning of PRcb2 can be avoided.

FIG. 4 is a flow chart for explaining the main part of the control operation of the electronic control unit 90. When the command pressures PRcb1 and PRcb2 set during the coast downshift to the first gear stage 1st of the automatic transmission 24 are excessively FIG. 10 is a flowchart for explaining a control operation for suppressing blow-up of the turbine rotation speed Nt due to correction to the depressurization side; FIG. This flowchart is repeatedly executed while the vehicle 10 is running.

In FIG. 4, first, in step S10 (hereinafter, the step is omitted) corresponding to the control function of the shift control unit 96, it is determined whether or not the coast down shift to the first gear stage 1st of the automatic transmission 24 is started. is determined. If the determination in S10 is negative, this routine is terminated. If the determination in S10 is affirmative, in S20 corresponding to the control function of the learning control section 98, it is determined whether the vehicle speed V is less than the first predetermined vehicle speed V1. If the determination in S20 is negative, in S40 corresponding to the control function of the learning control section 98, the learning values ΔPRcb1 and ΔPRcb2 calculated at the time of the coast downshift to the previous first gear stage 1st are converted to the command pressures PRcb1. , PRcb2. On the other hand, if the determination in S20 is affirmative, in S30 corresponding to the control function of the learning control section 98, the learning values ΔPRcb1 and ΔPRcb2 calculated during the previous coast downshift are reflected in the indicated pressures PRcb1 and PRcb2. is prohibited. Alternatively, the reflected gains K1 and K2 are made smaller than the reflected gains K1 and K2 defined in the region where the vehicle speed V is equal to or higher than the first predetermined vehicle speed V1. That is, the degree of reflection of the learning values ΔPRcb1 and ΔPRcb2 on the command pressures PRcb1 and PRcb2 is lowered. At S50 corresponding to the control function of the learning control section 98, it is determined whether or not the vehicle speed V is less than the second predetermined vehicle speed V2. If the determination in S50 is negative, in S70 corresponding to the control function of the learning control section 98, learning of the indicated pressures PRcb1 and PRcb2 is permitted during coast downshifting to the first gear stage 1st. That is, calculation of the learning values ΔPRcb1 and ΔPRcb2 of the indicated pressures PRcb1 and PRcb2 is permitted. On the other hand, if the determination in S50 is affirmative, in S60 corresponding to the control function of the learning control section 98, learning of the indicated pressures PRcb1 and PRcb2 is prohibited during coast downshifting to the first gear stage 1st. That is, calculation of the learned values ΔPRcb1 and ΔPRcb2 of the indicated pressures PRcb1 and PRcb2 is prohibited.

As described above, according to this embodiment, when the vehicle speed V is less than the first predetermined vehicle speed V1 and the coast downshift to the first gear stage 1st of the automatic transmission 24 is performed, the previously learned learning Since the reflected gains K1 and K2 for the values ΔPRcb1 and ΔPRcb2 are made smaller than when the vehicle speed is equal to or higher than the first predetermined vehicle speed V1, the command pressures PRcb1 and PRcb2 are prevented from being excessively decreased. As a result, in the coast downshift after the vehicle has stopped, the turbine rotation speed Nt of the automatic transmission 24 (that is, the AT input shaft rotation speed Ni) can be suppressed from blowing up, and the shift shock caused by this blowing up can be suppressed. can.

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 above embodiment, vehicle 10 is a hybrid vehicle that includes engine 12 and electric motor MG as driving force sources, but the present invention is not necessarily limited to hybrid vehicles. For example, the vehicle may use only the engine 12 as a driving force source. In short, the present invention can be applied to any vehicle provided with a stepped automatic transmission having a plurality of engagement devices.

Further, the specific numerical values of the first predetermined vehicle speed V1 and the second predetermined vehicle speed V2 exemplified in the above-described embodiment are merely examples, and may be appropriately changed according to the type and structure of the vehicle.

Further, in the above-described embodiment, the indicated pressure PRcb1 for the disengagement side engagement device CB1 and the indicated pressure PRcb2 for the engagement side engagement device CB2 are set to the respective learned values ΔPRcb1 and ΔPRcb2 was not reflected, or the reflected gains K1 and K2 were lowered. , K2 may be reduced.

Further, in the above-described embodiment, when the vehicle speed V is less than the second predetermined vehicle speed V2, learning of the command pressure PRcb1 for the release side engagement device CB1 and learning of the command pressure PRcb2 for the engagement side engagement device CB2 are prohibited. However, either one of the learning of the command pressure PRcb1 of the release side engagement device CB1 and the learning of the command pressure PRcb2 of the engagement side engagement device CB2 may be prohibited.

Further, in the above-described embodiment, when the vehicle speed V is less than the first predetermined vehicle speed V1, the learning value ΔPRcb1 of the command pressure PRcb1 of the release side engagement device CB1 and the command pressure PRcb2 of the engagement side engagement device CB2 Reflection of the learned value ΔPRcb2 is prohibited, and the reflected gains K1 and K2 are reduced. Different values may be set for each of the engagement device CB1 and the engagement side engagement device CB2.

In the above-described embodiment, when the vehicle speed V is less than the second predetermined vehicle speed V2, learning of the command pressure PRcb1 for the release side engagement device CB1 and learning of the command pressure PRcb2 for the engagement side engagement device CB2 are not performed. Although prohibited, the second predetermined vehicle speed V2, which is the determination threshold value for determining whether to perform learning, is set to a different value for each of the disengagement-side engagement device CB1 and the engagement-side engagement device CB2. I don't mind.

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 24: Automatic Transmission 90: Electronic Control Unit 98: Learning Control Unit CB: Engagement Device CB1: Disengagement Side Engagement Device CB2: Engagement Side Engagement Device V1: First Predetermined Vehicle Speed (Predetermined Vehicle Speed)
PRcb1: command pressure of release-side engagement device PRcb2: command pressure of engagement-side engagement device ΔPRcb1, ΔPRcb2: learning values K1, K2: reflection gain

Claims (1)

Applied to a vehicle equipped with a stepped automatic transmission that includes a plurality of engagement devices, and that shifts to a plurality of gear stages by switching the engagement state of the plurality of engagement devices, learns and corrects the command pressure of the disengagement side engagement device released during the coast downshift of the automatic transmission, and corrects the instruction pressure of the engagement side engagement device that is engaged during the coast downshift of the automatic transmission; A control device for a vehicle, comprising a learning control unit that learns and corrects the indicated pressure,
When the vehicle speed is less than a predetermined vehicle speed and the coast downshift to the first gear of the automatic transmission is to be performed, the learning control unit controls the learning value learned during the previous coast downshift. A control device for a vehicle, characterized in that a reflected gain for is made smaller than when the vehicle speed is equal to or higher than the predetermined vehicle speed.

Images