JP2023094427A - Control device of vehicle - Google Patents

Abstract

To provide a control device of a vehicle which can suppress blow-up of the input rotational speed during down-shift while suppressing reduction in the responsibility of torque when executing down-shift of a transmission followed by an acceleration operation in a vehicle that uses a motor as a drive source.SOLUTION: In a case where a rotational speed difference ΔNi between an input rotational speed Ni of an automatic transmission 24 during down-shift and a synchronous rotational speed Nsyc calculated on the basis of a transmission ratio γat of the automatic transmission 24 after down-shift is equal to or less than a preset prescribed value K, the increase ratio α of input torque Ti is restricted. With this, in a case where the rotational speed difference ΔNi is equal to or less than the prescribed value K, the time required for the input rotational speed Ni to reach the synchronous rotational speed Nsyc is short, and there is such a risk that blow-up of the input rotational speed Ni occurs during down-shift, the blow-up of the input rotational speed Ni during the down-shift is suppressed due to restriction on the increase ratio α of the input torque Ti.SELECTED DRAWING: Figure 1

Description

The present invention relates to a control device for a vehicle using at least an electric motor as a driving force source.

In Patent Document 1, in a vehicle using an engine and an electric motor as driving force sources, when performing a power-on downshift of a transmission interposed in a power transmission path between these driving force sources and drive wheels, the electric motor is used to assist the input torque to the transmission. Note that the power-on downshift of the transmission means a downshift that accompanies the driver's accelerator operation.

JP-A-2004-316831

By the way, when performing torque assist by an electric motor during a power-on downshift of the transmission, if there is a delay in increasing the torque capacity of the transmission with respect to the increase in the input torque, there is a possibility that the input rotational speed may rev up. be. On the other hand, if the input torque is limited for the purpose of suppressing the racing of the input rotational speed, there arises a problem that the responsiveness of the torque during the downshift deteriorates.

SUMMARY OF THE INVENTION The present invention has been made against the background of the above circumstances, and its object is to provide a vehicle using at least an electric motor as a driving force source, in which torque is reduced when downshifting a transmission accompanied by accelerator operation. To provide a control device for a vehicle capable of suppressing an increase in input rotation speed during a downshift while suppressing a decrease in responsiveness.

The gist of the first invention is (b) applied to a vehicle equipped with an electric motor as a driving force source and a transmission interposed in a power transmission path between the electric motor and the driving wheels, A control of a vehicle configured to control an input torque input to the transmission during the downshift by an electric motor torque of the electric motor when the transmission is downshifted with an accelerator operation by a driver. (b) when executing a downshift of the transmission that accompanies the accelerator operation, the calculation is based on the input rotation speed of the transmission during the downshift and the gear ratio of the transmission after the downshift; When the rotational speed difference from the synchronous rotational speed that is applied is equal to or less than a preset value, the increase rate of the input torque that is input to the transmission is limited.

According to the first invention, the rotational speed difference between the input rotational speed of the transmission during the downshift and the synchronous rotational speed calculated based on the gear ratio of the transmission after the downshift is a predetermined value. The rate of increase of the input torque is limited if: From this, when the rotation speed difference is equal to or less than a predetermined value, the time required for the input rotation speed to reach the synchronous rotation speed is short, and there is a possibility that the input rotation speed may rev up during the downshift, By limiting the rate of increase of the input torque, the input rotational speed is suppressed from racing up during the downshift. On the other hand, if the rotational speed difference is greater than a predetermined value and the transmission can have a torque capacity capable of transmitting the input torque until the input rotational speed reaches the synchronous rotational speed, the input torque increases. Since the rate is not limited, a decrease in torque responsiveness is suppressed. In this way, by limiting the increase rate of the input torque according to the rotational speed difference calculated during the downshift, the input rotational speed can rise while suppressing a decrease in torque responsiveness during the downshift. can be suppressed.

Here, preferably, in the first aspect of the invention, the input torque increase rate is restricted from the start of the inertia phase to the end of the torque phase. Before the start of the inertia phase and after the end of the torque phase, the transmission is still able to transmit the input torque. Prevents deterioration of sexuality.

Preferably, in the first invention, the predetermined value is a threshold value of a rotational speed difference that allows the transmission to transmit the input torque when the input rotational speed of the transmission reaches the synchronous rotational speed. is set. In this way, when the rotational speed difference is greater than the predetermined value, the transmission can transmit the input torque when the input rotational speed of the transmission reaches the synchronous rotational speed, so that the rate of increase of the input torque can be reduced. Rush-up of the input rotation speed is suppressed without restriction. On the other hand, if the rotational speed difference is equal to or less than the predetermined value, the torque capacity of the transmission may be insufficient for the input torque when the input rotational speed reaches the synchronous rotational speed, and there is a risk that the input rotational speed may rev up. There is In such a case, the rate of increase of the input torque is restricted, thereby suppressing the input rotation speed from rising during the downshift.

Preferably, in the first invention, the upper limit guard value of the input torque increase rate, which is set when the rotation speed difference calculated during downshifting is equal to or less than a predetermined value, is equal to the rotation speed difference. is set to a lower value as is smaller. In this way, the smaller the rotation speed difference, the shorter the time required for the input rotation speed to reach the synchronous rotation speed. However, while the input rotational speed is more likely to rev up, the lower the rotational speed difference, the lower the upper limit guard value of the input torque increase rate, so that the input torque is gradually increased. Rush-up of the input rotational speed 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. 4 is an engagement actuation table showing a combination of engagement devices for establishing gear stages of an automatic transmission; FIG. 9 is a diagram showing one aspect of a relationship map used when setting an upper limit guard value for a rate of increase based on a rotational speed difference; 4 is a flowchart for explaining the main part of the control operation of the electronic control unit, showing a rate of increase that suppresses a decrease in torque responsiveness and suppresses an increase in the turbine rotation speed in a power-on downshift of an automatic transmission. 4 is a flow chart for explaining a control operation for setting the upper limit guard value of . 4 is a time chart showing a control state when a rotational speed difference is equal to or less than a predetermined value in a power-on downshift of an automatic transmission; 4 is a time chart showing a control state when a gear shift stage is further changed to a lower gear stage during a power-on downshift of an automatic transmission;

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, which is a rotary 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. Electric motor MG is connected to a battery 54 provided in vehicle 10 via an inverter 52 provided in vehicle 10 . MG torque Tm, which is the output torque (motor torque) of the electric motor MG, is controlled by controlling the inverter 52 of the electric motor MG by an 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. Specifically, the electric motor MG generates power for running from electric power supplied from the battery 54 via the inverter 52 instead of the engine 12 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. Electric power is also synonymous with electrical energy when not specifically distinguished. The power is also 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 provided in a power transmission path between engine 12 and electric motor MG and drive wheels 14 . That is, the automatic transmission 24 forms part of a power transmission path between the engine 12 and the electric motor MG and the 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 a known lockup clutch 40 (hereinafter referred to as an LU clutch 40) that connects and disconnects between the pump impeller 22a and the turbine impeller 22b.

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 state of the LU clutch 40 includes 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 state in which the LU clutch 40 is engaged. There is a state, fully engaged.

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 a hydraulic friction engagement device configured by, for example, 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 changes its control state such as an engaged state and a disengaged state by changing the torque capacity Tcb of each by the regulated CB hydraulic pressure PRcb supplied from the hydraulic control circuit 56 . 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 different gear ratio (also referred to as gear ratio) γat (=input rotation speed Ni/output rotation speed No) depending on which one of the engagement devices CB is engaged. It is a stepped automatic transmission in which one of a plurality of gear stages (also called gear stages) is formed. That is, the automatic transmission 24 shifts to a plurality of speed stages according to a combination of engagement and release of a plurality of engagement devices CB (clutches C1-C4 and brakes B1, 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 the engaging device CB, and "x" indicates disengagement of the engaging device CB. As shown in FIG. 2, in the automatic transmission 24, by changing the combination of engagement and release of each engagement device CB, 10 gear stages from 1st gear stage 1st to 10th gear stage 10th. can be switched to . The input rotation speed Ni corresponds to the rotation speed of the transmission input shaft 38 of the automatic transmission 24, and the output rotation speed No corresponds to the rotation speed of the transmission output shaft 26 of the automatic transmission 24.

The automatic transmission 24 determines the shift stage based on the accelerator opening θacc, which is the operation amount of the accelerator pedal 42 by the driver (=driver), and the vehicle speed V by the 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 value related to the accelerator opening .theta.acc, such as the throttle opening .theta.th, which is correlated with the accelerator opening .theta.acc. Similarly, when determining whether to shift gears, the determination may be based not only on the vehicle speed V, but also on a value related to the vehicle speed V, such as the output rotation speed No. The input rotational speed Ni is the rotational speed of the transmission input shaft 38 and the input rotational speed of the automatic transmission 24 . The input 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 input rotation speed Ni can be represented by the turbine rotation speed Nt. The output rotation speed No is the rotation speed of the transmission output shaft 26 and the output rotation speed of the automatic transmission 24 . Note that the automatic transmission 24 corresponds to the transmission of the present invention.

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 adjusted from the hydraulic control circuit 56 is supplied to the hydraulic actuator, the torque capacity Tk0 of the K0 clutch 20 is changed, thereby switching the control state of the K0 clutch 20.

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 to connect and disconnect the power transmission path, that is, the engine 12 and the electric motor. It functions as a clutch that connects and disconnects the MG. That is, the K0 clutch 20 is a connecting/disconnecting clutch that connects the engine 12 and the electric motor MG when engaged, and disconnects the connection between the engine 12 and the electric motor MG when 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 MOP 58, an electric oil pump EOP 60, a pump motor 62, and the like. The MOP 58 is connected to the pump impeller 22a, and is driven to rotate by a driving 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 CB hydraulic pressure PRcb, K0 hydraulic pressure PRk0, LU hydraulic pressure PRlu, etc., each of which is adjusted based on hydraulic fluid discharged by at least one of MOP58 and 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.

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 opening sensor, etc.). engine speed sensor 80, brake switch 82, battery sensor 84, oil temperature sensor 86, shift position sensor 88). output rotation speed No corresponding to the vehicle speed V; MG rotation speed Nm, which is the rotation speed of the electric motor MG; The accelerator opening θacc, the throttle 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 44 for operating the wheel brake is being operated by the driver, and the battery 54 Battery temperature THbat, battery charging/discharging current Ibat, battery voltage Vbat, working oil temperature THoil, which is the temperature of the working oil in the hydraulic control circuit 56, and the operation position of the shift lever 48 of the shift operation device 46 operated by the driver. A shift operating position Psh) is supplied, respectively.

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.

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

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 the calculation of the required drive amount, instead of the vehicle speed V, the output rotation speed No or the like may be used.

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 hybrid control unit 92 performs regenerative control in which the electric motor MG is rotated by the driven torque transmitted from the drive wheels 14 to generate power during coasting (during coasting) when the accelerator pedal 42 is released. Execute. Electric power generated by regeneration is charged to the battery 54 via the inverter 52 . When braking is performed by depressing the brake pedal 44, the braking force generated by the hydraulic brake provided for each wheel and the braking force generated by the regeneration of the electric motor MG are obtained so that the braking force corresponding to the amount of operation of the brake pedal 44 can be obtained. and the braking force distribution is appropriately adjusted.

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 applies torque necessary for cranking the engine 12, which is torque for increasing the engine rotation speed Ne, to the engine 12 side. A 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 so as to obtain the K0 torque Tk0 for transmission to the hydraulic control circuit 56 .

The shift control unit 96 performs shift determination for the automatic transmission 24 based on, for example, a shift map that defines predetermined shift conditions, and a CB for executing shift control for the automatic transmission 24 as necessary. A hydraulic control command signal Scb is output to the hydraulic control circuit 56 . In the shift transition period, the CB1 oil pressure PRcb1 supplied to the engagement device (hereinafter referred to as the engagement-side engagement device CB1) that is engaged during gear shifting is increased, and the engagement that is released during engagement is increased. The CB2 hydraulic pressure PRcb2 supplied to the device (hereinafter referred to as the release side engagement device CB2) is controlled to be reduced.

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. For example, when the vehicle speed V or the accelerator opening θacc during running changes and the running state straddles a shift line defined on the relation map, it is determined that the shift condition is satisfied and the shift stage is changed. In the shift map, instead of the vehicle speed V, the output rotational speed No or the like may be used as a value related to the vehicle speed V, and instead of the accelerator opening θacc, a request Driving torque Trdem, required driving force Frdem, throttle opening θth, etc. may be used.

When the driver depresses the accelerator pedal 42 to downshift the automatic transmission 24 (i.e., power-on downshift), the shift control unit 96 outputs the MG torque Tm of the electric motor MG to the electric motor control unit 92b. outputs a command for controlling the input torque Ti to the automatic transmission 24 during downshifting. When the electric motor control unit 92b calculates the target input torque Titgt based on the accelerator opening θacc, the vehicle speed V, etc., the calculated target input torque Titgt is set as a target, and the input torque Ti increases according to, for example, the accelerator opening θacc. MG torque Tm is controlled so as to increase at rate α. Here, the MG torque Tm of the electric motor MG has higher responsiveness than the engine torque Te of the engine 12 . Therefore, during the power-on downshift of the automatic transmission 24, the input torque Ti is controlled exclusively by the MG torque Tm.

By the way, during the power-on downshift of the automatic transmission 24, it is preferable that the input torque Ti input to the automatic transmission 24 becomes substantially equal to the torque capacity (hereinafter referred to as torque capacity Tat) that can be transmitted by the automatic transmission 24. . However, at the initial stage of the downshift, the responsiveness of the torque capacity Tat of the automatic transmission 24 is worse than the responsiveness of the MG torque Tm of the electric motor MG. When the input rotation speed Ni of the transmission 24 reaches the synchronous rotation speed Nsyc, the input rotation speed Ni may race up. Restricting the input torque Ti is conceivable as means for suppressing the racing of the input rotational speed Ni, but the trade-off is that the response of the torque decreases. In this embodiment, the input rotation speed Ni is the same rotation speed as the turbine rotation speed Nt, so the input rotation speed Ni may be read as the turbine rotation speed Nt in the following.

On the other hand, in executing the power-on downshift, the shift control unit 96 controls the synchronous rotation speed calculated based on the input rotational speed Ni during the downshift and the gear ratio γat of the automatic transmission 24 after the downshift. When the rotation speed difference ΔNi (= |Nsyc−Ni|) from the speed Nsyc is equal to or less than a predetermined value K, setting the upper guard value αgd of the increase rate α of the input torque Ti allows the input Limit the rate of increase α of the torque Ti. Here, the increase rate α corresponds to the amount of increase in the input torque Ti per unit time. Therefore, when the rate of increase α is high, the slope of increase of the input torque Ti becomes steep, and when the rate of increase α is low, the slope of increase of the input torque Ti becomes gentle. The synchronous rotation speed Nsyc can be calculated by multiplying the output rotation speed No by the gear ratio γat of the automatic transmission 24 after the downshift (=No×γat).

In the power-on downshift, after the disengagement side engagement device CB2, which is released after the downshift, is released, the input torque Tin increases the input rotation speed Ni, thereby starting the inertia phase. Next, as the input rotation speed Ni rises, engagement of the engagement side engagement device CB1 is started, and the input rotation speed Ni reaches the synchronous rotation speed Nsyc, or the input rotation speed Ni approaches the synchronous rotation speed Nsyc. Then, a torque phase is started in which the CB1 oil pressure PRcb1 of the engagement side engagement device CB1 is increased until the torque capacity Tat of the automatic transmission 24 reaches a capacity sufficient to transmit the input torque Ti. When it is determined that the torque capacity Tat of the automatic transmission 24 has increased to the sufficient capacity, the torque phase ends and the downshift is completed.

The shift control unit 96 determines the start of the inertia phase, for example, based on whether or not the amount of change in the increasing side of the input rotational speed Ni has reached a predetermined value β1. The predetermined value β1 is obtained experimentally or by design in advance, and is set to a value that allows determination of the start of the inertia phase.

Further, the shift control unit 96 determines whether the rotational speed difference ΔNi between the input rotational speed Ni and the synchronous rotational speed Nsyc has become equal to or less than a predetermined value β2. In other words, it determines the start of the torque phase. The predetermined value β2 is obtained experimentally or by design in advance, and is set to a value at which it can be determined that the input rotation speed Ni has reached the synchronous rotation speed Nsyc.

Further, the shift control unit 96 determines the end of the torque phase, for example, based on whether or not a preset predetermined time β3 has elapsed since the start of the torque phase. The predetermined time β3 is obtained experimentally or by design in advance, and is set to a value at which it can be determined that the torque capacity Tat of the automatic transmission 24 has become large enough to transmit the input torque Ti.

When the shift control unit 96 determines that the inertia phase has started, it calculates the synchronous rotation speed Nsyc, and the rotation speed difference ΔNi between the synchronous rotation speed Nsyc and the input rotation speed Ni is equal to or less than a preset value K. It is determined whether or not. The predetermined value K is obtained experimentally or by design in advance. It is set to a threshold value of the rotation speed difference ΔNi that becomes a transferable capacity.

For example, when the rotational speed difference ΔNi is large, such as at high vehicle speeds, it takes a long time for the input rotational speed Ni to reach the synchronous rotational speed Nsyc. Therefore, until the input rotation speed Ni reaches the synchronous rotation speed Nsyc, the CB oil pressure PRcb (actual pressure) of the engagement device CB is made to follow the command pressure, and the torque capacity Tat of the automatic transmission 24 is changed to the input torque. Ti can be a transferable capacity. In this case, the racing of the input rotational speed Ni is suppressed without limiting the rate of increase α of the input torque Ti. Therefore, the predetermined value K can also be said to be a threshold value of the rotation speed difference ΔNi at which the input rotation speed Ni does not rise even when the rate of increase α of the input torque Ti is not limited. Note that the predetermined value K does not necessarily have to be a constant value, and can be appropriately changed according to the vehicle speed V, shift pattern, accelerator opening θacc, and the like.

When the rotation speed difference ΔNi is larger than a predetermined value K, the input rotation speed Ni does not rev up even if the input torque Ti is not limited. not set. As a result, during the power-on downshift, the responsiveness of the input torque Ti does not decrease, and the input rotational speed Ni does not rev up.

On the other hand, when the rotation speed difference ΔNi is equal to or less than the predetermined value K, the shift control unit 96 sets the increase rate α of the input torque Ti to the upper guard value αgd. The upper guard value αgd is obtained experimentally or by design in advance, and is set to a value that suppresses the racing of the input rotation speed Ni when the input rotation speed Ni reaches the synchronous rotation speed Nsyc during the power-on downshift. is set. Also, the upper guard value αgd is changed according to the rotation speed difference ΔNi.

FIG. 3 shows one aspect of the relationship map used when setting the upper limit guard value αgd of the rate of increase α based on the rotation speed difference ΔNi. In FIG. 3, the horizontal axis indicates the rotational speed difference ΔNi, and the vertical axis indicates the upper limit guard value αgd of the rate of increase α. As shown in FIG. 3, the upper guard value αgd is defined in a region where the rotation speed difference ΔNi is equal to or less than a predetermined value K. Further, as shown in FIG. 3, the lower the rotational speed difference ΔNi, the lower the upper limit guard value αgd of the rate of increase α.

As the rotational speed difference ΔNi becomes smaller, the time required for the input rotational speed Ni to reach the synchronous rotational speed Nsyc becomes shorter. As a result, the CB oil pressure PRcb (actual pressure) of the engagement device CB cannot follow the command pressure. Since the torque capacity Tat cannot be reached, the input rotational speed Ni will race up. Taking this into consideration, the upper guard value αgd in FIG. 3 is changed according to the rotation speed difference ΔNi. Specifically, the upper guard value αgd for each rotational speed difference ΔNi shown in FIG. 3 is obtained experimentally or by design in advance. is set to a threshold value of the input torque Ti at which racing does not occur. That is, the upper guard value αgd is set to a value that minimizes the decrease in the increase rate α of the input torque Ti while suppressing the racing of the input rotational speed Ni.

When the rate of increase α of the input torque Ti is limited by the upper guard value αgd, the change in the input torque Ti becomes gentler than when it is not limited by the upper guard value αgd. In relation to this, the rising gradient of the input rotation speed Ni is also moderated, and the time required for the input rotation speed Ni to reach the synchronous rotation speed Nsyc is delayed. As a result, the torque capacity Tat of the automatic transmission 24 can be increased to a capacity capable of transmitting the input torque Ti before the input rotation speed Ni reaches the synchronous rotation speed Nsyc, and the input rotation speed Ni can be driven up. is suppressed.

The relationship map shown in FIG. 3 is for a shift pattern during a power-on downshift (such as a downshift from 3rd gear to 2nd gear), or a relationship engaged or disengaged during a power-on downshift. They are defined separately according to the type of coupling device CB (clutch C1). This is because, even if the rotation speed difference ΔNi is the same, the responsiveness of the torque capacity Tcb of the engagement device CB differs depending on the shift pattern and the engagement device CB.

After calculating the rotation speed difference ΔNi, the shift control unit 96 applies the rotation speed difference ΔNi to the relationship map shown in FIG. 3 to determine an appropriate upper guard value αgd. After determining the upper limit guard value αgd, the shift control unit 96 issues a command to the hybrid control unit 92 to limit the rate of increase α of the input torque Ti to the upper limit guard value αgd or less. In response to this, the hybrid control unit 92 controls the input torque Ti so that the rate of increase α of the input torque Ti is equal to or lower than the upper guard value αgd.

For example, when the shift control unit 96 determines the upper limit guard value αgd based on the rotation speed difference ΔNi first calculated at the time when the start of the inertia phase is determined, the upper limit guard value αgd is maintained until the end of the torque phase is determined. , the upper limit guard value αgd is maintained. Alternatively, the shift control unit 96 calculates the rotation speed difference ΔNi as needed from when the start of the inertia phase is determined until the end of the torque phase is determined, and based on the calculated rotation speed difference ΔNi, the upper limit guard is applied. Change the value αgd at any time.

For example, when the destination gear stage of the automatic transmission 24 is changed during a power-on downshift, the shift control unit 96 resets the synchronous rotation speed Nsyc again based on the gear ratio γat of the new gear stage. A rotation speed difference ΔNi is calculated from the calculated synchronous rotation speed Nsyc. Next, the shift control unit 96 determines whether or not the rotation speed difference ΔNi is equal to or less than the predetermined value K, as described above. If the rotation speed difference ΔNi is equal to or less than the predetermined value K, the upper limit guard value αgd of the increase rate α is set again based on the rotation speed difference ΔNi.

Further, when the shift control unit 96 determines that the torque phase has ended, it cancels the setting of the upper guard value αgd. At the end of the torque phase, the torque capacity Tat of the automatic transmission 24 is sufficient to transmit the input torque Ti. is. Also, before the inertia phase starts, the input torque Ti can be transmitted to the automatic transmission 24 by the disengagement side engagement device CB2, so the upper guard value αgd is not set before the inertia phase starts. has no effect. Therefore, before the start of the inertia phase and after the end of the torque phase, the upper guard value αgd is not set, thereby suppressing the deterioration of the responsiveness of the input torque Ti due to the setting of the upper guard value αgd. In other words, from the start of the inertia phase to the end of the torque phase, the rate of increase α of the input torque Ti is limited by the upper guard value αgd, so that the rate of increase α of the input torque Ti is efficiently limited. becomes.

FIG. 4 is a flowchart for explaining the main part of the control operation of the electronic control unit 90. During the power-on downshift of the automatic transmission 24 accompanied by the depression of the accelerator pedal 42, the responsiveness of the input torque Ti is 4 is a flow chart for explaining a control operation for setting an upper limit guard value αgd of a rate of increase α that suppresses an increase in the input rotational speed Ni while suppressing a decrease. This flowchart is repeatedly executed while the vehicle is running.

First, in step S10 corresponding to the control function of the shift control unit 96 (hereinafter, step is omitted), it is determined whether or not a power-on downshift of the automatic transmission 24 accompanied by the driver's depression of the accelerator pedal 42 is executed. 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 shift control section 96, whether or not the downshift is between the start of the inertia phase (I phase) and the end of the torque phase (T phase). is determined. If the determination in S20 is negative, this routine is terminated. If the determination in S20 is affirmative, in S30 corresponding to the control function of the shift control section 96, it is determined whether or not the rotation speed difference ΔNi between the synchronous rotation speed Nsyc and the input rotation speed Ni is equal to or less than a predetermined value K. If the rotational speed difference ΔNi is greater than the predetermined value K, the determination in S30 is negative, and this routine is terminated. If the determination in S30 is affirmative, in S40 corresponding to the control function of the shift control section 96, the upper guard value αgd is set based on the rotational speed difference ΔNi. Note that once the upper guard value αgd is set, if it is maintained at that upper guard value αgd until the downshift is completed, once the upper guard value αgd is set in S40, then the downshift is completed, the step of S40 is passed without being executed. On the other hand, when the upper guard value αgd is changed as needed from the start of the inertia phase to the end of the torque phase, the upper guard value αgd is repeatedly set (updated) in S40.

5 and 6 are time charts showing the control state of the automatic transmission 24 in the power-on downshift. FIG. 5 is a time chart showing the control state when the rotation speed difference ΔNi during the power-on downshift is equal to or less than a predetermined value K. FIG. FIG. 6 is a time chart showing a control state when the gear is changed to a lower speed gear stage during power-on downshifting of the automatic transmission 24 .

First, the case where the rotation speed difference ΔNi is equal to or less than the predetermined value K during the power-on downshift of the automatic transmission 24 shown in FIG. 5 will be described.

At time t1 in FIG. 5, a downshift (power-on downshift) of the automatic transmission 24 associated with the depression of the accelerator pedal 42 is determined, and a downshift of the automatic transmission 24 is started. At time t2, when it is determined that the inertia phase has started, the rotation speed difference ΔNi is calculated, and it is determined whether or not the rotation speed difference ΔNi is equal to or less than a predetermined value K. When it is determined that the rotation speed difference ΔNi is equal to or less than the predetermined value K, the rotation speed difference ΔNi is applied to a relationship map as shown in FIG. 3 that defines the relationship between the rotation speed difference ΔNi and the upper guard value αgd. Thus, the upper guard value αgd is set.

After time t2, the input torque Ti becomes the post-guard input torque Tigd indicated by the solid line by setting the upper guard value αgd. As shown in FIG. 5, the post-guard input torque Tigd has an increase rate α limited to the upper guard value αgd after t2. Here, the dashed line indicates the input torque Ti when the upper guard value αgd is not set. there is As a result, the post-guard input torque Tigd gently increases compared to the input torque Ti when the upper guard value αgd is not set. The input rotational speed Ni indicated by the solid line also increases more slowly than when the rate of increase α indicated by the broken line is not limited.

At time t3, the input rotation speed Ni reaches the synchronous rotation speed Nsyc. At this time, the input torque Ti is limited by the upper guard value αgd, thereby suppressing the racing of the input rotational speed Ni. On the other hand, when the upper limit guard value αgd indicated by the dashed line is not set, the input rotational speed Ni reaches the synchronous rotational speed Nsyc earlier than time t3, and when it reaches the synchronous rotational speed Nsyc, as indicated by the dashed line, , since the torque capacity Tat of the automatic transmission 24 is less than the capacity capable of transmitting the input torque Ti, the input rotation speed Ni races up. At time t4, the upper limit guard value αgd is canceled because it is determined that the torque phase has ended. In relation to this, the increase rate α of the input torque Ti after time t4 increases, and quickly reaches the target input torque Titgt corresponding to the accelerator opening θacc.

Next, a description will be given of a case where, as shown in FIG. 6, during the power-on downshift of the automatic transmission 24, the shift destination is further changed to a lower gear as the accelerator pedal 42 is further depressed.

At time t1 in FIG. 6, it is determined that the automatic transmission 24 is downshifting (power-on downshifting) in response to the depression of the accelerator pedal 42, and the downshifting of the automatic transmission 24 is started. When it is determined that the inertia phase has started at time t2, the rotation speed difference ΔNi is calculated, and it is determined whether or not the rotation speed difference ΔNi is equal to or less than a predetermined value K. At this time, the upper limit guard value αgd is set by determining that the rotation speed difference ΔNi is equal to or less than the predetermined value K. Therefore, after time t2, the rate of increase α of the input torque Ti is limited to the upper guard value αgd, and the increase in the input torque Ti slows down. At time t3, the driver further depresses the accelerator pedal 42 to change the shift destination of the automatic transmission 24 to a lower gear stage. At this time, the synchronous rotation speed Nsyc is recalculated based on the gear ratio γat of the changed gear stage, and the rotation speed difference ΔNi is calculated based on the recalculated synchronous rotation speed Nsyc. It is determined whether or not the difference ΔNi is equal to or less than a predetermined value K. At time t3 in FIG. 6, it is determined that the rotation speed difference ΔNi is greater than the predetermined value K, so that the upper guard value αgd is canceled. As a result, after time t3, the input torque Ti increases at the rate of increase α that would be obtained when the upper guard value αgd is not set. At time t4, the input rotation speed Ni reaches the synchronous rotation speed Nsyc. rise is suppressed.

As described above, according to this embodiment, the input rotational speed Ni of the automatic transmission 24 during downshifting and the synchronous rotational speed Nsyc calculated based on the gear ratio γat of the automatic transmission 24 after downshifting are calculated. When the rotation speed difference ΔNi is equal to or less than a preset value K, the rate of increase α of the input torque Ti is limited. As a result, the rotation speed difference ΔNi is equal to or less than the predetermined value K, the time required for the input rotation speed Ni to reach the synchronous rotation speed Nsyc is short, and there is a risk that the input rotation speed Ni will race up during the downshift. In some cases, the rate of increase α of the input torque Ti is limited, thereby suppressing the racing of the input rotation speed Ni during the downshift. On the other hand, the automatic transmission 24 can have a torque capacity Tat capable of transmitting the input torque Ti until the rotational speed difference ΔNi is greater than the predetermined value K and the input rotational speed Ni reaches the synchronous rotational speed Nsyc. In this case, the rate of increase α of the input torque Ti is not restricted, so the decrease in torque responsiveness is suppressed. In this way, by limiting the increase rate α of the input torque Ti according to the rotation speed difference ΔNi calculated during the downshift, the input rotation speed Blowing up of Ni can be 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 above-described embodiment, when it is determined that the inertia phase has started, it is determined whether or not to set the upper guard value αgd. may be determined whether or not to set. For example, the time immediately before the start of the inertia phase, which is based on the time when it is determined that the downshift is to start, is determined experimentally or by design in advance, and the time from the time when it is determined that the downshift is to start is determined. When the time elapses, it is determined whether or not to set the upper guard value αgd.

Further, in the above-described embodiment, the upper guard value αgd is canceled when it is determined that the torque phase has ended. I don't mind.

In the above-described embodiment, the automatic transmission 24 is a planetary gear type stepped transmission comprising one or more sets of planetary gear devices and a plurality of engagement devices CB. However, the invention is not necessarily limited to this. For example, the present invention can be applied to a known DCT (Dual Clutch Transmission) type transmission including a first clutch that establishes an odd-numbered stage and a second clutch that establishes an even-numbered stage.

In the above-described embodiment, the vehicle 10 includes the engine 12 and the electric motor MG as driving force sources, the automatic transmission 24, and the K0 clutch 20 interposed between the engine 12 and the electric motor MG. Although the vehicle is a motor-type hybrid vehicle, the present invention is not necessarily limited to this. For example, a planetary gear set operating as a power split device, an engine connected to a first rotating element of the planetary gear set, a first electric motor connected to a second rotating element of the planetary gear set, and a planetary gear set. It may be a hybrid vehicle configured with a second electric motor and a transmission connected to the third rotating element of.

Further, in the above-described embodiment, the accelerator opening θacc increases as the accelerator pedal 42 is stepped on, but the present invention is not limited to stepping on the accelerator pedal 42, and is manually operated by the driver. It may be configured such that the accelerator opening θacc is increased.

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 (transmission)
90: Electronic control device (control device)
MG: Electric motor Ni: Input rotational speed (input rotational speed of transmission)
Nsyc: synchronous rotation speed ΔNt: rotation speed difference Ti: input torque Tm: MG torque (motor torque)
K: Predetermined value α: Rise rate γat: Gear ratio

Claims (1)

Applied to a vehicle provided with an electric motor as a driving force source and a transmission interposed in a power transmission path between the electric motor and the driving wheels, downshifting of the transmission accompanied by accelerator operation by the driver is configured to control the input torque input to the transmission during a downshift by the electric motor torque of the electric motor, the control device for a vehicle comprising:
When executing a downshift of the transmission that accompanies the accelerator operation, the rotation between the input rotation speed of the transmission during the downshift and the synchronous rotation speed calculated based on the gear ratio of the transmission after the downshift. A control device for a vehicle, wherein a rate of increase in input torque input to the transmission is limited when a speed difference is equal to or less than a predetermined value set in advance.

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