KR100980966B1 - Transmission method for hybrid electric vehicle - Google Patents

Abstract

The present invention relates to a method for shifting a hybrid vehicle, and more particularly, to a method for shifting a hybrid vehicle that can effectively reduce vibration generated during shifting during EV mode driving using a drive motor. In order to achieve the above object, when the vehicle speed decreases while driving the hybrid vehicle in the EV mode, the motor torque is gradually reduced to be the final target 0, and the transmission is applied while applying hydraulic pressure for initial charging of the transmission coupling shaft while reducing the transmission release shaft hydraulic pressure. A preparation step; A shift start step of completely releasing the transmission release shaft hydraulic pressure when the motor torque becomes zero; A rotation speed synchronizing step of performing motor speed control using a transmission speed of the output shaft × a gear ratio after the gear shift as a target speed; Synchronizing completion step of increasing the hydraulic pressure of the coupling shaft while maintaining the motor speed when the motor speed reaches the target speed; Disclosed is a shifting method of a hybrid vehicle including a shift end step of completing a restoring of a motor torque to satisfy a driver's required torque.

Hybrid vehicle, shift, motor torque

Description

How to shift hybrid vehicles {TRANSMISSION METHOD FOR HYBRID ELECTRIC VEHICLE}

The present invention relates to a method for shifting a hybrid vehicle, and more particularly, to a method for effectively reducing vibration generated during shifting during EV mode driving of a hybrid vehicle.

A hybrid vehicle means an efficient combination of two or more different power sources to drive a vehicle, but in most cases, an engine that burns fuel (fossil fuel such as gasoline) to obtain torque and an electric motor that obtains torque by battery power Means a vehicle driven by.

This hybrid vehicle is a futuristic vehicle that adopts not only an engine but also an electric motor as an auxiliary power source to reduce emissions and improve fuel efficiency, and is actively researching in response to the times demands to improve fuel efficiency and develop environmentally friendly products. It is becoming.

Hybrid vehicles are EV (Electric Vehicle) mode, which is a pure electric vehicle mode that uses only electric motor (drive motor) power, HEV (Hybrid Electric Vehicle) mode, which uses the rotational power of the engine as auxiliary power while the rotational power of the engine is the main power, When the vehicle is driven by braking or inertia, the vehicle travels in a driving mode such as regenerative braking (RB) mode in which braking and inertia energy is recovered through generation of the driving motor and charged in a battery.

As described above, in the hybrid vehicle, the mechanical energy of the engine and the electrical energy of the battery are used together, and the optimum operating area of the engine and the driving motor is used, and the energy is recovered by the driving motor during braking, thereby improving fuel efficiency and efficient energy use.

The hybrid vehicle is equipped with a hybrid control unit (HCU), and has a controller for each device constituting the system.

For example, an engine control unit (ECU) for controlling the overall operation of the engine, a motor control unit (MCU) (including an inverter) for controlling the overall operation of the driving motor, a transmission controller for controlling the transmission (CVT) (Transmission Control Unit (TCU)), a battery controller (Battery Management System (BMS)) that monitors and manages the battery status, and an air conditioner controller (Full Auto Temperature Controller, FATC) in charge of room temperature control.

Here, the HCU is a top-level controller in charge of driving control of each controller, hybrid driving mode setting, and overall vehicle control. Each of the controllers is connected to a high-speed CAN communication line centering on the HCU, which is the top-level controller. The upper controller is to transmit commands to the lower controller while exchanging information between them.

Referring to the configuration of the hybrid vehicle, as shown in Figure 1, the engine 10, the electric motor (drive motor) 20, the automatic transmission 30 has a layout arranged in a row. In particular, the engine 10 and the drive motor 20 are connected to the power transmission in the state via the engine clutch 50, the drive motor 20 and the automatic transmission 30 are directly connected to each other. In addition, an integrated starter generator (ie, an integrated starter & generator) 40 that provides rotational force (ie, outputs a cranking torque) to the engine 10 at start-up, is connected to the engine 10.

In such a configuration, the driving force is obtained only by the driving motor 20 at the time of starting the vehicle or at low speed, and since the engine efficiency is lower than the motor efficiency at the initial starting, the driving motor 20 having better efficiency than the engine 10 is used. It is advantageous in terms of fuel economy of the vehicle to start the initial start of the vehicle (vehicle oscillation). After the vehicle starts, the ISG 40 starts the engine 10 so that the engine output and the motor output can be used simultaneously.

As described above, the hybrid vehicle assists the rotational force of the driving motor 20 while the EV (Electric Vehicle) mode, which is a pure electric vehicle mode using only the rotational force of the driving motor 20, and the rotational force of the engine 10 as the main driving force for driving. The vehicle is driven in a driving mode such as a HEV (Hybrid Electric Vehicle) mode used as power, and mode switching from the EV mode to the HEV mode is performed by the cranking of the engine 10 by the ISG 40.

Meanwhile, in the hybrid system illustrated in FIG. 1, the acceleration and deceleration travel can be performed only by the driving motor 20 while the engine 10 is turned off by removing the clutch 50. Between the flywheel and torsion damper (Flywheel & Torsion Damper) (11) is installed to play a role of attenuating a part of the vibration of the drive system occurs.

However, when the clutch 50 is separated, such as when driving in the EV mode, there is no element that can attenuate it when an impact occurs. In this case, the driving motor 20 has the flywheel and the torsion damper in the state where the clutch 50 is separated. Since it is completely disconnected from (11), there is no way to dampen the impact of the drive motor (20).

Since the motor 20 has a smaller inertia than the engine 10, a relatively large amplitude is generated in the same impact. Moreover, when a shift occurs due to shifting while traveling, the driver may feel an abnormal phenomenon and greatly reduce the merchandise. There is this.

Accordingly, the present invention has been made to solve the above problems, and an object thereof is to provide a method that can effectively reduce vibration generated during shifting during EV mode driving of a hybrid vehicle.

In order to achieve the above object, the present invention, when the vehicle speed is decelerated during the EV mode of the hybrid vehicle, gradually reduces the motor torque to be the final target 0, the hydraulic pressure for the initial charge of the transmission coupling shaft while reducing the transmission release shaft hydraulic pressure A shift preparation step of applying a; A shift start step of completely releasing the transmission release shaft hydraulic pressure when the motor torque becomes zero; A rotation speed synchronizing step of performing motor speed control using a transmission speed of the output shaft × a gear ratio after the gear shift as a target speed; Synchronizing completion step of increasing the hydraulic pressure of the coupling shaft while maintaining the motor speed when the motor speed reaches the target speed; And a shift end step of completing the restoring of the motor torque so as to satisfy the driver's demand torque.

Preferably, in the shift preparation step, when the motor torque is reduced to a predetermined reference value or less, the coupling shaft hydraulic pressure is applied for initial filling of the transmission coupling shaft while reducing the hydraulic pressure of the transmission release shaft. It is done.

Further, in the rotation speed synchronization step, it is checked whether the hydraulic pressure of the transmission coupling shaft is reduced after the initial charge, and if the hydraulic pressure of the transmission coupling shaft is a constant value, the motor speed control is started and the hydraulic pressure of the transmission coupling shaft is constant. It is characterized by maintaining a constant after raising the slope.

Accordingly, according to the shift method of the hybrid vehicle according to the present invention, the motor torque is reduced to zero in the shift start and shift preparation steps, the motor speed is controlled to the target speed in the rotation speed synchronization step, and then the motor is completed in the synchronization completion step. Since the motor torque is ended so as to satisfy the driver's required torque while the speed is kept constant, the shift is completed, thereby effectively reducing the vibration generated during the shift during the EV mode of the hybrid vehicle.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

The present invention relates to a shift method using a drive motor of a hybrid vehicle, and provides a shift method by a motor assist (Motor Assist) that can reduce the vibration generated when the shift during the EV mode driving using the drive motor.

2 is a system configuration diagram for implementing the present invention. In the shifting process of the present invention, which will be described later, a motor torque control, a hydraulic control of a transmission operating element, a control of a hydraulic friction braking device, and the like are performed. (1), the cooperative control is performed between the motor controller 2, the transmission controller 3, and the friction brake system controller 4, for example, the vehicle controller 1 calculates and applies a motor torque command for each situation. Then, the motor controller 2 performs direct motor torque control in accordance with the motor torque command of the vehicle controller, and the transmission controller 3 performs hydraulic control of the transmission operating element.

3 is a flowchart illustrating a shift method according to the present invention, which shows a shift process of the present invention performed when the vehicle speed is decelerated during EV mode driving, and includes a shift preparation step, a shift start step, a rotation speed synchronization step, and a synchronization step. Proceeds to the completion phase and the end of the shift.

In addition, Figure 4 is a view showing an example of the control phase for each step in the motor auxiliary shift process of the present invention, the motor speed (Motor RPM) [= transmission input speed (TM Input RPM)], the transmission release shaft hydraulic pressure [Duty ( Release)], coupled shaft hydraulic pressure (Duty (Apply)), the motor torque (Motor Torque) and the hydraulic brake torque (Hydraulic Brake Torque).

First, in the EV mode, since the engine is turned off while the clutch is released and the driver's required torque is satisfied with the motor torque, the vehicle is driven with the motor torque applied in accordance with the driver's required torque (S11).

Thereafter, the gear shift preparation step of increasing the braking force (which is a friction braking force or a hydraulic braking force) of the hydraulic friction braking device 60 is performed while reducing the braking force of the driving motor 20.

That is, when the vehicle speed is decelerated and shifting starts (S21), the motor torque magnitude (motor braking force) starts to decrease (S22), and the motor torque magnitude is gradually decreased by a predetermined slope so as to become the final target 0, and no load rotation is performed during the shifting process. This is to be prevented ('A1', 'A2' state in Fig. 4).

In a situation where the motor torque magnitude is reduced to a certain slope so as to be the final target 0, when the motor torque magnitude is sufficiently reduced below a predetermined reference value (S24, S26), the hydraulic pressure of the transmission release shaft is reduced, and at the same time, The coupling shaft hydraulic pressure is started to be applied for initial filling (S27), at which time the motor torque magnitude continues to decrease ('A2' state in FIG. 4).

In this shift preparation step, it is determined whether the current vehicle deceleration is a deceleration by another driving or a braking state by brake pedal operation (S23). If the vehicle is decelerated by a driver brake pedal operation, that is, a braking situation, regenerative braking is performed. This is achieved by controlling the friction braking device 60 installed in the vehicle wheel to satisfy the 'driver's required braking amount-the braking amount due to the motor torque' (S25).

At this time, the vehicle controller 1 calculates a friction braking force command so that the friction braking force becomes 'driver's required braking amount-motor braking amount (braking amount due to motor torque)' and applies the friction braking force command to the friction braking device controller 4, and thus friction The braking device controller 4 controls the friction braking device 60 by controlling the hydraulic pressure so that the friction braking force is generated according to the command value (increasing the braking force of the friction braking device and raising the hydraulic braking force).

After that, the shift preparation is completed by checking whether the motor torque is negative (S28). This is to check the reverse torque state in which the motor torque becomes a negative value. Step proceeds.

In the shift preparation step as described above, while reducing the braking force (motor braking force) due to the motor torque, increasing the friction braking force (braking force of the hydraulic friction braking device) by the hydraulic pressure, and the motor torque and the resulting braking force is sufficiently reduced This reduces the release shaft hydraulic pressure of the transmission and applies the initial hydraulic pressure of the coupling shaft.

Next, the motor torque magnitude becomes zero (ie, the regenerative braking force of the motor is removed) in the shift start stage (the 'B' state in FIG. 4), and then the release shaft of the transmission is released after the motor torque magnitude is zero. When the situation may be, the release shaft hydraulic pressure is completely released (S31).

In the rotation speed synchronization step, the motor speed control entry step (C1 state in FIG. 4) and the motor speed control step (C2 state in FIG. 4) are performed. ), First check whether the hydraulic pressure of the transmission coupling shaft is reduced after the initial charge (S41), and then increase the hydraulic pressure of the transmission coupling shaft to a constant slope (prevention of time and rattling), and then control the motor speed. It starts.

In addition, in the speed control step (C2), while maintaining the hydraulic pressure of the transmission coupling shaft at a constant value, the motor speed control to increase the motor speed by using the transmission output shaft rotation speed x gear ratio after gear shift as the target speed ( Feed Forward + PI Control) (S42).

After the completion of the synchronization step, when the motor speed reaches the target speed (S43) while maintaining the motor speed constant at the target speed while increasing the hydraulic pressure of the transmission coupling shaft to a predetermined slope to complete the speed synchronization (S51) (in Figure 4) 'E1' state), and then the restoration of the motor torque magnitude (motor braking amount) is started (S61) to increase the hydraulic pressure of the coupling shaft to the maximum to complete the shift. At this time, the hydraulic braking amount (friction braking force due to hydraulic pressure) is reduced ('2' state in FIG. 4).

After that, the motor torque gradually increases in the state where the coupling shaft reaches the maximum value ('E3' state in FIG. 4), and the shift is completed when the restoration of the motor torque (motor braking amount) is completed to satisfy the driver's required torque (S62). ).

In this way, in the shift method using the motor of the present invention, in order to reduce vibration generated during shifting during EV driving, the motor torque is reduced to zero in the shift start and shift preparation stages, and the motor speed is adjusted in the rotation speed synchronization step. After controlling to the target speed, the shift is completed by restoring the motor torque to meet the driver's required torque while maintaining the motor speed at the synchronization completion step.

1 is a schematic diagram showing the configuration of a hybrid vehicle;

2 is a system configuration diagram for implementing the present invention;

3 is a flowchart illustrating a shift method according to the present invention;

Figure 4 is a view showing an example of the control phase for each step in the motor auxiliary shift process of the present invention.

<Explanation of symbols for the main parts of the drawings>

1: vehicle controller 2: motor controller

3: transmission controller 4: friction brake device controller

10 engine 11: flywheel and torsion damper

20: drive motor 30: transmission

Claims (3)

A shift preparation step of gradually reducing the motor torque to be the final target 0 when the vehicle speed is decelerated during the EV mode driving of the hybrid vehicle, and applying hydraulic pressure for initial charging of the transmission coupling shaft while reducing the transmission release shaft hydraulic pressure; A shift start step of completely releasing the transmission release shaft hydraulic pressure when the motor torque becomes zero; A rotation speed synchronizing step of performing motor speed control using a transmission speed of the output shaft × a gear ratio after the gear shift as a target speed; Synchronizing completion step of increasing the hydraulic pressure of the coupling shaft while maintaining the motor speed when the motor speed reaches the target speed; A shift end step of completing the restoring of the motor torque to satisfy the driver's required torque; Method of shifting a hybrid vehicle comprising a. The method according to claim 1, In the shift preparation step, And when the motor torque is reduced to a predetermined reference value or less, applying the coupling shaft hydraulic pressure for initial filling of the transmission coupling shaft while reducing the hydraulic pressure of the transmission release shaft. The method according to claim 2, In the rotation speed synchronization step, When the hydraulic pressure of the transmission coupling shaft is reduced after initial charging, it is checked whether it is a constant value. If the hydraulic pressure of the transmission coupling shaft is constant, the motor speed control is started and the hydraulic pressure of the transmission coupling shaft is raised to a constant slope and then maintained constant. A shift method of a hybrid vehicle, characterized in that.

Images