KR102370975B1 - Method for controlling auto transmission of hybrid vehicle - Google Patents

Abstract

The present invention relates to a shift control method of an automatic transmission for a hybrid vehicle, which enables shift control according to a change amount of a driver's required torque in an actual shift section of the automatic transmission, thereby improving shift feeling and transmission durability.
That is, the present invention provides PID control of the motor torque in consideration of the lack of hydraulic responsiveness of the transmission clutch to engage the transmission clutch when the amount of change in the torque required by the driver during shifting of a hybrid vehicle equipped with an automatic transmission is large or frequent over a predetermined level. The purpose of this invention is to provide a shift control method for an automatic transmission for a hybrid vehicle that can reduce the sense of disparity when the transmission clutch is engaged, shorten shift time, and minimize clutch slip.

Description

Shift control method of automatic transmission for hybrid vehicle

The present invention relates to a shift control method of an automatic transmission for a hybrid vehicle, and more particularly, to a shift control according to a change amount of a driver's demand torque in an actual shift section of an automatic transmission, thereby improving shift feeling and transmission durability. The present invention relates to a shift control method of an automatic transmission for a hybrid vehicle.

Among eco-friendly vehicles, a hybrid vehicle uses not only an engine as a power source but also a motor as a power source to reduce exhaust gas and improve fuel efficiency. It is equipped with a power transmission system that transmits power.

As one example, the power transmission system for a hybrid vehicle is arranged between the engine 10 and the motor 12 arranged in series with each other, and the engine 10 and the motor 12 as shown in the accompanying FIG. The engine clutch 13 for transmitting or disconnecting, the automatic transmission 14 for shifting the motor or motor and engine power to the driving wheel and outputting it, and the HSG, a kind of motor connected to the crank pulley of the engine to start the engine and generate battery 16, Hybrid Starter Generator), an inverter 18 for motor control and power generation control, and a high voltage battery 20 connected to the inverter so as to provide power to the motor 12 and the like to be charged and discharged.

This hybrid vehicle power transmission system is a type in which a motor is attached to the automatic transmission side, and is called a TMED (Transmission Mounted Electric Device) method. HEV (hybrid electric vehicle) mode that uses a motor as auxiliary power while driving, and regenerative braking (RB: Regenerative Braking) in which braking and inertia energy of the vehicle is recovered through power generation from the motor and charged to the battery during vehicle braking or inertia driving ) mode and other driving modes.

In the HEV mode, the vehicle runs with the sum of the engine and motor output torques at the same time as the engine clutch is locked-up, and in the EV mode, the vehicle is driven only by the output torque of the motor at the same time as the engine clutch is unlocked (opened). driving is made

In addition, when driving in the EV mode or HEV mode, the automatic transmission controls the shift according to the driver's demand torque, and the clutch for each stage in the transmission is connected, so that the output according to the driver's demand torque is output to the driving wheel.

At this time, during the shift of the hybrid vehicle, that is, during the clutch engagement control of the automatic transmission, when the transmission input torque is changed according to the change amount of the driver's required torque, the transmission clutch operating hydraulic pressure is feedback controlled to engage the gearshift clutch.

However, if the amount of change in the torque required by the driver is greater than a predetermined level, the torque fluctuation cannot be followed due to the lack of hydraulic reactivity of the transmission clutch. Transmission damage due to excessive slip of

The present invention was devised in view of the above points, and when the amount of change in the torque required by the driver during shifting of a hybrid vehicle equipped with an automatic transmission is large or frequent over a predetermined level, the motor torque is PID in consideration of the lack of hydraulic responsiveness of the transmission clutch. An object of the present invention is to provide a shift control method for a hybrid vehicle capable of realizing a reduction in a sense of disparity, reduction of shift time, and minimization of clutch slip when the transmission clutch is engaged by controlling the transmission clutch to be engaged.

In order to achieve the above object, the present invention provides the steps of: determining whether an actual shift section for shifting to a desired gear in a D-speed state of an automatic transmission for a hybrid vehicle; When the instantaneous change amount of the driver's demand torque in the actual shift section is greater than the reference value (A) or the instantaneous change amount of the turbine speed, which is the transmission input speed, is greater than the reference value (B), the shift reflecting the driver's demand torque in the actual shift section control is made; It provides a shift control method of an automatic transmission for a hybrid vehicle, comprising:

In particular, as a shift control that reflects the driver's requested torque in the actual shift section, as the instantaneous change in the driver's demand torque increases, the feedforward control increases the transmission clutch engagement pressure. At the same time, the greater the instantaneous change in the turbine speed, the greater the motor torque. It is characterized in that the control is performed in a direction to reduce the difference between the current turbine speed and the target turbine speed.

In addition, after the shift control that reflects the driver's demand torque is terminated in the actual shift section, if the difference between the current turbine speed and the target turbine speed is less than or equal to the reference value (C) compared to the reference value (C), the transmission clutch in the corresponding stage is engaged. It is characterized in that it is judged as

Preferably, a shift pattern to a shift stage other than the current shift stage is required, or the current turbine speed and target When the difference between the turbine speeds is within the reference value B, the shift control reflecting the driver's requested torque in the actual shift section is stopped.

Through the above-described problem solving means, the present invention provides the following effects.

If the instantaneous change in the driver's required torque in the actual shift section of the automatic transmission for hybrid vehicles is greater than a predetermined level, the motor torque that determines the current turbine speed, which is the transmission input speed, is controlled through PID control in consideration of the lack of hydraulic reactivity for coupling the transmission clutch. By reducing the control, the transmission clutch bonding at the corresponding stage can be smoothly performed within the shift setting time, and accordingly, it is possible to reduce the sense of disparity when the transmission clutch is engaged, shorten the shift time, and minimize the slip of the transmission clutch.

1 is a power transmission system diagram of a hybrid vehicle equipped with an automatic transmission;
2 is a diagram illustrating a conventional shift control method of a hybrid vehicle;
3 is a diagram illustrating a shift control method of a hybrid vehicle according to the present invention;
4 is a flowchart illustrating a shift control method of a hybrid vehicle according to the present invention.

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

First, in order to help the understanding of the present invention, an existing control process for an automatic transmission actual shift section of a hybrid vehicle will be described as follows.

2 is a diaphragm illustrating a shift control method of a hybrid vehicle, and shows a control process of an actual shift section of an automatic transmission.

In FIG. 2 , the current turbine speed represents the current transmission input speed, the Accel Position Sensor (APS) represents a sensor signal that measures the amount of stepping on the accelerator pedal, and the instantaneous change in the driver’s requested torque (ⓑ) represents the driver’s demand in the actual shift section. It refers to a change value in which torque increases instantaneously, and can be measured in APS as the accelerator pedal is pressed in the actual shift section.

The actual shift section (ⓐ) is a shift control section for coupling the transmission clutch of the automatic transmission and a clutch slip section before the clutch is completely coupled. and transmission durability may be a problem.

In this actual shift section (ⓐ), when the instantaneous change in the driver's demand torque (ⓑ) instantaneously exceeds a predetermined level, that is, when the driver operates the accelerator pedal so that the instantaneous change in the driver's demand torque (ⓑ) occurs above a predetermined level, the corresponding Since the hydraulic control amount (hydraulic feedback control) for the engagement of a single transmission clutch does not follow the instantaneous change amount of the driver's yoke torque, the current turbine speed, which is the speed at the input side of the transmission, may be abnormally changed.

For example, when driving in the EV mode or HEV mode of the hybrid vehicle, as shown in FIG. 1 , if the instantaneous change amount (ⓑ) of the driver's demand torque increases in the actual shift section (ⓐ) for attaching the clutch for each stage of the automatic transmission, To reflect this, the motor torque by the motor torque feedback control also increases momentarily, and eventually the instantaneous change amount (ⓒ) of the turbine speed, which is the transmission input speed of the transmission connected to the output stage of the motor, suddenly increases, causing the current turbine speed to increase abnormally. there is.

After the instantaneous change in the driver's requested torque (ⓑ) is reflected, when the motor torque decreases and the current turbine speed approaches the target turbine speed, the transmission clutch of the corresponding stage is finally engaged through the inflow feedforward control for coupling the transmission clutch ( Indicated by ⓓ in FIG. 1).

As such, when the change in the torque demanded by the driver occurs above a predetermined level, the change in the torque demanded by the driver cannot be followed due to the lack of hydraulic responsiveness of the transmission clutch, resulting in not only a sense of heterogeneity in the coupling of the transmission clutch, but also delay in shifting to the corresponding stage, Furthermore, due to the divergence of the turbine speed, which is the transmission input speed, the transmission may be damaged due to excessive slip of the transmission clutch.

Accordingly, in order to solve the above problems, the present invention reduces the motor torque in consideration of the lack of hydraulic responsiveness of the transmission clutch when the amount of change in the torque required by the driver during the actual shift section of the automatic transmission of the hybrid vehicle is large or frequent over a predetermined level. The main point is that the transmission clutch is engaged by PID control in a direction to reduce the difference between the current turbine speed and the target turbine speed.

Here, the shift control method of the automatic transmission for a hybrid vehicle according to the present invention will be described as follows.

3 is a diagram illustrating a shift control method of a hybrid vehicle according to the present invention, and FIG. 4 shows a flowchart thereof.

First, it is determined whether the automatic transmission is shifting while the hybrid vehicle is driving in the EV mode or HEV mode.

That is, it is determined whether it is an actual shift section for shifting to a desired gear from the D-speed state of the automatic transmission ( S101 ).

For example, the automatic transmission controller transmits a signal indicating that it is an actual shift section to an upper controller (HCU, Hybrid Control Unit) of the hybrid vehicle.

Next, it is determined whether there is a change in the driver's requested torque in the actual shift section ⓐ (S102).

In more detail, it is determined whether the instantaneous change amount of the driver's demand torque is greater than the reference value A in the actual shift section ⓐ or whether the instantaneous change amount of the turbine speed, which is the transmission input speed, is greater than the reference value B.

Accordingly, if the instantaneous change amount of the driver's demand torque in the actual shift section is greater than the reference value (A), or the instantaneous change amount of the turbine speed, which is the transmission input speed (the difference between the current turbine speed and the target turbine speed), is greater than the reference value (B), The upper level controller issues a shift control command that reflects the driver's request to the automatic transmission controller and motor controller.

Therefore, as a shift control that reflects the driver's requested torque in the actual shift section, the automatic transmission controller controls to increase the transmission clutch engagement pressure, and at the same time, the motor controller reduces the difference between the current turbine speed and the target turbine speed. control the motor torque.

More specifically, as a shift control that reflects the driver's demand torque in the actual shift section, as the instantaneous change amount of the driver's demand torque increases, the automatic transmission controller performs feed-forward control to increase the transmission clutch engagement pressure (S103-1), At the same time, as the instantaneous change of the turbine speed is larger, the motor controller controls the motor torque in a direction to reduce the difference between the current turbine speed and the target turbine speed through PID (Proportional-Integral-Derivative Control) control, a type of feedback control. (S103-2).

In this case, the current turbine speed is an input speed of the transmission connected to the motor, and may be reduced together when the motor torque is reduced.

In this way, even if the instantaneous change in the driver's requested torque occurs over a predetermined level in the actual shift section (ⓐ), the hydraulic pressure control amount (hydraulic feedback control) for coupling the transmission clutch of the corresponding stage is increased to increase the transmission clutch engagement pressure. At the same time, by reducing the difference between the current turbine speed and the target turbine speed by reducing the motor torque, the transmission clutch engagement at the corresponding stage can be smoothly performed within the shift setting time.

In addition, as a control that reflects the driver's requested torque in the actual shift section, when S103-1 and S103-2 are finished, the instantaneous turbine speed change amount, that is, the difference between the current turbine speed and the target turbine speed, is reduced. When the difference between the turbine speed and the target turbine speed is compared with the reference value C (S104) and is less than or equal to the reference value, it may be determined that the transmission clutch in the corresponding stage is engaged.

On the other hand, if the automatic transmission is not in D-speed (eg, P or N), or the amount of APS detected according to the amount of depressing the accelerator pedal by the driver is excessive, the shift pattern ( (eg, shift during shifting) is required, or when a stop condition such as the difference between the current turbine speed and the target turbine speed is within the reference value (B) is satisfied, the shift control reflecting the driver's requested torque in the actual shift section is stopped do.

In other words, the shift pattern to a shift stage other than the current (corresponding) shift stage because the automatic transmission is not in D stage (eg, P or N stage), or the amount of APS detected according to the amount of depressing the accelerator pedal by the driver is excessive If (eg, shifting during shifting) is required or the difference between the current turbine speed and the target turbine speed is within the reference value (B), S103-1 and S103 are shift control that reflects the driver's requested torque in the actual shift section. - Without step 2, the transmission clutch is engaged through the existing transmission clutch hydraulic control (feedback control).

As seen above, when the amount of change in the torque required by the driver in the actual shift section of the automatic transmission for a hybrid vehicle is large or frequent over a predetermined level, the current turbine speed, which is the transmission input speed, is determined in consideration of the lack of hydraulic reactivity for engagement of the transmission clutch. By controlling the reduction of the motor torque through PID control, the transmission clutch bonding at the corresponding stage can be smoothly made within the shift setting time, and accordingly, it is possible to reduce the sense of disparity when the transmission clutch is engaged, shorten the shift time, and minimize the slip of the transmission clutch. can be realized

10 : engine
12: motor
13: engine clutch
14: automatic transmission
16: HSG
18: inverter
20: battery

Claims (4)

determining whether an actual shift section for shifting to a desired gear in a D-speed state of the automatic transmission for a hybrid vehicle;
When the instantaneous change amount of the driver's demand torque in the actual shift section is greater than the reference value (A) or the instantaneous change amount of the turbine speed, which is the transmission input speed, is greater than the reference value (B), the shift reflecting the driver's demand torque in the actual shift section control is made;
including,
As a shift control that reflects the driver's requested torque in the actual shift section, as the instantaneous change in the driver's requested torque increases, the feedforward control increases the transmission clutch engagement pressure, and at the same time, the greater the instantaneous change in the turbine speed, the greater the instantaneous change in the turbine speed, the greater the motor torque is reduced to the current turbine. A shift control method of an automatic transmission for a hybrid vehicle, characterized in that the control is performed in a direction to reduce a difference between the speed and the target turbine speed.
delete The method according to claim 1,
After the shift control that reflects the driver's requested torque in the actual shift section is completed, if the difference between the current turbine speed and the target turbine speed is less than the reference value (C), it is determined that the transmission clutch in the corresponding stage has been engaged. A shift control method of an automatic transmission for a hybrid vehicle, characterized in that
The method according to claim 1,
If the automatic transmission is not in the D-stage state, or the amount of APS detected according to the amount of stepping on the accelerator pedal by the driver is excessive, a shift pattern to a shift stage other than the current shift stage is required, or a difference between the current turbine speed and the target turbine speed The shift control method of the automatic transmission for a hybrid vehicle, characterized in that when is within the reference value (B), the shift control reflecting the driver's requested torque in the actual shift section is stopped.

Images