KR20110002970A - The method of reducing tip-out shock in hev - Google Patents

Abstract

PURPOSE: A method for reducing the tip-out shock in hybrid vehicles is provided to improve ride comfort using a torque profile which capable of alleviating the change of engine friction torque. CONSTITUTION: In a clutch combined state, an engine torque profile is set based on fuel cut-off timing. Whether a battery(50) is in a chargeable mode or a charge restrictive mode is confirmed in a driving state. In a battery charge restrictive mode and a conversion state from tip-in to tip-out, engine friction torque is controlled by the engine torque profile. Fuel cut-off with respect to the engine(10) is implemented after the state of the engine friction torque is confirmed.

Description

The method of reducing tip-out shock in HEV}

The present invention relates to a method for reducing tip-out shock in a hybrid vehicle, wherein a shock phenomenon caused by a fuel cut occurs when a switch-over from tip-in to tip-out according to the driver's acceleration / deceleration operation in a battery charge limit state occurs. The present invention relates to a tip-out shock reduction method of a hybrid vehicle that can be reduced.

The hybrid vehicle is a future vehicle that can adopt a motor driving source as an auxiliary power source as well as an engine, and can reduce exhaust gas and improve fuel efficiency. Referring to the system configuration of the parallel hybrid vehicle, as shown in the configuration diagram of FIG. Similarly, the engine 10, the motor 20, and the automatic transmission 30 are directly connected on one axis, and the clutch 40 is arranged between the engine 10 and the motor 20, and the operation thereof is also performed. As a configuration for this, an ISG (70: Integrated Starter Generator) is directly connected to the crank pulley of the engine by a belt, and the high voltage battery 50 is connected to the motor 20 through the inverter 60 so as to be charged and discharged.

In such a hybrid vehicle, for example, the engine is started using a motor at the initial start of the vehicle, and then the engine is driven at constant speed, and the battery charge is managed by driving and generating the motor according to conditions.

In the hybrid vehicle, vehicle driving at medium speed or high speed is driven by engine power and motor power. For example, during rapid acceleration, battery power is used as vehicle driving.

On the other hand, during deceleration, the motor is developed to perform a charging operation that stores the inertial energy of the vehicle in the battery, that is, regenerative braking.

That is, as the engine power can be switched by the clutch, the battery is charged by recovering energy by the motor serving as the generator during the other run when the battery charging limit is not applied (the clutch is not engaged).

On the contrary, in the charging limit state in which the clutch is coupled, the other side driving (overdrive) is performed by the friction torque of the engine.

When the driver repeats the tip-in and the tip-out in the above charge limit situation, the engine repeats the fuel injection execution and the fuel cut.

However, when switching from tip-in to tip-out, the engine immediately stops fuel injection, and at that moment, the driving torque code of the engine is changed, causing a shock phenomenon. Due to this, there is a problem that the driver and passengers feel an uncomfortable ride.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and the torque that smoothes the change in the engine torque when switching from tip-in to tip-out according to the driver's acceleration / deceleration operation in the battery charge limit state with the clutch coupled It is an object of the present invention to provide a tip-out shock reduction method of a hybrid vehicle in which a profile is provided to reduce the occurrence of a shock phenomenon caused by a fuel cut.

The present invention for achieving the above object comprises the steps of setting the engine torque profile from the clutch engagement state to the fuel cut time and just before the fuel cut; Checking whether the battery is in a chargeable state or a charge limit state while driving; Controlling the engine friction torque to a preset torque profile when the battery charging limit state is switched from the tip-in state to the tip-out state; Checking whether the engine friction torque has dropped to a certain level, and performing an engine fuel cut when the engine friction torque has fallen to a certain level; It provides a tip-out shock reduction method of a hybrid vehicle comprising a.

In a preferred embodiment, the engine torque profile is set to a range that gently controls the torque change from the torque value at the time of switching from the engine driving state to the non-driving state according to the driver's required torque until it approaches zero based on the axial torque. It is characterized by.

In particular, the fuel injection is maintained until the engine friction torque approaches zero based on the axial torque, and the engine fuel cut is performed when the engine friction torque drops to a level approaching zero.

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

According to the present invention, when switching from the tip-in to the tip-out according to the driver's acceleration / deceleration operation in the battery charge limit state of the hybrid vehicle, by controlling the torque profile that smoothly changes the engine friction torque for traveling, It is possible to greatly reduce the shock phenomenon caused by the fuel cut to be transmitted to the drive shaft, thereby improving the riding comfort.

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

In order to help the understanding of the present invention, the powertrain of the hybrid vehicle and its operation will be described first.

Referring to FIG. 1, as an example of a power train configuration of a hybrid vehicle, an engine 10, a motor 20, and an automatic transmission 30 are directly connected on one axis, and the engine 10 and the motor ( A clutch 40 is arranged between 20, and for the operation of these components, an ISG (70: Integrated Starter Generator) is directly connected to the crank pulley of the engine by a belt, and the high voltage battery 50 is passed through the inverter 60. It is connected to the motor 20 so as to be charged and discharged.

In a hybrid vehicle having such a configuration, an EV (electric vehicle) driving mode, which is a pure electric vehicle mode, is implemented by driving a drive shaft using only motor power, and the battery is charged when the engine is started and idle by driving the motor. The mode is implemented.

In addition, when connecting the clutch arranged between the engine and the motor to transfer the power of the engine to the drive shaft, HEV driving mode using the power of the engine and the motor, that is, the power of the motor while the power of the engine as the main power A hybrid electric vehicle (HEV) driving mode using auxiliary power may be implemented, and when decelerating, a charging operation for generating an inertia energy of the vehicle to be stored in a battery, that is, regenerative braking is performed.

If the driver repeats the tip-in and the tip-out in the battery charging limit state of the hybrid vehicle, that is, the clutch engagement state, the tip-in to tip-out At the moment of switching, a shock phenomenon occurs due to the fuel cut of the engine.

The present invention switches from tip-in to tip-out at the moment of switching from tip-in to tip-out, in order to prevent shock on the drive shaft, ie drive shaft, due to the fuel cut of the engine. It is characteristic in that the torque profile which changes gently to the engine torque of the viewpoint is given.

The fuel injection can be maintained until the engine torque given this torque profile approaches 0 (zero) based on the axial torque, and the fuel cut can be performed when approaching 0 to reduce the shock phenomenon.

Here, the tip-out shock reduction method of the hybrid vehicle according to the present invention will be described in detail as follows.

2 is a flowchart illustrating a method for reducing tip-out shock of a hybrid vehicle according to the present invention, and FIG. 3 is a control diagram illustrating an engine torque profile for reducing tip-out shock of a hybrid vehicle according to the present invention. .

First, the engine torque profile from the clutch engagement state until the fuel cut time and immediately before the fuel cut is set (S101).

The engine torque profile is maintained in a target engine driving state according to a driver's required torque (for example, a tip-in state of stepping on the accelerator pedal for acceleration), and a stroke state (tip-out state of decelerating by removing the acceleration pedal). It is set to a range that can smoothly control the torque change by giving a filtering effect until the value closes to zero based on the axial torque from the value at the time of switching to.

At this time, the filter coefficient for the filtering is determined in consideration of the operability and fuel economy.

Next, it is checked whether the battery is in a chargeable state or a charge limit state while driving (S102).

If the battery can be charged, that is, the clutch is released and the fuel cut of the engine is performed according to the clutch release, and coasting is performed by the charging torque of the motor, that is, the battery can be charged and the tip-in state. If the engine is in the tip-out state, the shock from the engine fuel cut is not transmitted to the drive shaft because the engine and the drive shaft are disconnected.

On the other hand, if the battery charge limit state, that is, the state in which the charging torque generated by the motor (motor is 0 torque) and the engine friction torque by the coupling of the clutch is transmitted to the drive shaft to perform the other side driving, that is, the battery charge limit state When the engine fuel cut is made while the tip-in state is switched from the tip-in state to the tip-out state, the engine and the drive shaft are connected by the clutch, so that the shock caused by the engine fuel cut is transmitted to the drive shaft.

Therefore, when the battery charging limit state is switched from the tip-in state to the tip-out state, the engine friction torque is controlled to a preset torque profile (S103).

Therefore, the engine friction torque is controlled by a preset torque profile in accordance with the situation where the engine mode goes from engine driving to engine cruising according to the driver's demand, that is, when the battery charging is restricted and the tip-in state is changed from the tip-in state to the tip-out state. In addition, the change in torque is smoothly controlled by giving a filtering effect until it approaches zero based on the shaft torque.

Subsequently, after controlling the engine friction torque to a preset torque profile, it is checked whether the engine friction torque has dropped to a certain level (S104), and if it has fallen to a certain level, an engine fuel cut is performed (S105).

More specifically, the fuel injection is maintained until the engine friction torque approaches zero based on the axial torque, and the engine fuel cut is performed when the engine friction torque drops to a level near zero.

Of course, there is some fuel economy reduction as the fuel injection is made until the engine friction torque approaches zero, but since the fuel consumption is considerably shorter, the effects of fuel economy reduction and the required torque non-following will be very small.

In this way, since the impact caused by the engine fuel cut is made at the level at which the engine friction torque is significantly lowered, the shock transmitted by the engine friction torque is not transmitted to the drive shaft, thereby greatly improving the riding comfort.

1 is a block diagram illustrating a power train configuration of a hybrid vehicle;

2 is a flowchart illustrating a tip-out shock reduction method of a hybrid vehicle according to the present invention;

3 is a control diagram illustrating an engine torque profile for reducing tip-out shock in a hybrid vehicle according to the present invention.

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

10: engine

20: motor

30: automatic transmission

40: clutch

50: battery

60: inverter

70: ISG

Claims (3)

Setting an engine torque profile from the clutch engagement state to the fuel cut time point and just before the fuel cut; Checking whether the battery is in a chargeable state or a charge limit state while driving; Controlling the engine friction torque to a preset torque profile when the battery charging limit state is switched from the tip-in state to the tip-out state; Checking whether the engine friction torque has dropped to a certain level, and performing an engine fuel cut when the engine friction torque has fallen to a certain level; Tip-out shock reduction method of a hybrid vehicle comprising a. The method according to claim 1, The engine torque profile is set to a range in which the torque change is smoothly controlled from the torque value at the time when the engine driving state is changed to the other driving state according to the driver's required torque until it approaches zero based on the axial torque. How to reduce tip-out shock in a vehicle. The method according to claim 1, A method of reducing tip-out shock in a hybrid vehicle, wherein the fuel injection is maintained until the engine friction torque approaches zero based on the axial torque, and the engine fuel cut is performed when the engine friction torque drops to a level close to zero. .

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