KR101734759B1 - Method for preventing slip of engine clutch - Google Patents

Abstract

The present invention relates to an engine clutch slip prevention control method for an eco-friendly vehicle and, more specifically, to an engine clutch slip prevention control method for an eco-friendly vehicle capable of preventing a slip of an engine clutch by using control determining a bed-in treatment using accumulated slip energy and torque intervention control in case of shifting. Namely, the engine clutch slip prevention control method for an eco-friendly vehicle is capable of obtaining operability for power transmission by preventing the slip of the engine clutch by differently controlling a coupling degree of the engine clutch by determining the existence of the bed-in treatment using the accumulated slip energy in case of an HEV mode drive and performing the torque intervention control in case of shifting in consideration of intake torque which can be generated in case of the slip of the engine clutch and preventing damage to a DCT clutch and the like. The engine clutch slip prevention control method for an eco-friendly vehicle includes: a step of shifting a mode from an EV mode to an HEV mode; a step of variably controlling the coupling degree of the engine clutch; and a step of performing the torque intervention control in case of shifting.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method of preventing slippage of an engine-

The present invention relates to an engine clutch slip prevention control method for an environmentally friendly vehicle, and more particularly, to a control method for an engine clutch slip prevention control method for an environmentally friendly vehicle, The present invention relates to an engine clutch slip prevention control method for an environmentally friendly vehicle.

Among hybrid vehicles and plug-in hybrid vehicles, hybrid vehicles and plug-in hybrid vehicles are environmentally friendly vehicles that use a motor as a power source to reduce exhaust gas and improve fuel economy. They can transmit engine or motor power to a traveling wheel, And a power transmission system that transmits the power to the traveling wheels together.

1 attached herewith shows an example of a power transmission system of a hybrid vehicle which is an environmentally friendly vehicle.

The power transmission system shown in Fig. 1 is a type in which a drive motor is attached to the DCT transmission and is arranged between the engine 10 and the motor 14 arranged in series with each other, the engine 10 and the motor 14, A motor / motor and a DCT transmission 16 for outputting and outputting the engine power to the traveling wheel, a power transmission system for connecting the crank pulley of the engine to the engine for starting and charging the battery, And a hybrid starter generator (HSG) 18 as a kind of motor.

The DCT transmission 16 is a dual clutch transmission (DCT) in which the gear structure of the manual transmission is arranged on the odd-numbered side and the even-numbered side and is connected to the driving motor side and the clutch respectively.

The engine clutch 12 is a dry type engine clutch, which is disposed between the engine and the motor and performs switching (engagement: HEV mode, release: EV mode) between the EV mode and the HEV mode, Unlike the wet type, the power is transferred by the presence or absence of the disk friction material.

Preferably, the engine clutch 12 is engaged or released by operating an actuator stroke corresponding to an engine clutch transmission torque command of an HCU (Hybrid Control Unit), which is a host controller.

Meanwhile, the engine clutch 12 is manufactured through a bed-in process. The vane-in process is a process of forcibly slipping the disc friction material of the engine clutch to stabilize performance by friction at this time.

At this time, when the engine clutch is a new product or a product lacking in the bed-in process, the frictional material of the engine clutch is overloaded and the frictional coefficient is lowered. As a result, the fade phenomenon occurs and the performance of the disc friction material is not properly exhibited.

Such a hybrid vehicle basically travels in an EV mode using a motor as a power source, but travels in an HEV mode in which the engine is used as a power source in accordance with the demand of the driver and the degree of battery SOC.

At this time, the above-described engine clutch plays a role of positioning and connecting between the two power sources, and when the mode is switched from EV to HEV mode, the engine clutch engagement is engaged as much as the engine required torque.

Further, when shifting during the HEV mode running after switching from EV to HEV mode, the host controller distributes and controls the engine and motor torque intervention according to the torque intervention request of the shift control unit (TCU).

For reference, in the case of a hybrid vehicle equipped with an automatic transmission other than the DCT transmission, the torque intervention distribution control uses the fluid (transmission oil) during the shifting process to achieve optimal slip control of the clutch and brake in the transmission This is a control process that minimizes the generated heterogeneity and reduces the input torque of the transmission momentarily, in particular, to reduce the impact generated when the clutch in the transmission is engaged or disengaged during the shifting process.

At this time, in the torque intervention control, the torque reduction main body for reducing the transmission input torque may be an engine or a motor, an engine, and a motor.

Hereinafter, a conventional torque engaging procedure during engaging and shifting of the engine clutch will be described with reference to the flowchart of FIG. 2 as follows.

First, a request for engaging the engine clutch is confirmed during EV traveling (S101).

Subsequently, when there is a request for engaging the engine clutch, the engine clutch is engaged based on the set engine clutch engaging amount (= required engine torque) (S102).

Thus, the driving mode is switched from the EV mode to the HEV mode according to the engagement of the engine clutch (S103).

At this time, it is determined whether or not the shift is performed during the HEV mode running (S104). When the shift is made, the shift controller (TCU) issues a torque intervention request (S105).

Accordingly, the HCU distributes and controls the engine and motor torque intervention according to the torque intervention request of the shift control unit (TCU).

That is, the requested torque intervention amount is compared with the motor allowable torque intervention amount (S106). If the requested torque intervention amount is larger, the motor + engine torque intervention plus the engine torque is performed (S107) If the intervention amount is smaller, a motor torque intervention is performed (S108).

In such a hybrid system, the dry engine clutch is complementary to the transmission torque model through engine clutch learning control such as touch point learning, friction coefficient learning, etc., for precise torque transmission in its engagement.

However, the engine clutch slip occurs due to the instability of the transmission torque model, the reduction of the transmission torque due to the clutch wear, the inertial torque due to the speed change during shifting, and the like. Another reason for the occurrence of engine clutch slip is, The performance of the disc friction material according to the presence or absence of the in-process is not properly exhibited.

In addition, when the EV-HEV mode is switched, slippage occurs because the engine clutch can not be engaged by the transmission torque transmitted to the engine clutch. In this case, not only the engine clutch is disadvantageous but also deteriorates the shifting operation and DCT (dual clutch transmission) .

Therefore, it is necessary to protect the DCT clutch and the like, as well as to ensure the operability for power transmission through prevention of engine clutch slip occurrence.

SUMMARY OF THE INVENTION In view of the above, it is an object of the present invention to prevent slippage by engaging an engine clutch by a transmission torque transmitted to an engine clutch when switching from the EV mode to the HEV mode. In the HEV mode, The slip energy is determined to control the engagement amount of the engine clutch in a different manner and the torque intervention control at the time of shifting is also performed in consideration of the inflow torque that can be generated when the engine clutch slips, It is, of course, an object of the present invention to provide an engine clutch slippage prevention control method for an environmentally friendly vehicle which can prevent burnout of a DCT clutch and the like.

According to an aspect of the present invention, there is provided a hybrid vehicle including: i) switching from an EV mode to an HEV mode according to an engine clutch engagement; Ii) variably controlling the engine clutch engagement amount by determining the presence or absence of the bed-in process as cumulative slip energy when the vehicle is traveling in the HEV mode; And iii) performing a torque intervention control during shifting during an HEV mode running in consideration of an inflow torque that may be generated when the engine clutch slips; The present invention provides an engine clutch slip prevention control method for an environmentally friendly vehicle.

In a preferred embodiment of the present invention, the step ii) includes the steps of: calculating the cumulative slip energy of the engine clutch; Comparing the cumulative slip energy of the calculated engine clutch with a reference value; A control step of determining that the engine is in a bed-in-oil state, if the cumulative slip energy of the engine clutch is greater than a reference value, and keeping the engine clutch engagement amount at the engine required torque; And when the cumulative slip energy of the engine clutch is smaller than the reference value, determining that the engine is in a bed-in-silent state and performing engine torque reduction control; As shown in FIG.

Preferably, the cumulative slip energy is monitored by monitoring the engine and the motor speed at the time of HEV driving, judging that the slip occurs when a difference of more than a predetermined speed occurs, and comparing the engine clutch input torque (= engine torque) And the speed difference between the motor and the motor).

Alternatively, the cumulative slip energy is used to monitor the engine speed and the motor speed in real-time during the shift, determine that the slip occurs when a difference of more than a predetermined speed occurs, and determine an engine clutch input torque (= engine torque + The speed difference between the engine and the motor).

In particular, the step of performing the engine torque reduction control is characterized in that: the engine clutch engagement amount is set to a level obtained by subtracting the inflow torque amount at the time of engine clutch slip from the engine torque at the engine required torque.

In a preferred embodiment of the present invention, step (iii) comprises the steps of: comparing the requested torque intervention amount with the motor permitted torque intervention amount if there is a torque intervention request; When the requested torque intervention amount is larger, torque intervention control is performed with the motor + engine torque intervention (engine torque + inflow torque flowing into the engine clutch when shifting); And when the requested torque intervention amount is smaller, torque intervention control is performed with the motor + engine torque intervention (inflowing torque into the engine clutch at the time of shifting); As shown in FIG.

Through the above-mentioned means for solving the problems, the present invention provides the following effects.

First, it is possible to prevent the engine clutch slip by controlling the engine clutch engagement amount by judging whether or not the bed-in processing of the engine clutch is accumulated slip energy when the vehicle is traveling in the HEV mode.

Second, the torque intervention control during shifting during the HEV mode running is also performed in consideration of the inflow torque that can be generated when the engine clutch slips, thereby preventing the engine clutch slip from occurring.

Third, through the engine clutch slip prevention, it is possible to secure power transmission operability and to prevent burnout of the DCT clutch and the like.

Fourth, in the production of the engine clutch, it is not necessary to carry out a separate bed-in process, so that the number of engine clutch manufacturing processes and the production speed can be improved.

1 is a structural view showing an example of a power transmission system of a hybrid vehicle,
FIG. 2 is a flowchart showing a conventional torque intervention process during engine clutch engagement and shifting; FIG.
3 is a flowchart showing a torque intervention process during engaging and shifting of an engine clutch according to the present invention;

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

3 attached herewith shows a torque intervention process during engine clutch engagement and shifting according to the present invention.

First, a request for engaging the engine clutch is confirmed during EV traveling (S201).

Subsequently, when there is an engine clutch engagement request, the engine clutch is engaged based on the set engine clutch engagement amount (= the engine required torque) (S202).

Accordingly, in accordance with the engagement of the engine clutch, the HEV mode travel is performed together with the travel mode change from the EV mode to the HEV mode (S203).

In the meantime, the engine clutch is manufactured through a bed-in process in which the disc friction material is forcibly slipped so as to stabilize the performance by the friction at this time. When the new clutch or the bed-in process is insufficient, the performance of the disc friction material is not properly exhibited, Causing a slip.

More specifically, since the engine clutch is a dry clutch, a certain time is required for the clutch slip to be established and the friction coefficient is increased and stabilized, so that a bed-in process is carried out in manufacturing the engine clutch, Without a bed-in process for stabilization during manufacture, slip may occur even if the engine clutch is fully engaged.

According to the present invention, there is a first point in that the engine clutch can be prevented from slipping, regardless of the presence or absence of a bed-in process for the disc friction material of the engine clutch, that is, without performing a bed-in process for the disc friction material .

For this, in the HEV mode running (S203), the presence or absence of the bed-in processing is determined as the cumulative slip energy of the engine clutch, and the engine clutch engagement amount is variably controlled (S204).

The above-mentioned bed-in effect can be obtained as a cumulative slip energy since a certain amount of clutch slip is made and the friction coefficient is increased and stabilized.

Therefore, it is possible to calculate the energy at the time of engine clutch slip, with or without a bed-in process for the disk friction material of the engine clutch, that is, without the bed-in process for the disk friction material, (Presence or absence of the bed), and performs compensation control for the slip before stabilization.

To this end, data (engine torque, engine clutch transmission torque, engine and motor speed, etc.) are stored at the time of engine clutch slip and the accumulated slip energy of the engine clutch is calculated using accumulated data at S204-1.

At this time, the cumulative slip energy is calculated differently during normal driving and shifting during HEV driving.

In case of normal driving (HEV driving), the engine and motor speed are monitored in real time. If the difference exceeds a certain speed, it is judged as slip. At this time, the engine clutch input torque (= engine torque) The slip energy can be calculated.

In case of shifting (during shifting during HEV driving), engine and motor speed are monitored in real time, and it is judged as a slip when a difference of more than a certain speed occurs, and engine clutch input torque (= engine torque + inertial torque) The slip energy kJ can be calculated by the speed difference between the motors.

After the cumulative slip energy of the engine clutch is calculated as described above, it is compared with the reference value kJ (S204-2).

At this time, the reference value is used to determine the existence of bed-in as the cumulative slip energy, and can be obtained by calculating the slip energy at the time of producing the engine clutch or at the time when the bed-in effect occurs in the actual vehicle test conditions.

If it is determined in step S204-2 that the cumulative slip energy of the engine clutch is greater than the reference value, it is determined that the vehicle is in a state of bed-in oil (in which a bed-in effect or a bed-in effect is performed) Control is performed so that the engine clutch engagement amount is maintained at the engine required torque (S204-3), including when the HEV mode is switched in the EV mode.

That is, control for joining the engine clutch by the transmission torque (engine required torque) transmitted to the engine clutch is performed.

On the other hand, as a result of the comparison in step S204-2, if the accumulated slip energy of the engine clutch is smaller than the reference value, it is determined that the state is the bed-in state (the state in which the bed-in process is not performed or the bed- , The engine torque reduction control is performed to prevent slip (S204-4).

That is, in the idle state, the friction material of the engine clutch is overloaded and the frictional coefficient is lowered. Therefore, the engine torque reduction control is performed to prevent the overload and increase the frictional coefficient. The slip of the engine clutch can be prevented by controlling the level at which the input torque (e.g., inertia torque) at the time of engine clutch slip is subtracted.

Further, since engine clutch bonding and slip prevention can be performed without the above-described bed-in process, and a separate bed-in process is not required at the time of manufacturing the engine clutch, it is possible to reduce the number of engine clutch manufacturing processes and improve the production speed .

At this time, it is determined whether or not the shift is made during the HEV mode running (S205). When the shift is made, the shift controller (TCU) makes a torque intervention request (S206).

The torque intervention control at the time of shifting is performed for minimizing the sense of heterogeneity occurring during shifting and improving the speed change and the driving performance. The torque intervention amount requested by the shift control unit (TCU) Each engine and motor torque intervention is done.

According to the present invention, there is provided a torque intervention control step of distributing and controlling an engine and a motor torque intervention in an HCU according to a torque intervention request of the shift control unit (TCU), wherein the torque intervention control step (S207), the torque transmitted to the engine clutch is reduced, thereby preventing the engine clutch from slipping.

More specifically, the torque intervention requested by the transmission control unit (TCU) is not limited to the motor torque, but the inflow torque (inertia Torque) is performed by the engine torque intervention, the torque transmitted to the engine clutch is reduced, thereby preventing the engine clutch slip.

If the torque intervention is requested, the requested torque intervention amount is compared with the motor torque intervention amount (S207-1).

As a result of the comparison, when the requested torque intervention amount is larger, the torque intervention control is performed by the motor + engine torque intervention in addition to the motor torque in addition to the motor torque. The engine torque intervention amount at this time is the inflow torque (S207-3), the input torque of the transmission can be easily reduced instantaneously as an effect inherent to the torque intervention, so that the clutch in the transmission is engaged or disengaged Thereby minimizing a sense of heterogeneity occurring during shifting.

On the other hand, if the requested torque intervention amount is smaller than the motor allowable torque intervention amount, a motor + engine torque intervention in addition to the motor torque is added to the engine torque intervention amount. At this time, (S207-2), the torque transmitted to the engine clutch is reduced, thereby preventing the slip.

10: Engine
12: Engine clutch
14: Motor
16: Transmission
18: HSG

Claims (6)

I) switching from the EV mode to the HEV mode according to the engagement of the engine clutch;
Ii) variably controlling the engine clutch engagement amount by determining the presence or absence of the bed-in process as cumulative slip energy when the vehicle is traveling in the HEV mode; And
Iii) performing a torque intervention control during shifting during HEV mode traveling in consideration of an inflow torque that may be generated when the engine clutch slips;
And a control unit for controlling the slip prevention of the engine.
The method according to claim 1,
Wherein step ii) comprises:
Calculating an accumulated slip energy of the engine clutch;
Comparing the cumulative slip energy of the calculated engine clutch with a reference value;
A control step of determining that the engine is in a bed-in-oil state, if the cumulative slip energy of the engine clutch is greater than a reference value, and keeping the engine clutch engagement amount at the engine required torque;
If the cumulative slip energy of the engine clutch is smaller than the reference value, determining that the engine is in the idle state and performing the engine torque reduction control;
Wherein the control of the slip control of the engine clutch is carried out by the control means.
The method according to claim 1 or 2,
The cumulative slip energy is:
When the HEV is running, the engine and motor speed are monitored in real time. If the difference exceeds a predetermined speed, the engine is judged to be in a slip state, and the engine clutch input torque (= engine torque) and the speed difference Wherein the slip prevention control is performed in the following manner.
The method according to claim 1 or 2,
The cumulative slip energy is:
(Engine torque and inertia torque) and the speed difference (speed difference between the engine and the motor) at the time of the judgment, Of the engine (1).
The method of claim 2,
The step of performing the engine torque reduction control includes:
Wherein the engine clutch engagement amount is set to a level obtained by subtracting the inflow torque amount at the time of engine clutch slip from the engine torque at the engine required torque.
The method according to claim 1,
Wherein step iii) comprises:
Comparing the requested torque intervention amount with a motor allowed torque intervention amount if there is a torque intervention request;
When the requested torque intervention amount is larger, torque intervention control is performed with the motor + engine torque intervention (engine torque + inflow torque flowing into the engine clutch when shifting);
If the requested torque intervention amount is smaller, the torque intervention control is performed with the motor + engine torque intervention (the inflow torque flowing into the engine clutch at the time of shifting);
Wherein the control of the slip control of the engine clutch is carried out by the control means.

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