KR101610585B1 - Kiss point learning method for engine clutch of hybrid electric vehicle - Google Patents

Abstract

The present invention relates to a method of learning an engine clutch kiss point of a hybrid vehicle, in which a kiss point (torque transmission starting point position) at which torque transmission is started in a dry engine clutch is quickly and precisely The present invention has a main object to provide a method of learning an engine clutch kiss point of a hybrid vehicle which can be estimated and detected. In order to achieve the above object, there is provided a method for learning an engine clutch key point of a hybrid vehicle, comprising the steps of: stopping an input shaft and an output shaft of the engine clutch, A target torque control step of controlling a starter-generator connected to the engine so as to be able to transmit power to a target torque; Separating the engine clutch in a target torque control state of the starter-generator; Sensing rotation of the starter-generator during disengagement of the engine clutch; And determining a kiss point from an engine clutch release displacement (Xr) at the start of rotation of the starter-generator.

Description

[0001] The present invention relates to an engine clutch of a hybrid vehicle,

The present invention relates to a method of learning an engine clutch kiss point of a hybrid vehicle, and more particularly, to a method of learning an engine clutch kiss point of a hybrid vehicle in which a kiss point (torque transmission start point position) And more particularly, to a method of learning an engine clutch key point of a hybrid vehicle.

The demand for environmentally friendly automobiles is increasing due to the demand for continuous improvement of fuel economy for automobiles and the strengthening of exhaust gas regulations of each country. Hybrid vehicles are being offered as a real alternative to this.

A typical hybrid vehicle is a vehicle that travels by using an engine and a motor as its driving source. It is an eco-friendly vehicle that can reduce exhaust gas and improve fuel economy by using electric energy together with fossil fuel energy for traveling.

FIG. 1 schematically shows a power train configuration of a hybrid vehicle, which illustrates a power train configuration of a TMED (Transmission Mounted Electric Device) system having a drive motor and a transmission.

As shown in the figure, the engine 1, the drive motor 3, and the transmission 4, which serve as drive sources for running the vehicle, are arranged in series, and power transmission and interruption is provided between the engine 1 and the drive motor 3 The engine clutch 2 is disposed.

A starter-generator (HSG: Hybrid Starter and Generator or ISG: Integrated Starter and Generator) 5, which starts the engine 1 or performs power generation by the engine, is connected to the engine 1 So that power transmission is possible.

The engine clutch 2 selectively transmits power between the engine 1 and the drive motor 3 through a lock up, engage and release operation by the clutch actuator 6 Forward or block.

The engine clutch is driven by a clutch actuator. A dry engine clutch, which is usually applied to a parallel type hybrid vehicle, transmits a driving torque by a frictional force of a diaphragm spring. Driving performance is dependent on a transmission torque command.

In the case of a dry engine clutch, operation control is performed by a mechanical clutch actuator that is driven in accordance with an electrical control signal, unlike a fluid type in which clutch operation control by hydraulic pressure is performed. Such a clutch actuator is a hybrid controller Controlled by a control signal of a hybrid control unit (HCU) to engage or disengage the clutch.

The transmission 4 is connected to the output side of the drive motor 3 and transmits the power of the engine 1 and the drive motor 3 to the drive shaft of the vehicle. The transmission 4 is a manual transmission, an automatic transmission : Automatic Transmission, Automatic Manual Transmission (AMT), or Double Clutch Transmission (DCT).

A battery (not shown) serving as a power source for the drive motor 3 and the starter-generator 5 (hereinafter referred to as HSG) is connected to the drive motor 3 and the HSG The inverter drives the drive motor 3 and the HSG 5 by converting the direct current of the battery into a three-phase alternating current and applying the three-phase alternating current.

The hybrid vehicle is driven in an EV (Electric Vehicle) mode, which is a pure electric vehicle mode using only the power of the drive motor 3, or is driven in the EV mode in which the power of the engine 1 and the drive motor 3 ) In the hybrid electric vehicle (HEV) mode.

During coasting of the vehicle due to braking or inertia, a regenerative mode is performed in which braking and inertia energy is recovered through power generation of the drive motor 3 to charge the battery.

In addition, the HSG 5 operates as a generator by the self-power of the engine 1, or operates as a generator by the power transmitted through the engine 1 under regenerative conditions to charge the battery.

It is also known that the above-described HSG 5 assists the engine output as a driving source for driving the vehicle, depending on the vehicle.

On the other hand, the hybrid vehicle travels in the HEV mode and the EV mode by engaging or disengaging the engine clutch depending on whether the accelerator pedal of the driver and the brake pedal are operated or not, the load, the vehicle speed, the battery charging state (SOC) .

Further, by engaging the engine clutch after the engine speed and the drive motor speed are synchronized when switching from the EV mode running to the HEV mode running, the torque fluctuation does not occur during the power transmission process between the engine and the drive motor, which are different power sources So that the driving ability can be ensured.

More specifically, when switching from the EV mode to the HEV mode, the base oil pressure is applied to the engine clutch at a constant flow rate to secure an initial fill, and the flow rate supplied to the engine clutch is increased to a predetermined slope The engine clutch is slipped by controlling the speed of both ends of the engine clutch, that is, the speed of the engine and the speed of the driving motor to reach a predetermined speed difference after the engine cranking by the starter- do.

When a predetermined time elapses after the slip control of the engine clutch is started, it is determined that the engine speed and the speed of the drive motor are synchronized and the engine clutch is fully engaged to complete the shift to the HEV mode.

In this way, the process of fully engaging the clutch after the clutch slip and the clutch both ends synchronization is not different even in the case of the dry engine clutch using the clutch actuator, and the position where the torque transmission is started by the contact between the friction surfaces (clutch surfaces) That is, the position of the contact point at which the slip state starts is referred to as a kiss point (torque transmission starting point, KP: Kiss Point) of the engine clutch.

The most important factor in transmitting the engine power to the wheel (motor) through the clutch slip is to accurately grasp the kiss point, which is the time point at which the engine power starts to be transmitted through the clutch, and the physical transmission amount of the engine clutch transmission torque, It is precisely the detection.

To this end, engine clutch learning control is introduced in the hybrid system, and engine clutch learning largely consists of kiss point learning and engine clutch transmission torque learning.

Among them, the kiss point learning is performed by applying the hydraulic pressure to the engine clutch to find the hydraulic pressure at the time when the engine power is transmitted to the wheel shaft (the fluid type engine clutch) or the clutch actuator position (displacement) at the time when the engine power is transmitted to the wheel axis. (Dry engine clutch). If the kiss point is learned incorrectly, undesired transmission torque may be generated, resulting in a sense of heterogeneity. Also, when the offset is large, the clutch control responsiveness is degraded.

Fig. 2 is a view for explaining the characteristics of the dry-type engine clutch. Fig. 2 (a) shows the change of the diaphragm spring performance curve according to the wear, and Fig. 2 ) Represents the force acting on the clutch surface (friction surface) and the change of the kiss point with wear.

As shown in FIG. 2, when the wear of the engine clutch proceeds, the clamping load Fc and the release load Fr increase, and the kiss point of the clutch also changes according to the wear state.

Accordingly, when the kiss point is not learned, an action force may be generated on the clutch surface when approaching the kiss point, and a transmission torque and a sense of heterogeneity may occur in an undesired clutch.

Further, if the gap to the kiss point is too long, the clutch control responsiveness may be deteriorated, and learning of the kiss point is indispensable for accurate clutch torque control.

In the prior art, since it is necessary to generate a separate event during the vehicle driving in order to periodically perform the kiss point learning, it may interfere with the driving of the driver during learning, and the learning is performed at regular intervals, The phenomenon may become too short.

Also, there is a complication in the process of confirming various learning entry conditions from the information such as the vehicle condition and allowing the entry of learning only if all learning entry conditions are satisfied.

Registration No. 10-1371461 (March 3, 2014) Registration No. 10-1484233 (Jan. 1, 2015) Open Patent No. 10-2015-0012151 (Feb.

SUMMARY OF THE INVENTION Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and it is an object of the present invention to provide a clutch control device and a control method thereof that are capable of quickly and accurately estimating a kiss point (torque transmission starting point position) The present invention provides a method of learning an engine clutch kiss point of a hybrid vehicle.

In order to achieve the above object, according to the present invention, there is provided a method of learning an engine clutch key point of a hybrid vehicle, comprising the steps of: stopping an input shaft and an output shaft of the engine clutch, A target torque control step of controlling, at a target engine torque, a starter-generator connected to the engine in a power-off state in an engine off state; Separating the engine clutch in a target torque control state of the starter-generator; Sensing rotation of the starter-generator during disengagement of the engine clutch; And determining a kiss point from an engine clutch release displacement (Xr) at the start of rotation of the starter-generator.

In a preferred embodiment of the present invention, in a vehicle stop state, a brake on state, an accel pedal off state, a starter-generator stop state, and a drive motor stop state, And starting a kiss point learning process including a target torque control step.

Further, the present invention is characterized in that the drive motor is controlled to be Orpm or the transmission is controlled to a parking mode in order to control the input shaft and the output shaft of the engine clutch to a stopped state immediately after the key-on for vehicle operation.

Further, the kiss point is determined by adding a set error value to an engine clutch release displacement at the time when rotation of the starter-generator is sensed.

Also, the error value is set to a value according to a target torque for starter-generator control and is applied.

Further, the engine clutch is a dry engine clutch operated by a clutch actuator.

Further, the engine clutch release displacement Xr is detected from the signal of the displacement sensor which detects the operational displacement of the clutch actuator.

Thus, according to the method of learning the engine clutch key point of the hybrid vehicle according to the present invention, the following effects can be obtained.

1) When the hybrid vehicle is turned on, the vehicle must start driving in the EV mode, and when the dry engine clutch of the normal intake type is applied, the clutch is disengaged and starts traveling. The clutch must be separated immediately after the key-on. Accordingly, since the kiss point learning is performed immediately after the key-on before the start of the vehicle travel, it is not necessary to generate any separate event during the driving, and the kiss-point learning can be performed without obstructing the driver's vehicle driving.

2) It is possible to find the kiss point value quickly because it can start the kiss point learning immediately after the key stop, brake on, accelerator pedal off, HSG stop, drive motor stop, clutch fully engaged key state.

3) Since the characteristic of the dry engine clutch which changes the transmission torque according to the displacement is used, it is possible to know the displacement value which produces the desired transmission torque irrespective of the clutch friction coefficient, the clutch surface action force and the like.

1 is a schematic view showing a power train configuration of a hybrid vehicle.
2 is a view for explaining the characteristics of the dry engine clutch.
3 is a flowchart illustrating an engine clutch kiss point learning method according to an embodiment of the present invention.
4 is a view for explaining torque set for HSG target torque control in the engine clutch kiss point learning method according to the embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings, which will be readily apparent to those skilled in the art to which the present invention pertains.

In the case of a parallel type hybrid vehicle equipped with a dry engine clutch of a normal engage type, a situation in which the engine clutch is separated for EV drive necessarily occurs at the time of key on for vehicle operation, In this case, if the kiss point of the engine clutch can be memorized, learning can be performed without disturbing the driver's driving without any separate event during the vehicle operation, and the time for completing the learning can be shortened in terms of time.

In the present invention, the starter-generator (hereinafter referred to as "HSG") connected to the engine is stopped by the set torque (hereinafter, referred to as " stop ") when the engine clutch is fully engaged at the time of key- (Or the engine) starts to rotate, that is, the time when the input shaft of the engine clutch starts to rotate, while the low-torque control of the engine clutch is released Points are learned.

FIG. 3 is a flowchart showing an engine clutch key point learning method according to an embodiment of the present invention. Referring to FIG. 3, an engine clutch key point learning method of the embodiment will be described in more detail as follows.

In the present invention, the control unit for performing learning control is one or more microprocessors operated by a set program, and the set program includes a series of commands for performing a method of learning a kiss point of an engine clutch according to an embodiment of the present invention As shown in FIG.

In the embodiment of the present invention, the control unit includes a Hybrid Control Unit (HCU), which is a highest level controller for controlling overall operation of the hybrid vehicle, a Motor Control Unit (MCU) for controlling driving of the driving motor and the HSG, And a transmission control unit (TCU) for controlling the operation of the transmission. A kiss point learning process, which will be described later, can be performed under the coordinated control of the hybrid controller, the motor controller, and the shift controller, which are the highest level controllers.

First, the vehicle stop, engine off, brake on, accel pedal off, HSG stop, drive motor stop, engine clutch complete In the coupled state, kiss point learning starts.

When the kiss point learning starts, the motor controller controls the drive motor as Orpm, or the transmission controller controls the transmission in the parking mode (parking range stage) to keep the transmission input shaft at 0 rpm stop state (S11), thereby controlling the input speed and the output speed of the engine clutch to be 0 rpm in a state in which the engine clutch is fully engaged.

Then, in a state where the input shaft and the output shaft of the engine clutch are stopped as described above, the motor controller starts the HSG target torque control for controlling the HSG to the target torque with the preset torque as the target torque (S12) The hybrid controller controls the drive of the clutch actuator to gradually disconnect the engine clutch (S13).

At this time, the hybrid controller monitors the rotation of the HSG (S14). When the rotation of the HSG is sensed, the engine clutch release displacement Xr at the start of rotation of the HSG is stored (S15) (Step S16). In step S16, a value obtained by adding an error value preset in advance is determined as a kiss point value.

When the kiss point value is determined as described above and the engine clutch is completely disengaged (S17), the learning event ends.

In determining the kiss point value, the error value may be preset and applied as a value according to the target torque for HSG control.

In the present invention, whether or not the HSG is rotated can be determined by a signal from a normal sensor or a speed detecting unit for detecting the rotational speed of the HSG by a component in a control unit such as a control unit, for example, a hybrid controller, The scope of protection of the invention should not be construed as being limited thereto.

The technical idea of the present invention can be applied to a configuration in which HSG rotation or rotation speed can be substantially detected and judged even in a different configuration.

The engine clutch release displacement Xr may be the clutch actuator operation displacement at the time when the rotation of the HSG is sensed while the engine clutch is separated from the fully engaged state.

Thus, the engine clutch release displacement Xr can be detected from a signal of a displacement sensor that detects the operational displacement of a conventional displacement sensor installed in the clutch actuator, that is, the clutch actuator.

As described above, in the present invention, the engine clutch is gradually separated while one axis of the engine clutch is fixed and the set torque is applied to the opposite shaft through the HSG, and the clutch release displacement at the time when the HSG starts to rotate is set to the transmission torque Tc ) Is generated.

A target value having a small influence on the clutch friction material is set and applied while overcoming the internal resistance of the engine with the set torque, that is, the HSG target torque. At this time, the lower the target torque is set, the displacement measurement point approaches the actual kiss point, The setting error value can be lowered.

Fig. 4 is a diagram for explaining the torque set for the HSG target torque control, where Xr represents the clutch release displacement and Tc represents the clutch transmission torque.

As shown, it can be seen that, depending on the target torque to be set, the clutch displacement measurement point, that is, the measurement point at which the rotation of the HSG starts at the time of clutch disengagement, is close to the actual clutch kiss point.

As a result, the kiss point can be found by setting the target torque to the minimum value within a range in which the measurement of the clutch release displacement is possible, and adding a certain amount of error value determined through the preceding research.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the scope of the present invention is not limited to the disclosed exemplary embodiments. Forms are also included within the scope of the present invention.

1: engine 2: engine clutch
3: drive motor 4: transmission
5: HSG 6: Clutch actuator

Claims (7)

A method of learning an engine clutch kiss point of a hybrid vehicle,
A target torque for controlling the starter-generator, which is connected to the engine so as to be able to transmit power to the engine in a state where the input shaft and the output shaft of the engine clutch are stopped, the fully engaged state of the engine clutch and the engine off state, A control step;
Separating the engine clutch in a target torque control state of the starter-generator;
Sensing rotation of the starter-generator during disengagement of the engine clutch; And
Determining a kiss point from an engine clutch release displacement (Xr) at the start of rotation of the starter-generator;
Wherein the engine clutch kiss point learning method of the hybrid vehicle comprises the steps of:
The method according to claim 1,
The target torque control step of the starter-generator is performed immediately after the key-on for vehicle operation in a vehicle stop state, a brake on state, an accel pedal off state, a starter-generator stop state, Wherein the learning of the kiss point learning process is started.
The method according to claim 1 or 2,
Characterized in that the drive motor is controlled in an Orpm or the transmission is controlled in a parking mode so as to control the input shaft and the output shaft of the engine clutch to a stopped state immediately after a key for driving the vehicle.
The method according to claim 1,
Wherein the kiss point is determined by adding a set error value to an engine clutch release displacement at the time when rotation of the starter-generator is sensed.
The method of claim 4,
Wherein the error value is set and applied to a value according to a target torque for starter-generator control.
The method according to claim 1,
Wherein the engine clutch is a dry engine clutch operated by a clutch actuator.
The method according to claim 1,
Wherein the engine clutch release displacement Xr is detected from a signal of a displacement sensor that detects an operational displacement of the clutch actuator.

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