KR102163784B1 - Emergency control method and system of Continuously Variable Valve Duration Engine - Google Patents

Abstract

Disclosed are an emergency control method of a CVVD engine, and an emergency control system thereof. According to the present invention, the emergency control method of a CVVD engine comprises the steps of: operating a CVVD diagnostic logic to detect an error of a CVVD control unit; ignoring a duty value for current CVVD control and stopping control of a CVVD motor when the error of the CVVD control unit is detected; outputting a CVVT cleaning execution command to the CVVT control unit so as to execute CVVT cleaning; recognizing a current position of the CVVD motor on the basis of the amount of intake air measured by a manifold absolute pressure (MAP) sensor during execution of the CVVT cleaning; detecting the error of the CVVT control unit; and determining whether current position information on the CVVD motor recognized from an inverted CVVD duty value is reliable in accordance with an error detecting result of the CVVT control unit, and executing a corresponding response strategy in accordance with the reliability thereof. In the step of determining the current position of the CVVD motor, the current CVVD duty value is inverted based on the amount of the intake air measured by the MAP sensor of an intake manifold, and the current position of the CVVD motor is recognized by the inverted CVVD duty value. According to the present invention, it is possible to prevent knocking generation, thereby protecting an engine.

Description

Emergency control method and system of CVVD engine {Emergency control method and system of Continuously Variable Valve Duration Engine}

The present invention relates to an emergency control method and emergency control system of a CVVD engine, and in detail, when an error is detected in the CVVD control system, through CVVT cleaning, the position of the CVVD drive motor at the time of error detection is identified and identified. It relates to an emergency control method and emergency control system of a CVVD engine that prevents deterioration of drivability due to extreme limp groove operation by using different fail safety strategies depending on the location.

In general, in an internal combustion engine, the opening and closing of the intake valve and the exhaust valve are controlled by a camshaft. The camshaft is connected with a crankshaft (or a chain) that converts the linear motion of the piston in the engine cylinder into rotational motion, and air is sucked into the combustion chamber while the intake valve is opened by the camshaft, and the exhaust valve is While open, combustion gases are released.

CVVD (Continuous Variable Valve Duration) and CVVT (Continuous Variable Valve Timing) are technologies that control the opening and closing time of the valve, respectively. CVVD and CVVT are technologies designed to exhibit optimal engine performance by varying the valve opening time and opening/closing time according to the target value determined from the dedicated map according to the driving conditions such as engine rotation speed or load.

Among them, CVVD is a technology that improves the overall performance of the engine by freely adjusting the opening time of the intake valve, that is, the duration of the valve opening. In other words, CVVD is a technology that changes the time the valve is open according to the operating state of the engine, and uses the difference in speed at which the cam presses the valve when the center of rotation of the camshaft is moved to control the time the valve is open. Have.

CVVD systems can have a direct and catastrophic effect on drivability, fuel economy and exhaust gas emissions in case of failure. Therefore, it must be accompanied by a strict fail safety strategy. The conventional CVVD system is set to control the vehicle through an extreme limp home operation in order to protect the driver and the vehicle because it is impossible to determine the location of the CVVD motor when a control error occurs.

However, when the vehicle is controlled through an extreme limp home operation, since the covered road of the CVVD device is increased, the durability of the vehicle may be deteriorated and the driver's discomfort may be caused. In addition, since the air volume control is unstable, knocking may be caused, and the knocking generated as such has a problem that adversely affects drivability.

Korean Patent Registration No. 10-1864434 (Registration date 2018. 05. 29)

The technical problem to be solved by the present invention is to determine the position of the CVVD drive motor at the time of error detection through CVVT cleaning when an error is detected in the CVVD control system, and use different fail safety strategies according to the identified position. Therefore, it is intended to provide an emergency control method and system for CVVD engines that can prevent deterioration of drivability due to extreme lymph groove operation.

According to an aspect of the present invention as a means of solving the problem,

(a) detecting an error of the CVVD control unit by operating the CVVD diagnosis logic;

(b) when a CVVD control unit error is detected, ignoring a duty value for current CVVD control and stopping control of the CVVD motor;

(c) outputting a CVVT cleaning execution command to the CVVT control unit to perform CVVT cleaning;

(d) determining the current position of the CVVD motor based on the amount of intake air measured through the MAP sensor during the CVVT cleaning execution;

(e) detecting an error of the CVVT control unit; And

(f) determining whether to trust the current position information of the CVVD motor according to the error detection result of the CVVT control unit, and executing a corresponding response strategy according to the trust or not; and

In step (d),

An emergency control method for CVVD engines that calculates the current CVVD duty value based on the intake air volume measured through the intake manifold's MAP sensor (Manifold Absolute Pressure sensor), and determines the current position of the CVVD motor with the inverted CVVD duty value. to provide.

In step (a), preferably, when an overcurrent flows through the CVVD system, an error signal is output from a sensor inside the CVVD motor, a position learning of the CVVD motor fails, or the ECU fails in CAN communication with the CVVD controller. If at least one is true, it may be detected as an error of the CVVD control unit.

In addition, in step (d), the position of the CVVD motor according to the CVVD duty value during CVVT cleaning, and the change in the amount of intake air according to the position of the CVVD motor are quantified, and the current position of the CVVD motor can be determined using the intake map stored in the form of data. have.

In addition, when the CVVT control unit error is not detected in step (e), in step (f), the current position information of the CVVD motor determined from the inverted CVVD duty value is trusted, and mapping is different according to the current position of the CVVD motor. It is possible to emergency control the duty of the CVVD motor with the set duty value.

On the contrary, when an error of the CVVT control unit is detected in step (e), the current position information of the CVVD motor determined from the inverted CVVD duty value is ignored in step (f), and the CVVD motor is stopped or the valve duration The CVVD motor is rotated in the shortest direction, and the engine speed and throttle opening amount can be forcibly limited to the set value.

According to another aspect of the present invention as a means of solving the problem,

ECU;

A CVVD control unit for continuously varying the valve opening time according to the ECU control;

Including; CVVT control unit for continuously varying the valve opening and closing time according to the control of the ECU,

The ECU,

When an error is detected in the CVVD control unit, the current duty value for CVVD control is ignored and the control of the CVVD motor is stopped.

Applying a command for executing CVVT cleaning to the CVVT control unit,

The current position of the CVVD motor is determined in reverse based on the amount of intake air measured through the MAP sensor (Manifold Absolute Pressure sensor) during CVVT cleaning,

It provides an emergency control system for the CVVD engine that controls the duty of the CVVD motor with different values depending on the location of the identified CVVD motor.

Preferably, the ECU is at least one of a case where an overcurrent flows through the CVVD system, an error signal is output from a sensor inside the CVVD motor, a position learning of the CVVD motor fails, and a CAN communication with the CVVD controller fails. It can be determined as a CVVD control unit error.

In addition, the ECU can determine the current position of the CVVD motor using an intake map stored in the form of data by quantifying the position of the CVVD motor according to the CVVD duty value and the change in the amount of intake air according to the CVVD motor position during CVVT cleaning.

In addition, the ECU detects an error in the CVVT control unit during the CVVT cleaning execution, and if the CVVT control unit error is not detected, the ECU trusts the current position information of the CVVD motor, which is determined inversely from the intake air amount during the CVVT cleaning execution, and The duty value of the CVVD motor can be emergency controlled with a duty value mapped differently according to the current position.

In contrast, the ECU detects an error in the CVVT control unit during CVVT cleaning execution, and when a CVVT control unit error is detected, ignores the current position information of the CVVD motor, which is inverted from the intake air amount during CVVT cleaning, and stops the CVVD motor. Or, the CVVD motor is rotated in the short direction with the shortest valve duration, and the engine speed and throttle opening can be forcibly limited to a set value.

According to an embodiment of the present invention, when an error is detected in the CVVD control system, the position of the CVVD drive motor at the time of error detection is identified through CVVT cleaning, and other fail safety strategies are employed according to the identified position, It can prevent deterioration of drivability and durability due to extreme limp groove operation, and can suppress the occurrence of knocking, thereby protecting the engine.

1 is a schematic configuration diagram of a variable valve control device of a CVVD engine according to an embodiment of the present invention.
2 is a graph showing a change in an intake valve when entering a valve control mode according to constant speed driving.
3 is a flowchart illustrating a method of controlling a variable valve of a CVVD engine according to an embodiment of the present invention.

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

In describing the present invention, terms used in the following specification are only used to describe specific embodiments, and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise.

In addition, in the present specification, terms such as "comprise" or "have" are intended to designate the presence of features, numbers, steps, actions, components, parts, or a combination thereof described in the specification, but one or more other It is to be understood that the presence or addition of features, numbers, steps, actions, components, parts, or combinations thereof, does not preclude in advance the possibility of being excluded.

In addition, terms such as first and second may be used to describe various elements, but the elements should not be limited by the terms. These terms are used only for the purpose of distinguishing one component from another component.

In addition, terms such as "... unit", "... unit", "... module" described in the specification mean a unit that processes at least one function or operation, which can be implemented by hardware or software or a combination of hardware and software. I can.

In the description with reference to the accompanying drawings, the same drawing reference numerals are assigned to the same elements, and duplicate descriptions of the same elements will be omitted. In addition, in describing the present invention, when it is determined that a detailed description of a related known technology may unnecessarily obscure the subject matter of the present invention, a detailed description thereof will be omitted.

1 is a schematic configuration diagram of a CVVD engine emergency control system according to an embodiment of the present invention.

Referring to FIG. 1, the emergency control system of a CVVD engine according to an embodiment of the present invention includes an ECU 10, a continuous variable valve duration (CVVD) control unit 20, and a continuous variable valve timing (CVVT) control unit 30. Include. The ECU 10 controls the engine so that optimal performance can be exhibited according to the driver's request based on detection information of sensors mounted on each part of the vehicle.

The CVVD (Continuous Variable Valve Duration) control unit 20 and the CVVT (Continuous Variable Valve Timing) control unit 30 respectively control the opening time and opening/closing time of the valve. CVVD and CVVT are operated so that optimum engine performance can be exhibited by varying the valve opening time and opening/closing time according to the target value determined from the dedicated map according to the driving conditions such as engine rotation speed or load.

The CVVD control unit 20 freely adjusts the opening time of the intake valve, that is, the duration at which the valve is open, according to the control of the ECU 10, thereby improving the overall performance of the engine. That is, the CVVD control unit 20 is a technology that varies the time the valve is open according to the operating state of the engine, and uses the difference in speed at which the cam presses the valve when the rotation center of the camshaft is moved to determine the time the valve is open. Adjust.

The CVVD control unit 20 preferably adjusts the center of rotation of the camshaft according to the driving of the CVVD motor 22 and the CVVD motor 22 to generate and output a rotational force suitable for valve opening time control according to the control of the ECU 10. It may be configured with a variable controller 24 that is operated to vary. Since the CVVD control unit 20 having such a configuration is a known technology, a detailed description will be omitted below.

The CVVT control unit 30 continuously changes the valve opening/closing timing according to the control of the ECU 10. The CVVT control unit 30 includes a rotor vane 32 mounted on one end of the camshaft, and a housing 34 that is mounted on the rotor vane 32 to form a retarding chamber and an advancing chamber therein. The valve opening/closing timing by the CVVT control unit 30 is adjusted by adjusting the pressure of the oil supplied to the advance chamber and the retard chamber in the housing 34 by the oil control valve 36.

As mentioned above, the ECU 10 controls the CVVD control unit 20 and the CVVT control unit 30 respectively according to target values outputted as different values according to driving conditions such as engine rotation speed or load, thereby opening the valve. The time and opening/closing timing are adjusted, and in particular, while controlling the CVVD control unit 20, the CVVD control unit 20 continuously monitors whether an error is detected.

ECU 10 is preferably, when an overcurrent flows through the CVVD control unit 20, when it is impossible to determine the rotation position of the CVVD motor 22 due to a sensor error in the CVVD motor 22, the CVVD motor 22 A case in which the position learning fails, a case in which CAN communication with the CVVD controller 20 fails, etc. may be determined as an error in the CVVD controller 20. Of course, depending on the specification, new fault diagnosis conditions may be added in addition to the listed conditions.

When an error is detected in the CVVD control unit 20, accurate feedback control is impossible because it is difficult to grasp the current position of the variable controller 24 including the rotational position of the CVVD motor 22. In this case, the ECU 10 ignores the current control value for CVVD control (duty value for CVVD motor control) and stops the control of the CVVD motor 22. Then, a command for executing CVVT cleaning is applied to the CVVT control unit 30.

The CVVT cleaning mode is entered according to the CVVT cleaning execution command from the ECU 10. In the CVVT cleaning mode, the spool of the oil control valve 36 is closed several times from a full close (0% duty cycle) to a full open position (100% duty cycle) with a control signal from the ECU (10). By moving, the operation of removing various foreign substances accumulated between the flow path and the spool in the oil control valve 36 proceeds.

For reference, the control method and operation for CVVT cleaning are in Korean Patent Registration No. 10-1637837 (registration date 2016. 07.07), and the structure of the CVVT device is in Korean Patent Application Publication No. 2003-0030203 (published on April 18, 2003). Since it is already known, a detailed description thereof will be omitted below.

Assuming that the input conditions such as coolant temperature, engine speed, and air pressure are the same during CVVT cleaning, the amount of intake air measured from the MAP sensor (Manifold Absolute Pressure sensor) 40 is the rotational position of the CVVD motor 22 at the time of error detection. , More specifically, a significant change appears according to the operating position of the variable controller 24 for varying the rotation center of the shaft.

Therefore, if there is only information on the amount of intake air during CVVT cleaning (which can be found from the output of the MAP sensor 40), conversely, the rotation position of the CVVD motor 22 at the time of CVVD error detection according to the current vehicle state, more specifically As a result, it is possible to relatively accurately grasp the operating position of the variable controller 24 for varying the rotation center of the shaft.

The present invention executes the CVVT cleaning at the time when the CVVD error is detected, and the rotation position of the CVVD motor 22, more specifically, of the variable controller 24, is performed by using the point that a change in the amount of intake air occurs during the CVVT cleaning. Reverse the operating position. In addition, according to the identified position, it is not an extreme limp home mode, but an appropriate response strategy according to the current position of the CVVD motor 22.

Specifically, the ECU 10 inversely calculates the current position of the CVVD motor 22 based on the amount of intake air measured through the MAP sensor 40 during CVVT cleaning. Map data may be used to inversely derive the current position of the CVVD motor 22 based on the amount of intake air measured through the MAP sensor 40 during CVVT cleaning.

Map data (hereinafter, referred to as'intake map 50') is the position of the CVVD motor 22 according to the CVVD duty value during CVVT cleaning, and the change in the amount of intake air according to the position of the CVVD motor 22 through repeated experiments. The derived and derived values are quantified and stored in a data format, and when the intake air amount is input during CVVT cleaning, it may be set to automatically output the input CVVD duty value and the position of the CVVD motor 22 in response to the corresponding air amount. .

When the position of the CVVD motor 22 is derived from the change in the amount of intake air during CVVT cleaning, the ECU 10 again detects an error of the CVVT control unit 30 during CVVT cleaning. And when the CVVT control unit 30 error is not detected, the current position information of the CVVD motor 22 derived through the intake air map is trusted, and the CVVD is a duty value mapped differently according to the position value of the CVVD motor 22. Emergency control of the motor 22 adjusts the valve duration.

In addition, by limiting the engine speed and throttle opening amount to the values recorded in the dedicated map according to the adjusted valve duration, the entry of the extreme limp groove mode is avoided.

In contrast, when an error of the CVVT control unit 30 is detected during the CVVT cleaning execution, the ECU 10 ignores the current position information of the CVVD motor 22, which is determined inversely from the amount of intake air during the CVVT cleaning execution. The engine is protected by stopping the CVVD motor 22 or rotating the CVVD motor 22 in the short direction with the shortest valve duration, and forcibly restricting the engine speed and throttle opening to a set value.

Hereinafter, an emergency control method of a CVVD engine according to an embodiment of the present invention will be described with reference to FIG. 2.

2 is a flowchart illustrating an emergency control method of a CVVD engine according to an embodiment of the present invention. For convenience of explanation, the configuration illustrated in FIG. 1 will be described with reference to the corresponding reference number.

2, the emergency control method of the CVVD engine according to an embodiment of the present invention starts from the step of detecting an error of the CVVD control unit 20 by operating the CVVD diagnosis logic (S100).

In step S100, preferably, when overcurrent flows through the CVVD control unit 20, when it is impossible to determine the rotational position of the CVVD motor 22 due to a sensor error in the CVVD motor 22, the position of the CVVD motor 22 is learned. When the CVVD control unit 20 and CAN communication fail, it may be determined that the CVVD control unit 20 is an error. Of course, depending on the specification, new fault diagnosis conditions may be added in addition to the listed conditions.

When an error of the CVVD control unit 20 is detected in step S100, a step (S200) of ignoring the duty value for current CVVD control and stopping the control of the CVVD motor 22 is executed. This is because when an error is detected in the CVVD control unit 20, it is difficult to grasp the current position of the variable controller 24 as well as the rotation position of the CVVD motor 22, making accurate feedback control impossible.

After the step S200, a CVVT cleaning command is output to the CVVT control unit 30 to perform CVVT cleaning (S300). CVVT cleaning is performed by moving the spool of the oil control valve 36 from the fully closed position to the fully open position several times with a control signal from the ECU 10, thereby removing various foreign substances deposited between the flow path and the spool in the oil control valve 36. It can be done in the form of removing.

Next, a step S400 of determining the current position of the CVVD motor 22 based on the amount of intake air measured through the MAP sensor 40 along with the CVVT cleaning is performed. In step S400, the current CVVD duty value is inverted based on the intake air amount measured through the MAP sensor 40 of the intake manifold, and the current position of the CVVD motor 22 is determined using the inverted CVVD duty value.

To determine the position of the CVVD motor 22 at the time of error detection, preferably, the position of the CVVD motor 22 according to the CVVD duty value during CVVT cleaning and the change in the amount of intake air according to the position of the CVVD motor 22 are derived through repeated experiments. The intake air map stored in the form of data by quantifying the derived value can be used.

Here, the intake map may be preferably set to output the CVVD duty value and the position of the CVVD motor 22 automatically corresponding to the air amount when the intake air amount is input during CVVT cleaning.

When the position of the CVVD motor 22 is derived from the change in the amount of intake air during CVVT cleaning, the ECU 10 proceeds to step S500 of detecting an error of the CVVT control unit 30 during CVVT cleaning. In step S500, when an overcurrent is detected in the oil control valve 36, CAN communication with the oil control valve 36 fails, and the hydraulic pressure flowing into the oil control valve 36 is less than the set pressure, the CVVT control unit 30 It can be detected as an error.

On the other hand, in step S600 performed after step S500, whether the current position information of the CVVD motor 22 identified from the inverted CVVD duty value is trusted according to the error detection result of the CVVT control unit 30 in the step S500 immediately preceding step. They decide and use the corresponding response strategy depending on their trust. Let's look at the S600 step in more detail.

If, in step S500, the error of the CVVT control unit 30 is not detected, in step S600, the current position information of the CVVD motor 22 derived from the intake air map is trusted, and mapping differently according to the position value of the CVVD motor 22 The valve duration is adjusted by emergency control of the CVVD motor 22 with the defined duty value, and the entry of the lymphatic home mode is avoided by limiting the engine speed and throttle opening amount to the values recorded in the dedicated map according to the duration (S610). do.

On the contrary, when an error of the CVVT control unit 30 is detected in step S500, the current position information of the CVVD motor 22, which is inverted from the amount of intake air during CVVT cleaning, is ignored. In addition, the CVVD motor 22 is stopped or the CVVD motor 22 is rotated in the short direction with the shortest valve duration, and the engine is protected by forcibly limiting the engine speed and throttle opening to a set value (S620). do.

CVVD systems have a direct and catastrophic effect on drivability, fuel economy and exhaust gas emissions in case of failure, so a strict fail safety strategy must be followed. The conventional CVVD system is set to control the vehicle through an extreme limp home operation in order to protect the driver and the vehicle because it is impossible to determine the position of the CVVD motor 22 when a control error occurs.

However, if the vehicle is controlled through an extreme limp home operation, the vehicle's durability may be deteriorated because the covered road of the CVVD mechanism is increased, and the intended acceleration/deceleration operation is impossible, causing inconvenience to the driver. do. In addition, since the air volume control is unstable, knocking may be caused, and the knocking generated in this way adversely affects drivability.

According to an embodiment of the present invention, when an error is detected in the CVVD control system, the position of the CVVD drive motor at the time of error detection is identified through CVVT cleaning, and other fail safety strategies are employed according to the identified position, It can prevent deterioration of drivability and durability due to extreme limp groove operation, and can suppress the occurrence of knocking, thereby protecting the engine.

In the above detailed description of the present invention, only specific embodiments according thereto have been described. However, it should be understood that the present invention is not limited to a particular form mentioned in the detailed description, but rather, it is understood to include all modifications, equivalents, and substitutes within the spirit and scope of the present invention as defined by the appended claims. Should be.

10: ECU
20: CVVD control unit
30: CVVT control unit
40: MAP sensor
50: intake map

Claims (10)

(a) detecting an error of the CVVD control unit by operating the CVVD diagnosis logic;
(b) when a CVVD control unit error is detected, ignoring a duty value for current CVVD control and stopping control of the CVVD motor;
(c) outputting a CVVT cleaning execution command to the CVVT control unit to perform CVVT cleaning;
(d) determining the current position of the CVVD motor based on the amount of intake air measured through the MAP sensor during the CVVT cleaning execution;
(e) detecting an error of the CVVT control unit; And
(f) determining whether to trust the current position information of the CVVD motor according to the error detection result of the CVVT control unit, and executing a corresponding response strategy according to the trust or not
In step (d),
An emergency control method for CVVD engines in which the current CVVD duty value is inverted based on the intake air volume measured through the intake manifold's MAP sensor (Manifold Absolute Pressure sensor), and the current position of the CVVD motor is determined using the inverted CVVD duty value.
The method of claim 1,
In step (a),
If overcurrent flows in the CVVD system,
When an error signal is output from the sensor inside the CVVD motor,
If the position learning of the CVVD motor fails,
Emergency control method of CVVD engine in which at least one of the cases where ECU fails in CAN communication with CVVD controller is detected as an error of CVVD control unit.
The method of claim 1,
In step (d),
Emergency control method of CVVD engine to determine the current position of CVVD motor by quantifying the position of the CVVD motor according to the CVVD duty value and the intake air volume change according to the CVVD motor position during CVVT cleaning, and using the intake map saved in data format.
The method of claim 1,
When the CVVT control unit error is not detected in step (e),
In the step (f), the CVVD engine emergency control of the duty of the CVVD motor with a duty value mapped differently according to the current position of the CVVD motor, trusting the current position information of the CVVD motor identified from the inverted CVVD duty value. Control method.
The method of claim 1,
When a CVVT control unit error is detected in step (e),
In step (f), the current position information of the CVVD motor determined from the inverted CVVD duty value is ignored, the CVVD motor is stopped, or the CVVD motor is rotated in the short direction with the shortest valve duration, and the engine is rotated. Emergency control method of CVVD engine that forcibly restricts the number and throttle opening amount to a set value.
ECU;
A CVVD control unit for continuously varying the valve opening time according to the ECU control;
Including; CVVT control unit for continuously varying the valve opening and closing time according to the control of the ECU,
The ECU,
When an error is detected in the CVVD control unit, the current duty value for CVVD control is ignored and the control of the CVVD motor is stopped.
Applying a command for executing CVVT cleaning to the CVVT control unit,
The current position of the CVVD motor is determined in reverse based on the amount of intake air measured through the MAP sensor (Manifold Absolute Pressure sensor) during CVVT cleaning,
Emergency control system of the CVVD engine that controls the duty of the CVVD motor with different values according to the identified CVVD motor position.
The method of claim 6,
The ECU,
If overcurrent flows through the CVVD control unit
When an error signal is output from the sensor inside the CVVD motor,
If the position learning of the CVVD motor fails,
Emergency control system of CVVD engine that judges as CVVD control unit error if at least one of CVVD controller and CAN communication fails.
The method of claim 6,
The ECU,
CVVD engine emergency control system that quantifies the position of the CVVD motor according to the CVVD duty value and the intake air volume change according to the CVVD motor position during CVVT cleaning, and uses the intake air map saved in data format to determine the current position of the CVVD motor.
The method of claim 6,
The ECU,
CVVT control unit error is detected during CVVT cleaning,
If an error in the CVVT control unit is not detected, the current position information of the CVVD motor, which is determined inversely from the intake air amount during CVVT cleaning, is trusted, and the duty of the CVVD motor is emergency with a duty value mapped differently according to the current position of the CVVD motor. Emergency control system of the controlling CVVD engine.
The method of claim 6,
The ECU,
CVVT control unit error is detected during CVVT cleaning,
If an error is detected in the CVVT control unit, the CVVD motor is stopped, or the CVVD motor is rotated in the direction of the shortest valve duration, ignoring the current position information of the CVVD motor, which is determined inversely from the intake air amount during CVVT cleaning. The emergency control system of the CVVD engine forcibly restricting the engine speed and throttle opening to a set value.

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