KR101072097B1 - A method for prevention of knocking using valve timing control in dual continuously variable valve timing - Google Patents

Abstract

The present invention relates to an engine control method of an intake / exhaust independent variable valve mechanism (Dual CVVT) for preventing knocking.

Knocking control region determination step;

Determining whether knocking has occurred in the knocking control region;

Perception of the ignition timing at the occurrence of knocking in the above;

Determining whether the learning condition is satisfied after the perception of the ignition timing;

Determining the EVC valve timing control region if the learning condition is satisfied as a result of the determination; And

As a result of the determination, in the case of the EVC valve timing control region, the EVC advance learning is performed.

CVVT, Knocking, Ignition Timing, EVC Valve Timing, Advancement, Perception

Description

A method for prevention of knocking using valve timing control in dual continuously variable valve timing}

1 is a fuel efficiency correlation graph according to the EVC timing in a conventional Dual CVVT engine.

2 is a fuel efficiency correlation graph according to the EVC timing and ignition timing in the Dual CVVT engine according to the present invention.

3 is a flowchart illustrating a knock prevention control method according to the present invention;

Figure 4a is a knocking control method selection map for each driving region according to the present invention.

4B is an EVC valve timing learning variable map diagram in accordance with the present invention.

The present invention relates to a knock prevention method through the valve timing control of the intake and exhaust variable valve mechanism, and more specifically, to prevent knocking through the ignition timing and EVC advancement during engine control of the intake and exhaust independent variable valve mechanism (Dual CVVT). It relates to a knock prevention method through the valve timing control of the intake and exhaust variable independent variable valve mechanism.                         

In general, in the engine control of the intake / exhaust independent variable valve mechanism (Dual CVVT), selection of valve timing for optimum performance of fuel economy and exhaust gas is one of the most important items. That is, in the low-load operation region, the valve overlap, which is a section in which the intake and exhaust valves are simultaneously opened, is increased for the purpose of reducing pumping loss in order to realize the best fuel economy. Generally, the exhaust valve is closed in the Dual CVVT engine. Increase overlap by retarding EVC (Exhaust Valve Closing).

In order to improve fuel efficiency in the above manner, it is better to delay the EVC as much as possible, but it is restricted in two aspects.

First, excessive valve overlap will cause instability of combustion. In other words, theoretically, when the EVC timing is late, the pumping loss should be reduced and fuel economy improved. However, fuel economy deteriorates after a certain limit due to instability of combustion. As shown in FIG. 1, fuel economy A becomes better as the EVC is perceived and deteriorates after a certain threshold, while combustion stability B becomes worse as the EVC is perceived, thereby increasing the probability of knocking. For reference, in the graph of FIG. 1, the x-axis denotes an EVC crank angle, and the fuel economy and combustion stability of the y-axis mean a better state.

Second, as the overlap increases, the amount of residual gas in the cylinder increases, which increases the possibility of knocking. In other words, in order to realize the best fuel economy, it should be operated in MBT (Maximum Brake Torque) ignition period, but when the probability of knocking increases, the control of ignition timing is inevitable, which leads to loss in terms of performance as well as fuel efficiency. Rather worsen fuel economy.

The present invention has been made to solve the problems of the prior art, the object of the present invention is to knock, by considering both methods of ignition timing and EVC advance in the engine control of the intake and exhaust independent variable valve mechanism (Dual CVVT), It is to provide a knocking prevention method through the valve timing control of the intake and exhaust independent variable valve mechanism to prevent and thereby improve fuel economy performance.

To achieve the above object, the knocking prevention method according to the present invention

Knocking control region determination step;

Determining whether knocking has occurred in the knocking control region;

Perception of the ignition timing at the occurrence of knocking in the above;

Determining whether the learning condition is satisfied after the perception of the ignition timing;

Determining the EVC valve timing control region if the learning condition is satisfied as a result of the determination; And

As a result of the determination, in the case of the EVC valve timing control region, the EVC advance learning is achieved, and in the case of the non-EVC valve timing control region, the ignition timing perception learning is performed.

According to the present invention, both the ignition timing and the EVC advancement are considered in the engine control of the dual inlet / outlet variable valve mechanism (Dual CVVT), thereby preventing knocking and thereby improving fuel efficiency. Anti-knocking method through valve timing control.

summary

The fuel efficiency correlation according to the EVC timing and the ignition timing in the Dual CVVT engine according to the present invention will be described with reference to FIG. 2.

As shown in FIG. 2, in the present invention, when the EVC period is selected as '40' in order to realize the optimum fuel economy, the fuel economy at this time becomes fuel economy a. If knocking occurs at this time, if the ignition timing (C) is perceived as point c to suppress this, the fuel economy at this time becomes fuel economy c. However, if the EVC timing A having the same knocking suppression effect is point b, it can be seen that fuel economy at this time is superior to fuel economy c as fuel economy b.

Therefore, in the present invention, when considering the fuel economy aspect, by applying the EVC timing advance control rather than the ignition timing perception control, it is possible to achieve the knocking prevention and fuel economy synergistic effect.

Hereinafter, with reference to the drawings will be described a preferred embodiment according to the present invention.

Example

A method for preventing knocking in the dual CVVT engine control according to the present embodiment will be described with reference to FIG. 3, which is a flowchart.

As shown in FIG. 3, after driving of the vehicle is made [S10], it is determined whether or not it is a knocking control region [S20]. The knocking control region refers to an operation region in which knocking control is to be performed as a result of the determination in the ECU. That is, when the load is low for each rpm of the engine, the knocking control is not performed. When the load exceeds a certain threshold value, the knocking control area (knocking control enable area) becomes.

When it corresponds to the knocking control region in step S20, it is determined whether knocking is generated by detecting the knocking sensor [S30]. As known to those skilled in the art, the knocking sensor is installed on the cylinder block of the engine and converts the high frequency vibration generated by the knocking during the operation of the engine into an electrical signal.

When knocking occurs in step S30, knocking is prevented by a method of perceiving an ignition timing [S40], and it is determined whether the learning function of the ignition timing is performed after the perception of the ignition timing [S50]. That is, it is determined whether or not the "long term" control in which the learning function of the ignition timing is performed is performed after the ignition timing perception is continued for a long time.

As a result of the determination in step S50, when the learning function of the ignition timing is performed, that is, when the "long term" control, which is the learning function of the ignition timing, is determined, it is determined whether it is the EVC valve timing control region [S60]. As shown in the table shown in FIG. 4A to be described later, the reference for applying the EVC valve timing control or the ignition timing control in the “long term” control section in which the ignition timing learning function is performed is based on the engine speed (rpm) and the load (load). ) Is determined and applied for each operation area.

As a result of the determination in step S60, in the case of the EVC valve timing control region, the EVC advance learning control is achieved [S70], but when it corresponds to the ignition timing control region other than the EVC valve timing control region, prevention of knocking through ignition timing perception learning Control is made [S80].

In step S70, the EVC advance learning control according to the present embodiment is performed by the following equation (1).

EVC Advancement Learning Variable New = EVC Advancement Learning Variable Old + 3

In Equation 1, the EVC is advanced by + 3 °, and EVC (Exhaust Valve Closing) timing is generally expressed as a crank angle of ATDC (After Top Dead Center). For example, the equation is ATDC 30 °-> ATDC. It means to be 27 degrees. In other words, a + 3 ° advance is made in the TDC direction.

On the other hand, in step S80, the ignition timing perception learning control according to the present embodiment is made by the method shown in Equation 2 below.

Ignition timing perception learning variable New = Ignition timing perception learning variable Old -3

Meaning that the ignition timing is −3 ° in Equation 2, the ignition timing is normally expressed by a crank angle of the BEDC (Before Top Dead Center). For example, the equation may be BTDC 20 °-> BTDC 17 °. Means that. That is, a -3 ° perception is made in the TDC direction.

However, the EVC timing control should consider the following two points.

First, the EVC advancement method should set a better fuel economy than the ignition timing perception method. This means that knocking control can be achieved through the ignition timing recognition method without applying the EVC advance method if the method through the ignition timing recognition is less deteriorated in terms of fuel efficiency.

In the present embodiment, as shown in FIG. 4A, a control method for preventing knocking may be set using map data set for each driving area. In FIG. 4A, the load value and the rpm value can be changed and set by those skilled in the art. In the present embodiment, rpm1 = 1400, rpm2 = 2500, rpm3 = 3500, load1 = 50%, load2 = 70%, load3 = 90% It means the value of degree.

Secondly, in applying the EVC timing control in FIG. 4A, the EVC timing control has a slow control speed and a greater influence on the operability due to the change than the ignition timing perception control. That is, in the case of ignition timing control, it is perceived when knocking occurs and when it does not occur, it is advancing again. However, the EVC timing control, which is a valve timing, cannot be controlled in the same way as the ignition timing. That is, the ignition timing control includes a "short term" control and a "long term" control, which is a learning function, and the EVC forward angle sets a learning variable as shown in FIG. 4B to achieve control through the "long term" control learning function. Put it. For reference, the load and rpm values in FIG. 4B may be applied in the same manner as those mentioned in FIG. 4A, but may be changed to other values by those skilled in the art. That is, when the same applies, only EVC1, EVC2, EVC5, EVC6 and EVC10 among the EVC learning variables may be applied as valid learning variables.                     

As described above, the present invention belongs to the EVC valve timing control region in a "long term" control section in which a technique for preventing knocking is performed only by a method of controlling the ignition timing in the related art, and the ignition timing learning function in which the perception control of the ignition timing lasts for a long time is performed. In this case, by applying EVC real-time learning control, not only knocking prevention but also optimum fuel efficiency can be obtained.

In interpreting the technical scope of the present invention, it should not be construed as being limited to the embodiments described above, and the technical scope of the present invention should be determined by reasonable interpretation of the matters described in the claims.

According to the knocking prevention method through the valve timing control of the intake / exhaust independent variable valve mechanism of the present invention, the knocking prevention and the optimum fuel efficiency performance improvement effect are achieved by preventing knocking in parallel with the ignition timing and the valve timing control.

Claims (6)

In engine control of the intake / exhaust independent variable valve mechanism (Dual CVVT) for preventing knocking, Knocking control region determination step; Determining whether knocking has occurred in the knocking control region; Perception of the ignition timing at the occurrence of knocking in the above; Determining whether the learning condition is satisfied after the perception of the ignition timing; Determining the EVC valve timing control region if the learning condition is satisfied as a result of the determination; And As a result of the determination, in the case of the EVC valve timing control region, knocking prevention method through the valve timing control of the intake / exhaust independent variable valve mechanism, characterized in that the step of achieving the EVC advance learning. The method of claim 1, The learning condition after the ignition timing perception is a knock prevention method through the valve timing control of the intake and exhaust independent variable valve mechanism, characterized in that the "long term" control of the ignition timing learning function due to the long time ignition timing. The method of claim 1, The criterion for applying the EVC valve timing control or the ignition timing control for the anti-knock control is determined for each driving region according to the engine speed (rpm) and the load (load). How to prevent knocking through The method of claim 1, The EVC advance learning is a knock prevention method through the valve timing control of the intake / exhaust independent variable valve mechanism, characterized in that the following formula. EVC Advancement Learning Variable New = EVC Advancement Learning Variable Old + 3 The method of claim 1, If not the EVC valve timing control region, the knocking prevention method through the valve timing control of the intake and exhaust independent variable valve mechanism further comprises the step of making the ignition timing perception learning. The method of claim 5, The ignition timing perception learning is a knock prevention method through the valve timing control of the intake and exhaust independent variable valve mechanism, characterized in that the following formula. Ignition timing perception learning variable New = Ignition timing perception learning variable Old -3

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