KR101976761B1 - Method for controlling ignition timing of vvl typed engine cylinder - Google Patents

Abstract

In the present invention, a cylinder-by-cylinder ignition timing control method in a valve lift variable control system capable of solving the engine roughness phenomenon in an area outside the MBT is disclosed.
A method for controlling ignition timing of a cylinder according to the present invention includes the steps of: a) reducing a torque deviation by perceptually controlling an ignition timing of a cylinder having a large torque from an engine rupture measurement value of an engine RPM having an air- b) deriving a cylinder-by-cylinder ignition timing according to the torque deviation; And c) determining a base ignition timing for the cylinder-by-cylinder ignition timing based on the current engine RPM-specific engine rpm ratio of the engine RPM measured by the engine RPM having the set air- and correcting an ignition timing in an advance for best torque region.
Therefore, when the base ignition timing is misdetected and exists in the advancing direction region, it is possible to compensate the inter-cylinder deviation by perceiving the direction of the retarding region, thereby minimizing the engine roughness.

Description

TECHNICAL FIELD [0001] The present invention relates to a method of controlling ignition timing of a cylinder in a variable valve lift control system,

The present invention relates to a valve lift variable control method, and more particularly, to a valve lift variable control method in which a weight is given in consideration of the height of a valve lift and the engine RPM region, which have the greatest adverse effect of a height difference caused by a lift manufacturing tolerance, To an ignition timing control method for each cylinder in a valve lift variable control system capable of eliminating the roughness divergence phenomenon in an area outside the minimum spark advance for best torque (MBT).

Generally, an automobile engine is provided with a combustion chamber in which fuel is combusted to generate power, and the combustion chamber is provided with a valve train including an intake / exhaust valve capable of controlling intake air and exhaust gas, So as to open and close the combustion chamber while interlocking with the crankshaft. In such a valve train, the valve is usually always given a constant lift value by a cam having a constant shape, so that the amount of gas sucked or discharged is limited to a certain amount.

Accordingly, if the design is made in accordance with the low-speed operation state, the time and amount of opening of the valve becomes insufficient in the high-speed operation state. If the design is made in accordance with the high-speed operation state, the opposite phenomenon occurs in the low- In the case of a general engine, since the valve lift is set to a large value when tuned for high speed, excellent performance in a high speed range is obtained, but it is very disadvantageous in idling stability in a low speed region and low speed torque. On the contrary, However, in the case of the above-described variable valve lift, the valve lift is suitably changed in the high and low speed ranges, respectively, so that the valve lift can be controlled at low speeds and at high speeds It is possible to take advantage of this simultaneously.

Therefore, in recent years, techniques for improving filling efficiency have been developed in order to improve fuel efficiency and output, followed by multi-valveization. As a result thereof, the length or sectional area of the intake manifold A Variable Induction System (VIS) for changing the valve opening / closing timing and opening / closing amount of the valve according to the rotation range of the engine to control the overlap timing so as to control the cylinder filling amount and the residual gas amount Timing: VVT) and Variable Valve Lift (VVL).

The accompanying patent document is for explaining the variable valve lift described above and is applied to an engine adopting two intake valves per cylinder as shown in Fig. That is, the hydraulic tappet (not shown) opposite to the intake valves 2 and 4 is positioned in each of the swing arms 6 and 8 for driving the two intake valves 2 and 4, And rollers 10 and 12 are disposed on the upper side, respectively.

An output cam 14 for driving the rollers 10 and 12 of the swing arms 6 and 8 is disposed right above the rollers 10 and 12 of the swing arms 6 and 8. The output cam 14 includes roller pressing portions 16 and 18 which are formed substantially horizontally and press rollers 10 and 12 of the swing arm 6 and 8, respectively, 16) 18 between the two intake valves (2) (4) and protruding downward by a predetermined length in the opposite direction.

The bottom surface of each of the roller pressing portions 16 and 18 has a roller contact surface 22 having a predetermined curvature so that the rollers 10 and 12 of the swing arm 4 and 6 can be contacted at any rotation angle The cam 28 of the camshaft 26 is positioned between the roller pressing portions 16 and 18 and the cam contact roller 30 driven by the cam 28 rotates And is disposed between the two intake valves 2 and 4, which form the upper end of the pivot 20, while the roller pressurizing portions 16 and 18 are connected.

The hinge shaft 34 connecting the rotation link 20 and the link for variable link 32 is connected to the guide 32 disposed on both sides of the link 32. [ 36 (38), respectively. Accordingly, the hinge shaft 34 can be moved forward and backward within the length of the movement guide slots 40 and 42, and the rotation interspace 20 connected thereto is also rotated forward and backward .

When the rotary member 20 is rotated forward and backward as described above, the roller pressing units 16 and 18 integrally formed therewith also rotate. At this time, the reference of the rotation is the elastic member 44 composed of the torsion coil spring, The cam contact roller 30 always rotates while being in contact with the cam 28 because the cam contact roller 30 is resilient on the side of the intake valves 2 and 4 of the roller pressing portions 16 and 18 .

The variable link 32 connected to the pivot 20 is hingedly connected to a connection port 48 projecting at a predetermined length from the variable rotation shaft 46 while being inclined upward. Accordingly, when the variable rotation shaft 46 is rotated by an actuator (not shown), the connecting link 48 integrally formed therewith is rotated to move the variable link 32 forward and backward, thereby moving the hinge shaft 34 And are moved forward and backward in the guide slots 40 and 42 formed in the guides 36 and 38, respectively.

The portion of the roller pressing portions 16 and 18 and the rollers 10 and 12 of the swing arm 6 and 8 are in contact with each other due to the rotation of the rotating shaft 20 along the hinge shaft 34 So that the lift of the intake valves 2 and 4 can be changed.

However, in the above-described conventional variable valve lift, when the inter-cylinder torque deviation occurs, a problem of high engine roughness arises due to the inability to perform precise control, and the derivation of the minimum spark advance for best torque (MBT) When an error occurs, engine vibration becomes worse due to cylinder-dependent control. The above-mentioned inter-cylinder torque deviation means the shape of the inter-cylinder port, the shape of the combustion chamber, the shape of the intake manifold, the injector deviation, and the like. Since the height difference due to the lift manufacturing tolerance is very large, .

[0001] The present invention relates to a variable valve lift apparatus for an automobile engine,

SUMMARY OF THE INVENTION The present invention has been made in order to solve such problems, and it is an object of the present invention to minimize the torque deviation per cylinder under various valve lift and engine RPM conditions, taking valve lift, engine RPM, And an ignition timing control method for each cylinder in a valve lift variable control system capable of generating a maximum torque.

Another object of the present invention is to provide an engine control system and a control method thereof which can control the engine vibration in an area outside the MBT by controlling the ignition timing for each cylinder by weighting in consideration of the height of the valve lift and the engine RPM area, The present invention provides an ignition timing control method for each cylinder in a valve lift variable control system capable of solving the engine roughness phenomenon.

It is still another object of the present invention to provide a valve lift variable control system capable of minimizing engine roughness by compensating inter-cylinder deviation by perceiving the base ignition timing in the direction of the retarded region when the base ignition timing is mis- And an ignition timing control method for each cylinder in a control system.

A method for controlling a cylinder-by-cylinder ignition timing in a valve lift variable control system according to an embodiment includes: a) increasing an inter-cylinder torque deviation by setting the same air-fuel ratio for all cylinders; b) measuring Engine Roughness by valve lift height and engine RPM, and storing the Engine Roughness as a reference value; And c) controlling a cylinder-by-cylinder ignition timing, wherein the step c) includes the steps of: c-1) calculating a cylinder-by-cylinder ignition timing compensation amount in a direction in which the torque deviation is reduced; c-2) assigning a weight according to the valve lift height and the engine RPM to the calculated compensation amount; c-3) correcting the ignition timing by applying the compensation amount to each of the cylinders to which the weight is assigned; c-4) comparing the current engine vibration with the reference value after measurement; c-5) deriving an ignition timing at which the engine vibration is minimized by perceptually controlling the base ignition timing when the engine vibration is increased with respect to the reference value; And (c-6) if the present engine vibration is decreased with respect to the reference value, advance ignition timing of the base ignition timing to derive an ignition timing at which the engine vibration becomes minimum.

Further, the set air-fuel ratio is '= 1', where? Can be a value obtained by dividing the actual intake air amount by the theoretically required air amount.

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The ignition timing control method for each cylinder in the valve lift variable control system proposed in the present invention is a method for controlling the ignition timing for each cylinder by giving a weight considering the height of the valve lift and the engine RPM region having the greatest adverse effect of the height difference due to lift manufacturing tolerance, It is possible to solve the engine roughness phenomenon in an area outside the MBT. Further, in the present invention, when the base ignition timing is erroneously present and exists in the advancing direction region, the inter-cylinder deviation compensation is performed by perceiving the direction of the retarding region, thereby providing the effect of minimizing the engine roughness.

1 is a view for explaining a conventional valve lift apparatus.
2 is a hardware block diagram for explaining an ignition timing control apparatus for each cylinder according to the present invention.
Fig. 3 is a flowchart for explaining the main operation of Fig. 2. Fig.
4 is a graph for explaining the retardation and advance angle control in the present invention.

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

The valve lift of the valve lift variable control system is substantially less than about 1 mm, the valve lift of the conventional fixed valve lift control system is about 10 mm, and the valve lift variable control system has a valve Keep the lift. This is because even if the same inter-cylinder hardware deviation, the valve lift variable control system has a very large adverse effect on the cylinder torque deviation.

Therefore, the cylinder-by-cylinder ignition timing control method in the valve lift variable control system proposed in the present invention must perform cylinder-based deviation learning, mixer control, and ignition timing control very precisely. In principle, the change in air volume is small and stable. This is to prevent false learning that is expected when learning in a dynamic section such as an acceleration / deceleration section.

2 is a diagram illustrating a hardware configuration according to the present invention.

As shown in the figure, the weights for the areas of valve lift, engine RPM, and engine roughness increase / decrease are set, and cylinder perception and advance angle control for torque deviation reduction are performed to obtain a minimum spark advance (MBT) engine torque, engine RPM, and valve preload information based on the cylinder-by-cylinder ignition timing algorithm in real time, and outputs the engine torque, engine RPM, (MBT), which generates a maximum torque by reducing the torque deviation by performing the retarding and advance angle control of the base ignition timing according to the calculation result, An engine control device (ECU) 201 for extracting an area of the engine, an engine controller 201 connected to an input port of the engine controller 201, A fuel injection control device 203 for performing fuel injection timing control and air-fuel ratio control, which is connected to an output port of the engine control device 201, a combustion chamber pressure sensor 207 for measuring the deviation of the cylinder, ).

The initial environment is for cylinder-by-cylinder deviation learning and cylinder-by-cylinder ignition timing control in the mixing control system, and it is preferable that the variation of the valve lift and engine RPM is small and the variation of the air amount is small. The initial environment will guide you to the optimal initial state for system control, but you will not need to present a regulated environment.

In addition, the engine control unit 201 may perform weight and weight control according to the valve lift height and the engine RPM in order to reduce the torque deviation. This gives a predetermined weight value for each item of the valve lift, the engine RPM, and the increase / decrease of the engine roughness, and it can be set differently according to the type of the vehicle.

On the other hand, the vibration measuring device 205 may be a laser displacement measuring device for measuring the bending vibration in the axial direction of the crankshaft, or a torsional vibration meter for measuring the torsional vibration in the rotating direction of the crankshaft pulley.

3 is a flow chart for explaining an operation according to the present invention.

As shown in step S301, it is determined whether the learning condition is suitable for the initial environment. As described above, the initial environment is for performing cylinder-based deviation learning, mixer control, and ignition timing control in a region where the variation of the valve lift or the engine RPM is small and the variation of the air amount is small. .

The engine control device 201 receives the engine torque, the engine RPM, and the valve lift information in real time due to the algorithm activation of the program memory 209, and judges whether the engine torque, the engine RPM, and the valve lift information are suitable for the initial environment. Since the initial environment is essentially to set initial values for learning, it may not need to be presented as a quantified environment.

Thereafter, the flow advances to step S303 to perform inter-cylinder deviation learning in the initial environment through cylinder-by-cylinder monitoring, and to set the air-fuel ratio for each cylinder for deviation learning. That is, the electronic control unit 201 uses the combustion chamber pressure sensor 207 to set the air-fuel ratio to the same for each cylinder in order to calculate the inter-cylinder deviation in the initial environment, thereby amplifying the torque deviation per cylinder.

At this time, the air-fuel ratio per cylinder is set to 'λ = 1', λ is the actual intake air amount / theoretically required air amount, and a lean mixer when λ> 1.0 and a rich mixer when λ <1.0. Therefore, in the present invention, it is set to an intermediate state rather than a lean and rich state of the mixer, thereby facilitating subsequent correction.

To uniformly adjust the air-fuel ratio per cylinder as described above is to increase the torque deviation between the cylinders. In step S305, the engine control unit 201 assumes an increased torque deviation as a reference value of engine vibration (Roughness), and stores the estimated torque deviation in the internal memory. The engine control device 201 measures the engine vibration by the vibration measuring device 205 and is performed for each engine RPM.

Of course, the measured values of the engine vibration and the valve lift are provided as information shaped through a predetermined filtering circuit, and the engine control device 201 calculates the ignition timing compensation amount per cylinder in step S307. That is, in order to reduce the amplified torque deviation, the inter-cylinder torque deviation is reduced by perceiving a cylinder having a large torque.

FIG. 4 is a graph showing the relationship between the engine torque and the ignition timing. As can be seen, when the torque is large, the ignition timing is lowered and the crank angle is controlled by reducing the torque. In the present invention, MBT area.

However, in order to find the MBT region, it is difficult to find an accurate MBT region simply by setting the cylinder-by-cylinder ignition timing by simply the torque deviation as in the step S307. This is because the engine vibration varies in accordance with the height of the valve lift and the engine RPM Because. Therefore, when the ignition timing is compensated by retard control, the engine vibration can be increased by the engine RPM as much as the engine vibration is reduced by the height of the valve lift, so that substantial engine vibration can not be reduced.

Accordingly, as shown in step S309, the engine control unit 201 can calculate the optimal ignition timing by measuring the engine vibration by assigning weights to the respective items according to the valve lift and the engine RPM. That is, weights are assigned to the engine vibration measurement values per engine RPM, and the ignition timing for the torque deviation is derived therefrom.

The weight for each item is given as a percentage and may be defined differently depending on the vehicle operating environment according to the vehicle type. For example, in the case of a middle- or large-sized vehicle having a large valve lift, it is preferable to increase the weight. In the case of an engine of a vehicle produced for the purpose of high-speed traveling, it is appropriate to increase the weight per engine RPM.

If the valve lift and weight per engine RPM are applied as described above, the compensation value for the ignition timing for each cylinder is set in step S311. The engine control unit 201 measures the current engine vibration value that is numerically compensated with respect to the engine vibration value assumed to be the reference value set in step S305. That is, the current engine vibration value / reference engine vibration value (Reference Engine Roughness) is calculated.

If the result of the calculation is that the result is greater than the current engine vibration value, the base ignition timing is perceptually controlled by performing the reverse control as in step S319. This is controlled to be set in the retard direction based on MBT. In step S317, the minimum engine vibration is generated and the ignition timing is derived so as to have the MBT region having the optimum engine torque.

On the other hand, if it is determined in step S313 that the resultant value is less than the current engine vibration value, the process proceeds to step S315 to perform forward control. This is to advance the base ignition timing and to advance the base ignition timing to derive the optimum torque and ignition timing. In addition, in step S317, the minimum engine vibration is generated, and the ignition timing is derived so as to have the MBT region having the optimum engine torque.

201: engine control unit (ECU) 203: fuel injection control device
205: Vibration measuring device 207: Combustion chamber pressure sensor

Claims (5)

a) increasing the inter-cylinder torque deviation by setting the same air-fuel ratio for all the cylinders;
b) measuring Engine Roughness by valve lift height and engine RPM, and storing the Engine Roughness as a reference value; And
c) controlling the cylinder-by-cylinder ignition timing,
The step c)
c-1) calculating an ignition timing compensation amount for each cylinder in a direction in which the torque deviation is reduced;
c-2) assigning a weight according to the valve lift height and the engine RPM to the calculated compensation amount;
c-3) correcting the ignition timing by applying the compensation amount to each of the cylinders to which the weight is assigned;
c-4) comparing the current engine vibration with the reference value after measurement;
c-5) deriving an ignition timing at which the engine vibration is minimized by perceptually controlling the base ignition timing when the engine vibration is increased with respect to the reference value; And
c-6) when the current engine vibration is decreased with respect to the reference value, advancing the base ignition timing so as to obtain an ignition timing at which the engine vibration is minimized, wherein the ignition timing control for each cylinder in the valve lift variable control system Way. delete delete The method according to claim 1,
Wherein the set air-fuel ratio is [lambda] = 1, wherein lambda is a value obtained by dividing an actual intake air amount by a theoretically required air amount.
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