KR20040036129A - Cylinder injection controling method of common rail system in diesel engine - Google Patents

Abstract

PURPOSE: A method for controlling fuel quantity by a cylinder in a common rail type diesel engine is provided to stabilize output of the engine by removing deflection of fuel quantity for each of the cylinders. CONSTITUTION: A method includes the steps of: a step setting learning value of pilot injection fuel quantity classified by cylinders; a determining step(S210) whether state of an engine satisfies learning conditions for main injection fuel quantity; a determining step(S220) whether pilot injection fuel quantity for each of the cylinders is within a set first range; a step(S230) calculating main injection fuel quantity by setting main injection fuel quantity compensation ratio for the corresponding cylinder as fixed percentage of pilot injection fuel quantity learning value got from the corresponding cylinder; a determining step(S240) whether pilot injection fuel quantity learning value of the corresponding cylinder is within a set second range; a step(S250) calculating main injection fuel quantity by setting main injection fuel quantity compensation ratio for the corresponding cylinder as fixed percentage of the pilot injection fuel quantity learning value get from the corresponding cylinder; a determining step(S260) whether pilot injection fuel quantity learning value of the corresponding cylinder is within a set third range; and a step(S270) calculating main injection fuel quantity by setting main injection fuel quantity compensation ratio as fixed percentage of pilot injection fuel quantity learning value got from the corresponding cylinder, and determining the cylinder to be outworn if the cylinder exceeds the third range.

Description

CYLINDER INJECTION CONTROLING METHOD OF COMMON RAIL SYSTEM IN DIESEL ENGINE}

The present invention relates to a diesel engine to which the common rail system is applied. More specifically, the learning value for pilot injection fuel amount correction is extended to the main fuel amount correction value, and the application rate is applied to each injector. The present invention relates to a method of controlling the amount of fuel in a cylinder in a common rail type diesel engine, which is applied differently according to aging to exclude a variation in the amount of fuel in each cylinder to provide engine stability.

In the case of diesel engines, the common rail system is adopted for the purpose of reducing engine speed, high power and fuel economy. The system is equipped with an accelerometer at the center of the engine block, and the signal generated from the engine is displayed every hour. The pilot fuel amount is adjusted according to the injector state of each cylinder, and the configuration of the device is as follows.

As shown in FIG. 1, in a diesel engine to which a common rail system is applied, a pilot fuel amount learning apparatus includes an engine speed detector 10 for detecting engine speed, and a rail pressure detector 20 for detecting pressure in a common rail. A water temperature detector 30 for detecting the temperature of the coolant, a vehicle speed detector 40 for detecting the current running vehicle speed, a vibration detector 70 for detecting the vibration generated by the combustion reaction when the fuel is injected into the test target cylinder, and the Analyze information of each detection unit to determine whether the engine condition condition satisfies the learning condition of the pilot injection fuel amount, and if the learning condition is satisfied, perform pilot injection fuel amount learning for each cylinder and then set and control the learning correction value. And a control unit 50 and an injector 60 that performs fuel amount injection calculated on each cylinder.

The operation for pilot injection fuel amount learning in the configuration including the function as described above is as follows.

As can be seen in Figure 2, the temperature of the coolant in the state information of the vehicle detected in the state in which the vibration learning value for all cylinders is set to '0 (Zero)' (S101) is a predetermined temperature, for example 70 ℃ As described above, it is determined whether the engine is sufficiently warmed and the vehicle satisfies the pilot injection fuel amount learning condition for maintaining a constant speed or more, for example, 60 KM / H or more (S102).

In the above determination, if it is determined that the pilot injection fuel amount learning condition is satisfied, the control unit 50 cuts off the pilot injection fuel amount of all cylinders (S103), and then raises the pressure in the common rail to a pressure higher than the normal pressure ( S104).

Subsequently, the pilot fuel is injected only to the cylinder to be trained for a predetermined time through the driving of the injector 60 (S105), and the vibration detection unit 70 is installed at the center of the engine block to generate vibrations caused by the injection of the pilot fuel. Sense through (S106).

At this time, the detected vibration value is '0', that is, it is determined whether the vibration is not detected (S107), and when the vibration is not detected, it is determined that there is no combustion reaction by the pilot injection and the injector is opened until the vibration is detected. The pilot injection fuel amount is increased by increasing the time, and then the flow returns to the process of S105 to repeat the above process (S108).

If the vibration is detected by the combustion reaction by the pilot injection in the determination of S107, it is determined whether the detected vibration value is greater than or equal to the set reference value (S109), and if too severe vibration is detected above the reference value, excessive pilot injection fuel amount is supplied. If it is determined that the vibration time is eliminated until the vibration is eliminated (S110), and the vibration value detected by the combustion reaction by the pilot injection is determined that the reference value is less than the reference value is determined that the small pilot injection fuel amount is supplied The pilot injection fuel amount is increased by increasing the opening time of the injector until the vibration satisfactory is detected (S111).

By repeating the above process and determining whether the combustion reaction vibration value by pilot injection satisfies the set reference value (S112), if the reference value is not satisfied, it is returned and repeatedly performs the above process (S113), and the vibration value is the reference value. If the state is satisfied, the pilot injection fuel amount of the injector is learned and set, and the pilot injection fuel amount is precisely controlled according to this learning value later (S114).

The above-described learning correction of the pilot injection fuel amount is applied only to the pilot injection, and the main injection fuel amount is controlled according to the engine speed, the accelerator opening degree, and the rail pressure.

Therefore, in the case of the injector injecting the amount of fuel calculated in accordance with the condition of the vehicle to each cylinder, it is common to show a tendency to increase the amount of fuel injection due to wear and the like as the use time elapses. Due to the continuous increase in the injection amount, there is a problem that causes deterioration in durability due to smoke deterioration and exhaust system deterioration.

In order to solve this problem, a certain ratio of the learning value is uniformly applied without considering the period of use of the injector, but in this case, if the correction ratio is too large, the engine output initially falls short of the target value. After driving a certain distance after the target performance occurs, or if the ratio is too small on the contrary, the increase in fuel injection amount when the vehicle is aging recurs the problem that the main fuel amount correction effect is lost.

Therefore, the main injection fuel amount correction method has been devised and applied to improve the injector period, in which case it is a good useful method to achieve a constant output regardless of the engine operating time, but the mechanical wear of each injector is minute It may be different, and thus, there is a high possibility that the fuel amount increase patterns are different from each other.

However, in the main injection fuel amount correction method considering the injector usage period, the main injection fuel amount correction ratio is calculated by arithmetically averaging the learning values of all the cylinders, so that a deviation occurs between cylinders, so that the stable main injection fuel amount correction control is not performed.

The present invention has been invented to solve the above problems, and the object of the present invention is to extend the correction value obtained through the pilot injection fuel amount learning during the main injection fuel amount correction, and to change the application ratio for each injector so that the injector use time is increased. The increase in fuel injection amount due to wear and the like is prevented from increasing, and the variation in fuel injection amount caused by cylinders caused by different wear levels is improved to maintain the output of the engine.

1 is a schematic configuration diagram of a pilot fuel amount learning device in a common rail type diesel engine;

2 is a flowchart illustrating a pilot fuel amount learning process in a common rail diesel engine;

3 is a flow chart showing a learning process for controlling the amount of fuel for each cylinder in the diesel engine of the common rail method according to the present invention.

In the present invention for realizing the above object in the main injection fuel amount correction method of a diesel engine,

Classifying and setting a pilot injection fuel amount learning value for each cylinder; Determining whether the engine condition satisfies the main injection fuel amount learning condition; Determining whether the pilot injection fuel amount learning value for each cylinder is within a set first range if a learning condition is satisfied; Calculating a main injection fuel amount by applying a main injection fuel amount correction ratio for the cylinder to a predetermined percentage of the pilot injection fuel amount learning value obtained from the cylinder, when a cylinder included in the first range is present; Determining whether a pilot injection fuel amount learning value of the corresponding cylinder is included in the set second range when a cylinder not included in the first range exists; Calculating a main injection fuel amount by applying a main injection fuel amount correction ratio for the cylinder to a predetermined percentage of the pilot injection fuel amount learning value obtained from the cylinder, when a cylinder included in the second range is present; Determining whether a pilot injection fuel amount learning value of the corresponding cylinder is included in the set third range when a cylinder not included in the second range exists; If a cylinder included in the third range is present, the main injection fuel amount is calculated by applying a main injection fuel amount correction ratio for the cylinder as a predetermined percentage of the pilot injection fuel amount learning value obtained from the cylinder, and exceeds the third range. If there is a cylinder, it is determined that the injector of the cylinder is old and outputs a failure message.

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

In the common rail type diesel engine according to the present invention, the fuel level control device for each cylinder has the same configuration as that of FIG. 1 set in the prior art, and the description thereof is replaced with the conventional description, and the pilot injection fuel amount learning correction The operation of correcting the main injection fuel amount by applying the value to the main injection fuel amount is as follows.

First, the learning values for the pilot injection fuel amount correction described in the above-described prior art are separately stored through flag setting for each cylinder.

Here, the value A is the learning value obtained from cylinder 1, the value Ｂ is the learning value obtained from cylinder 2, the value C is the learning value obtained from cylinder 3, and the value D is the learning value obtained from cylinder 4 Defined as a value.

In the state in which the pilot injection fuel amount correction learning value is divided into cylinders and separately stored as described above, the state information of the engine is a main injection fuel amount learning condition, that is, a predetermined RPM at which the engine speed is set, for example, 2500 RPM or less, and the pressure in the common rail It is determined whether the set constant pressure, for example, 1300 Bar or less is satisfied (S210).

When the main injection fuel amount learning condition is satisfied, it is determined whether the stored pilot injection fuel amount correction learning value for each cylinder is included in the set first range, for example, 0 to 30 (S220).

When it is determined that there is a cylinder included in the first range in which the pilot injection fuel amount correction learning value for each cylinder is set, the percentage of main injection fuel amount correction for the cylinder is a constant percentage of the value obtained from the pilot injection learning for the cylinder. Preferably, it is determined as 30% (S230) to calculate the main injection fuel amount and then control the driving of the injector so that the calculated main injection fuel amount is injected into the cylinder (S1000).

If it is determined in S220 that there is a cylinder whose pilot injection fuel amount correction learning value for each cylinder is not included in the set first range, the second range in which the stored pilot injection fuel amount correction learning value for each cylinder is set, for example For example, it is determined whether or not included in the range of 31 ~ 60 (S240).

When it is determined that there is a cylinder included in the second range in which the pilot injection fuel amount correction learning value for each cylinder is set, the main injection fuel amount correction ratio for the cylinder is a constant% of the value obtained from the pilot injection learning for the cylinder. Preferably, it is determined as 60% (S250) to calculate the main injection fuel amount and then control the driving of the injector so that the calculated main injection fuel amount is injected into the cylinder (S1000).

However, if it is determined in S240 that there is a cylinder whose pilot injection fuel amount correction learning value for each cylinder is not included in the set second range, the third range in which the stored pilot injection fuel amount correction learning value for each cylinder is set, For example, it is determined whether or not included in the range of 61 ~ 140 (S260).

If it is determined that there is a cylinder included in the third range in which the pilot injection fuel amount correction learning value for each cylinder is set, the cylinder is determined to be old due to its long service life, and thus the main injection fuel amount correction ratio for the cylinder is determined. Determine the main injection fuel amount by determining a constant%, preferably 100%, of the value obtained from the pilot injection learning of the cylinder (S270), and then control the driving of the injector so that the calculated main injection fuel amount is injected into the cylinder ( S1000).

That is, in the case of main injection fuel amount correction according to the present invention, the pilot injection learning value is divided into three ranges of 0 to 30, 31 to 60, and 61 to 140, and the correction ratio is 30% and 60% of the learning value in each case. The difference is applied to% and 100%, but the learning values obtained from the cylinder apply only to the correction of the fuel volume of the cylinder.

However, if it is determined in S260 that there is a cylinder exceeding the third range, it is determined that correction is impossible due to damage of the injector, and the driver turns on a warning light in operation S2000.

At this time, the number of the fault injector is stored in the self-diagnostic means so that only the corresponding injector can be replaced in the future to prevent unnecessary work.

As described above, the present invention applies the pilot injection fuel amount correction learning value as the main injection fuel amount correction learning value, and changes the application ratio for each injector, thereby increasing the fuel injection amount due to wear and the like while increasing the injector use time. It is possible to prevent the occurrence of fuel injection quantity variation for each cylinder caused by the wear level being different for each injector, and to keep the engine output constant.

Claims (8)

In the main injection fuel amount correction method of the diesel engine, Classifying and setting a pilot injection fuel amount learning value for each cylinder; Determining whether the engine condition satisfies the main injection fuel amount learning condition; Determining whether the pilot injection fuel amount learning value for each cylinder is within a set first range if a learning condition is satisfied; Calculating a main injection fuel amount by applying a main injection fuel amount correction ratio for the cylinder to a predetermined percentage of the pilot injection fuel amount learning value obtained from the cylinder, when a cylinder included in the first range is present; Determining whether a pilot injection fuel amount learning value of the corresponding cylinder is included in the set second range when a cylinder not included in the first range exists; Calculating a main injection fuel amount by applying a main injection fuel amount correction ratio for the cylinder to a predetermined percentage of the pilot injection fuel amount learning value obtained from the cylinder, when a cylinder included in the second range is present; Determining whether a pilot injection fuel amount learning value of the corresponding cylinder is included in the set third range when a cylinder not included in the second range exists; If a cylinder included in the third range is present, the main injection fuel amount is calculated by applying a main injection fuel amount correction ratio for the cylinder as a predetermined percentage of the pilot injection fuel amount learning value obtained from the cylinder, and exceeds the third range. If the cylinder is present, the method of controlling the fuel amount for each cylinder in the common rail-type diesel engine comprising the step of outputting a failure message by determining that the injector of the cylinder is old. The method of claim 1, The main injection fuel amount learning condition is the engine speed is 2500rpm or less, the fuel level control method for each cylinder in the common rail type diesel engine, characterized in that the pressure in the common rail meets the condition of 1300Bar or less. The method of claim 1, And a first range of the pilot injection fuel amount learning value is set in a range of 0 to 30. The method of claim 1, And a second range of the pilot injection fuel amount learning value is set in a range of 31 to 60. The method of claim 1, And a third range of the pilot injection fuel amount learning value is set in a range of 61 to 140. 3. The method of claim 1, In the common rail type diesel engine, if a cylinder having the pilot injection fuel amount learning value is present in the first range exists, 30% of the pilot injection fuel amount learning value for the cylinder is applied as the main injection fuel amount correction value. Fuel level control method by star. The method of claim 1, In the common rail type diesel engine, when the cylinder having the pilot injection fuel amount learning value is present in the second range, 60% of the pilot injection fuel amount learning value for the cylinder is applied as the main injection fuel amount correction value. Fuel level control method by star. The method of claim 1, In the common rail type diesel engine, if the cylinder having the pilot injection fuel amount learning value exists in the third range, 1000% of the pilot injection fuel amount learning value for the cylinder is applied as the main injection fuel amount correction value. Fuel level control method by star.