KR20030096943A - Fuel distribution method in a common rail injection system - Google Patents

Abstract

PURPOSE: A method for distributing the fuel for a common rail fuel injection device is provided to distribute the fuel required to the pilot injection, the main injection and the after injection by calculating the fuel to the driving required of an engine. CONSTITUTION: A method for distributing the fuel for a common rail fuel injection device comprises steps of calculating the fuel required to the maximum limit, the fuel required to the outside, the idle required fuel, the fuel required an active surge damper, the fuel required to a cylinder balance, and a starting fuel(S1); calculating the active surge damper fuel, the cylinder balance fuel, and the fuel except for the active surge damper based on the required fuel to the maximum limit, the fuel required to the outside, the idle required fuel, the fuel required the active surge damper, and the fuel required to the cylinder balance(S2); determining the active surge damper fuel, the cylinder balance fuel, and the fuel except for the active surge damper as the starting fuel at starting(S4); determining the fuel except for the active surge damper as zero at the fuel shutting off caused by the engine overrun; and determining the active surge damper fuel and the cylinder balance fuel as zero step by step(S6).

Description

Fuel distribution method in common rail fuel injection device {Fuel distribution method in a common rail injection system}

The present invention relates to a fuel amount distribution method in a common rail fuel injection device, and more particularly, to a fuel amount distribution method for decomposing fuel amounts required for pilot injection, main injection post injection, etc. by calculating the fuel amount for each driving region of an engine. .

The diesel fuel injectors used up to now use cam drive to obtain the injection pressure. The principle is that the injection pressure increases with speed and the injection fuel amount increases accordingly. Such a device could only be used in practice with very low injection pressures.

Unlike the cam driving method, in the common rail injection apparatus used in a passenger car or a commercial vehicle, the generation of the injection pressure and the injection process are completely separate. In order to separate the pressure generation and injection, a high pressure accumulator or a rail capable of maintaining a high pressure is required. In this system, a nozzle equipped with a solenoid is mounted on a conventional nozzle holder, and a high pressure is generated by a radial piston pump, and the rotation speed can be freely adjusted independently of the engine speed within a certain range.

The advantage of the common rail system is that the design of the combustion and injection process can be freed because the engine pressure can be considered separately from the pressure generation and injection of the fuel. That is, since the fuel pressure and the injection timing can be adjusted according to the engine operating conditions by using the engine member, even when the engine rotation speed is low, high-pressure injection is possible, thereby pursuing complete combustion. In addition, the pilot injection can further reduce the exhaust gas and noise, and the fuel injection curve is adjusted by the nozzle needle by the hydraulic control can be adjusted quickly until the end of the injection. After all, the common rail system has made it possible for diesel engines to significantly reduce emissions and improve fuel economy.

However, in the conventional injection method applied in the common rail injection system as described above, there is a problem that it is difficult to precisely control the fuel injection and combustion stability due to the high pressure of the combustion pressure. In particular, when calculating the total fuel amount from the signals sensed by the various sensors, there was a problem that can not accurately reflect the fuel amount according to engine idle conditions, cylinder vibration, combustion variation of each cylinder.

Accordingly, the present invention has been made to solve the above-mentioned problems of the prior art, and calculates the fuel amount for each driving region of the engine and distributes the fuel amount required for pilot injection, main injection, and after injection, respectively, for more accurate fuel amount calculation and distribution. It is an object of the present invention to provide a method for distributing fuel amount in a common rail fuel injector capable of increasing fuel efficiency due to fuel injection stability and reduced fuel amount.

The fuel amount distribution method in the common rail fuel injection device according to the present invention for achieving the above object includes the maximum limit demand fuel amount, external demand fuel amount, idle demand fuel amount, active surge damper demand fuel amount, cylinder balance demand fuel amount, and starting fuel amount Calculating a fuel amount excluding an active surge damper, an active surge damper fuel amount, and a cylinder balance fuel amount based on the maximum limit demand fuel amount, external demand fuel amount, idle demand fuel amount, active surge damper demand fuel amount, and cylinder balance demand fuel amount. Calculating the fuel amount excluding the active surge damper, the active surge damper fuel amount, and the cylinder balance fuel amount as the starting fuel amount at start-up, and the fuel amount excluding the active surge damper at the time of shut off of the fuel due to engine overrun. Is set to "0", and the active surge damper fuel amount And setting the cylinder balance fuel amount stepwise to " 0 ".

1 is a schematic configuration diagram of a common rail fuel injection device for performing a fuel amount distribution method according to the present invention;

2 is a flowchart illustrating a fuel amount distribution method in a common rail fuel injection device according to the present invention.

<Explanation of symbols for the main parts of the drawings>

11: electronic control unit 12: high pressure pump

13: fuel supply control valve 14: common rail

15: injector 16: injector coil

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

1 is a schematic configuration diagram of a common rail fuel injector for performing a fuel amount distribution method according to the present invention, which includes an electronic control unit 11, a high pressure pump 12, a fuel supply control valve 13, and a common rail ( 14), the injector 15, the injector coil 16, and various sensors 21-27 are comprised.

The high pressure pump 12 is a pump using a rotational force of the engine to compress the diesel fuel up to 1,350 bar to supply to the common rail 14, the fuel supply control valve 13 is the high pressure pump 12 It is built in the inside, and controls the amount of fuel required for the engine by controlling the amount of fuel sent to the high pressure chamber of the high-pressure pump 12 under the control of the electronic control unit (11).

The common rail 14 stores the high-pressure fuel supplied from the high-pressure pump 12 and sends the fuel at the same fuel pressure to each combustion chamber, and a check valve and a high pressure sensor are installed to prevent backflow. For example, the fuel pressure in the rail is regulated by an electromagnetic pressure control valve, and the fuel pressure is always monitored by a pressure sensor and continuously adjusted according to the requirements of the engine.

The injector 15 serves to inject high pressure fuel into the combustion chamber, and the injector coil 16 operates under the control of the electronic control unit 11 to open and close the needle valve of the injector 15. have.

The electronic control unit 11 receives the detection signals of the various sensors 21-27 to operate the high pressure fuel pump 12, the fuel supply control valve 13, the injector coil 16, and the like, thereby providing fuel injection amount, Injection timing, injection rate, etc. are controlled.

The fuel amount distribution method according to the present invention performed in the apparatus configured as described above will be described in detail with reference to FIG. 2 as follows.

FIG. 2 is a flowchart illustrating a fuel amount distribution method in a common rail fuel injection device according to the present invention, and in FIG. 2, S denotes a step.

As shown in Fig. 2, in step S1, the maximum limit demand fuel amount, external demand fuel amount, idle demand fuel amount, active surge damper demand fuel amount, cylinder balance demand fuel amount, and starting fuel amount are calculated.

At this time, the maximum limit required fuel amount is obtained by correcting the atmospheric pressure and the cooling water temperature to the base amount obtained from the air mass and the engine speed, the external required fuel amount is determined from the maximum vehicle speed limit value and the minimum transmission control unit (TCU) interference, The idle demand fuel amount is determined according to the engine speed, water temperature, battery voltage, and the like.

In addition, the amount of fuel required for active surge damper is to reduce the fluctuation of the engine speed, and it is determined according to the current demanded fuel amount and the engine speed, and the amount of fuel required to balance the cylinder is to reduce the fuel amount variation and combustion deviation between cylinders. The amount of surge damper is determined by the amount of fuel in consideration, and the amount of starting fuel is determined by the coolant temperature and engine speed.

Subsequently, in step S2, the fuel amount excluding the active surge damper, the active surge damper fuel amount, and the cylinder balance based on the maximum limit demand fuel amount, external demand fuel amount, idle demand fuel amount, active surge damper demand fuel amount, and cylinder balance demand fuel amount. Calculate the fuel amount.

In this case, the fuel amount excluding the active surge damper is a value obtained by adding a smaller value (amount of idle fuel) to a smaller value (required fuel amount excluding the active surge damper) among the maximum limited demand fuel amount and the external demand fuel amount. Is calculated.

The active surge damper fuel amount is the smaller of the maximum limit demand fuel amount and idle demand fuel amount (the idle fuel amount) plus the active surge damper demand fuel amount, and the maximum limit demand fuel amount and the active surge damper offset fuel amount. It is calculated as a value.

The cylinder balance fuel amount is calculated by adding the cylinder balance demand amount to the active surge damper fuel amount.

Subsequently, in step S3, it is determined whether startup is performed, and if startup is performed, step S4 is performed. If not, startup is performed in step S5. In the step S4, both the fuel amount, the active surge damper fuel amount, and the cylinder balance fuel amount except the active surge damper are set as the starting fuel amount.

In the step S5, it is determined whether the fuel is cut off according to the engine overrun, and if the fuel is cut off, step S6 is performed. Then, the active surge damper fuel amount and the cylinder balance fuel amount are set to "0" step by step.

As described above, according to the present invention, by calculating the amount of fuel for each operating region of the engine and distributing the amount of fuel required for pilot injection, main injection, and after injection, the fuel quantity can be calculated and distributed more precisely, and the fuel injection stability and fuel amount can be reduced. There is an effect that can increase the fuel economy due to.

Claims (4)

Calculating the maximum limit demand fuel amount, external demand fuel amount, idle demand fuel amount, active surge damper demand fuel amount, cylinder balance demand fuel amount, and starting fuel amount, the maximum limit demand fuel amount, external demand fuel amount, idle demand fuel amount, and active amount Calculating fuel amount excluding active surge damper, active surge damper fuel amount, and cylinder balance fuel amount based on surge damper demand fuel amount and cylinder balance demand fuel amount; Setting both the balanced fuel amount as the starting fuel amount, and when the fuel is cut off due to the engine overrun, the fuel amount excluding the active surge damper is set to "0", and the active surge damper fuel amount and the cylinder balance fuel amount are set to "0" step by step. Kerr characterized in that it comprises a step of setting to Method of distributing fuel amount in far rail fuel injector. The fuel amount excluding the active surge damper is a value smaller than the maximum limit demand fuel amount and the external demand fuel amount (required fuel amount excluding active surge damper) and smaller than the maximum limit demand fuel amount and idle demand fuel amount (idle fuel amount). A fuel amount distribution method in a common rail fuel injection device, characterized in that it is set to the value plus. 2. The method of claim 1, wherein the active surge damper fuel amount is a value obtained by adding a smaller value (idle fuel amount) among the maximum limited demand fuel amount and idle demand fuel amount to the active surge damper demand fuel amount, and the maximum limited demand fuel amount and active surge damper offset fuel amount. A fuel amount distribution method in a common rail fuel injector, characterized by being set to a smaller value among the added values. 4. The fuel amount distribution method according to claim 3, wherein the cylinder balance fuel amount is set to a value obtained by adding the active balance damper fuel amount to a cylinder balance demand amount.