JPH08144826A - Fuel injection controller of internal combustion engine - Google Patents

Abstract

PURPOSE: To ensure the accuracy of injection amount at each cylinder, even in such constitution that the injection timing of an injector is not synchronized with the fuel press-feed timing of a high pressure supply pump. CONSTITUTION: A basic injection pulse TQB is calculated from the real common rail pressure NPC of a high pressure fuel in a common rail by making an order injection amount QFIN in an operation state by an injection timing for the cylinder No. of an internal combustion engine as a parameter (S201-S204). Revised injection pulses TQn per cylinder are calculated based on that the pressure of high pressure fuel in the common rail is different by the injection timing at every cylinder (S205). An injector is driven based on the injection pulse TQ to which they are added (S206-S207). Thereby, even if the pressure of high pressure fuel fed out from the common rail is different by the injection timing at every cylinder of the internal combustion engine, the injector can inject and supply a prescribed injection amount corresponding to the operation state and the accuracy of the injection amount at every cylinder is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection control device for an internal combustion engine having a common rail (accumulation pipe) used for a diesel engine or the like and supplying high pressure fuel to each cylinder.

[0002]

2. Description of the Related Art Conventionally, as a prior art document relating to a fuel injection control device for an internal combustion engine, there is Japanese Patent Laid-Open No. 62-25816.
The one disclosed in Japanese Patent No. 0 is known. In this article, it is described that it is suitable to improve the accuracy of the injection amount by pumping and replenishing the fuel in synchronism with the injection timing of the injector in the high-pressure supply pump that generates the high-pressure fuel. That is, it is also possible to replenish the fuel for each injection of the injector asynchronously with the injection timing to generate high-pressure fuel by pumping the fuel with the high-pressure supply pump.
This is not preferable because the variation in the injection amount among the cylinders becomes large.

[0003]

By the way, in order to correspond to internal combustion engines having different number of cylinders and to replenish the fuel by pumping the fuel by the high pressure supply pump in synchronization with the injection timing of the injector, separate high pressure supply pumps are used. It will have to be used. This hinders standardization and causes a cost increase.

Therefore, the present invention has been made in order to solve such a problem, and the accuracy of the injection amount for each cylinder is improved even in the case where the injection timing of the injector and the fuel pressure feeding timing of the high-pressure supply pump are not synchronized. It is an object of the present invention to provide a fuel injection control device for an internal combustion engine that can ensure the above.

[0005]

According to a first aspect of the present invention, there is provided a fuel injection control device for an internal combustion engine, which comprises a high-pressure supply pump for generating a high-pressure fuel having a predetermined pressure by inflowing and pumping a low-pressure fuel, and the high-pressure supply. A common rail for accumulating the high-pressure fuel pumped from the pump, a common rail pressure sensor for detecting the pressure of the high-pressure fuel in the common rail, and an electrical connection for the high-pressure fuel from the common rail provided for each cylinder of the internal combustion engine. An injector that supplies and injects the fuel into the injector, and a control unit that controls the injection amount from the injector at the injection time of the injector for each cylinder calculated based on the pressure of the high-pressure fuel detected by the common rail pressure sensor. It is equipped with.

A fuel injection control device for an internal combustion engine according to claim 2 calculates the injection time in the control means according to claim 1 by adding a correction injection time for each cylinder to a basic injection time common to each of the cylinders. To do.

[0007]

According to the present invention, the common rail pressure sensor detects the pressure of the high pressure fuel in the common rail which is pressure-fed by the high pressure supply pump and accumulated. Based on the pressure of the high-pressure fuel, the control means calculates the injection time of the injector provided for each cylinder of the internal combustion engine and controls the injection amount. Therefore, even if the pressure of the high-pressure fuel delivered from the common rail differs depending on the injection timing for each cylinder of the internal combustion engine, the injector can inject and supply a predetermined injection amount that is suitable for the operating state.

In the control means of the fuel injection control device for the internal combustion engine according to claim 2, the injection time in claim 1 is calculated by adding the corrected injection time for each cylinder to the basic injection time common to each cylinder.

[0009]

EXAMPLES The present invention will be described below based on specific examples.

FIG. 1 is a schematic configuration diagram showing a fuel injection control device for an internal combustion engine according to an embodiment of the present invention.

In FIG. 1, reference numeral 10 denotes an internal combustion engine, and an injector 3 is arranged in each fuel chamber of each cylinder of the internal combustion engine 10. The fuel injection amount to each cylinder of the internal combustion engine 10 is controlled by turning on / off the injection control solenoid valve 3a arranged in the injector 3. The injector 3 is connected to a so-called common rail 4 which is a high pressure accumulating pipe common to each cylinder. The common rail 4 is provided with a common rail pressure sensor 5 that detects the pressure inside the common rail 4. The common rail 4 is connected to the high pressure supply pump 2. Low-pressure fuel is supplied from a fuel tank (not shown) to the solenoid valves 21a and 21b arranged in parallel in the high-pressure supply pump 2 via a low-pressure supply pump.

Reference numeral 1 denotes an ECU (Electronic Control Unit), and the ECU 1 includes, for example, an internal combustion engine 1
The detection signals from the crank angle sensor 7 that detects the cylinder No., which is the fuel injection timing, and the accelerator opening sensor 9 that detects the depression amount of the accelerator pedal 8 are input from the rotation of the crankshaft 10a of 0. Further, a common rail pressure signal Pc from a common rail pressure sensor 5 arranged on the common rail 4 is input to the ECU 1. 6 is a battery, and the power supply voltage (+ B) from the battery 6 is the electromagnetic valves 21a and 21b of the ECU 1 and the high-pressure supply pump 2.
Has been applied.

The electromagnetic valves 21a and 21b in the high-pressure supply pump 2 are ON / OFF controlled by the ECU 1, and the internal combustion engine 10
At this time, the cams 22a, 22b in the high pressure supply pump 2 are rotated and the pistons 23a, 23b are raised / lowered, so that the low pressure fuel that has flowed in through the solenoid valves 21a, 21b is pressure-converted into the high pressure fuel and the high pressure supply pump. It is supplied from 2 to the common rail 4.

Next, the CP in the ECU 1 used in the fuel injection control device for the internal combustion engine according to the embodiment of the present invention.
The processing procedure of U will be described based on the flowcharts of FIGS. 2 and 3. The flowcharts of FIGS. 2 and 3 are
8 at every injection timing of the injector 3 of each cylinder based on the output signal from the crank angle sensor 7, that is, at every 120 ° CA (crank angle) in the 6-cylinder diesel engine.
In the cylinder diesel engine, it is executed by the CPU every 90 ° CA.

<< Fuel Injection Control Main Routine: See FIG. 2 >> FIG. 2 is a flowchart showing a fuel injection control process.

First, the load ACCP based on the operating state is read in step S101, and the engine speed NE is read in step S102. Next, the process proceeds to step S103, and the command injection amount QFIN is calculated from the load ACCP read in step S101 and the engine speed NE read in step S102. Next, the process proceeds to step S104, and the command injection timing TFIN is calculated from the load ACCP read in step S101 and the engine speed NE read in step S102. Next, in step S105, the command common rail pressure PFIN is calculated from the load ACCP read in step S101 and the engine speed NE read in step S102. Then, the process proceeds to step S106, and the injector 3 is subjected to an injector control process described later.

Next, in step S107, the common rail pressure signal Pc from the common rail pressure sensor 5 disposed in the common rail 4 is increased to the command common rail pressure PFIN calculated in step S105 as the common rail pressure control process. ON / OFF control for the solenoid valves 21a and 21b in the supply pump 2 is executed,
This main routine ends. Note that step S107
In order to increase the pressure of the fuel in the common rail 4 in the common rail pressure control process of 1, the solenoid valves 21a and 21b are turned on earlier than when the pistons 23a and 23b reach the lowest point by the cams 22a and 22b. This is achieved by closing the state from the OFF state to the ON state. On the contrary, in order to decrease the fuel pressure in the common rail 4, the cam 2
This is achieved by delaying the pistons 23a, 23b from the time when the pistons 23a, 23b have reached the lowest point by 2a, 22b, and closing the solenoid valves 21a, 21b from the previous OFF state to the ON state.

<Injector Control Subroutine: See FIG. 3> FIG. 3 is a flowchart showing the injector control process of step S106 of FIG.

In step S201, step S103
The command injection amount QFIN calculated in step 1 is read. Next, in step S202, the common rail pressure sensor 5
The actual common rail pressure NPC which is the pressure of the fuel in the common rail 4 is read. Next, the routine proceeds to step S203, where the cylinders No. (# 1, # 2, # 2) for which fuel injection control is to be performed
# 3, ...) is read. Next, in step S204, the basic injection pulse TQB is set in step S201 using the command injection amount QFIN read in step S201 as a parameter.
It is calculated from the map corresponding to the actual common rail pressure NPC read in 202. Next, the process proceeds to step S205, and the cylinder-specific correction injection pulse TQn corresponding to the cylinder No. read in step S203 uses the command injection amount QFIN read in step S201 as a parameter and is read in step S202. It is calculated from a map for each cylinder No. (# 1, # 2, # 3, ...) Corresponding to the pressure NPC.

Next, in step S206, the injection pulse TQ is calculated by adding the basic injection pulse TQB calculated in step S204 and the cylinder-specific correction injection pulse TQn calculated in step S205. Then, the process proceeds to step S207, and the injector 3 corresponding to the cylinder No. (# 1, # 2, # 3, ...) Is controlled based on the injection pulse TQ calculated in step S206 as the injector drive process, that is, the injector 3 Of the injection control solenoid valve 3a is turned on (open state), the common rail 4
The high-pressure fuel therein is injected from the injector 3 to the corresponding cylinder of the internal combustion engine 10, and the present subroutine ends.

FIG. 4 corresponds to the injection timing for each cylinder (# 1, # 2, # 3, ...) In the 6-cylinder diesel engine and the 8-cylinder diesel engine when the flowcharts of FIGS. 2 and 3 are executed. 5 is a time chart showing the relationship between the common rail pressure and the pumping amount of high-pressure fuel from the high-pressure supply pump 2.

In FIG. 4, the high-pressure supply pump 2 is common to the 6-cylinder diesel engine and the 8-cylinder diesel engine. The high-pressure supply pump 2 is designed for a 6-cylinder diesel engine, and its pumping amount is synchronized with the injection timing (120 ° CA) of the 6-cylinder diesel engine. Therefore, the pump pressure feed amount is not synchronized with the injection timing (90 ° CA) of the 8-cylinder diesel engine.

In an 8-cylinder diesel engine, cylinders # 1 and # 5 which are injected in synchronization with pumping by the high-pressure supply pump 2 and cylinders # 2 and # which are injected at other times.
The common rail pressure at the time of injection is different between 3, # 4, # 6, # 7, and # 8. Therefore, the predetermined fuel amount required for the cylinders according to the operating state at that time is not supplied to each cylinder with the same injection pulse width, and as a result, the fuel supply amount for each cylinder varies. Will be lost.
Here, by utilizing the fact that the deviation between the cylinder No. at the injection timing of the 8-cylinder diesel engine and the pump pressure feeding timing of the high-pressure supply pump 2 is always constant, as described in the flowchart of FIG. Eliminate variations in fuel quantity.

That is, the basic injection pulse TQB is calculated from the command injection amount QFIN and the actual common rail pressure NPC (see S204 in FIG. 3). Next, the cylinders (# 1, # 2, #
3), the cylinder-specific correction injection pulse TQn is calculated based on a map in which the difference between the command injection amount QFIN and the actual injection amount Q is converted into an injection pulse in advance (see S205 in FIG. 3). Then, the injection pulse T for driving the injector 3
Q is calculated (see S206 in FIG. 3), and the injector 3 is driven (see S207 in FIG. 3).

By such control, it is possible to eliminate the variation in the injection amount which is the fuel supply amount for each cylinder. That is, by correcting the injection pulse TQ for each cylinder, the injection amount can be accurately controlled without synchronizing the fuel injection timing of each cylinder from the high-pressure supply pump 2. Therefore, the high-pressure supply pump 2 designed for the 6-cylinder diesel engine can be commonly used for the 8-cylinder diesel engine.

As described above, the fuel injection control device for the internal combustion engine according to the present embodiment includes the high-pressure supply pump 2 for generating the high-pressure fuel having a predetermined pressure by inflowing and pumping the low-pressure fuel,
A common rail 4 for accumulating the high-pressure fuel pumped from the high-pressure supply pump 2, a common rail pressure sensor 5 for detecting the pressure of the high-pressure fuel in the common rail 4, and a common rail 4 arranged for each cylinder of the internal combustion engine 10 The injector 3 that electrically injects and supplies the high-pressure fuel, and the injection time corresponding to the injection pulse TQ of the injector 3 for each cylinder calculated based on the pressure of the high-pressure fuel detected by the common rail pressure sensor 5. The control means achieved by the CPU in the ECU 1 for controlling the injection amount from the injector 3 is provided, and this can be the embodiment of claim 1.

Therefore, the low-pressure fuel flowing from the fuel tank side is pumped by the high-pressure supply pump 2, high-pressure fuel of a predetermined pressure is generated, and the pressure is accumulated in the common rail 4. The injector 3 is provided for each cylinder of the internal combustion engine 10, and the high-pressure fuel from the common rail 4 is electrically injected and supplied. The control unit calculates the injection time of the injector 3 for each cylinder based on the pressure of the high-pressure fuel in the common rail 4 detected by the common rail pressure sensor 5, and controls the injection amount from the injector 3. Therefore, in the combination of a plurality of internal combustion engines with different number of cylinders and one type of high pressure supply pump,
It is possible to eliminate the variation in the injection amount for each cylinder according to the operating state.

In the fuel injection control device for the internal combustion engine of this embodiment, the control means achieved by the CPU in the ECU 1 controls the injection time corresponding to the injection pulse TQ to the basic injection pulse TQB common to the cylinders. The correction injection time for each cylinder corresponding to the cylinder-specific correction injection pulse TQn is added to the basic injection time corresponding to
Can be used as an example.

Therefore, the control means calculates the injection time by adding the basic injection time common to each cylinder and the corrected injection time corresponding to each cylinder. Therefore, the memory capacity in the ECU for storing the map can be made smaller than that in which the injection time is collectively obtained for each cylinder, and the calculation time can be expected to be shortened.

By the way, in the above-mentioned embodiment, the case where the high pressure supply pump 2 for the 6-cylinder diesel engine is used for the 8-cylinder diesel engine has been described. However, the present invention is not limited to this. However, by adopting the fuel injection control device for this internal combustion engine, a common high-pressure supply pump is used, and even for a plurality of internal combustion engines having different numbers of cylinders, variations in the injection amount for each cylinder are eliminated with good accuracy. Injection control becomes possible.

Further, the high pressure supply pump 2 of the above embodiment is
The parallel type triangular cams 22a and 22b are used to drive the pistons 23a and 23b three times per revolution.
When the present invention is carried out, the present invention is not limited to this, and it is essential only that the high pressure fuel accumulated in the common rail 4 can be efficiently boosted to a predetermined pressure.

[0032]

As described above, according to the fuel injection control device for the internal combustion engine of the first aspect, the pressure of the high-pressure fuel in the common rail which is pressure-fed from the high-pressure supply pump and accumulated is detected by the common-rail pressure sensor, Based on the pressure of the high-pressure fuel, the control means calculates the injection time of the injector provided for each cylinder of the internal combustion engine and controls the injection amount. As a result, even if the pressure of the high-pressure fuel delivered from the common rail varies depending on the injection timing for each cylinder of the internal combustion engine, the injector can inject and supply a predetermined injection amount that matches the operating state. That is, it is possible to improve the accuracy of the injection amount for each cylinder in the combination of one type of high-pressure supply pump and a plurality of internal combustion engines having different numbers of cylinders.

According to the fuel injection control device for an internal combustion engine of claim 2, in addition to the effect of claim 1, the injection time is calculated by adding the correction injection time for each cylinder to the basic injection time common to each cylinder. It As a result, it is possible to reduce the memory capacity in the ECU that stores the map, as compared with the case where the injection time is collectively calculated for each cylinder.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing a fuel injection control device for an internal combustion engine according to an embodiment of the present invention.

FIG. 2 is a flowchart showing a processing procedure of fuel injection control of a CPU in an ECU used in a fuel injection control device for an internal combustion engine according to an embodiment of the present invention.

FIG. 3 is a flowchart showing a procedure of injector control processing of a CPU in an ECU used in a fuel injection control device for an internal combustion engine according to an embodiment of the present invention.

FIG. 4 is a time chart showing a relationship between a common rail pressure and a pump delivery amount corresponding to injection timing of each cylinder in a 6-cylinder diesel engine and an 8-cylinder diesel engine when the flowcharts of FIGS. 2 and 3 are executed. It is a chart.

[Explanation of symbols]

 1 ECU (Electronic Control Unit) 2 High Pressure Supply Pump 3 Injector 4 Common Rail 5 Common Rail Pressure Sensor 7 Crank Angle Sensor 10 Internal Combustion Engine

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display area F02M 55/02 350 E

Claims (2)

[Claims] 1. A high-pressure supply pump for generating high-pressure fuel having a predetermined pressure by inflowing and pumping low-pressure fuel, a common rail for accumulating the high-pressure fuel pumped from the high-pressure supply pump, and a common rail in the common rail. A common rail pressure sensor that detects the pressure of the high-pressure fuel; an injector that is provided for each cylinder of an internal combustion engine to electrically inject and supply the high-pressure fuel from the common rail; and the high-pressure fuel that is detected by the common-rail pressure sensor. And a control means for controlling the injection amount of the injector based on the injection time of the injector for each cylinder calculated based on the pressure of the fuel injection control device for an internal combustion engine. 2. The internal combustion engine according to claim 1, wherein the control means calculates the injection time by adding a correction injection time for each cylinder to a basic injection time common to each of the cylinders. Fuel injection control device.