KR100612784B1 - Accumulator injection system - Google Patents

Abstract

The fuel supply pump 3 pressurizes the fuel supplied to each cylinder of the engine 1 through the fuel injection valve 5 for each cylinder. The engine control unit 10 has the same cylinder as the pumping period of the fuel supply pump 3 and the case where the pumping period of the fuel supply pump 3 overlaps with the fuel injection period of the fuel injection valve 5 for the cylinder. The signal for driving the fuel injection valve 5 is set so as to suppress the difference in fuel injection volume between when the fuel injection periods of the fuel injection valve 5 do not overlap. In the former case, the overlapping time was defined as the period of time in which the pumping period and the fuel injection period overlap. If the overlap period is variable, the engine control unit 10 sets a signal for driving the fuel injection valve 5 in accordance with the overlap period.

Fuel injection valve, engine control unit, fuel supply pump, cylinder, engine

Description

Accumulated Fuel Injection System {ACCUMULATOR INJECTION SYSTEM}

1 is a block diagram of a common rail fuel injection system implemented by a first embodiment of the present invention;

2 is a graph showing a characteristic map for determining a reference fuel injection period in the first embodiment of the present invention.

Fig. 3 is a graph showing a characteristic map for determining a reference fuel injection period in the first embodiment of the present invention.

4 is a flowchart showing fuel injection control performed by the first embodiment of the present invention;

Fig. 5 is a flowchart showing fuel injection control performed by the second embodiment of the present invention.

Fig. 6 is a flowchart showing fuel injection control performed by the second embodiment of the present invention.

Fig. 7 is a characteristic map for determining the correction amount in the second embodiment of the present invention.

Fig. 8 is a flowchart showing fuel injection control performed by the third embodiment of the present invention.

Fig. 9 is a flow chart showing fuel injection control performed by the third embodiment of the present invention.

10 is a graph showing a characteristic map for determining a pump discharge volume in a third embodiment of the present invention.

Fig. 11 is a view showing a collection of waveforms showing a time chart related to fuel injection in the third embodiment of the present invention.

Fig. 12 is a characteristic map for determining the correction amount in the third embodiment of the present invention.

Fig. 13 is a flowchart showing a process for detecting a phase of a fuel supply pump in a fourth embodiment of the present invention.

14 is a flowchart showing a process for detecting fuel leakage in a fifth embodiment of the present invention.

Figure 15 shows a time chart of the operation performed by the fuel supply pump in the fifth embodiment of the present invention.

Figure 16 shows a characteristic map for determining the static leak amount in the fifth embodiment of the present invention.

Fig. 17 is a diagram showing a characteristic map for determining the correction amount in the fifth embodiment of the present invention.

Figure 18 shows a characteristic map for determining the dynamic leak amount in the fifth embodiment of the present invention.

Fig. 19 is a diagram showing a time chart of changes in common rail fuel pressure in the fifth embodiment of the present invention.

Figure 20 is a diagram showing the distribution of fuel consumption in the fifth embodiment of the present invention.

Fig. 21 is a block diagram showing an engine control unit implemented by the sixth embodiment of the present invention.

FIG. 22 shows waveforms showing a time chart of common rail fuel pressure in a sixth embodiment of the present invention; FIG.

<Explanation of symbols for main parts of drawing>

1: engine

2: common rail

3: fuel supply pump

4: suction control valve

5: fuel injection valve

7: fuel tank

10: electronic control unit

16: crankshaft

17, 19: fuel return passage

The present invention provides a accumulator for storing a high pressure fuel volume discharged by a fuel supply facility such as a feed pump in an accumulator and for supplying the high pressure fuel accumulated in the accumulator to each cylinder of an internal combustion engine such as a multicylinder diesel engine through a fuel injection valve. A fuel injection system.

As fuel injection systems for internal combustion engines, such as conventional multicylinder diesel engines, accumulating fuel injection systems comprising a common rail, a plurality of fuel injection valves and a supply pump are known. The common rail is used as an accumulator for pressurizing and storing high pressure fuel at a pressure at which fuel is injected into a cylinder of an engine. The fuel injection valves are each implemented by an electromagnetic fuel injection valve mounted to each cylinder of the engine. The feed pump is a fuel supply pump for applying pressure to the fuel entering the pressurization chamber of the fuel supply pump from the fuel tank through the pump electromagnetic valve and pressurizing the fuel while fuel is supplied to the common rail (ie, during fuel discharge). Function.

However, in the conventional accumulator fuel injection system, when the fuel injection period of the fuel injection valve overlaps with the pump injection period of the feed pump, the injection pressure and the fuel injection rate are equal to the pump injection period of the feed pump. It is higher than it does not overlap. As a result, the actual fuel injection volume increases to a value exceeding the target fuel injection volume set according to the operating conditions of the engine. The pump pumping period of the feed pump is defined as the period between the pump pumping period start phase and the pump pumping period end phase. The fuel injection volume is the volume of fuel injected into the cylinder of the engine.

In the case of synchronous injection such as one injection per pump pumping operation, the fuel injection period of the fuel injection valve may or may not overlap with the pump pumping period of the feed pump, depending on the phase of the pump pumping period end. In the case of asynchronous injection, such as two injections per pump pumping operation or six injections per pump pumping operation, a cylinder and a feed pump having a fuel injection period of the fuel injection valve overlapping the pumping period of the supply pump There is a cylinder having a fuel injection period of a fuel injection valve which does not overlap with the pump pressure period of.

Accordingly, the fuel injection volume, i.e. the volume of fuel injected into the cylinder of the engine where the fuel injection period of the fuel injection valve overlaps with the pump injection period of the feed pump, overlaps with the pump injection period of the fuel injection valve. Different from the non-fuel injection volume, which adversely affects the control precision of the fuel injection volume, and the volume is deteriorated.

On the other hand, the accumulator fuel injection system has a configuration configured to control a pumping volume defined by the volume of fuel discharged by the fuel supply pump by adjusting the energizing current flowing to the pump control valve to achieve the target common rail fuel pressure. . It is also known to find a pump delivery volume based on the magnitude of the energizing current flowing to the pump control valve to set the pump delivery volume of the fuel discharged by the fuel supply pump by adjusting the opening of the pump control valve. Therefore, the magnitude of the energizing current flowing to the pump control valve can be considered as the command pump pressure volume. However, the method of finding the pumping pressure volume based on the magnitude of the energizing current flowing to the pump control valve causes an error due to a fuel supply pump, a factor including a difference in air and a state of fuel including viscosity. As a result, a problem arises in that the precision for obtaining the pump pumping volume is poor.

When the pump drive shaft of the fuel supply pump rotates synchronously with the crank shaft of the engine, it is impossible to detect the error if there is an error in the assembly of the engine crankshaft and the fuel supply pump. The error in assembling the crankshaft of the engine and the fuel supply pump causes a problem that the effect of the fuel injection correction according to the overlapping period described above becomes small, even if the overlapping period is known in advance through experiments or the like.

Accordingly, an object of the present invention is to provide a fuel between a cylinder in which the fuel injection period of the fuel injection valve overlaps with the pump compression period of the fuel supply pump and a fuel between the cylinder in which the fuel injection period of the fuel injection valve does not overlap with the pump injection period of the fuel supply pump. It is to provide a accumulator fuel injection system which can improve the precision of controlling the fuel injection volume of each cylinder of the engine by eliminating the difference in the injection volume.

Another object of the present invention is that the fuel injection period of the fuel injection valve overlaps the pumping period of the fuel supply pump in the same cylinder as the case where the fuel injection period of the fuel injection valve in the specific cylinder overlaps with the pumping period of the fuel supply pump. It is to provide a accumulator fuel injection system that can improve the precision of controlling the fuel injection volume of a particular cylinder of the engine by eliminating the difference in fuel injection volume between the case if not.

Another object of the present invention is to detect the cam phase of the fuel supply pump, more specifically the pump compression period start phase and the pump compression period end phase, with high precision, and reflect the phase detected in the engine control performed subsequently. To provide a possible accumulator fuel injection system.

It is another object of the present invention to provide a accumulator fuel injection system capable of detecting with high precision an overlapping period between a fuel injection period of a fuel injection valve and a pump injection period of a fuel supply pump.

Another object of the present invention is to provide a accumulator fuel injection system capable of correcting the fuel injection volume with high precision according to an overlapping period in which the fuel injection period of the fuel injection valve overlaps with the pump injection period of the fuel supply pump.

Another object of the present invention is to provide a accumulator fuel injection system capable of calculating the pumping volume of a fuel supply pump with high precision.

Another object of the present invention is to provide a accumulator fuel injection system capable of detecting an assembly error of a fuel supply pump.

According to the present invention, a cylinder having a fuel injection period of a fuel injection valve overlapping with a pump injection period of a fuel supply pump and a cylinder having a fuel supply period of a fuel injection valve not overlapping with a pump injection period of a fuel supply pump are known in advance. If so, the fuel injection period of the cylinder having the fuel injection period of the fuel injection valve not overlapping with the pumping period of the fuel supply pump is detected by the target fuel injection volume and the fuel pressure detecting means set according to the operating conditions of the engine. Obtained from pressure On the other hand, the fuel injection period of the cylinder in which the fuel injection period of the fuel injection valve overlaps with the pump injection period of the fuel supply pump is the target fuel injection volume, the detected fuel pressure and the fuel injection period of the fuel injection valve and the pump pressure of the fuel supply pump. It is calculated | required from the overlapping period of period.

Thus, the volume of the fuel injection volume between the cylinder having the fuel injection period of the fuel injection valve overlapping the pump injection period of the fuel supply pump and the cylinder having the fuel injection period of the fuel injection valve not overlapping the pump injection period of the fuel supply pump It is possible to reduce the difference. In addition, it is also possible to suppress the combustion force difference between the cylinders of the engine. In addition, it is also possible to suppress the exhaust reduction.

According to the invention, for a particular cylinder of an engine, the fuel injection period of the fuel injection valve in the specific cylinder is equal to the case where the fuel injection period of the fuel injection valve in the specific cylinder overlaps the pumping period of the fuel supply pump. It is possible to reduce the difference in the actual fuel injection volume between the pumping period and not overlapping.

According to the present invention, the change in fuel pressure exceeding a predetermined value detected by the fuel pressure detecting means is detected in the case where the cam phase of the fuel supply pump can be regarded as the pump compression period start phase. The change in the fuel pressure detected by the fuel pressure detecting means which becomes smaller than the predetermined value after exceeding the predetermined value is detected in the case where the cam phase of the fuel supply pump can be regarded as the pump pressure cycle end phase. Alternatively, the geometric pumping period end phase of the fuel supply pump in the engine assembly is stored. In this way, the cam phase of the fuel supply pump, in particular, the pump pumping period starting phase and the pump pumping period ending phase can be obtained with high precision.

The pump pumping period starting phase and the pump pumping period ending phase are reflected in the engine control performed after the pump pumping period starting phase and the pump pumping period ending phase are detected. Examples of engine control are fuel injection control and pump control. For example, it is possible to identify the overlapping period between the fuel injection cycle of the fuel injection valve and the pump compression period of the fuel supply pump from the pump injection period start phase and the pump injection period end phase. Next, it is possible to perform fuel injection control in accordance with the overlap period. In addition, it is possible to obtain the pump pressure volume with high accuracy from the pump pressure period start phase and the pump pressure period end phase. Next, it is possible to perform pump control in accordance with the pump pressure volume.

According to the present invention, the length of the overlapping period can be obtained with high precision from the pump pumping period end phase, the target fuel injection period and the target fuel injection timing.

Accurately determining the pump delivery volume of the pump pumped fuel from the fuel supply pump into the accumulator from the fuel supply pump based on the cam profile (or cam phase or plunger position), pump delivery period start phase and pump delivery period end phase of the fuel supply pump. It is possible.

The amount of fuel leaking out of the high pressure pipe can be known with high precision from, for example, the target pump pressure volume of the fuel, the injector static leak amount and the injector dynamic leak amount.

When the leakage amount of fuel exceeds a predetermined value, fuel injection control is performed, for example, to improve pump control. More specifically, when an abnormality occurs in the fuel supply pump, when an open abnormality occurs in the fuel injection valve or when an abnormality occurs in the fuel pipe system, for example, the engine is stopped or fuel injection control or pump control is performed. Is performed so that the vehicle can continue to travel.

For example, it is desirable to provide an electronic control unit having a low pass filter and a high pass filter used to process electrical signals generated from fuel pressure sensors. By providing such a filter, a process for detecting the pump pumping period starting phase and the pump pumping period ending phase can be performed at high speed.

By finding the difference between the detection position of the pump pumping period end phase and the reference position of the pump pumping period end phase, for example, the cam difference of the fuel supply pump can be detected from the turning angle of the output shaft of the engine. It is therefore possible to detect the assembly phase of the fuel supply pump with high precision.

Preferred embodiments of the present invention are described with reference to the accompanying drawings.

(First embodiment)

1 to 4 show a first embodiment of the present invention. In particular, Fig. 1 is a block diagram showing the configuration of a common rail fuel injection system.

The common rail fuel injection system is applied to an engine 1 such as a four cylinder diesel engine. The common rail fuel injection system includes a common rail 2 which is used as an accumulator in which high pressure fuel accumulates at the same pressure as the fuel injection pressure to inject fuel into each cylinder. The common rail fuel injection system also has a fuel supply pump 3 for applying pressure to the sucked fuel and pumping the pressurized fuel to the common rail 2. The common rail fuel injection system also includes a plurality of electromagnetic fuel injection valves 5 for supplying the cylinder of the engine 1 with the high pressure fuel accumulated in the common rail 2. Typically, the engine 1 has four cylinders. The electromagnetic fuel injection valves 5 are hereafter also referred to as injectors respectively. The common rail fuel injection system is also provided with an electronic control unit 10 for controlling the fuel supply pump 3 and the electromagnetic fuel injection valve 5. In the description below, the electronic control unit 10 is simply referred to as an ECU.

It is necessary to continuously pressurize and store the high pressure fuel into the common rail 2 at the same pressure as the fuel injection pressure. For this reason, the fuel supply pump 3 is used to pressurize and store the high pressure fuel in the common rail 2 via the high pressure pipe 11. In the release pipe 14 for releasing fuel from the common rail 2 to the fuel tank 7, a pressure limiter for blocking the high pressure to prevent the fuel pressure in the common rail 2 from exceeding the set pressure limit ( 13) is installed.

The fuel supply pump 3, also referred to simply as the supply pump, is a pump for supplying fuel to the common rail 2. The fuel supply pump 3 pressurizes the fuel and discharges the high pressure fuel from the discharge port thereof to the common rail 2. The fuel supply pump 3 has a pump drive shaft 16 driven by the crankshaft 15 of the engine 1. The fuel supply pump 3 also has a transfer pump for pumping fuel from the fuel tank 7 when driven by the pump drive shaft 16. The transfer pump is a low pressure fuel feed pump.

In addition, the fuel supply pump 3 comprises a cam, one or more plungers and one or more cylinders. The cam is rotationally driven by the pump drive shaft 16. The plungers are then driven in a forward and backward motion in the cylinder by the cam. The plungers and cylinders form a pressure application chamber or plunger chamber for sucking fuel and applying pressure to the sucked fuel. The fuel supply pump 3 also includes a discharge valve that opens when the pressure of the fuel in the pressure application chamber reaches or exceeds a predetermined level. In addition, the fuel supply pump 3 is provided with two plungers having phases different from each other by 180 degrees.

In addition, the fuel supply pump 3 has a leakage port for preventing the fuel temperature in the pump chamber from becoming high. The fuel leaking out from the leak port of the fuel supply pump 3 is returned to the fuel tank 7 through the fuel return passages 17 and 19. In the fuel passage connecting the pump chamber to the pressure application chamber in the fuel supply pump 3, the discharge volume (or pump discharge volume or pump pressure volume) of the fuel flowing from the fuel supply pump 3 to the common rail 2 is changed. A suction control valve (SCV) 4 is provided for adjusting the opening (or opening) of the fuel passage. The SCV 4 is an electromagnetic valve which functions as a pump discharge volume changing means or a pump pressure volume changing means.

The SCV 4 is electronically controlled by the pump drive signal output by the ECU 10 to the SCV 4 via a pump drive circuit not shown in the figure. The SCV 4 adjusts the suction volume of the fuel drawn out to the pressure application chamber of the fuel supply pump 3. Thus, the SCV 4 changes the fuel injection pressure, and thus the fuel pressure in the common rail 2. SCV 4 is a normally open type valve. Normally open valves are fully open when the flow of current to the valve is interrupted. SCV 4 is also called a pump current control valve.

The common rail 2 is provided with a plurality of branch pipes 12. Each fuel injection valve 5 is provided at the downstream end of one of the branch pipes 12. Each fuel injection valve 5 is provided with a forcing means such as a nozzle, an electromagnetic actuator and a spring for forcing the nozzle needle in the valve closing direction. The nozzle has an injection hole formed therein. The electromagnetic actuator drives the nozzle needle in the valve opening direction.

The injection of fuel is controlled electronically by allowing or disallowing current to flow into the fuel control electromagnetic valve which is used as an electromagnetic actuator for controlling fuel pressure in the pressure control chamber behind the nozzle needle. When the electromagnetic valve of the fuel injection valve 5 is open, for example, the fuel injection valve 5 injects high pressure fuel into a cylinder associated with the fuel injection valve 5. The fuel leaked from the fuel injection valve 5 and the fuel returned from the rear pressure control chamber flow through the fuel return passages 18 and 19 to the fuel tank 7.

The ECU 10 includes a microcomputer having a known structure with a configuration including the functions of a CPU, a storage unit, an input circuit, an output circuit, a power supply circuit, an injector drive circuit, and a pump drive circuit. The CPU performs processes such as control and normal processes. Storage units used to store various programs and various kinds of data are typically ROM and / or RAM. Sensor signals from various sensors and signals generated by the A / D converter as a result of the A / D process are fed to the microcomputer.

The common rail fuel injection system has cylinder determination means comprising a cylinder determination sensor 31. The cylinder determination sensor 31 includes a signal rotor, a plurality of cylinder teeth (or protrusions) and an electromagnetic pickup. The signal rotor rotates with the rotation of the camshaft. For example, the signal rotor rotates once while the crankshaft 15 rotates two times. The cylinder teeth provided at the outer periphery of the signal rotor are respectively associated with the cylinders. The electromagnetic pickup generates cylinder decision signal pulses depending on the distance to the cylinder teeth. More specifically, when the piston of the first cylinder reaches a position immediately before fuel injection, a reference cylinder determination signal pulse having a large pulse width is output. Then, when the piston of the third cylinder reaches a position immediately before fuel injection, a cylinder determination signal pulse having a small pulse width is output. Then, when the piston of the fourth cylinder reaches the position just before fuel injection, a cylinder determination signal pulse having a small pulse width is output. Then, when the piston of the second cylinder reaches the position immediately before the fuel injection, a cylinder determination signal pulse having a small pulse width is output. Each of these pulses is called a G signal.

The common rail fuel injection system also has a rotational speed detection means comprising a crank angle sensor 32. The crank angle sensor 32 includes a signal rotor, a plurality of crank angle detection teeth (or protrusions) and an electromagnetic pickup. The signal rotor rotates in synchronism with the rotation of the crankshaft 15. For example, the signal rotor rotates once while the crankshaft 15 rotates once. A crank angle detection tooth is provided at the outer periphery of the signal rotor. The electromagnetic pickup generates an NE signal pulse based on the distance to the crank angle detection tooth. The crank angle sensor 32 generates a plurality of NE signal pulses during one revolution of the signal rotor. By measuring the interval between the NE signal pulses, the ECU 10 finds the engine speed NE.

The common rail fuel injection system also has an accelerator sensor 33 for detecting the opening of the accelerator pedal (ACCP). In addition, the common rail fuel injection system also has a water temperature sensor 34 for detecting the coolant temperature THW of the engine 1. In addition, the common rail fuel injection system also has a fuel pressure detection sensor 35 for detecting the fuel pressure Pc of the fuel in the common rail 2. In addition, the common rail fuel injection system also has a fuel temperature sensor 36 for detecting the fuel temperature THF.

The ECU 10 finds the common rail fuel pressure optimum for the operating state of the engine 1. The ECU 10 has a discharge volume control means (or SCV control means) for driving the SCV 4. In detail, the ECU 10 obtains the target common rail fuel pressure Pt from the information on the operating state of the engine 1. This information includes engine speed (NE) and accelerator opening (ACCP). The ECU 10 adjusts the pump drive signal supplied to the SCV 4 so that the common rail fuel pressure Pc is equal to the target common rail fuel pressure Pt. The pump drive signal indicates the magnitude of the current driving the SCV 4 or the magnitude of the SCV conduction current.

It is preferable to set the pump drive signal supplied to the SCV 4 as feedback control so that the common rail fuel pressure Pc detected by the common rail fuel pressure sensor 35 is equal to the target common rail fuel pressure Pt. It is preferable to perform the duty control as the control of the pump drive signal supplied to the SCV 4. In other words, the duty ratio of the pump drive signal is adjusted in accordance with the common rail fuel pressure Pt with the duty control to change the opening of the SCV 4. In this way, digital control is performed with high precision. The duty ratio is determined as the ratio of the on period of the pump drive signal to the off period of the pump drive signal.

The ECU 10 has control means for performing fuel injection period control and fuel injection timing control for the fuel injection valve 5 of each cylinder. The control means is configured to determine the fuel injection volume Q (or current energization time) and the fuel injection timing T (or current energization start timing) that are optimal for the operating state of the engine 1. It has a timing determining means. The control means determines the fuel injection command pulse period Tq (or fuel injection command pulse width or fuel injection pulse period) according to the operating state of the engine 1, the common rail fuel pressure Pc, and the target fuel injection volume Q. It has a fuel injection period determination means for obtaining. In addition, the control means also has fuel injection valve drive means for applying a pulse fuel injection valve drive current (fuel injection command pulse) to the electromagnetic valve of the fuel injection valve 5 of each cylinder via the fuel injection valve drive circuit. .

For example, the ECU 10 finds a target fuel injection volume Q for the operating state of the engine 1. In this case, the operating state is represented by engine speed NE, accelerator opening (ACCP) and water temperature (THW). Next, the ECU 10 obtains the fuel injection command pulse period Tq from the common rail fuel pressure Pc and the target fuel injection volume Q.

The operating state detecting means for detecting the operating state of the engine 1 may include an intake air flow sensor, an intake air temperature sensor, an intake air pressure sensor, a fuel temperature sensor and a fuel injection volume sensor. The target fuel injection volume Q, fuel injection timing T and target common rail fuel pressure Pt can be corrected according to the signals generated by these sensors.

In the common rail fuel injection system implemented by this embodiment, two fuel injections are performed per pump pumping operation. The pumping period of the operation of pumping fuel by raising the first plunger of the fuel supply pump 3 overlaps with the fuel injection period of the fuel injection valve 5 of the second cylinder. In addition, the pump injection period of the operation of pumping fuel by raising the second plunger of the fuel supply pump 3 overlaps with the fuel injection period of the fuel injection valve of the third cylinder. The fuel injection period of each fuel injection valve 5 of the first and fourth cylinders does not overlap any pumping period. The fuel supply pump 3 is connected to the engine 1 to have the above-described relationship between the fuel injection period and the pump compression period.

The ECU 10 of this embodiment performs control to suppress a difference in fuel injection volume between a cylinder having a pump compression period overlapping with a fuel injection period and a cylinder having a pump compression period not overlapping with the fuel injection period. More specifically, in order to carry out this control, the ECU 10 has first and second fuel injection period determination means. The first fuel injection period determination means finds from the first reference characteristic map shown in Fig. 2 a first reference fuel injection period Tqa for a cylinder having a pumping period that does not overlap with the fuel injection period. Cylinders having a pumping pressure period not overlapping with the fuel injection period in the first reference characteristic map are first and fourth cylinders. On the other hand, the second fuel injection period determining means finds out the second reference fuel injection period Tqb for the cylinder having the pump pumping period overlapping with the fuel injection period from the second reference characteristic map shown in FIG. Cylinders having a pumping pressure period overlapping with the fuel injection period from the first reference characteristic map are the third and second cylinders. As shown in Figs. 2 and 3, the second reference fuel injection period Tqb for the target fuel injection volume Q is shorter than the reference fuel injection period Tqa for the same target fuel injection volume Q.

The following description describes the fuel injection volume control method of the fuel injection valve of this embodiment. 4 is a flowchart showing fuel injection volume control. The routine shown by the flowchart shown in Fig. 4 is repeatedly performed at a predetermined timing after turning on an ignition switch not shown in the figure.

The flowchart starts from step S1 for determining whether the crank angle of the engine 1 coincides with the control reference position for performing fuel injection volume control of the fuel injection valve 5 mounted on the given cylinder, that is, the k-th cylinder. . If the determination result is "NO", the performance control returns to the calling routine. For example, the fuel injection volume control of the fuel injection valve 5 mounted on the kth cylinder may be started immediately after the end of the volume injection of the fuel injection valve 5 mounted on the kth cylinder in the previous cycle. Optionally, the fuel injection volume control of the fuel injection valve 5 mounted on the k-th cylinder may be started immediately after the end of the volume injection of the fuel injection valve 5 mounted on the cylinder immediately before the k-cylinder in the order of injection in the same cycle. Can be. If the k-th cylinder is the first cylinder, the cylinder immediately before the k-th cylinder in the injection order is the second cylinder. If the k-th cylinder is the third cylinder, the cylinder immediately before the k-th cylinder in the spraying order is the first cylinder. If the k-th cylinder is the fourth cylinder, the cylinder immediately before the k-th cylinder in the injection order is the third cylinder. If the k-th cylinder is the second cylinder, the cylinder immediately before the k-th cylinder in the injection order is the fourth cylinder.

The determination result obtained in step S1 is YES, while the control flow proceeds to step S2 in which engine parameters such as a G signal, an NE signal, and an ACCP signal are input. In particular, the NE signal and the accelerating opening (ACCP) are required to find the target fuel injection volume Q and the target fuel injection timing T. Then, in the next step S3, the target fuel injection volume Q is obtained from the NE signal and the acceleration open (ACCP) signal. Next, in the next step S4, the target fuel injection timing T is obtained from the NE signal and the acceleration opening degree (ACCP) signal. Thereafter, in the next step S5, the common rail fuel pressure Pc is input.

The control flow then proceeds to step S6 to identify the k-th cylinder from which fuel is injected based on the G and NE signals. Thereafter, the control flow proceeds to step S7 for determining whether the k-th cylinder identified in step S6 is a cylinder having a pump pumping period overlapping with the fuel injection period or a cylinder having a pump pumping period not overlapping with the fuel injection period. do. If the determination result is "NO", that is, the kth cylinder is a non-redundant cylinder which is determined as a cylinder having a pumping period not overlapping with the fuel injection period, the control flow proceeds to step S8. In step S8, the first reference fuel injection period Tqa is derived from a first reference characteristic map showing a relationship between the target fuel injection volume Q, the common rail fuel pressure Pc, and the first reference fuel injection period Tqa. It is calculated | required by using. The first reference characteristic map is typically preset from the experimental results. In this embodiment, the cylinders having pump pumping periods each not overlapping with the fuel injection period are first and fourth cylinders. Next, the control flow proceeds to step S10.

If the determination result obtained in step S7 is "Yes", that is, the kth cylinder is an overlapping cylinder defined as a cylinder having a pump pumping period overlapping with the fuel injection period, the control flow proceeds to step S9. In step S9, the second reference fuel injection period Tqb uses a second reference characteristic map showing the relationship between the target fuel injection volume Q, the common rail fuel pressure Pc, and the second reference fuel injection period Tqb. Obtained by The second reference characteristic map is typically preset from the experimental results. In this embodiment, the cylinders each having a pumping period overlapping with the fuel injection period are the third and second cylinders. Alternatively, it should be noted that the second reference fuel injection period Tqb is obtained for the calculated overlap period which is part of the pumping period overlapping with the fuel injection period.

The control flow proceeds from step S8 or S9 to step 10 where the target fuel injection timing T is converted to the final fuel injection timing TFIN. In addition, the final fuel injection timing TFIN and the first reference fuel injection period Tqa or the second reference fuel injection period Tqb are converted into the final fuel volume command value, that is, the valve opening command value and the valve closing command value. Thereafter, the fuel injection volume command value is set in the output state. Subsequently, in the next step S11, the fuel injection valve fuel injection command pulse indicating the fuel injection volume command value is output to the electromagnetic valve of the fuel injection valve 5 for the k-th cylinder for driving the fuel injection valve 5 of the k-th cylinder. do. Next, control returns to the calling routine.

According to the first embodiment, it is possible to reduce the difference in fuel injection volume between fuel injected into the overlapping cylinder and fuel injected into the non-redundant cylinder. In other words, the output of the cylinder can be adjusted to the same magnitude. As a result, vibration of the engine and exhaust gas can be suppressed.

Two or more first reference Tqa Q Pc characteristic maps and two or more Tqb Q Pc characteristic maps may be provided. For example, a plurality of first reference Tqa Q Pc characteristic maps and / or a plurality of second reference Tqb Q Pc characteristic maps may be provided for different magnitudes of overlap between the fuel injection period and the pump compression period.

The following description describes a plurality of other embodiments applied to the present invention. These focus on the differences between the first embodiment and other embodiments. In the following description, the same or similar components as the counterparts employed in the first embodiment use the same reference numerals as the counterparts and do not repeat the description.

(2nd Example)

In the case of the second embodiment, only one reference characteristic map is used. The reference characteristic map is used to find the first reference fuel injection period Tqa for the non-redundant cylinder. The first reference fuel injection period Tqa is corrected according to the actual overlap period t to find out the second reference fuel injection period Tqb for the overlapping cylinder.

More specifically, the correction means is a first reference fuel injection period Tqa for the non-redundant cylinder to change the difference between the second reference fuel injection period Tqb for the cylinder from the first reference fuel injection period Tqa. Or to correct the second reference fuel injection period Tqb to change the difference from the first reference fuel injection period Tqa to the second reference fuel injection period Tqb. Let Tqb be shorter than the first reference fuel injection period Tqa. In addition, the correction means corrects the first reference fuel injection period Tqa to change the difference between the first reference fuel injection period Tqa from the second reference fuel injection period Tqb by using the correction amount ΔTq or The second fuel injection period Tqb is corrected so as to change the difference between the first reference fuel injection period Tqa and the second reference fuel injection period Tqb.

For example, the second reference fuel injection period Tqb is set based on the first reference fuel injection period Tqa and the correction amount ΔTq. The correction amount [Delta] Tq is given by the setting means. The setting means can provide a correction amount for the non-redundant cylinder and another correction amount for the overlapping cylinder. The setting means can provide the correction amount [Delta] Tq in accordance with the overlap period t between the pump pumping period and the fuel injection period. For example, the setting means provides the correction amount [Delta] Tq in accordance with the overlap period t and the common rail fuel pressure Pc. The overlap period t can be given by the detecting means. The actual overlapping period t is given based on the actual pumping period PSTART-PEND and the actual volume injection period Tq. The actual pumping period PSTART-PEND can be detected by monitoring a typical change in the common rail fuel pressure Pc.

For example, pump pumping period start timing PSTART and pump pumping period end timing PEND are detected from common rail fuel pressure Pc. The pump pumping period start timing PSTART is also referred to as pump pumping period start phase. On the other hand, the pump compression period end timing PEND is also referred to as the pump compression period end phase. The actual volume injection period Tq is replaced by substituting the expected value. For example, a value close to the actual volume injection period Tq can be found from the final fuel injection timing TFIN and the first reference fuel injection period Tqa. Therefore, the detection means detects the overlap period t based on the pump compression period start timing PSTART, the pump compression period end timing PEND, the final fuel injection timing TFIN, and the reference first fuel injection period Tqa. do.

5, 6 and 7 show the method applied to the second embodiment for controlling fuel injection. In the case of the second embodiment, step S9 of the flowchart of FIG. 4 is replaced by steps S12, S13 and S14 of the flowchart shown in FIG. In addition, new steps S21 to S24 of the flowchart shown in FIG. 6 are performed. If the cylinder into which the fuel is injected is a redundant cylinder, the control flow proceeds from step S7 to step S12. In step S12, the first reference fuel injection period Tqa is found by using the first reference characteristic map shown in FIG.

Thereafter, in the next step S13, the correction amount [Delta] Tq of the fuel injection volume is obtained after performing the process shown by the flowchart shown in FIG. The correction amount [Delta] Tq of the fuel injection volume is obtained by using the characteristic map shown in FIG. More specifically, the correction amount ΔTq of the fuel injection volume is known from the overlap period t and the common rail fuel pressure Pc. The characteristic map of FIG. 7 is preset as a result of many experiments. The correction amount [Delta] Tq is set to a value that reduces the difference in fuel injection volume between fuel injected into the overlapping cylinder and fuel injected into the non-overlapping cylinder. Next, in the next step S14, the correction amount ΔTq is subtracted from the first reference fuel injection period Tqa to find out the second reference fuel injection period Tqb for the overlapping cylinder. In step S13, the process shown by the flowchart shown in Fig. 6 is performed to find out the overlapping period t.

The ECU 10 detects the pump pumping period starting timing PSTART and the pump pumping period ending timing PEND by monitoring the common rail fuel pressure Pc. By analyzing the waveform of the common rail fuel pressure Pc, it is possible to find out the pump pumping period start timing PSTART and the pump pumping period end timing PEND. The pump pumping period starting timing PSTART and the pump pumping period ending timing PEND can also be obtained by using an electronic circuit for detecting a predetermined waveform. It is also possible for the executing software to detect the pump pumping period start timing PSTART and the pump pumping period end timing PEND by using the ECU 10 to perform the process.

The flowchart shown in FIG. 6 inputs the pump pumping period starting timing PSTART and the pump pumping period ending timing PEND closest to the standard fuel injection timing of the k-th cylinder identified in step S6 of the flowchart shown in FIG. Start at step S21. The pump pumping period starting timing PSTART and the pump pumping period ending timing PEND are the pump pumping period starting timing PSTART and the pump pumping period ending timing PEND detected by the ECU 10 in the cycle immediately before the k-th cylinder. )to be. The processing performed in step S21 corresponds to means for finding out the pump compression period start phase and means for finding out the pump compression period end phase. Pump pumping period start timing PSTART and pump pumping period end timing PEND are respectively shown as a rotational phase. The pump compression period start timing PSTART is a timing at which the discharge valve of the fuel supply pump 3 is opened. The pump feed period start timing PSTART is a point where the increasing slope of the common rail fuel pressure Pc reaches a predetermined value. Typically, the pump compression period start timing PSTART corresponds to a position near BTDC 78 degrees CA of the second or third cylinder. On the other hand, the pump injection period end timing PEND is a timing at which the plunger of the fuel supply pump 3 reaches a top dead center (maximum lift amount position). The pump pumping period end timing PEND is a point in time at which the rising slope of the common rail fuel pressure Pc returns to the predetermined value after it exceeds the predetermined value once. The pump compression period end timing PEND typically corresponds to a position near the ATDC 48 degrees CA of the second or third cylinder.

Then, in the next step S22, the first reference fuel injection period Tqa obtained in step S12 of the flowchart shown in FIG. 5 is input. Next, in the next step S23, the final fuel injection timing TFIN is input. Subsequently, in the next step S24, the overlap period t is obtained. The actual pump pumping period of the fuel supply pump 3 differs between the pump pumping period start timing PSTART and the pump pumping period end timing PEND (PEND-PSTART). The experimental actual pumping period is represented by the final fuel injection timing TFIN and the first reference fuel injection period Tqa. In step S24, the overlapping period t is obtained from the actual pumping period and the experimental actual pumping period. The process performed in step S24 corresponds to a means for finding the overlapping period t. The process performed in step S24 includes a process performed by means for obtaining the actual pump pumping period.

According to the second embodiment, the second reference fuel injection period Tqb can be obtained for different overlapping periods so that it is possible to perform control of the fuel injection volume with high precision.

(Third Embodiment)

8 to 12 show a third embodiment, and FIG. 8 shows a flowchart showing a method of controlling fuel injection by the fuel injection valve. 9 shows a flowchart showing a method of finding a duplicate period. The routine shown by the flowcharts shown in Figs. 8 and 9 is repeatedly performed at a predetermined timing after the ignition switch is turned on.

The flowchart shown in Fig. 8 starts from step S31 in which engine parameters are input. Engine parameters include engine speed NE and acceleration opening degree ACCP. Thereafter, in the next step S32, the target fuel injection volume Q is obtained from the engine speed NE and the acceleration opening degree ACCP. Next, in the next step S33, the target fuel injection timing T is obtained from the engine speed NE and the acceleration opening degree ACCP. Next, in the next step S34, the common rail fuel pressure Pc is input.

Subsequently, in the next step S35, the target fuel injection timing T is converted to the reference fuel injection timing TBASE. Thereafter, the reference fuel injection period TqBASE is obtained from the common rail fuel pressure Pc and the reference fuel injection timing TBASE. Next, in the next step S36, the reference fuel injection timing TBASE and the reference fuel injection period TqBASE are corrected. The corrected reference fuel injection timing TBASE and the corrected reference fuel injection period TqBASE are also referred to as TCOM and TqCOM, respectively.

Thereafter, in the next step S37, the overlapping period t is obtained. As shown in Fig. 12, the correction amount [Delta] Tq is obtained using a characteristic map showing the relationship between the correction amount [Delta] Tq, the overlap period t and the common rail fuel pressure Pc. Fig. 9 shows a flowchart showing a detailed process for obtaining the overlap period t and the common rail fuel pressure Pc. Next, in the next step S38, the correction amount [Delta] Tq is subtracted from the corrected reference fuel injection period TqCOM to calculate the final fuel injection period TqFINAL.

Then, in the next step S39, the corrected reference fuel injection timing TCOM is converted to the final reference fuel injection timing TFINAL. The final fuel injection period TqFINAL and the final reference fuel injection timing TFINAL are converted into a fuel injection volume command value, that is, a valve open command value and a valve close command value. Next, the fuel injection volume command values are set in the output state. Next, in the next step S40, the fuel injection valve fuel injection command pulse indicating the fuel injection volume command value is an electromagnetic valve of the fuel injection valve 5 for the k-th cylinder for driving the fuel injection valve 5 of the k-th cylinder. Is output. Thereafter, control returns to the calling routine.

The flowchart shown in FIG. 9 starts from step S41 in which a drive signal for the SCV 4 of the fuel supply pump 3 is input. Then, in the next step S42, the pump discharge volume Qp is obtained using the characteristic map shown in FIG. The characteristic map shows the relationship between the engine speed NE, the SCV drive signal and the pump discharge volume Qp, which are usually obtained in advance from the results of the experiment. In other words, the pump discharge volume Qp is obtained from the engine speed Qp and the SCV drive signal.

Subsequently, the pump pumping period in the next step S43 is obtained from the pump pumping discharge volume Qp and the crank angle. As shown in Fig. 11, the pump compression period Pd and the pump discharge volume Qp have a fixed relationship. Then, in the next step S44, the reference fuel injection period TCOM, the basic fuel injection timing TqCOM, the fuel injection start delay time TDM and the fuel injection end delay time TDEM are input. Therefore, the process performed in step S44 includes the process performed by the fuel injection start delay time calculating means and the fuel injection end delay time calculating means.

As shown in Fig. 11, the fuel injection start delay time TDM is a time period from the start of the operation of raising the nozzle needle to the actual fuel injection after the fuel injection timing has been reached. The fuel injection valve 5 is configured to open its electromagnetic valve by raising the nozzle needle in accordance with the common rail fuel pressure Pc. Therefore, the fuel injection start delay time TDM varies depending on the common rail fuel pressure Pc. For this reason, it is usually desirable to create a characteristic map by finding the relationship between the fuel injection start delay time TDM and the common rail fuel pressure Pc in advance from the results of the experiment.

On the other hand, the fuel injection end delay time TDEM is a time period from the operation of blocking the current flowing to the electromagnetic valve of the fuel injection valve 5 to the actual end of the injection of fuel as shown in FIG. In this case, it is usually best to generate the characteristic map in advance by finding the relationship between the fuel injection end delay time TDEM and the common rail fuel pressure Pc from the results of the experiment.

Next, in next step S45, the fuel injection start timing calculation means calculates the fuel injection start timing T1 of the fuel injection valve 5 from the fuel injection start delay time TDM and the reference fuel injection period TCOM. Then, the fuel injection end timing calculating means calculates the fuel injection end timing T2 of the fuel injection valve 5 from the fuel injection end delay time TDEM, the reference fuel injection period TCOM, and the reference fuel injection timing TqCOM. Obtain Then, the actual fuel injection period calculating means calculates the actual fuel injection period ATq from the fuel injection start timing T1 and the fuel injection end timing T2.

Then, in the next step S46, the overlap period calculating means calculates the overlap period t of the pump pumping period Pd and the actual fuel injection period ATq. Then, in the next step S47, the fuel injection period correction amount calculation means usually calculates the correction amount [Delta] Tq from the result of the experiment using the characteristic map generated in advance. As shown in Fig. 12, the characteristic map shows the relationship between the common rail fuel pressure Pc, the overlap period t and the correction amount [Delta] Tq.

For synchronous injection, such as one injection per pump operation or two injections per two pump operations, the fuel injection period may or may not overlap the pumping period in any manner dependent on the pumping period end phase. Things are in the range of possibilities. In the case of asynchronous injection, such as two injections per pumping operation or six injections per four pumping operations, on the other hand some cylinders are certainly redundant cylinders, while others are certainly non-redundant cylinders.

According to the third embodiment, the fuel injection period of the fuel injection valve in the same cylinder as the case where the fuel injection period of the fuel injection valve overlaps with the pump compression period of the fuel supply pump in the cylinder does not overlap with the pump compression period of the fuel supply pump. If not, it is possible to suppress the difference in fuel injection volume between. As a result, it is possible to suppress the difference in fuel injection volume between the overlapping and non-overlapping cases of the cylinders used for the engine 1 in which the pump pressure period of the fuel supply pump 3 is different from the operation period of the cylinder. . In addition, it is possible to suppress the difference in fuel injection volume between the overlapping cylinder and the non-overlapping cylinder.

(Example 4)

In the case of the fourth embodiment, the ECU 10 performs a process for detecting the pump pumping period starting timing PSTART and the pump pumping period ending timing PEND in addition to the process performed by the second embodiment.

The ECU 10 includes a low pass filter 10a and a high pass filter 10b, which are used to perform a filtering process on signals received from the common rail fuel pressure detection sensor 35. The low pass filter 10a detects a slow change in the common rail fuel pressure Pc. The value output by the low pass filter 10a represents the average common rail fuel pressure Pc. The low pass filter 10a outputs a stable signal used to control the SVC 4. The value output by the low pass filter 10a is an average value of the common rail fuel pressure Pc taken in the period between the end of the pumping pressure stroke of the fuel supply pump 3 and the next injection. On the other hand, the high pass filter 10b detects a fast change. The value output by the high pass filter 10b represents the instantaneous common rail fuel pressure Pc. The high pass filter 10b outputs a signal used for detecting the pump pumping period starting timing PSTART and the pump pumping period ending timing PEND. The pump feed period start timing PSTART and the pump feed period end timing PEND are detected based on the change of the common rail fuel pressure Pc having a relatively large slope. The low pass filter 10a and the high pass filter 10b reduce the load of the software process executed by the ECU 10, thereby increasing the processing speed.

Fig. 13 is a flowchart showing a detection process performed by the fourth embodiment to detect pump pumping period starting timing PSTART and pump pumping period ending timing PEND. In the case of the fourth embodiment, the process of the second embodiment is performed based on the pump pumping period starting timing PSTART and the pump pumping period ending timing PEND detected in the process shown by the flowchart shown in FIG.

After the ignition switch is turned on, the routine shown by the flowchart shown in Fig. 13 is performed at a predetermined timing, such as a timing in a range of 0.5 msec to 1.0 msec or 6 degrees CA.

The flowchart shown in FIG. 13 starts with step S131 where the output of the high pass filter 10b is input as the current common rail fuel pressure Pci. Then, the common rail fuel pressure Pci1 just before is read out from the memory. The previous common rail fuel pressure Pci1 is input to and stored in the memory at the previous time leading by the predetermined time at the current time or at the previous crank angle preceding the predetermined crank angle by the current crank angle. Subsequently, the flow of the routine proceeds to step S132 where the difference ΔPc of the current common rail fuel pressure Pci is obtained from the common rail fuel pressure Pci1 immediately preceding. Then, the routine proceeds to step S133 to determine whether or not the difference ΔPc is equal to or greater than the first predetermined value PR1. If the result of the determination is YES, the flow of the routine is used as the pump compression period start phase PSTART and stored in the memory. Thereafter, the current common rail fuel pressure Pci is stored as the common rail fuel pressure Pci1 immediately before in the memory.

On the other hand, if the determination result obtained in step S133 is NO, the flow of the routine proceeds to step S135 in which it is determined whether the difference ΔPc is greater than or equal to the second predetermined value PR2 or less than or equal to the third predetermined value PR3. do. Note that the first predetermined value PR1, the second predetermined value PR2, and the third predetermined value PR3 satisfy the following relationship, that is, PR1> PR3> PR2. If the result of the determination is no, the current common rail fuel pressure Pci is stored in the memory as the common rail fuel pressure Pci1 immediately before. It is necessary to know that the second predetermined value PR2 is a value for distinguishing the difference ΔPc from the voltage drop generated by the injection of the fuel. On the other hand, the first predetermined value PR3 is a value for distinguishing the difference? Pc from the voltage drop generated by the static leakage of the fuel injection valve 5.

On the other hand, if the determination result obtained in step S135 is YES, the flow of the routine proceeds to step S136 in which the current phase is stored as the pump pumping period end phase PEND. Then, the current common rail fuel pressure Pci is stored in the memory as the immediately common rail fuel pressure Pci1.

In order to obtain the determination result of YES in step S135, it is possible to add a condition in which the pump pumping period start timing PSTART has already been detected in addition to the current condition. Alternatively, it is also possible to add a condition in which the common rail fuel pressure Pc already increases in addition to the current conditions in order to obtain the determination result of YES in step S135.

According to the fourth embodiment, the pump compression period can be obtained by performing a software process. Therefore, the overlap period t can be obtained for the variable pump compression period. As a result, the fuel injection volume can be adjusted with high precision.

The methods adopted for finding the overlap period in the second and fourth embodiments can also be applied to the asynchronous fuel supply pump. For example, the overlapping period t obtained by using the method provided by the fourth embodiment can be used to find the correction amount [Delta] Tq described in the description of the third embodiment. In addition, between the case where the fuel injection period of the fuel injection valve overlaps with the pump compression period of the fuel supply pump in the cylinder and when the fuel injection period of the fuel injection valve does not overlap with the pump compression period of the fuel supply pump in the same cylinder It is possible to eliminate the difference in fuel injection volume.

(Example 5)

14 to 20 show a fifth embodiment of the present invention. The routine shown by the flowchart shown in Fig. 14 is repeatedly performed at a predetermined timing after the ignition switch is turned on.

The flowchart starts at step S141 where the common rail fuel pressure Pc is input. Then, at step S142, the routine shown by the flowchart shown in Fig. 13 is called to detect the pump pumping period starting phase PSTART and the pump pumping period ending phase PEND and store them in the memory. Subsequently, in the next step S143, the pump pumping volume Qp for the period of 360 degrees CA includes the pump pumping period starting phase PSTART, the pump pumping period ending phase PEND, and the cam profile of the fuel supply pump 3 ( Or plunger position) and crank angle. As shown in Fig. 15, the pumping volume Qp can be obtained geometrically from a cam profile that can be approximated to a sinusoidal curve.

Then, in the next step S144, the reference fuel injection valve static leakage amount QSLBASE is shown in Fig. 16 as the relationship between the common rail fuel pressure Pc, the engine speed NE, and the reference fuel injection valve static leakage amount QSLBASE. It is obtained using a property map or an expression generated in advance from the results of the experiment to represent. Subsequently, the fuel temperature correction coefficient α uses a characteristic map or equation previously generated from the results of the experiment to show the relationship between the fuel temperature THF and the fuel temperature correction coefficient α as shown in FIG. Obtained by Finally, the reference fuel injection valve static leak amount QSLBASE is multiplied by the fuel temperature correction coefficient α to obtain the static leak amount QSL.

Next, in the next step S145, the fuel injection valve dynamic leak amount QDL is determined as shown in FIG. 18 between the target fuel injection period Tq, the common rail fuel pressure Pc, and the fuel injection valve dynamic leak amount QDL. It is obtained using a property map or an expression generated in advance from the results of the experiment. Then, in the next step S146, the target fuel injection volume Q is converted into fuel injection volume QINJ, and then stored in the memory.

Next, in the next step S147, the difference ΔP of the common rail fuel pressure Pc occurring during the 360 degree CA period as shown in the timing chart of FIG. 19 is obtained. To illustrate this in more detail, the common rail fuel pressure Pc is monitored to find the difference ΔP. For example, the common rail fuel pressure Pc is stored periodically. Then, the difference ΔP is calculated as the difference ΔP from the previous common rail fuel pressure Pcn360 to the current common rail fuel pressure Pcn.

Then, in the next step S148, the fuel volume increase (ΔV) of the high pressure portion of the fuel injection system, which is the fuel volume increase necessary to increase the fuel pressure by the pressure increase (ΔP), is obtained from the result map of the experiment or below. Calculated using the formula given in.

ΔV = (V / E) × ΔP

Where the symbol E is the bulk modulus.

Then, in the next step S149, the fuel leakage amount calculating means calculates the fuel leakage amount QLEAK in the period of 360 degrees CA using the equation given below and the fuel consumption distribution shown in FIG.

QLEAK = Qp-(QSL × 4)-(QDL × 2)-(QINJ × 2)-ΔV

The above equation is for a four cylinder engine with two injections per pump compression operation and two injections every 360 degrees CA.

Then, the flow of the routine proceeds to step S150 in which it is determined whether the fuel leakage amount QLEAK is larger than the predetermined value QL1. If the result of the determination is NO, the process flow deviates from the routine indicated by the flowchart shown in FIG. On the other hand, if the determination result obtained in step S150 is YES, it is determined that there is fuel leakage in the high pressure fuel pipe passage. In this case, the flow of the routine proceeds to step S151 where various kinds of processes are performed. As a process, it is desirable to perform fuel injection control or pump control to maintain minimum operating conditions or to stop the engine.

As described above, the fuel leakage QLEAK can be accurately obtained from PSTART or PEND, which can be obtained by performing the process shown by the flowchart shown in FIG. In case of abnormality and failure of the fuel supply pump 3, in case of abnormality of opening of the fuel injection valve 5 and in case of abnormality or failure of the fuel distribution system, fuel injection control to maintain minimum operating conditions or stop the engine Alternatively it is possible to carry out pump control.

(Example 6)

21 is a block diagram showing the engine control unit 10 realized by the sixth embodiment. The ECU 10 has detection means 61 for detecting the actual pump pumping period end phase PEND. The detection means 61 detects the actual pump pressure period end phase PEND by performing the process shown by the flowchart shown in FIG. The ECU 10 also has a reference pump compression period end phase storing means 62 for storing the reference pump end phase. The reference pump compression period end phase storage means 62 is typically EEPROM or RAM. The reference pump termination phase is determined based on the ideal assembly state assumed in the design of the engine system. The reference pump end phase can also be obtained experimentally in the assembled state of the engine 1 and the fuel supply pump 3 adjusted to the ideal state. For example, common rail fuel pressure Pc changes to the ideal state shown by waveform Pc0 of FIG. In addition, the ECU 10 has a phase difference calculating means 63. The phase difference calculating means 63 calculates the difference CC between the actual pump pumping period end phase PEND and the reference value PRR. The difference CC is supplied to the engine control means 64 for controlling the engine according to the difference CC. For example, the control of the fuel injection volume or the pump control is corrected according to the difference CC. The difference CC represents an error in the assembly of the fuel supply pump 3 and the engine 1. For example, the difference CC increases when the phase of the camshaft of the fuel supply pump 3, which is in phase with respect to the rotational position of the crankshaft 15, is moved from the normal phase. When such an error exists, the common rail fuel pressure Pc typically changes as shown by waveform Pc1 or Pc2 in FIG. In this case, the phase difference calculating means 63 generates phase difference C1 or phase difference C2, respectively.

As described above, in the case of the sixth embodiment, an assembly error of the fuel supply pump 3 can be detected. It is also possible to perform engine control in accordance with assembly errors.

(Change example)

 As an alternative for the components of the above-described embodiments, the following components can be adopted. For example, it is possible to use the pressure of the fuel discharged by the fuel supply pump 3 as an alternative to the common rail fuel pressure Pc. The pressure of the fuel discharged by the fuel supply pump 3 can be detected using a fuel pressure sensor provided on the fuel passage between the fuel supply pump 3 and the fuel injection valve 5.

In addition, the signal for driving the electromagnetic valve of the fuel injection valve 5 can be adjusted in multiple stages. For example, the ECU 10 is guided by the first current to the fuel injection valve 5 during the first period starting from the operation of opening the electromagnetic valve of the fuel injection valve 5, and then terminated by the operation of closing the electromagnetic valve. It is possible to set up a control arrangement in which the second current is directed to the fuel injection valve 5 during the second period. In this case, correction according to the overlap period t can be applied to the first or second period or both periods. For example, for the long overlapping period t, the first or second period is shortened.

As an alternative to the calculation methods used in the embodiments, the pump pressure volume Qp is the engine speed NE, the opening of the intake control valve 4 or the current flowing into the intake control valve 4 (or so-called SCV energization). It is possible to provide an embodiment obtained from the current) and the common rail fuel pressure Pc. Furthermore, it is also possible to provide an embodiment in which the fuel leakage amount QL is obtained from the pump pressure volume Qp, the target fuel injection volume Q and the fuel leakage amount QL.

In addition, as an alternative to the process performed in the embodiment, the following process may be performed. The process of geometrically calculating the pump pressure volume Qp from the cam profile (or cam phase or plunger position), pump pressure period start phase PSTART and pump pressure period end phase PEND of the fuel supply pump 3 is performed. Can be. In addition, the process of geometrically calculating the actual pumping period from the pumping volume Qp and the cam profile of the fuel injection pump 3 can be performed. Furthermore, a process is performed to geometrically calculate the actual fuel injection timing of the fuel injection valve 5 from the target fuel injection period Tq, target fuel injection timing T, fuel injection start delay time and fuel injection end delay time. Can be. In addition, a process of geometrically calculating the actual overlapping period from the actual pumping period and the actual fuel injection period can be performed. Furthermore, as the pump compression period end phase, information on the geometric position of the engine assembly of the fuel supply pump 3 can be stored in the memory so that it can be obtained when needed.

Although the overlapping period is indicated by the time period in the above-described embodiment, the overlapping period may be measured and indicated by the crank angle or the cam angle.

According to the present invention, the fuel injection volume between a cylinder in which the fuel injection period of the fuel injection valve overlaps with the pump compression period of the fuel supply pump and a cylinder in which the fuel injection period of the fuel injection valve does not overlap with the pump injection period of the fuel supply pump An accumulator fuel injection system is provided that can improve the precision of controlling the fuel injection volume of each cylinder of an engine by eliminating the difference of.

Claims (30)

Accumulated fuel injection system used for internal combustion engines, An accumulator for pressurizing and storing high pressure fuel at a pressure for injecting fuel, A fuel supply pump driven by the internal combustion engine to suck fuel and apply pressure for pumping the sucked fuel into the accumulator; A fuel injection valve provided to each cylinder of the internal combustion engine and used to supply the high pressure fuel accumulated in the accumulator to the cylinder by injecting the high pressure fuel into the cylinder; Fuel pressure detecting means for detecting a pressure of fuel discharged by the fuel supply pump; From the target fuel injection volume set in accordance with the operating conditions of the internal combustion engine and the fuel pressure detected from the fuel pressure detecting means, the pump injection period of the fuel supply pump does not overlap with the fuel injection period of the fuel injection valve. First fuel injection period determining means for determining a fuel injection period of the cylinder of the fuel cell; Determining the fuel injection period of the cylinder of the internal combustion engine in which the pump injection period overlaps with the fuel injection period from the target fuel injection volume, the detected fuel pressure and the overlapping period of the pump injection period and the fuel injection period. And a second fuel injection period determining means. The method of claim 1, wherein the first fuel injection period determining means determines the fuel injection period using a first basic map defined by the target fuel injection volume and the detected fuel pressure, and determines the second fuel injection period. And means for determining the fuel injection period using a second base map different from the first base map and defined by the target fuel injection volume and the detected fuel pressure. The method of claim 1, wherein the first fuel injection period determining means obtains a first fuel injection period using a basic map defined by the target fuel injection volume and the detected fuel pressure, and the second fuel injection period determining means And a second fuel injection period is obtained by correcting the first fuel injection period obtained by the first fuel injection period determination means in accordance with the overlap period. Accumulated fuel injection system used for internal combustion engines, An accumulator for pressurizing and storing high pressure fuel at a pressure for injecting fuel, A fuel supply pump driven by the internal combustion engine to suck fuel and apply pressure for pumping the sucked fuel into the accumulator; A fuel injection valve provided to each cylinder of the internal combustion engine and used to supply the high pressure fuel accumulated in the accumulator to the cylinder by injecting the high pressure fuel into the cylinder; Fuel pressure detecting means for detecting a pressure of fuel discharged by the fuel supply pump; Fuel injection period determination means for determining a fuel injection period from a target fuel injection volume set in accordance with an operating condition of the internal combustion engine and the fuel pressure detected by the fuel pressure detection means; Overlapping period calculating means for calculating an overlapping period in which a pump pressure period of the fuel supply pump overlaps with a fuel injection period of the fuel injection valve; And a fuel injection period correcting means for correcting the fuel injection period in accordance with the overlapping period. The fuel injection period correcting means includes correction amount calculating means for calculating a fuel injection period correction amount from the overlapping period, and the fuel injection period is corrected based on the fuel injection period correction amount. Accumulated fuel injection system. 5. The method of claim 4, wherein the overlapping period determining means comprises: pumping period starting phase calculating means for obtaining a pumping period starting phase from the detected fuel pressure, and obtaining a pumping period ending phase from the detected fuel pressure; A pump pumping period end phase calculating means, and an actual pump pumping period calculating means for obtaining an actual pump pumping period from the pump pumping period starting phase and the pump pumping period ending phase, And the overlapping period is obtained from a fuel injection timing set according to the actual pumping period, the fuel injection period and the operating state of the internal combustion engine. 6. The pumping period starting phase calculating means for calculating a pumping pressure period starting phase from the detected fuel pressure, and the pump for calculating a pumping period ending phase from the detected fuel pressure. A pumping period end phase calculating means, and an actual pump pumping period calculating means for obtaining an actual pump pumping period from the pump pumping period starting phase and the pump pumping period ending phase, And the overlapping period is obtained from a fuel injection timing set according to the actual pumping period, the fuel injection period and the operating state of the internal combustion engine. 5. The pumping period calculation means according to claim 4, wherein the overlapping period calculating means has pump pumping period calculating means for calculating a pumping pressure period from the discharge volume of the fuel supply pump, and the overlapping period calculating means includes the pumping period and the fuel injection. A cumulative fuel injection system, characterized in that for calculating the overlapping period from the period. 6. The pumping period calculation means according to claim 5, wherein the overlapping period calculating means has pump pumping period calculating means for calculating a pumping pressure period from the discharge volume of the fuel supply pump, and the overlapping period calculating means includes the pumping period and the fuel injection. A cumulative fuel injection system, characterized in that for calculating the overlapping period from the period. 5. The fuel injection start timing means according to claim 4, wherein the overlap period calculating means includes: fuel injection start timing calculation means for calculating fuel injection start timing, fuel injection end timing calculation means for calculating fuel injection end timing, and the fuel injection start timing; An actual fuel injection period calculating means for calculating an actual fuel injection period from the fuel injection end timing, and a pump compression period calculating means for calculating a pump compression period, And said overlap period calculating means calculates the overlap period from said actual fuel injection period and said pump compression period. 6. The fuel injection start timing means according to claim 5, wherein the overlap period calculating means includes: fuel injection start timing calculation means for calculating fuel injection start timing, fuel injection end timing calculation means for calculating fuel injection end timing, the fuel injection start timing and An actual fuel injection period calculating means for calculating an actual fuel injection period from the fuel injection end timing, And said overlap period calculating means calculates the overlap period from said actual fuel injection period and said pump compression period. 7. The fuel injection start timing means according to claim 6, wherein the overlap period calculating means includes: fuel injection start timing calculation means for calculating fuel injection start timing, fuel injection end timing calculation means for calculating fuel injection end timing, the fuel injection start timing and An actual fuel injection period calculating means for calculating an actual fuel injection period from the fuel injection end timing, and a pump compression period calculating means for calculating a pump compression period, And said overlap period calculating means calculates the overlap period from said actual fuel injection period and said pump compression period. 9. The fuel injection start timing means according to claim 8, wherein the overlap period calculating means comprises: fuel injection start timing calculation means for calculating fuel injection start timing, fuel injection end timing calculation means for calculating fuel injection end timing, the fuel injection start timing and An actual fuel injection period calculating means for calculating an actual fuel injection period from the fuel injection end timing, and a pump compression period calculating means for calculating a pump compression period, And said overlap period calculating means calculates the overlap period from said actual fuel injection period and said pump compression period. Accumulated fuel injection system used for internal combustion engines, An accumulator for pressurizing and storing high pressure fuel at a pressure for injecting fuel, A fuel supply pump having a cam driven by the internal combustion engine and a plunger driven to slide back and forth within the pump cylinder by the cam and allowing pressure to be applied to the sucked fuel and pumping the sucked fuel into the accumulator. Wow, A fuel injection valve provided for each cylinder of the internal combustion engine and used to supply the high pressure fuel accumulated in the accumulator to the cylinder by injection of the high pressure fuel into the cylinder; Fuel pressure detecting means for detecting fuel pressure of fuel discharged by the fuel supply pump; Pump pumping period starting phase detecting means for detecting a cam phase of the fuel supply pump as a pump pumping period starting phase when a change in fuel pressure detected by the fuel pressure detecting means becomes equal to or more than a first predetermined level; When the change in fuel pressure detected by the fuel pressure detecting means becomes less than or equal to the second predetermined level after exceeding the first predetermined level, the cam phase of the fuel supply pump is detected as the pump pumping period end phase, or the fuel Pump compression period end phase detection means for storing a pump compression period end phase geometrically determined from an assembly relationship between a supply pump and the internal combustion engine; And an engine control means for controlling the pump compression period starting phase and the pump compression period ending phase by the control of the internal combustion engine. 15. The method of claim 14, wherein a cam phase is detected as the pump pumping period start phase when a difference in current fuel pressure from a previous fuel pressure increases to a value at least equal to a first predetermined value, wherein the previous fuel pressure is a time of a predetermined period. By the fuel pressure detected by the fuel pressure detecting means at a previous time preceding the present time, wherein the current fuel pressure is determined by the fuel pressure detecting means at the current time past the previous time by the time of the predetermined period. An accumulator type fuel injection system, characterized as being defined as the fuel pressure to be detected. 16. The pump fuel period as claimed in claim 15, wherein a cam phase is detected as the pump pumping period end phase when a difference in the subsequent fuel pressure from the current fuel pressure decreases to a value less than or equal to a third predetermined value, wherein the current fuel pressure is a later time The fuel pressure detected by the fuel pressure detecting means at the current time preceding by a predetermined period of time, wherein the subsequent fuel pressure is later than the predetermined time after the current time; An accumulator type fuel injection system characterized by being limited to fuel pressure detected by fuel pressure detecting means. 15. The fuel injection volume and fuel injection timing determining means for obtaining a command fuel injection timing and a command fuel injection volume according to an operating state of the internal combustion engine, and the fuel pressure and the command fuel injection. Fuel injection period determination means for determining a command fuel injection period from a volume, and pump pumping of the fuel supply pump from the pump pumping period starting phase, the pump pumping period ending phase, the command fuel injection period, and the command fuel injection timing And an overlapping period calculating means for calculating an overlapping period in which a period and a fuel injection period of the fuel supply valve overlap. 16. The fuel injection volume and fuel injection timing determining means for obtaining a command fuel injection timing and a command fuel injection volume according to an operating state of the internal combustion engine, and the fuel pressure and the command fuel injection. Fuel injection period determination means for determining a command fuel injection period from a volume, and pump pumping of the fuel supply pump from the pump pumping period starting phase, the pump pumping period ending phase, the command fuel injection period, and the command fuel injection timing And an overlapping period calculating means for calculating an overlapping period in which a period overlaps with the fuel injection period of the fuel supply valve. 17. The fuel injection volume and fuel injection timing determining means for obtaining a command fuel injection timing and a command fuel injection volume according to an operating state of the internal combustion engine, and the fuel pressure and the command fuel injection. Fuel injection period determination means for determining the command fuel injection period from the volume; From the pump pumping period starting phase, the pump pumping period ending phase, the command fuel injection period and the command fuel injection timing, the overlapping period in which the pump pumping period of the fuel supply pump overlaps with the fuel injection period of the fuel supply valve is calculated. Accumulating period means for calculating the accumulating fuel injection system, characterized in that. 18. The fuel injection period correcting means according to claim 17, wherein the engine control means includes fuel injection period correcting means for correcting the command fuel injection period in accordance with the overlapping period, and the fuel injection period correcting means includes fuel from the fuel pressure and the overlapping period. And a correction amount calculating means for calculating an injection period correction amount, wherein the corrected fuel injection period is obtained from the command fuel injection period and the fuel injection period correction amount. 15. The accumulator of claim 14, wherein the engine control means pumps from the cam profile of the fuel supply pump, the cam position or the plunger position, the pump pumping period start phase and the pump pumping period end phase to the accumulator by the fuel supply pump. And a pump pumping volume calculating means for calculating a pump pumping volume of the fuel to be pumped. 16. The accumulator according to claim 15, wherein the engine control means is connected to the accumulator by the fuel supply pump from the cam profile, the cam position or the plunger position, the pump pumping period start phase and the pump pumping period end phase of the fuel supply pump. And a pump pumping volume calculating means for calculating a pump pumping volume of the fuel to be pumped. 17. The accumulator according to claim 16, wherein the engine control means is connected to the accumulator by the fuel supply pump from the cam profile of the fuel supply pump, the cam position or the plunger position, the pump pumping period start phase and the pump pumping period end phase. And a pump pumping volume calculating means for calculating a pump pumping volume of the fuel to be pumped. The engine control means according to claim 21, wherein the engine control means determines fuel injection volume determination means for determining a command fuel injection volume in accordance with an operating state of the internal combustion engine, and a command fuel injection period from the fuel pressure and the command fuel injection volume. Fuel injection period determination means for detecting, fuel temperature detection means for detecting fuel temperature, Static leakage amount calculation means for calculating a fuel injection valve static leakage amount from said fuel temperature and said fuel pressure, dynamic leakage amount calculation means for calculating a fuel injection valve dynamic leakage amount from said fuel pressure and said command fuel injection period, and said fuel injection And fuel leakage amount calculation means for calculating an amount of fuel leaking from the high pressure pipe passage based on the valve static leakage amount and the fuel injection valve dynamic leakage amount. 25. The accumulator fuel injection according to claim 24, wherein the engine control means performs pump control or fuel injection volume control to improve safety when the amount of fuel leaking from the high pressure pipe passage is increased above a predetermined value. system. 15. The fuel pressure detector according to claim 14, wherein the fuel pressure detecting means is a fuel pressure detector for generating an electrical signal indicative of the detected fuel pressure, and the pump pumping period starting phase detecting means, the pumping pumping period ending phase detecting means and the engine An electronic control unit is provided that includes an embedded computer configured to include the functions of the control means, The electronic control unit includes a low pass filter for transmitting only a small variation in the electrical signal of the fuel pressure sensor to the computer and a high pass filter for transmitting only a large variation in the electrical signal of the fuel pressure sensor to the computer. Accumulated fuel injection system, characterized in that. Accumulated fuel injection system used for internal combustion engines, An accumulator for pressurizing and storing high pressure fuel at a pressure for injecting fuel, A fuel driven pump having a cam driven by the internal combustion engine and a plunger driven by the cam to slide back and forth within the pump cylinder and allowing pressure to be applied to the sucked fuel and pumping the absorbed fuel into the accumulator Wow, A fuel injection valve provided for each cylinder of the internal combustion engine and for supplying the high pressure fuel accumulated in the accumulator into the cylinder by injecting the high pressure fuel into the cylinder; Fuel pressure detecting means for detecting fuel pressure of fuel discharged by the fuel supply pump; Pump pumping period end phase detection for detecting a cam phase of the fuel supply pump as a pump pumping period end phase when a change in fuel pressure detected by the fuel pressure detecting means becomes below the predetermined level after exceeding a predetermined level. Sudan, Pump pumping period end phase storing means for storing a reference value of the pump pumping period end phase previously obtained from the relationship between the rotation angle of the output shaft of the internal combustion engine and the cam phase of the fuel supply pump; And phase difference calculating means for calculating a phase difference between one of said reference values and a camshaft detected as a pump pumping period end phase, corresponding to said pump pumping period end phase. The accumulating fuel injection system according to claim 1, wherein the overlapping period is expressed in time, crank angle or cam angle. 5. The accumulator fuel injection system according to claim 4, wherein the overlap period is represented by time, crank angle or cam angle. 15. The accumulating fuel injection system according to claim 14, wherein the first predetermined level is the same as the second predetermined level.

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